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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
"__vmalloc()/kvmalloc() and no-block support" (Uladzislau Rezki)
Rework the vmalloc() code to support non-blocking allocations
(GFP_ATOIC, GFP_NOWAIT)
"ksm: fix exec/fork inheritance" (xu xin)
Fix a rare case where the KSM MMF_VM_MERGE_ANY prctl state is not
inherited across fork/exec
"mm/zswap: misc cleanup of code and documentations" (SeongJae Park)
Some light maintenance work on the zswap code
"mm/page_owner: add debugfs files 'show_handles' and 'show_stacks_handles'" (Mauricio Faria de Oliveira)
Enhance the /sys/kernel/debug/page_owner debug feature by adding
unique identifiers to differentiate the various stack traces so
that userspace monitoring tools can better match stack traces over
time
"mm/page_alloc: pcp->batch cleanups" (Joshua Hahn)
Minor alterations to the page allocator's per-cpu-pages feature
"Improve UFFDIO_MOVE scalability by removing anon_vma lock" (Lokesh Gidra)
Address a scalability issue in userfaultfd's UFFDIO_MOVE operation
"kasan: cleanups for kasan_enabled() checks" (Sabyrzhan Tasbolatov)
"drivers/base/node: fold node register and unregister functions" (Donet Tom)
Clean up the NUMA node handling code a little
"mm: some optimizations for prot numa" (Kefeng Wang)
Cleanups and small optimizations to the NUMA allocation hinting
code
"mm/page_alloc: Batch callers of free_pcppages_bulk" (Joshua Hahn)
Address long lock hold times at boot on large machines. These were
causing (harmless) softlockup warnings
"optimize the logic for handling dirty file folios during reclaim" (Baolin Wang)
Remove some now-unnecessary work from page reclaim
"mm/damon: allow DAMOS auto-tuned for per-memcg per-node memory usage" (SeongJae Park)
Enhance the DAMOS auto-tuning feature
"mm/damon: fixes for address alignment issues in DAMON_LRU_SORT and DAMON_RECLAIM" (Quanmin Yan)
Fix DAMON_LRU_SORT and DAMON_RECLAIM with certain userspace
configuration
"expand mmap_prepare functionality, port more users" (Lorenzo Stoakes)
Enhance the new(ish) file_operations.mmap_prepare() method and port
additional callsites from the old ->mmap() over to ->mmap_prepare()
"Fix stale IOTLB entries for kernel address space" (Lu Baolu)
Fix a bug (and possible security issue on non-x86) in the IOMMU
code. In some situations the IOMMU could be left hanging onto a
stale kernel pagetable entry
"mm/huge_memory: cleanup __split_unmapped_folio()" (Wei Yang)
Clean up and optimize the folio splitting code
"mm, swap: misc cleanup and bugfix" (Kairui Song)
Some cleanups and a minor fix in the swap discard code
"mm/damon: misc documentation fixups" (SeongJae Park)
"mm/damon: support pin-point targets removal" (SeongJae Park)
Permit userspace to remove a specific monitoring target in the
middle of the current targets list
"mm: MISC follow-up patches for linux/pgalloc.h" (Harry Yoo)
A couple of cleanups related to mm header file inclusion
"mm/swapfile.c: select swap devices of default priority round robin" (Baoquan He)
improve the selection of swap devices for NUMA machines
"mm: Convert memory block states (MEM_*) macros to enums" (Israel Batista)
Change the memory block labels from macros to enums so they will
appear in kernel debug info
"ksm: perform a range-walk to jump over holes in break_ksm" (Pedro Demarchi Gomes)
Address an inefficiency when KSM unmerges an address range
"mm/damon/tests: fix memory bugs in kunit tests" (SeongJae Park)
Fix leaks and unhandled malloc() failures in DAMON userspace unit
tests
"some cleanups for pageout()" (Baolin Wang)
Clean up a couple of minor things in the page scanner's
writeback-for-eviction code
"mm/hugetlb: refactor sysfs/sysctl interfaces" (Hui Zhu)
Move hugetlb's sysfs/sysctl handling code into a new file
"introduce VM_MAYBE_GUARD and make it sticky" (Lorenzo Stoakes)
Make the VMA guard regions available in /proc/pid/smaps and
improves the mergeability of guarded VMAs
"mm: perform guard region install/remove under VMA lock" (Lorenzo Stoakes)
Reduce mmap lock contention for callers performing VMA guard region
operations
"vma_start_write_killable" (Matthew Wilcox)
Start work on permitting applications to be killed when they are
waiting on a read_lock on the VMA lock
"mm/damon/tests: add more tests for online parameters commit" (SeongJae Park)
Add additional userspace testing of DAMON's "commit" feature
"mm/damon: misc cleanups" (SeongJae Park)
"make VM_SOFTDIRTY a sticky VMA flag" (Lorenzo Stoakes)
Address the possible loss of a VMA's VM_SOFTDIRTY flag when that
VMA is merged with another
"mm: support device-private THP" (Balbir Singh)
Introduce support for Transparent Huge Page (THP) migration in zone
device-private memory
"Optimize folio split in memory failure" (Zi Yan)
"mm/huge_memory: Define split_type and consolidate split support checks" (Wei Yang)
Some more cleanups in the folio splitting code
"mm: remove is_swap_[pte, pmd]() + non-swap entries, introduce leaf entries" (Lorenzo Stoakes)
Clean up our handling of pagetable leaf entries by introducing the
concept of 'software leaf entries', of type softleaf_t
"reparent the THP split queue" (Muchun Song)
Reparent the THP split queue to its parent memcg. This is in
preparation for addressing the long-standing "dying memcg" problem,
wherein dead memcg's linger for too long, consuming memory
resources
"unify PMD scan results and remove redundant cleanup" (Wei Yang)
A little cleanup in the hugepage collapse code
"zram: introduce writeback bio batching" (Sergey Senozhatsky)
Improve zram writeback efficiency by introducing batched bio
writeback support
"memcg: cleanup the memcg stats interfaces" (Shakeel Butt)
Clean up our handling of the interrupt safety of some memcg stats
"make vmalloc gfp flags usage more apparent" (Vishal Moola)
Clean up vmalloc's handling of incoming GFP flags
"mm: Add soft-dirty and uffd-wp support for RISC-V" (Chunyan Zhang)
Teach soft dirty and userfaultfd write protect tracking to use
RISC-V's Svrsw60t59b extension
"mm: swap: small fixes and comment cleanups" (Youngjun Park)
Fix a small bug and clean up some of the swap code
"initial work on making VMA flags a bitmap" (Lorenzo Stoakes)
Start work on converting the vma struct's flags to a bitmap, so we
stop running out of them, especially on 32-bit
"mm/swapfile: fix and cleanup swap list iterations" (Youngjun Park)
Address a possible bug in the swap discard code and clean things
up a little
[ This merge also reverts commit ebb9aeb980e5 ("vfio/nvgrace-gpu:
register device memory for poison handling") because it looks
broken to me, I've asked for clarification - Linus ]
* tag 'mm-stable-2025-12-03-21-26' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (321 commits)
mm: fix vma_start_write_killable() signal handling
mm/swapfile: use plist_for_each_entry in __folio_throttle_swaprate
mm/swapfile: fix list iteration when next node is removed during discard
fs/proc/task_mmu.c: fix make_uffd_wp_huge_pte() huge pte handling
mm/kfence: add reboot notifier to disable KFENCE on shutdown
memcg: remove inc/dec_lruvec_kmem_state helpers
selftests/mm/uffd: initialize char variable to Null
mm: fix DEBUG_RODATA_TEST indentation in Kconfig
mm: introduce VMA flags bitmap type
tools/testing/vma: eliminate dependency on vma->__vm_flags
mm: simplify and rename mm flags function for clarity
mm: declare VMA flags by bit
zram: fix a spelling mistake
mm/page_alloc: optimize lowmem_reserve max lookup using its semantic monotonicity
mm/vmscan: skip increasing kswapd_failures when reclaim was boosted
pagemap: update BUDDY flag documentation
mm: swap: remove scan_swap_map_slots() references from comments
mm: swap: change swap_alloc_slow() to void
mm, swap: remove redundant comment for read_swap_cache_async
mm, swap: use SWP_SOLIDSTATE to determine if swap is rotational
...
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Patch series "mm: Add soft-dirty and uffd-wp support for RISC-V", v15.
This patchset adds support for Svrsw60t59b [1] extension which is ratified
now, also add soft dirty and userfaultfd write protect tracking for
RISC-V.
The patches 1 and 2 add macros to allow architectures to define their own
checks if the soft-dirty / uffd_wp PTE bits are available, in other words
for RISC-V, the Svrsw60t59b extension is supported on which device the
kernel is running. Also patch1-2 are removing "ifdef
CONFIG_MEM_SOFT_DIRTY" "ifdef CONFIG_HAVE_ARCH_USERFAULTFD_WP" and "ifdef
CONFIG_PTE_MARKER_UFFD_WP" in favor of checks which if not overridden by
the architecture, no change in behavior is expected.
This patchset has been tested with kselftest mm suite in which soft-dirty,
madv_populate, test_unmerge_uffd_wp, and uffd-unit-tests run and pass, and
no regressions are observed in any of the other tests.
This patch (of 6):
Some platforms can customize the PTE PMD entry soft-dirty bit making it
unavailable even if the architecture provides the resource.
Add an API which architectures can define their specific implementations
to detect if soft-dirty bit is available on which device the kernel is
running.
This patch is removing "ifdef CONFIG_MEM_SOFT_DIRTY" in favor of
pgtable_supports_soft_dirty() checks that defaults to
IS_ENABLED(CONFIG_MEM_SOFT_DIRTY), if not overridden by the architecture,
no change in behavior is expected.
We make sure to never set VM_SOFTDIRTY if !pgtable_supports_soft_dirty(),
so we will never run into VM_SOFTDIRTY checks.
[lorenzo.stoakes@oracle.com: fix VMA selftests]
Link: https://lkml.kernel.org/r/dac6ddfe-773a-43d5-8f69-021b9ca4d24b@lucifer.local
Link: https://lkml.kernel.org/r/20251113072806.795029-1-zhangchunyan@iscas.ac.cn
Link: https://lkml.kernel.org/r/20251113072806.795029-2-zhangchunyan@iscas.ac.cn
Link: https://github.com/riscv-non-isa/riscv-iommu/pull/543 [1]
Signed-off-by: Chunyan Zhang <zhangchunyan@iscas.ac.cn>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexandre Ghiti <alex@ghiti.fr>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Conor Dooley <conor@kernel.org>
Cc: Deepak Gupta <debug@rivosinc.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Andrew Jones <ajones@ventanamicro.com>
Cc: Conor Dooley <conor.dooley@microchip.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The page faults may be spurious because of the racy access to the page
table. For example, a non-populated virtual page is accessed on 2
CPUs simultaneously, thus the page faults are triggered on both CPUs.
However, it's possible that one CPU (say CPU A) cannot find the reason
for the page fault if the other CPU (say CPU B) has changed the page
table before the PTE is checked on CPU A. Most of the time, the
spurious page faults can be ignored safely. However, if the page
fault is for the write access, it's possible that a stale read-only
TLB entry exists in the local CPU and needs to be flushed on some
architectures. This is called the spurious page fault fixing.
In the current kernel, there is spurious fault fixing support for pte,
but not for huge pmd because no architectures need it. But in the
next patch in the series, we will change the write protection fault
handling logic on arm64, so that some stale huge pmd entries may
remain in the TLB. These entries need to be flushed via the huge pmd
spurious fault fixing mechanism.
Signed-off-by: Huang Ying <ying.huang@linux.alibaba.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Will Deacon <will@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Christoph Lameter (Ampere) <cl@gentwo.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Yin Fengwei <fengwei_yin@linux.alibaba.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-mm@kvack.org
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
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static inlines
For all the usual reasons, plus a new one. Calling
(void)arch_enter_lazy_mmu_mode();
deservedly blows up.
Cc: Balbir Singh <balbirs@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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print_bad_pte() looks like something that should actually be a WARN or
similar, but historically it apparently has proven to be useful to detect
corruption of page tables even on production systems -- report the issue
and keep the system running to make it easier to actually detect what is
going wrong (e.g., multiple such messages might shed a light).
As we want to unify vm_normal_page_*() handling for PTE/PMD/PUD, we'll
have to take care of print_bad_pte() as well.
Let's prepare for using print_bad_pte() also for non-PTEs by adjusting the
implementation and renaming the function to print_bad_page_map(). Provide
print_bad_pte() as a simple wrapper.
Document the implicit locking requirements for the page table re-walk.
To make the function a bit more readable, factor out the ratelimit check
into is_bad_page_map_ratelimited() and place the printing of page table
content into __print_bad_page_map_pgtable(). We'll now dump information
from each level in a single line, and just stop the table walk once we hit
something that is not a present page table.
The report will now look something like (dumping pgd to pmd values):
[ 77.943408] BUG: Bad page map in process XXX pte:80000001233f5867
[ 77.944077] addr:00007fd84bb1c000 vm_flags:08100071 anon_vma: ...
[ 77.945186] pgd:10a89f067 p4d:10a89f067 pud:10e5a2067 pmd:105327067
Not using pgdp_get(), because that does not work properly on some arm
configs where pgd_t is an array. Note that we are dumping all levels even
when levels are folded for simplicity.
[david@redhat.com: drop warning]
Link: https://lkml.kernel.org/r/923b279c-de33-44dd-a923-2959afad8626@redhat.com
Link: https://lkml.kernel.org/r/20250811112631.759341-9-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Juegren Gross <jgross@suse.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Let's factor it out, and convert all checks for unsupported levels to
BUILD_BUG(). The code is written in a way such that force-inlining will
optimize out the levels.
[nathan@kernel.org: always inline __folio_rmap_sanity_checks()]
Link: https://lkml.kernel.org/r/20250814-rmap-fix-build_bug-conversion-v1-1-fb7b10a0b362@kernel.org
Link: https://lkml.kernel.org/r/20250811112631.759341-8-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Vrabel <david.vrabel@citrix.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jann Horn <jannh@google.com>
Cc: Juegren Gross <jgross@suse.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Nathan Chancellor <nathan@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Introduce and use {pgd,p4d}_populate_kernel() in core MM code when
populating PGD and P4D entries for the kernel address space. These
helpers ensure proper synchronization of page tables when updating the
kernel portion of top-level page tables.
Until now, the kernel has relied on each architecture to handle
synchronization of top-level page tables in an ad-hoc manner. For
example, see commit 9b861528a801 ("x86-64, mem: Update all PGDs for direct
mapping and vmemmap mapping changes").
However, this approach has proven fragile for following reasons:
1) It is easy to forget to perform the necessary page table
synchronization when introducing new changes.
For instance, commit 4917f55b4ef9 ("mm/sparse-vmemmap: improve memory
savings for compound devmaps") overlooked the need to synchronize
page tables for the vmemmap area.
2) It is also easy to overlook that the vmemmap and direct mapping areas
must not be accessed before explicit page table synchronization.
For example, commit 8d400913c231 ("x86/vmemmap: handle unpopulated
sub-pmd ranges")) caused crashes by accessing the vmemmap area
before calling sync_global_pgds().
To address this, as suggested by Dave Hansen, introduce _kernel() variants
of the page table population helpers, which invoke architecture-specific
hooks to properly synchronize page tables. These are introduced in a new
header file, include/linux/pgalloc.h, so they can be called from common
code.
They reuse existing infrastructure for vmalloc and ioremap.
Synchronization requirements are determined by ARCH_PAGE_TABLE_SYNC_MASK,
and the actual synchronization is performed by
arch_sync_kernel_mappings().
This change currently targets only x86_64, so only PGD and P4D level
helpers are introduced. Currently, these helpers are no-ops since no
architecture sets PGTBL_{PGD,P4D}_MODIFIED in ARCH_PAGE_TABLE_SYNC_MASK.
In theory, PUD and PMD level helpers can be added later if needed by other
architectures. For now, 32-bit architectures (x86-32 and arm) only handle
PGTBL_PMD_MODIFIED, so p*d_populate_kernel() will never affect them unless
we introduce a PMD level helper.
[harry.yoo@oracle.com: fix KASAN build error due to p*d_populate_kernel()]
Link: https://lkml.kernel.org/r/20250822020727.202749-1-harry.yoo@oracle.com
Link: https://lkml.kernel.org/r/20250818020206.4517-3-harry.yoo@oracle.com
Fixes: 8d400913c231 ("x86/vmemmap: handle unpopulated sub-pmd ranges")
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Suggested-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: Kiryl Shutsemau <kas@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: bibo mao <maobibo@loongson.cn>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Christoph Lameter (Ampere) <cl@gentwo.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Huth <thuth@redhat.com>
Cc: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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During our internal testing, we started observing intermittent boot
failures when the machine uses 4-level paging and has a large amount of
persistent memory:
BUG: unable to handle page fault for address: ffffe70000000034
#PF: supervisor write access in kernel mode
#PF: error_code(0x0002) - not-present page
PGD 0 P4D 0
Oops: 0002 [#1] SMP NOPTI
RIP: 0010:__init_single_page+0x9/0x6d
Call Trace:
<TASK>
__init_zone_device_page+0x17/0x5d
memmap_init_zone_device+0x154/0x1bb
pagemap_range+0x2e0/0x40f
memremap_pages+0x10b/0x2f0
devm_memremap_pages+0x1e/0x60
dev_dax_probe+0xce/0x2ec [device_dax]
dax_bus_probe+0x6d/0xc9
[... snip ...]
</TASK>
It turns out that the kernel panics while initializing vmemmap (struct
page array) when the vmemmap region spans two PGD entries, because the new
PGD entry is only installed in init_mm.pgd, but not in the page tables of
other tasks.
And looking at __populate_section_memmap():
if (vmemmap_can_optimize(altmap, pgmap))
// does not sync top level page tables
r = vmemmap_populate_compound_pages(pfn, start, end, nid, pgmap);
else
// sync top level page tables in x86
r = vmemmap_populate(start, end, nid, altmap);
In the normal path, vmemmap_populate() in arch/x86/mm/init_64.c
synchronizes the top level page table (See commit 9b861528a801 ("x86-64,
mem: Update all PGDs for direct mapping and vmemmap mapping changes")) so
that all tasks in the system can see the new vmemmap area.
However, when vmemmap_can_optimize() returns true, the optimized path
skips synchronization of top-level page tables. This is because
vmemmap_populate_compound_pages() is implemented in core MM code, which
does not handle synchronization of the top-level page tables. Instead,
the core MM has historically relied on each architecture to perform this
synchronization manually.
We're not the first party to encounter a crash caused by not-sync'd top
level page tables: earlier this year, Gwan-gyeong Mun attempted to address
the issue [1] [2] after hitting a kernel panic when x86 code accessed the
vmemmap area before the corresponding top-level entries were synced. At
that time, the issue was believed to be triggered only when struct page
was enlarged for debugging purposes, and the patch did not get further
updates.
It turns out that current approach of relying on each arch to handle the
page table sync manually is fragile because 1) it's easy to forget to sync
the top level page table, and 2) it's also easy to overlook that the
kernel should not access the vmemmap and direct mapping areas before the
sync.
# The solution: Make page table sync more code robust and harder to miss
To address this, Dave Hansen suggested [3] [4] introducing
{pgd,p4d}_populate_kernel() for updating kernel portion of the page tables
and allow each architecture to explicitly perform synchronization when
installing top-level entries. With this approach, we no longer need to
worry about missing the sync step, reducing the risk of future
regressions.
The new interface reuses existing ARCH_PAGE_TABLE_SYNC_MASK,
PGTBL_P*D_MODIFIED and arch_sync_kernel_mappings() facility used by
vmalloc and ioremap to synchronize page tables.
pgd_populate_kernel() looks like this:
static inline void pgd_populate_kernel(unsigned long addr, pgd_t *pgd,
p4d_t *p4d)
{
pgd_populate(&init_mm, pgd, p4d);
if (ARCH_PAGE_TABLE_SYNC_MASK & PGTBL_PGD_MODIFIED)
arch_sync_kernel_mappings(addr, addr);
}
It is worth noting that vmalloc() and apply_to_range() carefully
synchronizes page tables by calling p*d_alloc_track() and
arch_sync_kernel_mappings(), and thus they are not affected by this patch
series.
This series was hugely inspired by Dave Hansen's suggestion and hence
added Suggested-by: Dave Hansen.
Cc stable because lack of this series opens the door to intermittent
boot failures.
This patch (of 3):
Move ARCH_PAGE_TABLE_SYNC_MASK and arch_sync_kernel_mappings() to
linux/pgtable.h so that they can be used outside of vmalloc and ioremap.
Link: https://lkml.kernel.org/r/20250818020206.4517-1-harry.yoo@oracle.com
Link: https://lkml.kernel.org/r/20250818020206.4517-2-harry.yoo@oracle.com
Link: https://lore.kernel.org/linux-mm/20250220064105.808339-1-gwan-gyeong.mun@intel.com [1]
Link: https://lore.kernel.org/linux-mm/20250311114420.240341-1-gwan-gyeong.mun@intel.com [2]
Link: https://lore.kernel.org/linux-mm/d1da214c-53d3-45ac-a8b6-51821c5416e4@intel.com [3]
Link: https://lore.kernel.org/linux-mm/4d800744-7b88-41aa-9979-b245e8bf794b@intel.com [4]
Fixes: 8d400913c231 ("x86/vmemmap: handle unpopulated sub-pmd ranges")
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Acked-by: Kiryl Shutsemau <kas@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: "Uladzislau Rezki (Sony)" <urezki@gmail.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: bibo mao <maobibo@loongson.cn>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Christoph Lameter (Ampere) <cl@gentwo.org>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Dmitriy Vyukov <dvyukov@google.com>
Cc: Gwan-gyeong Mun <gwan-gyeong.mun@intel.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Joao Martins <joao.m.martins@oracle.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Thomas Huth <thuth@redhat.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "Optimizations for khugepaged", v4.
If the underlying folio mapped by the ptes is large, we can process those
ptes in a batch using folio_pte_batch().
For arm64 specifically, this results in a 16x reduction in the number of
ptep_get() calls, since on a contig block, ptep_get() on arm64 will
iterate through all 16 entries to collect a/d bits. Next, ptep_clear()
will cause a TLBI for every contig block in the range via
contpte_try_unfold(). Instead, use clear_ptes() to only do the TLBI at
the first and last contig block of the range.
For split folios, there will be no pte batching; the batch size returned
by folio_pte_batch() will be 1. For pagetable split folios, the ptes will
still point to the same large folio; for arm64, this results in the
optimization described above, and for other arches, a minor improvement is
expected due to a reduction in the number of function calls and batching
atomic operations.
This patch (of 3):
Let's add variants to be used where "full" does not apply -- which will
be the majority of cases in the future. "full" really only applies if
we are about to tear down a full MM.
Use get_and_clear_ptes() in existing code, clear_ptes() users will
be added next.
Link: https://lkml.kernel.org/r/20250724052301.23844-2-dev.jain@arm.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Mariano Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Batch ptep_modify_prot_start/commit in preparation for optimizing
mprotect, implementing them as a simple loop over the corresponding single
pte helpers. Architecture may override these helpers.
Link: https://lkml.kernel.org/r/20250718090244.21092-4-dev.jain@arm.com
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Joey Gouly <joey.gouly@arm.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <yang@os.amperecomputing.com>
Cc: Yicong Yang <yangyicong@hisilicon.com>
Cc: Zhenhua Huang <quic_zhenhuah@quicinc.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Now that DAX and all other reference counts to ZONE_DEVICE pages are
managed normally there is no need for the special devmap PTE/PMD/PUD page
table bits. So drop all references to these, freeing up a software
defined page table bit on architectures supporting it.
Link: https://lkml.kernel.org/r/6389398c32cc9daa3dfcaa9f79c7972525d310ce.1750323463.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Acked-by: Will Deacon <will@kernel.org> # arm64
Acked-by: David Hildenbrand <david@redhat.com>
Suggested-by: Chunyan Zhang <zhang.lyra@gmail.com>
Reviewed-by: Björn Töpel <bjorn@rivosinc.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Björn Töpel <bjorn@kernel.org>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Deepak Gupta <debug@rivosinc.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Inki Dae <m.szyprowski@samsung.com>
Cc: John Groves <john@groves.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
DAX was the only thing that created pmd_devmap and pud_devmap entries
however it no longer does as DAX pages are now refcounted normally and
pXd_trans_huge() returns true for those. Therefore checking both
pXd_devmap and pXd_trans_huge() is redundant and the former can be removed
without changing behaviour as it will always be false.
Link: https://lkml.kernel.org/r/d58f089dc16b7feb7c6728164f37dea65d64a0d3.1750323463.git-series.apopple@nvidia.com
Signed-off-by: Alistair Popple <apopple@nvidia.com>
Cc: Balbir Singh <balbirs@nvidia.com>
Cc: Björn Töpel <bjorn@kernel.org>
Cc: Björn Töpel <bjorn@rivosinc.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Chunyan Zhang <zhang.lyra@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Deepak Gupta <debug@rivosinc.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Inki Dae <m.szyprowski@samsung.com>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: John Groves <john@groves.net>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "use vm_flags_t consistently".
The VMA flags field vma->vm_flags is of type vm_flags_t. Right now this
is exactly equivalent to unsigned long, but it should not be assumed to
be.
Much code that references vma->vm_flags already correctly uses vm_flags_t,
but a fairly large chunk of code simply uses unsigned long and assumes
that the two are equivalent.
This series corrects that and has us use vm_flags_t consistently.
This series is motivated by the desire to, in a future series, adjust
vm_flags_t to be a u64 regardless of whether the kernel is 32-bit or
64-bit in order to deal with the VMA flag exhaustion issue and avoid all
the various problems that arise from it (being unable to use certain
features in 32-bit, being unable to add new flags except for 64-bit, etc.)
This is therefore a critical first step towards that goal. At any rate,
using the correct type is of value regardless.
We additionally take the opportunity to refer to VMA flags as vm_flags
where possible to make clear what we're referring to.
Overall, this series does not introduce any functional change.
This patch (of 3):
We abstract the type of the VMA flags to vm_flags_t, however in may places
it is simply assumed this is unsigned long, which is simply incorrect.
At the moment this is simply an incongruity, however in future we plan to
change this type and therefore this change is a critical requirement for
doing so.
Overall, this patch does not introduce any functional change.
[lorenzo.stoakes@oracle.com: add missing vm_get_page_prot() instance, remove include]
Link: https://lkml.kernel.org/r/552f88e1-2df8-4e95-92b8-812f7c8db829@lucifer.local
Link: https://lkml.kernel.org/r/cover.1750274467.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/a12769720a2743f235643b158c4f4f0a9911daf0.1750274467.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: Catalin Marinas <catalin.marinas@arm.com> [arm64]
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kees Cook <kees@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Jarkko Sakkinen <jarkko@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Change the readahead config so that if it is being requested for an
executable mapping, do a synchronous read into a set of folios with an
arch-specified order and in a naturally aligned manner. We no longer
center the read on the faulting page but simply align it down to the
previous natural boundary. Additionally, we don't bother with an
asynchronous part.
On arm64 if memory is physically contiguous and naturally aligned to the
"contpte" size, we can use contpte mappings, which improves utilization of
the TLB. When paired with the "multi-size THP" feature, this works well
to reduce dTLB pressure. However iTLB pressure is still high due to
executable mappings having a low likelihood of being in the required folio
size and mapping alignment, even when the filesystem supports readahead
into large folios (e.g. XFS).
The reason for the low likelihood is that the current readahead algorithm
starts with an order-0 folio and increases the folio order by 2 every time
the readahead mark is hit. But most executable memory tends to be
accessed randomly and so the readahead mark is rarely hit and most
executable folios remain order-0.
So let's special-case the read(ahead) logic for executable mappings. The
trade-off is performance improvement (due to more efficient storage of the
translations in iTLB) vs potential for making reclaim more difficult (due
to the folios being larger so if a part of the folio is hot the whole
thing is considered hot). But executable memory is a small portion of the
overall system memory so I doubt this will even register from a reclaim
perspective.
I've chosen 64K folio size for arm64 which benefits both the 4K and 16K
base page size configs. Crucially the same amount of data is still read
(usually 128K) so I'm not expecting any read amplification issues. I
don't anticipate any write amplification because text is always RO.
Note that the text region of an ELF file could be populated into the page
cache for other reasons than taking a fault in a mmapped area. The most
common case is due to the loader read()ing the header which can be shared
with the beginning of text. So some text will still remain in small
folios, but this simple, best effort change provides good performance
improvements as is.
Confine this special-case approach to the bounds of the VMA. This
prevents wasting memory for any padding that might exist in the file
between sections. Previously the padding would have been contained in
order-0 folios and would be easy to reclaim. But now it would be part of
a larger folio so more difficult to reclaim. Solve this by simply not
reading it into memory in the first place.
Benchmarking
============
The below shows pgbench and redis benchmarks on Graviton3 arm64 system.
First, confirmation that this patch causes more text to be contained in
64K folios:
+----------------------+---------------+---------------+---------------+
| File-backed folios by| system boot | pgbench | redis |
| size as percentage of+-------+-------+-------+-------+-------+-------+
| all mapped text mem |before | after |before | after |before | after |
+======================+=======+=======+=======+=======+=======+=======+
| base-page-4kB | 78% | 30% | 78% | 11% | 73% | 14% |
| thp-aligned-8kB | 1% | 0% | 0% | 0% | 1% | 0% |
| thp-aligned-16kB | 17% | 4% | 17% | 3% | 20% | 4% |
| thp-aligned-32kB | 1% | 1% | 1% | 2% | 1% | 1% |
| thp-aligned-64kB | 3% | 63% | 3% | 81% | 4% | 77% |
| thp-aligned-128kB | 0% | 1% | 1% | 1% | 1% | 2% |
| thp-unaligned-64kB | 0% | 0% | 0% | 1% | 0% | 1% |
| thp-unaligned-128kB | 0% | 1% | 0% | 0% | 0% | 0% |
| thp-partial | 0% | 0% | 0% | 1% | 0% | 1% |
+----------------------+-------+-------+-------+-------+-------+-------+
| cont-aligned-64kB | 4% | 65% | 4% | 83% | 6% | 79% |
+----------------------+-------+-------+-------+-------+-------+-------+
The above shows that for both workloads (each isolated with cgroups) as
well as the general system state after boot, the amount of text backed by
4K and 16K folios reduces and the amount backed by 64K folios increases
significantly. And the amount of text that is contpte-mapped
significantly increases (see last row).
And this is reflected in performance improvement. "(I)" indicates a
statistically significant improvement. Note TPS and Reqs/sec are rates so
bigger is better, ms is time so smaller is better:
+-------------+-------------------------------------------+------------+
| Benchmark | Result Class | Improvemnt |
+=============+===========================================+============+
| pts/pgbench | Scale: 1 Clients: 1 RO (TPS) | (I) 3.47% |
| | Scale: 1 Clients: 1 RO - Latency (ms) | -2.88% |
| | Scale: 1 Clients: 250 RO (TPS) | (I) 5.02% |
| | Scale: 1 Clients: 250 RO - Latency (ms) | (I) -4.79% |
| | Scale: 1 Clients: 1000 RO (TPS) | (I) 6.16% |
| | Scale: 1 Clients: 1000 RO - Latency (ms) | (I) -5.82% |
| | Scale: 100 Clients: 1 RO (TPS) | 2.51% |
| | Scale: 100 Clients: 1 RO - Latency (ms) | -3.51% |
| | Scale: 100 Clients: 250 RO (TPS) | (I) 4.75% |
| | Scale: 100 Clients: 250 RO - Latency (ms) | (I) -4.44% |
| | Scale: 100 Clients: 1000 RO (TPS) | (I) 6.34% |
| | Scale: 100 Clients: 1000 RO - Latency (ms)| (I) -5.95% |
+-------------+-------------------------------------------+------------+
| pts/redis | Test: GET Connections: 50 (Reqs/sec) | (I) 3.20% |
| | Test: GET Connections: 1000 (Reqs/sec) | (I) 2.55% |
| | Test: LPOP Connections: 50 (Reqs/sec) | (I) 4.59% |
| | Test: LPOP Connections: 1000 (Reqs/sec) | (I) 4.81% |
| | Test: LPUSH Connections: 50 (Reqs/sec) | (I) 5.31% |
| | Test: LPUSH Connections: 1000 (Reqs/sec) | (I) 4.36% |
| | Test: SADD Connections: 50 (Reqs/sec) | (I) 2.64% |
| | Test: SADD Connections: 1000 (Reqs/sec) | (I) 4.15% |
| | Test: SET Connections: 50 (Reqs/sec) | (I) 3.11% |
| | Test: SET Connections: 1000 (Reqs/sec) | (I) 3.36% |
+-------------+-------------------------------------------+------------+
[ryan.roberts@arm.com: fix use-after-free]
Link: https://lkml.kernel.org/r/ea7f9da7-9a9f-4b85-9d0a-35b320f5ed25@arm.com
[ryan.roberts@arm.com: use the vma_pages() helper instead of open-coding]
Link: https://lkml.kernel.org/r/0e0f674b-3b7e-494f-ae7a-fc9dbb98dad4@arm.com
Link: https://lkml.kernel.org/r/20250609092729.274960-6-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Acked-by: Will Deacon <will@kernel.org>
Cc: Chaitanya S Prakash <chaitanyas.prakash@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
We can now get rid of the old interface along with get_pat_info() and
follow_phys().
Link: https://lkml.kernel.org/r/20250512123424.637989-6-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org> [x86 bits]
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Dave Airlie <airlied@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Tvrtko Ursulin <tursulin@ursulin.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's provide variants of track_pfn_remap() and untrack_pfn() that won't
mess with VMAs, and replace the usage in mm/memremap.c.
Add some documentation.
Link: https://lkml.kernel.org/r/20250512123424.637989-4-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org> [x86 bits]
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Dave Airlie <airlied@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Tvrtko Ursulin <tursulin@ursulin.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
... by factoring it out from track_pfn_remap() into
pfnmap_setup_cachemode() and provide pfnmap_setup_cachemode_pfn() as a
replacement for track_pfn_insert().
For PMDs/PUDs, we keep checking a single pfn only. Add some
documentation, and also document why it is valid to not check the whole
pfn range.
We'll reuse pfnmap_setup_cachemode() from core MM next.
Link: https://lkml.kernel.org/r/20250512123424.637989-3-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Acked-by: Ingo Molnar <mingo@kernel.org> [x86 bits]
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Dave Airlie <airlied@gmail.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jann Horn <jannh@google.com>
Cc: Jonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: "Masami Hiramatsu (Google)" <mhiramat@kernel.org>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: Tvrtko Ursulin <tursulin@ursulin.net>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Remove pgd_offset_gate() completely and simply make the single caller use
pgd_offset().
It appears that the gate area resides in the kernel-mapped segment
exclusively on IA64. Therefore, removing pgd_offset_k is safe since IA64
is now obsolete.
Link: https://lkml.kernel.org/r/tencent_503130C3CD56569191396268CF4D12F09A06@qq.com
Signed-off-by: Feng Lee <379943137@qq.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: bibo mao <maobibo@loongson.cn>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
We got a late smatch warning and some additional review feedback.
smatch warnings:
mm/memory.c:1428 copy_page_range() error: uninitialized symbol 'pfn'.
We actually use the pfn only when it is properly initialized; however, we
may pass an uninitialized value to a function -- although it will not use
it that likely still is UB in C.
So let's just fix it by always initializing pfn in the caller of
track_pfn_copy(), and improving the documentation of track_pfn_copy().
While at it, clarify the doc of untrack_pfn_copy(), that internal checks
make sure if we actually have to untrack anything.
Link: https://lkml.kernel.org/r/20250408085950.976103-1-david@redhat.com
Fixes: dc84bc2aba85 ("x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page_range()")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <error27@gmail.com>
Closes: https://lore.kernel.org/r/202503270941.IFILyNCX-lkp@intel.com/
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull MM updates from Andrew Morton:
- The series "Enable strict percpu address space checks" from Uros
Bizjak uses x86 named address space qualifiers to provide
compile-time checking of percpu area accesses.
This has caused a small amount of fallout - two or three issues were
reported. In all cases the calling code was found to be incorrect.
- The series "Some cleanup for memcg" from Chen Ridong implements some
relatively monir cleanups for the memcontrol code.
- The series "mm: fixes for device-exclusive entries (hmm)" from David
Hildenbrand fixes a boatload of issues which David found then using
device-exclusive PTE entries when THP is enabled. More work is
needed, but this makes thins better - our own HMM selftests now
succeed.
- The series "mm: zswap: remove z3fold and zbud" from Yosry Ahmed
remove the z3fold and zbud implementations. They have been deprecated
for half a year and nobody has complained.
- The series "mm: further simplify VMA merge operation" from Lorenzo
Stoakes implements numerous simplifications in this area. No runtime
effects are anticipated.
- The series "mm/madvise: remove redundant mmap_lock operations from
process_madvise()" from SeongJae Park rationalizes the locking in the
madvise() implementation. Performance gains of 20-25% were observed
in one MADV_DONTNEED microbenchmark.
- The series "Tiny cleanup and improvements about SWAP code" from
Baoquan He contains a number of touchups to issues which Baoquan
noticed when working on the swap code.
- The series "mm: kmemleak: Usability improvements" from Catalin
Marinas implements a couple of improvements to the kmemleak
user-visible output.
- The series "mm/damon/paddr: fix large folios access and schemes
handling" from Usama Arif provides a couple of fixes for DAMON's
handling of large folios.
- The series "mm/damon/core: fix wrong and/or useless damos_walk()
behaviors" from SeongJae Park fixes a few issues with the accuracy of
kdamond's walking of DAMON regions.
- The series "expose mapping wrprotect, fix fb_defio use" from Lorenzo
Stoakes changes the interaction between framebuffer deferred-io and
core MM. No functional changes are anticipated - this is preparatory
work for the future removal of page structure fields.
- The series "mm/damon: add support for hugepage_size DAMOS filter"
from Usama Arif adds a DAMOS filter which permits the filtering by
huge page sizes.
- The series "mm: permit guard regions for file-backed/shmem mappings"
from Lorenzo Stoakes extends the guard region feature from its
present "anon mappings only" state. The feature now covers shmem and
file-backed mappings.
- The series "mm: batched unmap lazyfree large folios during
reclamation" from Barry Song cleans up and speeds up the unmapping
for pte-mapped large folios.
- The series "reimplement per-vma lock as a refcount" from Suren
Baghdasaryan puts the vm_lock back into the vma. Our reasons for
pulling it out were largely bogus and that change made the code more
messy. This patchset provides small (0-10%) improvements on one
microbenchmark.
- The series "Docs/mm/damon: misc DAMOS filters documentation fixes and
improves" from SeongJae Park does some maintenance work on the DAMON
docs.
- The series "hugetlb/CMA improvements for large systems" from Frank
van der Linden addresses a pile of issues which have been observed
when using CMA on large machines.
- The series "mm/damon: introduce DAMOS filter type for unmapped pages"
from SeongJae Park enables users of DMAON/DAMOS to filter my the
page's mapped/unmapped status.
- The series "zsmalloc/zram: there be preemption" from Sergey
Senozhatsky teaches zram to run its compression and decompression
operations preemptibly.
- The series "selftests/mm: Some cleanups from trying to run them" from
Brendan Jackman fixes a pile of unrelated issues which Brendan
encountered while runnimg our selftests.
- The series "fs/proc/task_mmu: add guard region bit to pagemap" from
Lorenzo Stoakes permits userspace to use /proc/pid/pagemap to
determine whether a particular page is a guard page.
- The series "mm, swap: remove swap slot cache" from Kairui Song
removes the swap slot cache from the allocation path - it simply
wasn't being effective.
- The series "mm: cleanups for device-exclusive entries (hmm)" from
David Hildenbrand implements a number of unrelated cleanups in this
code.
- The series "mm: Rework generic PTDUMP configs" from Anshuman Khandual
implements a number of preparatoty cleanups to the GENERIC_PTDUMP
Kconfig logic.
- The series "mm/damon: auto-tune aggregation interval" from SeongJae
Park implements a feedback-driven automatic tuning feature for
DAMON's aggregation interval tuning.
- The series "Fix lazy mmu mode" from Ryan Roberts fixes some issues in
powerpc, sparc and x86 lazy MMU implementations. Ryan did this in
preparation for implementing lazy mmu mode for arm64 to optimize
vmalloc.
- The series "mm/page_alloc: Some clarifications for migratetype
fallback" from Brendan Jackman reworks some commentary to make the
code easier to follow.
- The series "page_counter cleanup and size reduction" from Shakeel
Butt cleans up the page_counter code and fixes a size increase which
we accidentally added late last year.
- The series "Add a command line option that enables control of how
many threads should be used to allocate huge pages" from Thomas
Prescher does that. It allows the careful operator to significantly
reduce boot time by tuning the parallalization of huge page
initialization.
- The series "Fix calculations in trace_balance_dirty_pages() for cgwb"
from Tang Yizhou fixes the tracing output from the dirty page
balancing code.
- The series "mm/damon: make allow filters after reject filters useful
and intuitive" from SeongJae Park improves the handling of allow and
reject filters. Behaviour is made more consistent and the documention
is updated accordingly.
- The series "Switch zswap to object read/write APIs" from Yosry Ahmed
updates zswap to the new object read/write APIs and thus permits the
removal of some legacy code from zpool and zsmalloc.
- The series "Some trivial cleanups for shmem" from Baolin Wang does as
it claims.
- The series "fs/dax: Fix ZONE_DEVICE page reference counts" from
Alistair Popple regularizes the weird ZONE_DEVICE page refcount
handling in DAX, permittig the removal of a number of special-case
checks.
- The series "refactor mremap and fix bug" from Lorenzo Stoakes is a
preparatoty refactoring and cleanup of the mremap() code.
- The series "mm: MM owner tracking for large folios (!hugetlb) +
CONFIG_NO_PAGE_MAPCOUNT" from David Hildenbrand reworks the manner in
which we determine whether a large folio is known to be mapped
exclusively into a single MM.
- The series "mm/damon: add sysfs dirs for managing DAMOS filters based
on handling layers" from SeongJae Park adds a couple of new sysfs
directories to ease the management of DAMON/DAMOS filters.
- The series "arch, mm: reduce code duplication in mem_init()" from
Mike Rapoport consolidates many per-arch implementations of
mem_init() into code generic code, where that is practical.
- The series "mm/damon/sysfs: commit parameters online via
damon_call()" from SeongJae Park continues the cleaning up of sysfs
access to DAMON internal data.
- The series "mm: page_ext: Introduce new iteration API" from Luiz
Capitulino reworks the page_ext initialization to fix a boot-time
crash which was observed with an unusual combination of compile and
cmdline options.
- The series "Buddy allocator like (or non-uniform) folio split" from
Zi Yan reworks the code to split a folio into smaller folios. The
main benefit is lessened memory consumption: fewer post-split folios
are generated.
- The series "Minimize xa_node allocation during xarry split" from Zi
Yan reduces the number of xarray xa_nodes which are generated during
an xarray split.
- The series "drivers/base/memory: Two cleanups" from Gavin Shan
performs some maintenance work on the drivers/base/memory code.
- The series "Add tracepoints for lowmem reserves, watermarks and
totalreserve_pages" from Martin Liu adds some more tracepoints to the
page allocator code.
- The series "mm/madvise: cleanup requests validations and
classifications" from SeongJae Park cleans up some warts which
SeongJae observed during his earlier madvise work.
- The series "mm/hwpoison: Fix regressions in memory failure handling"
from Shuai Xue addresses two quite serious regressions which Shuai
has observed in the memory-failure implementation.
- The series "mm: reliable huge page allocator" from Johannes Weiner
makes huge page allocations cheaper and more reliable by reducing
fragmentation.
- The series "Minor memcg cleanups & prep for memdescs" from Matthew
Wilcox is preparatory work for the future implementation of memdescs.
- The series "track memory used by balloon drivers" from Nico Pache
introduces a way to track memory used by our various balloon drivers.
- The series "mm/damon: introduce DAMOS filter type for active pages"
from Nhat Pham permits users to filter for active/inactive pages,
separately for file and anon pages.
- The series "Adding Proactive Memory Reclaim Statistics" from Hao Jia
separates the proactive reclaim statistics from the direct reclaim
statistics.
- The series "mm/vmscan: don't try to reclaim hwpoison folio" from
Jinjiang Tu fixes our handling of hwpoisoned pages within the reclaim
code.
* tag 'mm-stable-2025-03-30-16-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (431 commits)
mm/page_alloc: remove unnecessary __maybe_unused in order_to_pindex()
x86/mm: restore early initialization of high_memory for 32-bits
mm/vmscan: don't try to reclaim hwpoison folio
mm/hwpoison: introduce folio_contain_hwpoisoned_page() helper
cgroup: docs: add pswpin and pswpout items in cgroup v2 doc
mm: vmscan: split proactive reclaim statistics from direct reclaim statistics
selftests/mm: speed up split_huge_page_test
selftests/mm: uffd-unit-tests support for hugepages > 2M
docs/mm/damon/design: document active DAMOS filter type
mm/damon: implement a new DAMOS filter type for active pages
fs/dax: don't disassociate zero page entries
MM documentation: add "Unaccepted" meminfo entry
selftests/mm: add commentary about 9pfs bugs
fork: use __vmalloc_node() for stack allocation
docs/mm: Physical Memory: Populate the "Zones" section
xen: balloon: update the NR_BALLOON_PAGES state
hv_balloon: update the NR_BALLOON_PAGES state
balloon_compaction: update the NR_BALLOON_PAGES state
meminfo: add a per node counter for balloon drivers
mm: remove references to folio in __memcg_kmem_uncharge_page()
...
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|
If track_pfn_copy() fails, we already added the dst VMA to the maple
tree. As fork() fails, we'll cleanup the maple tree, and stumble over
the dst VMA for which we neither performed any reservation nor copied
any page tables.
Consequently untrack_pfn() will see VM_PAT and try obtaining the
PAT information from the page table -- which fails because the page
table was not copied.
The easiest fix would be to simply clear the VM_PAT flag of the dst VMA
if track_pfn_copy() fails. However, the whole thing is about "simply"
clearing the VM_PAT flag is shaky as well: if we passed track_pfn_copy()
and performed a reservation, but copying the page tables fails, we'll
simply clear the VM_PAT flag, not properly undoing the reservation ...
which is also wrong.
So let's fix it properly: set the VM_PAT flag only if the reservation
succeeded (leaving it clear initially), and undo the reservation if
anything goes wrong while copying the page tables: clearing the VM_PAT
flag after undoing the reservation.
Note that any copied page table entries will get zapped when the VMA will
get removed later, after copy_page_range() succeeded; as VM_PAT is not set
then, we won't try cleaning VM_PAT up once more and untrack_pfn() will be
happy. Note that leaving these page tables in place without a reservation
is not a problem, as we are aborting fork(); this process will never run.
A reproducer can trigger this usually at the first try:
https://gitlab.com/davidhildenbrand/scratchspace/-/raw/main/reproducers/pat_fork.c
WARNING: CPU: 26 PID: 11650 at arch/x86/mm/pat/memtype.c:983 get_pat_info+0xf6/0x110
Modules linked in: ...
CPU: 26 UID: 0 PID: 11650 Comm: repro3 Not tainted 6.12.0-rc5+ #92
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014
RIP: 0010:get_pat_info+0xf6/0x110
...
Call Trace:
<TASK>
...
untrack_pfn+0x52/0x110
unmap_single_vma+0xa6/0xe0
unmap_vmas+0x105/0x1f0
exit_mmap+0xf6/0x460
__mmput+0x4b/0x120
copy_process+0x1bf6/0x2aa0
kernel_clone+0xab/0x440
__do_sys_clone+0x66/0x90
do_syscall_64+0x95/0x180
Likely this case was missed in:
d155df53f310 ("x86/mm/pat: clear VM_PAT if copy_p4d_range failed")
... and instead of undoing the reservation we simply cleared the VM_PAT flag.
Keep the documentation of these functions in include/linux/pgtable.h,
one place is more than sufficient -- we should clean that up for the other
functions like track_pfn_remap/untrack_pfn separately.
Fixes: d155df53f310 ("x86/mm/pat: clear VM_PAT if copy_p4d_range failed")
Fixes: 2ab640379a0a ("x86: PAT: hooks in generic vm code to help archs to track pfnmap regions - v3")
Reported-by: xingwei lee <xrivendell7@gmail.com>
Reported-by: yuxin wang <wang1315768607@163.com>
Reported-by: Marius Fleischer <fleischermarius@gmail.com>
Signed-off-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rik van Riel <riel@surriel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Link: https://lore.kernel.org/r/20250321112323.153741-1-david@redhat.com
Closes: https://lore.kernel.org/lkml/CABOYnLx_dnqzpCW99G81DmOr+2UzdmZMk=T3uxwNxwz+R1RAwg@mail.gmail.com/
Closes: https://lore.kernel.org/lkml/CAJg=8jwijTP5fre8woS4JVJQ8iUA6v+iNcsOgtj9Zfpc3obDOQ@mail.gmail.com/
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|
Patch series "Fix lazy mmu mode", v2.
I'm planning to implement lazy mmu mode for arm64 to optimize vmalloc. As
part of that, I will extend lazy mmu mode to cover kernel mappings in
vmalloc table walkers. While lazy mmu mode is already used for kernel
mappings in a few places, this will extend it's use significantly.
Having reviewed the existing lazy mmu implementations in powerpc, sparc
and x86, it looks like there are a bunch of bugs, some of which may be
more likely to trigger once I extend the use of lazy mmu. So this series
attempts to clarify the requirements and fix all the bugs in advance of
that series. See patch #1 commit log for all the details.
This patch (of 5):
The docs, implementations and use of arch_[enter|leave]_lazy_mmu_mode() is
a bit of a mess (to put it politely). There are a number of issues
related to nesting of lazy mmu regions and confusion over whether the
task, when in a lazy mmu region, is preemptible or not. Fix all the
issues relating to the core-mm. Follow up commits will fix the
arch-specific implementations. 3 arches implement lazy mmu; powerpc,
sparc and x86.
When arch_[enter|leave]_lazy_mmu_mode() was first introduced by commit
6606c3e0da53 ("[PATCH] paravirt: lazy mmu mode hooks.patch"), it was
expected that lazy mmu regions would never nest and that the appropriate
page table lock(s) would be held while in the region, thus ensuring the
region is non-preemptible. Additionally lazy mmu regions were only used
during manipulation of user mappings.
Commit 38e0edb15bd0 ("mm/apply_to_range: call pte function with lazy
updates") started invoking the lazy mmu mode in apply_to_pte_range(),
which is used for both user and kernel mappings. For kernel mappings the
region is no longer protected by any lock so there is no longer any
guarantee about non-preemptibility. Additionally, for RT configs, the
holding the PTL only implies no CPU migration, it doesn't prevent
preemption.
Commit bcc6cc832573 ("mm: add default definition of set_ptes()") added
arch_[enter|leave]_lazy_mmu_mode() to the default implementation of
set_ptes(), used by x86. So after this commit, lazy mmu regions can be
nested. Additionally commit 1a10a44dfc1d ("sparc64: implement the new
page table range API") and commit 9fee28baa601 ("powerpc: implement the
new page table range API") did the same for the sparc and powerpc
set_ptes() overrides.
powerpc couldn't deal with preemption so avoids it in commit b9ef323ea168
("powerpc/64s: Disable preemption in hash lazy mmu mode"), which
explicitly disables preemption for the whole region in its implementation.
x86 can support preemption (or at least it could until it tried to add
support nesting; more on this below). Sparc looks to be totally broken in
the face of preemption, as far as I can tell.
powerpc can't deal with nesting, so avoids it in commit 47b8def9358c
("powerpc/mm: Avoid calling arch_enter/leave_lazy_mmu() in set_ptes"),
which removes the lazy mmu calls from its implementation of set_ptes().
x86 attempted to support nesting in commit 49147beb0ccb ("x86/xen: allow
nesting of same lazy mode") but as far as I can tell, this breaks its
support for preemption.
In short, it's all a mess; the semantics for
arch_[enter|leave]_lazy_mmu_mode() are not clearly defined and as a result
the implementations all have different expectations, sticking plasters and
bugs.
arm64 is aiming to start using these hooks, so let's clean everything up
before adding an arm64 implementation. Update the documentation to state
that lazy mmu regions can never be nested, must not be called in interrupt
context and preemption may or may not be enabled for the duration of the
region. And fix the generic implementation of set_ptes() to avoid
nesting.
arch-specific fixes to conform to the new spec will proceed this one.
These issues were spotted by code review and I have no evidence of issues
being reported in the wild.
Link: https://lkml.kernel.org/r/20250303141542.3371656-1-ryan.roberts@arm.com
Link: https://lkml.kernel.org/r/20250303141542.3371656-2-ryan.roberts@arm.com
Fixes: bcc6cc832573 ("mm: add default definition of set_ptes()")
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Acked-by: Juergen Gross <jgross@suse.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Borislav Betkov <bp@alien8.de>
Cc: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Juegren Gross <jgross@suse.com>
Cc: Matthew Wilcow (Oracle) <willy@infradead.org>
Cc: Thomas Gleinxer <tglx@linutronix.de>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
In the generic ptep_get_and_clear() implementation, it is just a simple
combination of ptep_get() and pte_clear(). But for some architectures
(such as x86 and arm64, etc), the hardware will modify the A/D bits of the
page table entry, so the ptep_get_and_clear() needs to be overwritten
and implemented as an atomic operation to avoid contention, which has a
performance cost.
The commit d283d422c6c4 ("x86: mm: add x86_64 support for page table
check") adds the ptep_clear() on the x86, and makes it call
ptep_get_and_clear() when CONFIG_PAGE_TABLE_CHECK is enabled. The page
table check feature does not actually care about the A/D bits, so only
ptep_get() + pte_clear() should be called. But considering that the page
table check is a debug option, this should not have much of an impact.
But then the commit de8c8e52836d ("mm: page_table_check: add hooks to
public helpers") changed ptep_clear() to unconditionally call
ptep_get_and_clear(), so that the CONFIG_PAGE_TABLE_CHECK check can be
put into the page table check stubs (in include/linux/page_table_check.h).
This also cause performance loss to the kernel without
CONFIG_PAGE_TABLE_CHECK enabled, which doesn't make sense.
Currently ptep_clear() is only used in debug code and in khugepaged
collapse paths, which are fairly expensive. So the cost of an extra atomic
RMW operation does not matter. But this may be used for other paths in the
future. After all, for the present pte entry, we need to call ptep_clear()
instead of pte_clear() to ensure that PAGE_TABLE_CHECK works properly.
So to be more precise, just calling ptep_get() and pte_clear() in the
ptep_clear().
Link: https://lkml.kernel.org/r/20241122073652.54030-1-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Jann Horn <jannh@google.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Tong Tiangen <tongtiangen@huawei.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
pud_init(), pmd_init() and kernel_pte_init() are duplicated defined in
file kasan.c and sparse-vmemmap.c as weak functions. Move them to generic
header file pgtable.h, architecture can redefine them.
Link: https://lkml.kernel.org/r/20241104070712.52902-1-maobibo@loongson.cn
Signed-off-by: Bibo Mao <maobibo@loongson.cn>
Reviewed-by: Huacai Chen <chenhuacai@loongson.cn>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: WANG Xuerui <kernel@xen0n.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
set_pxd_safe() helpers that serve a specific purpose for both x86 and
riscv platforms, do not need to be in the common memory code. Otherwise
they just unnecessarily make the common API more complicated. This moves
the helpers from common code to platform instead.
Link: https://lkml.kernel.org/r/20241003044842.246016-1-anshuman.khandual@arm.com
Signed-off-by: Anshuman Khandual <anshuman.khandual@arm.com>
Suggested-by: David Hildenbrand <david@redhat.com>
Acked-by: Dave Hansen <dave.hansen@linux.intel.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: David Hildenbrand <david@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
There're:
- 8 archs (arc, arm64, include, mips, powerpc, s390, sh, x86) that
support pte_pgprot().
- 2 archs (x86, sparc) that support pmd_pgprot().
- 1 arch (x86) that support pud_pgprot().
Always define them to be used in generic code, and then we don't need to
fiddle with "#ifdef"s when doing so.
Link: https://lkml.kernel.org/r/20240826204353.2228736-9-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alex Williamson <alex.williamson@redhat.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gavin Shan <gshan@redhat.com>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Niklas Schnelle <schnelle@linux.ibm.com>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Introduce arch_check_zapped_pud() to sanity check shadow stack on PUD
zaps. It has the same logic as the PMD helper.
One thing to mention is, it might be a good idea to use page_table_check
in the future for trapping wrong setups of shadow stack pgtable entries
[1]. That is left for the future as a separate effort.
[1] https://lore.kernel.org/all/59d518698f664e07c036a5098833d7b56b953305.camel@intel.com
Link: https://lkml.kernel.org/r/20240812181225.1360970-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@intel.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Dave Jiang <dave.jiang@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Sean Christopherson <seanjc@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
On powerpc 8xx, when a page is 8M size, the information is in the PMD
entry. So allow architectures to provide __pte_leaf_size() instead of
pte_leaf_size() and provide the PMD entry to that function.
When __pte_leaf_size() is not defined, define it as a pte_leaf_size() so
that architectures not interested in the PMD arguments are not impacted.
Only define a default pte_leaf_size() when __pte_leaf_size() is not
defined to make sure nobody adds new calls to pte_leaf_size() in the core.
Link: https://lkml.kernel.org/r/c7c008f0a314bf8029ad7288fdc908db1ec7e449.1719928057.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Jason Gunthorpe <jgg@nvidia.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Xu <peterx@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Should do_swap_page() have the capability to directly map a large folio,
metadata restoration becomes necessary for a specified number of pages
denoted as nr. It's important to highlight that metadata restoration is
solely required by the SPARC platform, which, however, does not enable
THP_SWAP. Consequently, in the present kernel configuration, there exists
no practical scenario where users necessitate the restoration of nr
metadata. Platforms implementing THP_SWAP might invoke this function with
nr values exceeding 1, subsequent to do_swap_page() successfully mapping
an entire large folio. Nonetheless, their arch_do_swap_page_nr()
functions remain empty.
Link: https://lkml.kernel.org/r/20240529082824.150954-5-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Khalid Aziz <khalid.aziz@oracle.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Chuanhua Han <hanchuanhua@oppo.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Gao Xiang <xiang@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <kasong@tencent.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's make update_mmu_tlb() simply a generic wrapper around
update_mmu_tlb_range(). Only the latter can now be overridden by the
architecture. We can now remove __HAVE_ARCH_UPDATE_MMU_TLB as well.
Link: https://lkml.kernel.org/r/20240522061204.117421-3-libang.li@antgroup.com
Signed-off-by: Bang Li <libang.li@antgroup.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "Add update_mmu_tlb_range() to simplify code", v4.
This series of commits mainly adds the update_mmu_tlb_range() to batch
update tlb in an address range and implement update_mmu_tlb() using
update_mmu_tlb_range().
After commit 19eaf44954df ("mm: thp: support allocation of anonymous
multi-size THP"), We may need to batch update tlb of a certain address
range by calling update_mmu_tlb() in a loop. Using the
update_mmu_tlb_range(), we can simplify the code and possibly reduce the
execution of some unnecessary code in some architectures.
This patch (of 3):
Add update_mmu_tlb_range(), we can batch update tlb of an address range.
Link: https://lkml.kernel.org/r/20240522061204.117421-1-libang.li@antgroup.com
Link: https://lkml.kernel.org/r/20240522061204.117421-2-libang.li@antgroup.com
Signed-off-by: Bang Li <libang.li@antgroup.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm/madvise: enhance lazyfreeing with mTHP in madvise_free",
v10.
This patchset adds support for lazyfreeing multi-size THP (mTHP) without
needing to first split the large folio via split_folio(). However, we
still need to split a large folio that is not fully mapped within the
target range.
If a large folio is locked or shared, or if we fail to split it, we just
leave it in place and advance to the next PTE in the range. But note that
the behavior is changed; previously, any failure of this sort would cause
the entire operation to give up. As large folios become more common,
sticking to the old way could result in wasted opportunities.
Performance Testing
===================
On an Intel I5 CPU, lazyfreeing a 1GiB VMA backed by PTE-mapped folios of
the same size results in the following runtimes for madvise(MADV_FREE) in
seconds (shorter is better):
Folio Size | Old | New | Change
------------------------------------------
4KiB | 0.590251 | 0.590259 | 0%
16KiB | 2.990447 | 0.185655 | -94%
32KiB | 2.547831 | 0.104870 | -95%
64KiB | 2.457796 | 0.052812 | -97%
128KiB | 2.281034 | 0.032777 | -99%
256KiB | 2.230387 | 0.017496 | -99%
512KiB | 2.189106 | 0.010781 | -99%
1024KiB | 2.183949 | 0.007753 | -99%
2048KiB | 0.002799 | 0.002804 | 0%
This patch (of 4):
This commit introduces clear_young_dirty_ptes() to replace mkold_ptes().
By doing so, we can use the same function for both use cases
(madvise_pageout and madvise_free), and it also provides the flexibility
to only clear the dirty flag in the future if needed.
Link: https://lkml.kernel.org/r/20240418134435.6092-1-ioworker0@gmail.com
Link: https://lkml.kernel.org/r/20240418134435.6092-2-ioworker0@gmail.com
Signed-off-by: Lance Yang <ioworker0@gmail.com>
Suggested-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Jeff Xie <xiehuan09@gmail.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Rework madvise_cold_or_pageout_pte_range() to avoid splitting any large
folio that is fully and contiguously mapped in the pageout/cold vm range.
This change means that large folios will be maintained all the way to swap
storage. This both improves performance during swap-out, by eliding the
cost of splitting the folio, and sets us up nicely for maintaining the
large folio when it is swapped back in (to be covered in a separate
series).
Folios that are not fully mapped in the target range are still split, but
note that behavior is changed so that if the split fails for any reason
(folio locked, shared, etc) we now leave it as is and move to the next pte
in the range and continue work on the proceeding folios. Previously any
failure of this sort would cause the entire operation to give up and no
folios mapped at higher addresses were paged out or made cold. Given
large folios are becoming more common, this old behavior would have likely
lead to wasted opportunities.
While we are at it, change the code that clears young from the ptes to use
ptep_test_and_clear_young(), via the new mkold_ptes() batch helper
function. This is more efficent than get_and_clear/modify/set, especially
for contpte mappings on arm64, where the old approach would require
unfolding/refolding and the new approach can be done in place.
Link: https://lkml.kernel.org/r/20240408183946.2991168-8-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Barry Song <v-songbaohua@oppo.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Gao Xiang <xiang@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Now that we no longer have a convenient flag in the cluster to determine
if a folio is large, free_swap_and_cache() will take a reference and lock
a large folio much more often, which could lead to contention and (e.g.)
failure to split large folios, etc.
Let's solve that problem by batch freeing swap and cache with a new
function, free_swap_and_cache_nr(), to free a contiguous range of swap
entries together. This allows us to first drop a reference to each swap
slot before we try to release the cache folio. This means we only try to
release the folio once, only taking the reference and lock once - much
better than the previous 512 times for the 2M THP case.
Contiguous swap entries are gathered in zap_pte_range() and
madvise_free_pte_range() in a similar way to how present ptes are already
gathered in zap_pte_range().
While we are at it, let's simplify by converting the return type of both
functions to void. The return value was used only by zap_pte_range() to
print a bad pte, and was ignored by everyone else, so the extra reporting
wasn't exactly guaranteed. We will still get the warning with most of the
information from get_swap_device(). With the batch version, we wouldn't
know which pte was bad anyway so could print the wrong one.
[ryan.roberts@arm.com: fix a build warning on parisc]
Link: https://lkml.kernel.org/r/20240409111840.3173122-1-ryan.roberts@arm.com
Link: https://lkml.kernel.org/r/20240408183946.2991168-3-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Barry Song <v-songbaohua@oppo.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Gao Xiang <xiang@kernel.org>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Lance Yang <ioworker0@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Yu Zhao <yuzhao@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The "prot" parameter is unused, and using it instead of what's stored in
that particular PTE would very likely be wrong. Let's simply remove it.
Link: https://lkml.kernel.org/r/20240327143301.741807-1-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andreas Larsson <andreas@gaisler.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The comment in the code explains the reasons. We took a different
approach comparing to pmd_pfn() by providing a fallback function.
Another option is to provide some lower level config options (compare to
HUGETLB_PAGE or THP) to identify which layer an arch can support for such
huge mappings. However that can be an overkill.
[peterx@redhat.com: fix loongson defconfig]
Link: https://lkml.kernel.org/r/20240403013249.1418299-4-peterx@redhat.com
Link: https://lkml.kernel.org/r/20240327152332.950956-6-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Tested-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Andrew Jones <andrew.jones@linux.dev>
Cc: Aneesh Kumar K.V (IBM) <aneesh.kumar@kernel.org>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: David Hildenbrand <david@redhat.com>
Cc: James Houghton <jthoughton@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Rik van Riel <riel@surriel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Convert directly from a pmd to a folio without going through another
representation first. For now this is just a slightly shorter way to
write it, but it might end up being more efficient later.
Link: https://lkml.kernel.org/r/20240326202833.523759-4-willy@infradead.org
Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Commit d0637c505f8a1 ("arm64: enable THP_SWAP for arm64") brings up
THP_SWAP on ARM64, but it doesn't enable THP_SWP on hardware with MTE as
the MTE code works with the assumption tags save/restore is always
handling a folio with only one page.
The limitation should be removed as more and more ARM64 SoCs have this
feature. Co-existence of MTE and THP_SWAP becomes more and more
important.
This patch makes MTE tags saving support large folios, then we don't need
to split large folios into base pages for swapping out on ARM64 SoCs with
MTE any more.
arch_prepare_to_swap() should take folio rather than page as parameter
because we support THP swap-out as a whole. It saves tags for all pages
in a large folio.
As now we are restoring tags based-on folio, in arch_swap_restore(), we
may increase some extra loops and early-exitings while refaulting a large
folio which is still in swapcache in do_swap_page(). In case a large
folio has nr pages, do_swap_page() will only set the PTE of the particular
page which is causing the page fault. Thus do_swap_page() runs nr times,
and each time, arch_swap_restore() will loop nr times for those subpages
in the folio. So right now the algorithmic complexity becomes O(nr^2).
Once we support mapping large folios in do_swap_page(), extra loops and
early-exitings will decrease while not being completely removed as a large
folio might get partially tagged in corner cases such as, 1. a large
folio in swapcache can be partially unmapped, thus, MTE tags for the
unmapped pages will be invalidated; 2. users might use mprotect() to set
MTEs on a part of a large folio.
arch_thp_swp_supported() is dropped since ARM64 MTE was the only one who
needed it.
Link: https://lkml.kernel.org/r/20240322114136.61386-2-21cnbao@gmail.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Acked-by: Chris Li <chrisl@kernel.org>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Lorenzo Stoakes <lstoakes@gmail.com>
Cc: "Mike Rapoport (IBM)" <rppt@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Cc: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
There's one small section already, but since we're going to remove
pXd_huge(), that comment may start to obsolete.
Rewrite that section with more information, hopefully with that the API is
crystal clear on what it implies.
Link: https://lkml.kernel.org/r/20240318200404.448346-15-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andreas Larsson <andreas@gaisler.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bjorn Andersson <andersson@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Fabio Estevam <festevam@denx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Konrad Dybcio <konrad.dybcio@linaro.org>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Cc: Lucas Stach <l.stach@pengutronix.de>
Cc: Mark Salter <msalter@redhat.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Shawn Guo <shawnguo@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The last architecture redefining pgd_offset_k() was IA64 and it was
removed by commit cf8e8658100d ("arch: Remove Itanium (IA-64)
architecture")
There is no need anymore to guard generic version of pgd_offset_k()
with #ifndef pgd_offset_k
Link: https://lkml.kernel.org/r/59d3f47d5615d18cca1986f269be2fcb3df34556.1710589838.git.christophe.leroy@csgroup.eu
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Even if pXd_leaf() API is defined globally, it's not clear on the retval,
and there are three types used (bool, int, unsigned log).
Always return a boolean for pXd_leaf() APIs.
Link: https://lkml.kernel.org/r/20240305043750.93762-11-peterx@redhat.com
Signed-off-by: Peter Xu <peterx@redhat.com>
Suggested-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Alexander Potapenko <glider@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Kirill A. Shutemov <kirill@shutemov.name>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Some architectures (e.g. arm64) can tell from looking at a pte, if some
follow-on ptes also map contiguous physical memory with the same pgprot.
(for arm64, these are contpte mappings).
Take advantage of this knowledge to optimize folio_pte_batch() so that it
can skip these ptes when scanning to create a batch. By default, if an
arch does not opt-in, folio_pte_batch() returns a compile-time 1, so the
changes are optimized out and the behaviour is as before.
arm64 will opt-in to providing this hint in the next patch, which will
greatly reduce the cost of ptep_get() when scanning a range of contptes.
Link: https://lkml.kernel.org/r/20240215103205.2607016-16-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Tested-by: John Hubbard <jhubbard@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morse <james.morse@arm.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Now that the all architecture overrides of pte_next_pfn() have been
replaced with pte_advance_pfn(), we can simplify the definition of the
generic pte_next_pfn() macro so that it is unconditionally defined.
Link: https://lkml.kernel.org/r/20240215103205.2607016-7-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morse <james.morse@arm.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The goal is to be able to advance a PTE by an arbitrary number of PFNs.
So introduce a new API that takes a nr param. Define the default
implementation here and allow for architectures to override.
pte_next_pfn() becomes a wrapper around pte_advance_pfn().
Follow up commits will convert each overriding architecture's
pte_next_pfn() to pte_advance_pfn().
Link: https://lkml.kernel.org/r/20240215103205.2607016-4-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morse <james.morse@arm.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "Transparent Contiguous PTEs for User Mappings", v6.
This is a series to opportunistically and transparently use contpte
mappings (set the contiguous bit in ptes) for user memory when those
mappings meet the requirements. The change benefits arm64, but there is
some (very) minor refactoring for x86 to enable its integration with
core-mm.
It is part of a wider effort to improve performance by allocating and
mapping variable-sized blocks of memory (folios). One aim is for the 4K
kernel to approach the performance of the 16K kernel, but without breaking
compatibility and without the associated increase in memory. Another aim
is to benefit the 16K and 64K kernels by enabling 2M THP, since this is
the contpte size for those kernels. We have good performance data that
demonstrates both aims are being met (see below).
Of course this is only one half of the change. We require the mapped
physical memory to be the correct size and alignment for this to actually
be useful (i.e. 64K for 4K pages, or 2M for 16K/64K pages). Fortunately
folios are solving this problem for us. Filesystems that support it (XFS,
AFS, EROFS, tmpfs, ...) will allocate large folios up to the PMD size
today, and more filesystems are coming. And for anonymous memory,
"multi-size THP" is now upstream.
Patch Layout
============
In this version, I've split the patches to better show each optimization:
- 1-2: mm prep: misc code and docs cleanups
- 3-6: mm,arm64,x86 prep: Add pte_advance_pfn() and make pte_next_pfn() a
generic wrapper around it
- 7-11: arm64 prep: Refactor ptep helpers into new layer
- 12: functional contpte implementation
- 23-18: various optimizations on top of the contpte implementation
Testing
=======
I've tested this series on both Ampere Altra (bare metal) and Apple M2 (VM):
- mm selftests (inc new tests written for multi-size THP); no regressions
- Speedometer Java script benchmark in Chromium web browser; no issues
- Kernel compilation; no issues
- Various tests under high memory pressure with swap enabled; no issues
Performance
===========
High Level Use Cases
~~~~~~~~~~~~~~~~~~~~
First some high level use cases (kernel compilation and speedometer JavaScript
benchmarks). These are running on Ampere Altra (I've seen similar improvements
on Android/Pixel 6).
baseline: mm-unstable (mTHP switched off)
mTHP: + enable 16K, 32K, 64K mTHP sizes "always"
mTHP + contpte: + this series
mTHP + contpte + exefolio: + patch at [6], which series supports
Kernel Compilation with -j8 (negative is faster):
| kernel | real-time | kern-time | user-time |
|---------------------------|-----------|-----------|-----------|
| baseline | 0.0% | 0.0% | 0.0% |
| mTHP | -5.0% | -39.1% | -0.7% |
| mTHP + contpte | -6.0% | -41.4% | -1.5% |
| mTHP + contpte + exefolio | -7.8% | -43.1% | -3.4% |
Kernel Compilation with -j80 (negative is faster):
| kernel | real-time | kern-time | user-time |
|---------------------------|-----------|-----------|-----------|
| baseline | 0.0% | 0.0% | 0.0% |
| mTHP | -5.0% | -36.6% | -0.6% |
| mTHP + contpte | -6.1% | -38.2% | -1.6% |
| mTHP + contpte + exefolio | -7.4% | -39.2% | -3.2% |
Speedometer (positive is faster):
| kernel | runs_per_min |
|:--------------------------|--------------|
| baseline | 0.0% |
| mTHP | 1.5% |
| mTHP + contpte | 3.2% |
| mTHP + contpte + exefolio | 4.5% |
Micro Benchmarks
~~~~~~~~~~~~~~~~
The following microbenchmarks are intended to demonstrate the performance of
fork() and munmap() do not regress. I'm showing results for order-0 (4K)
mappings, and for order-9 (2M) PTE-mapped THP. Thanks to David for sharing his
benchmarks.
baseline: mm-unstable + batch zap [7] series
contpte-basic: + patches 0-19; functional contpte implementation
contpte-batch: + patches 20-23; implement new batched APIs
contpte-inline: + patch 24; __always_inline to help compiler
contpte-fold: + patch 25; fold contpte mapping when sensible
Primary platform is Ampere Altra bare metal. I'm also showing results for M2 VM
(on top of MacOS) for reference, although experience suggests this might not be
the most reliable for performance numbers of this sort:
| FORK | order-0 | order-9 |
| Ampere Altra |------------------------|------------------------|
| (pte-map) | mean | stdev | mean | stdev |
|----------------|------------|-----------|------------|-----------|
| baseline | 0.0% | 2.7% | 0.0% | 0.2% |
| contpte-basic | 6.3% | 1.4% | 1948.7% | 0.2% |
| contpte-batch | 7.6% | 2.0% | -1.9% | 0.4% |
| contpte-inline | 3.6% | 1.5% | -1.0% | 0.2% |
| contpte-fold | 4.6% | 2.1% | -1.8% | 0.2% |
| MUNMAP | order-0 | order-9 |
| Ampere Altra |------------------------|------------------------|
| (pte-map) | mean | stdev | mean | stdev |
|----------------|------------|-----------|------------|-----------|
| baseline | 0.0% | 0.5% | 0.0% | 0.3% |
| contpte-basic | 1.8% | 0.3% | 1104.8% | 0.1% |
| contpte-batch | -0.3% | 0.4% | 2.7% | 0.1% |
| contpte-inline | -0.1% | 0.6% | 0.9% | 0.1% |
| contpte-fold | 0.1% | 0.6% | 0.8% | 0.1% |
| FORK | order-0 | order-9 |
| Apple M2 VM |------------------------|------------------------|
| (pte-map) | mean | stdev | mean | stdev |
|----------------|------------|-----------|------------|-----------|
| baseline | 0.0% | 1.4% | 0.0% | 0.8% |
| contpte-basic | 6.8% | 1.2% | 469.4% | 1.4% |
| contpte-batch | -7.7% | 2.0% | -8.9% | 0.7% |
| contpte-inline | -6.0% | 2.1% | -6.0% | 2.0% |
| contpte-fold | 5.9% | 1.4% | -6.4% | 1.4% |
| MUNMAP | order-0 | order-9 |
| Apple M2 VM |------------------------|------------------------|
| (pte-map) | mean | stdev | mean | stdev |
|----------------|------------|-----------|------------|-----------|
| baseline | 0.0% | 0.6% | 0.0% | 0.4% |
| contpte-basic | 1.6% | 0.6% | 233.6% | 0.7% |
| contpte-batch | 1.9% | 0.3% | -3.9% | 0.4% |
| contpte-inline | 2.2% | 0.8% | -1.6% | 0.9% |
| contpte-fold | 1.5% | 0.7% | -1.7% | 0.7% |
Misc
~~~~
John Hubbard at Nvidia has indicated dramatic 10x performance improvements
for some workloads at [8], when using 64K base page kernel.
[1] https://lore.kernel.org/linux-arm-kernel/20230622144210.2623299-1-ryan.roberts@arm.com/
[2] https://lore.kernel.org/linux-arm-kernel/20231115163018.1303287-1-ryan.roberts@arm.com/
[3] https://lore.kernel.org/linux-arm-kernel/20231204105440.61448-1-ryan.roberts@arm.com/
[4] https://lore.kernel.org/lkml/20231218105100.172635-1-ryan.roberts@arm.com/
[5] https://lore.kernel.org/linux-mm/633af0a7-0823-424f-b6ef-374d99483f05@arm.com/
[6] https://lore.kernel.org/lkml/08c16f7d-f3b3-4f22-9acc-da943f647dc3@arm.com/
[7] https://lore.kernel.org/linux-mm/20240214204435.167852-1-david@redhat.com/
[8] https://lore.kernel.org/linux-mm/c507308d-bdd4-5f9e-d4ff-e96e4520be85@nvidia.com/
[9] https://gitlab.arm.com/linux-arm/linux-rr/-/tree/features/granule_perf/contpte-lkml_v6
This patch (of 18):
set_ptes() spec implies that it can only be used to set a present pte
because it interprets the PFN field to increment it. However,
set_pte_at() has been implemented on top of set_ptes() since set_ptes()
was introduced, and set_pte_at() allows setting a pte to a not-present
state. So clarify the spec to state that when nr==1, new state of pte may
be present or not present. When nr>1, new state of all ptes must be
present.
While we are at it, tighten the spec to set requirements around the
initial state of ptes; when nr==1 it may be either present or not-present.
But when nr>1 all ptes must initially be not-present. All set_ptes()
callsites already conform to this requirement. Stating it explicitly is
useful because it allows for a simplification to the upcoming arm64
contpte implementation.
Link: https://lkml.kernel.org/r/20240215103205.2607016-1-ryan.roberts@arm.com
Link: https://lkml.kernel.org/r/20240215103205.2607016-2-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Barry Song <21cnbao@gmail.com>
Cc: Borislav Petkov (AMD) <bp@alien8.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: James Morse <james.morse@arm.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Will Deacon <will@kernel.org>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Similar to how we optimized fork(), let's implement PTE batching when
consecutive (present) PTEs map consecutive pages of the same large folio.
Most infrastructure we need for batching (mmu gather, rmap) is already
there. We only have to add get_and_clear_full_ptes() and
clear_full_ptes(). Similarly, extend zap_install_uffd_wp_if_needed() to
process a PTE range.
We won't bother sanity-checking the mapcount of all subpages, but only
check the mapcount of the first subpage we process. If there is a real
problem hiding somewhere, we can trigger it simply by using small folios,
or when we zap single pages of a large folio. Ideally, we had that check
in rmap code (including for delayed rmap), but then we cannot print the
PTE. Let's keep it simple for now. If we ever have a cheap
folio_mapcount(), we might just want to check for underflows there.
To keep small folios as fast as possible force inlining of a specialized
variant using __always_inline with nr=1.
Link: https://lkml.kernel.org/r/20240214204435.167852-11-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Naveen N. Rao" <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yin Fengwei <fengwei.yin@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's implement PTE batching when consecutive (present) PTEs map
consecutive pages of the same large folio, and all other PTE bits besides
the PFNs are equal.
We will optimize folio_pte_batch() separately, to ignore selected PTE
bits. This patch is based on work by Ryan Roberts.
Use __always_inline for __copy_present_ptes() and keep the handling for
single PTEs completely separate from the multi-PTE case: we really want
the compiler to optimize for the single-PTE case with small folios, to not
degrade performance.
Note that PTE batching will never exceed a single page table and will
always stay within VMA boundaries.
Further, processing PTE-mapped THP that maybe pinned and have
PageAnonExclusive set on at least one subpage should work as expected, but
there is room for improvement: We will repeatedly (1) detect a PTE batch
(2) detect that we have to copy a page (3) fall back and allocate a single
page to copy a single page. For now we won't care as pinned pages are a
corner case, and we should rather look into maintaining only a single
PageAnonExclusive bit for large folios.
Link: https://lkml.kernel.org/r/20240129124649.189745-14-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Russell King (Oracle) <linux@armlinux.org.uk>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Let's provide pte_next_pfn(), independently of set_ptes(). This allows
for using the generic pte_next_pfn() version in some arch-specific
set_ptes() implementations, and prepares for reusing pte_next_pfn() in
other context.
Link: https://lkml.kernel.org/r/20240129124649.189745-9-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Tested-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Mike Rapoport (IBM) <rppt@kernel.org>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: Alexandre Ghiti <alexghiti@rivosinc.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@kernel.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Dinh Nguyen <dinguyen@kernel.org>
Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Naveen N. Rao <naveen.n.rao@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Russell King (Oracle) <linux@armlinux.org.uk>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux
Pull RISC-V updates from Palmer Dabbelt:
- Support for many new extensions in hwprobe, along with a handful of
cleanups
- Various cleanups to our page table handling code, so we alwayse use
{READ,WRITE}_ONCE
- Support for the which-cpus flavor of hwprobe
- Support for XIP kernels has been resurrected
* tag 'riscv-for-linus-6.8-mw1' of git://git.kernel.org/pub/scm/linux/kernel/git/riscv/linux: (52 commits)
riscv: hwprobe: export Zicond extension
riscv: hwprobe: export Zacas ISA extension
riscv: add ISA extension parsing for Zacas
dt-bindings: riscv: add Zacas ISA extension description
riscv: hwprobe: export Ztso ISA extension
riscv: add ISA extension parsing for Ztso
use linux/export.h rather than asm-generic/export.h
riscv: Remove SHADOW_OVERFLOW_STACK_SIZE macro
riscv; fix __user annotation in save_v_state()
riscv: fix __user annotation in traps_misaligned.c
riscv: Select ARCH_WANTS_NO_INSTR
riscv: Remove obsolete rv32_defconfig file
riscv: Allow disabling of BUILTIN_DTB for XIP
riscv: Fixed wrong register in XIP_FIXUP_FLASH_OFFSET macro
riscv: Make XIP bootable again
riscv: Fix set_direct_map_default_noflush() to reset _PAGE_EXEC
riscv: Fix module_alloc() that did not reset the linear mapping permissions
riscv: Fix wrong usage of lm_alias() when splitting a huge linear mapping
riscv: Check if the code to patch lies in the exit section
riscv: Use the same CPU operations for all CPUs
...
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Add dummy pmd_dirty() for architectures that don't provide it.
This is similar to commit 6617da8fb565 ("mm: add dummy pmd_young()
for architectures not having it").
Link: https://lkml.kernel.org/r/20231227141205.2200125-5-kinseyho@google.com
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202312210606.1Etqz3M4-lkp@intel.com/
Closes: https://lore.kernel.org/oe-kbuild-all/202312210042.xQEiqlEh-lkp@intel.com/
Signed-off-by: Kinsey Ho <kinseyho@google.com>
Suggested-by: Yu Zhao <yuzhao@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Cc: Donet Tom <donettom@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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