| Age | Commit message (Collapse) | Author | Files | Lines |
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The select of KEXEC for CRASH_DUMP in kernel/Kconfig.kexec will be
dropped, then compiling errors will be triggered if below config items are
set:
===
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
===
--------------------------------------------------------------------
mipsel-linux-ld: kernel/kexec_core.o: in function `kimage_free':
kernel/kexec_core.c:(.text+0x2200): undefined reference to `machine_kexec_cleanup'
mipsel-linux-ld: kernel/kexec_core.o: in function `__crash_kexec':
kernel/kexec_core.c:(.text+0x2480): undefined reference to `machine_crash_shutdown'
mipsel-linux-ld: kernel/kexec_core.c:(.text+0x2488): undefined reference to `machine_kexec'
mipsel-linux-ld: kernel/kexec_core.o: in function `kernel_kexec':
kernel/kexec_core.c:(.text+0x29b8): undefined reference to `machine_shutdown'
mipsel-linux-ld: kernel/kexec_core.c:(.text+0x29c0): undefined reference to `machine_kexec'
--------------------------------------------------------------------
Here, change the dependency of building kexec_core related object files,
and the ifdeffery in mips from CONFIG_KEXEC to CONFIG_KEXEC_CORE.
Link: https://lkml.kernel.org/r/20231208073036.7884-4-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311302042.sn8cDPIX-lkp@intel.com/
Cc: Eric DeVolder <eric_devolder@yahoo.com>
Cc: Ignat Korchagin <ignat@cloudflare.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The select of KEXEC for CRASH_DUMP in kernel/Kconfig.kexec will be
dropped, then compiling errors will be triggered if below config items are
set:
===
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
===
Here, change the dependency of buinding machine_kexec.o relocate_kernel.o
and the ifdeffery in asm/kexe.h to CONFIG_KEXEC_CORE.
Link: https://lkml.kernel.org/r/20231208073036.7884-3-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Cc: Eric DeVolder <eric_devolder@yahoo.com>
Cc: Ignat Korchagin <ignat@cloudflare.com>
Cc: kernel test robot <lkp@intel.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "kexec: fix the incorrect ifdeffery and dependency of
CONFIG_KEXEC".
The select of KEXEC for CRASH_DUMP in kernel/Kconfig.kexec will be
dropped, then compiling errors will be triggered if below config items are
set:
===
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
===
E.g on mips, below link error are seen:
--------------------------------------------------------------------
mipsel-linux-ld: kernel/kexec_core.o: in function `kimage_free':
kernel/kexec_core.c:(.text+0x2200): undefined reference to `machine_kexec_cleanup'
mipsel-linux-ld: kernel/kexec_core.o: in function `__crash_kexec':
kernel/kexec_core.c:(.text+0x2480): undefined reference to `machine_crash_shutdown'
mipsel-linux-ld: kernel/kexec_core.c:(.text+0x2488): undefined reference to `machine_kexec'
mipsel-linux-ld: kernel/kexec_core.o: in function `kernel_kexec':
kernel/kexec_core.c:(.text+0x29b8): undefined reference to `machine_shutdown'
mipsel-linux-ld: kernel/kexec_core.c:(.text+0x29c0): undefined reference to `machine_kexec'
--------------------------------------------------------------------
Here, change the incorrect dependency of building kexec_core related
object files, and the ifdeffery on architectures from CONFIG_KEXEC to
CONFIG_KEXEC_CORE.
Testing:
========
Passed on mips and loognarch with the LKP reproducer.
This patch (of 5):
Currently, in arch/loongarch/kernel/Makefile, building machine_kexec.o
relocate_kernel.o depends on CONFIG_KEXEC.
Whereas, since we will drop the select of KEXEC for CRASH_DUMP in
kernel/Kconfig.kexec, compiling error will be triggered if below config
items are set:
===
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
===
---------------------------------------------------------------
loongarch64-linux-ld: kernel/kexec_core.o: in function `.L209':
>> kexec_core.c:(.text+0x1660): undefined reference to `machine_kexec_cleanup'
loongarch64-linux-ld: kernel/kexec_core.o: in function `.L287':
>> kexec_core.c:(.text+0x1c5c): undefined reference to `machine_crash_shutdown'
>> loongarch64-linux-ld: kexec_core.c:(.text+0x1c64): undefined reference to `machine_kexec'
loongarch64-linux-ld: kernel/kexec_core.o: in function `.L2^B5':
>> kexec_core.c:(.text+0x2090): undefined reference to `machine_shutdown'
loongarch64-linux-ld: kexec_core.c:(.text+0x20a0): undefined reference to `machine_kexec'
---------------------------------------------------------------
Here, change the dependency of machine_kexec.o relocate_kernel.o to
CONFIG_KEXEC_CORE can fix above building error.
Link: https://lkml.kernel.org/r/20231208073036.7884-1-bhe@redhat.com
Link: https://lkml.kernel.org/r/20231208073036.7884-2-bhe@redhat.com
Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lore.kernel.org/oe-kbuild-all/202311300946.kHE9Iu71-lkp@intel.com/
Cc: Eric DeVolder <eric_devolder@yahoo.com>
Cc: Ignat Korchagin <ignat@cloudflare.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The cleanup tasks of kdamond threads including reset of corresponding
DAMON context's ->kdamond field and decrease of global nr_running_ctxs
counter is supposed to be executed by kdamond_fn(). However, commit
0f91d13366a4 ("mm/damon: simplify stop mechanism") made neither
damon_start() nor damon_stop() ensure the corresponding kdamond has
started the execution of kdamond_fn().
As a result, the cleanup can be skipped if damon_stop() is called fast
enough after the previous damon_start(). Especially the skipped reset
of ->kdamond could cause a use-after-free.
Fix it by waiting for start of kdamond_fn() execution from
damon_start().
Link: https://lkml.kernel.org/r/20231208175018.63880-1-sj@kernel.org
Fixes: 0f91d13366a4 ("mm/damon: simplify stop mechanism")
Signed-off-by: SeongJae Park <sj@kernel.org>
Reported-by: Jakub Acs <acsjakub@amazon.de>
Cc: Changbin Du <changbin.du@intel.com>
Cc: Jakub Acs <acsjakub@amazon.de>
Cc: <stable@vger.kernel.org> # 5.15.x
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Doing a ksft_print_msg() before the ksft_print_header() seems to confuse
the ksft framework in a strange way: running the test on the cmdline
results in the expected output.
But piping the output somewhere else, results in some odd output,
whereby we repeatedly get the same info printed:
# [INFO] detected THP size: 2048 KiB
# [INFO] detected hugetlb page size: 2048 KiB
# [INFO] detected hugetlb page size: 1048576 KiB
# [INFO] huge zeropage is enabled
TAP version 13
1..190
# [INFO] Anonymous memory tests in private mappings
# [RUN] Basic COW after fork() ... with base page
# [INFO] detected THP size: 2048 KiB
# [INFO] detected hugetlb page size: 2048 KiB
# [INFO] detected hugetlb page size: 1048576 KiB
# [INFO] huge zeropage is enabled
TAP version 13
1..190
# [INFO] Anonymous memory tests in private mappings
# [RUN] Basic COW after fork() ... with base page
ok 1 No leak from parent into child
# [RUN] Basic COW after fork() ... with swapped out base page
# [INFO] detected THP size: 2048 KiB
# [INFO] detected hugetlb page size: 2048 KiB
# [INFO] detected hugetlb page size: 1048576 KiB
# [INFO] huge zeropage is enabled
Doing the ksft_print_header() first seems to resolve that and gives us
the output we expect:
TAP version 13
# [INFO] detected THP size: 2048 KiB
# [INFO] detected hugetlb page size: 2048 KiB
# [INFO] detected hugetlb page size: 1048576 KiB
# [INFO] huge zeropage is enabled
1..190
# [INFO] Anonymous memory tests in private mappings
# [RUN] Basic COW after fork() ... with base page
ok 1 No leak from parent into child
# [RUN] Basic COW after fork() ... with swapped out base page
ok 2 No leak from parent into child
# [RUN] Basic COW after fork() ... with THP
ok 3 No leak from parent into child
# [RUN] Basic COW after fork() ... with swapped-out THP
ok 4 No leak from parent into child
# [RUN] Basic COW after fork() ... with PTE-mapped THP
ok 5 No leak from parent into child
Link: https://lkml.kernel.org/r/20231206103558.38040-1-david@redhat.com
Fixes: f4b5fd6946e2 ("selftests/vm: anon_cow: THP tests")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Nico Pache <npache@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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After converting selinux to VMA heap check helper, the gcl triggers an
execheap SELinux denial, which is caused by a changed logic check.
Previously selinux only checked that the VMA range was within the VMA heap
range, and the implementation checks the intersection between the two
ranges, but the corner case (vm_end=start_brk, brk=vm_start) isn't handled
correctly.
Since commit 11250fd12eb8 ("mm: factor out VMA stack and heap checks") was
only a function extraction, it seems that the issue was introduced by
commit 0db0c01b53a1 ("procfs: fix /proc/<pid>/maps heap check"). Let's
fix above corner cases, meanwhile, correct the wrong indentation of the
stack and heap check helpers.
Fixes: 11250fd12eb8 ("mm: factor out VMA stack and heap checks")
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reported-by: Ondrej Mosnacek <omosnace@redhat.com>
Closes: https://lore.kernel.org/selinux/CAFqZXNv0SVT0fkOK6neP9AXbj3nxJ61JAY4+zJzvxqJaeuhbFw@mail.gmail.com/
Tested-by: Ondrej Mosnacek <omosnace@redhat.com>
Link: https://lkml.kernel.org/r/20231207152525.2607420-1-wangkefeng.wang@huawei.com
Cc: David Hildenbrand <david@redhat.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephen Smalley <stephen.smalley.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When below config items are set, compiler complained:
--------------------
CONFIG_CRASH_CORE=y
CONFIG_KEXEC_CORE=y
CONFIG_CRASH_DUMP=y
......
-----------------------
-------------------------------------------------------------------
arch/riscv/kernel/crash_core.c: In function 'arch_crash_save_vmcoreinfo':
arch/riscv/kernel/crash_core.c:11:58: warning: format '%lx' expects argument of type 'long unsigned int', but argument 2 has type 'int' [-Wformat=]
11 | vmcoreinfo_append_str("NUMBER(VMALLOC_START)=0x%lx\n", VMALLOC_START);
| ~~^
| |
| long unsigned int
| %x
----------------------------------------------------------------------
This is because on riscv macro VMALLOC_START has different type when
CONFIG_MMU is set or unset.
arch/riscv/include/asm/pgtable.h:
--------------------------------------------------
Changing it to _AC(0, UL) in case CONFIG_MMU=n can fix the warning.
Link: https://lkml.kernel.org/r/ZW7OsX4zQRA3mO4+@MiWiFi-R3L-srv
Signed-off-by: Baoquan He <bhe@redhat.com>
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # build-tested
Cc: Eric DeVolder <eric_devolder@yahoo.com>
Cc: Ignat Korchagin <ignat@cloudflare.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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In commit f8ff23429c62 ("kernel/Kconfig.kexec: drop select of KEXEC for
CRASH_DUMP") we tried to fix a config regression, where CONFIG_CRASH_DUMP
required CONFIG_KEXEC.
However, it was not enough at least for arm64 platforms. While further
testing the patch with our arm64 config I noticed that CONFIG_CRASH_DUMP
is unavailable in menuconfig. This is because CONFIG_CRASH_DUMP still
depends on the new CONFIG_ARCH_SUPPORTS_KEXEC introduced in commit
91506f7e5d21 ("arm64/kexec: refactor for kernel/Kconfig.kexec") and on
arm64 CONFIG_ARCH_SUPPORTS_KEXEC requires CONFIG_PM_SLEEP_SMP=y, which in
turn requires either CONFIG_SUSPEND=y or CONFIG_HIBERNATION=y neither of
which are set in our config.
Given that we already established that CONFIG_KEXEC (which is a switch for
kexec system call itself) is not required for CONFIG_CRASH_DUMP drop
CONFIG_ARCH_SUPPORTS_KEXEC dependency as well. The arm64 kernel builds
just fine with CONFIG_CRASH_DUMP=y and with both CONFIG_KEXEC=n and
CONFIG_KEXEC_FILE=n after f8ff23429c62 ("kernel/Kconfig.kexec: drop select
of KEXEC for CRASH_DUMP") and this patch are applied given that the
necessary shared bits are included via CONFIG_KEXEC_CORE dependency.
[bhe@redhat.com: don't export some symbols when CONFIG_MMU=n]
Link: https://lkml.kernel.org/r/ZW03ODUKGGhP1ZGU@MiWiFi-R3L-srv
[bhe@redhat.com: riscv, kexec: fix dependency of two items]
Link: https://lkml.kernel.org/r/ZW04G/SKnhbE5mnX@MiWiFi-R3L-srv
Link: https://lkml.kernel.org/r/20231129220409.55006-1-ignat@cloudflare.com
Fixes: 91506f7e5d21 ("arm64/kexec: refactor for kernel/Kconfig.kexec")
Signed-off-by: Ignat Korchagin <ignat@cloudflare.com>
Signed-off-by: Baoquan He <bhe@redhat.com>
Acked-by: Baoquan He <bhe@redhat.com>
Cc: Alexander Gordeev <agordeev@linux.ibm.com>
Cc: <stable@vger.kernel.org> # 6.6+: f8ff234: kernel/Kconfig.kexec: drop select of KEXEC for CRASH_DUMP
Cc: <stable@vger.kernel.org> # 6.6+
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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mas_split_final_node() always returns true and its return value is never
checked.
Change return type to void.
Link: https://lkml.kernel.org/r/20231109160821.16248-2-ppbuk5246@gmail.com
Signed-off-by: Levi Yun <ppbuk5246@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Testing shows fast_isolate_freepages can blindly choose an unsuitable
pageblock from time to time particularly while the min mark is used from
XXX path:
if (!page) {
cc->fast_search_fail++;
if (scan_start) {
/*
* Use the highest PFN found above min. If one was
* not found, be pessimistic for direct compaction
* and use the min mark.
*/
if (highest >= min_pfn) {
page = pfn_to_page(highest);
cc->free_pfn = highest;
} else {
if (cc->direct_compaction && pfn_valid(min_pfn)) { /* XXX */
page = pageblock_pfn_to_page(min_pfn,
min(pageblock_end_pfn(min_pfn),
zone_end_pfn(cc->zone)),
cc->zone);
cc->free_pfn = min_pfn;
}
}
}
}
The reason is that no code is doing any check on the min_pfn
min_pfn = pageblock_start_pfn(cc->free_pfn - (distance >> 1));
In contrast, slow path of isolate_freepages() is always skipping
unsuitable pageblocks in a decent way.
This issue doesn't happen quite often. When running 25 machines with
16GiB memory for one night, most of them can hit this unexpected code
path. However the frequency isn't like many times per second. It might
be one time in a couple of hours. Thus, it is very hard to measure the
visible performance impact in my machines though the affection of choosing
the unsuitable migration_target should be negative in theory.
I feel it's still worth fixing this to at least make the code
theoretically self-explanatory as it is quite odd an unsuitable
migration_target can be still migration_target.
Link: https://lkml.kernel.org/r/20231206110054.61617-1-v-songbaohua@oppo.com
Signed-off-by: Barry Song <v-songbaohua@oppo.com>
Reported-by: Zhanyuan Hu <huzhanyuan@oppo.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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vma_pages() is more readable and also better at avoiding error codes, so
use vma_pages() instead of direct operations on vma
Link: https://lkml.kernel.org/r/tencent_151850CF327EB055BBC83298A929BD06CD0A@qq.com
Signed-off-by: Chen Haonan <chen.haonan2@zte.com.cn>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The ret variable can be defined without assigning a value, as it is
assigned before use.
Link: https://lkml.kernel.org/r/20231205021751.100459-1-zeming@nfschina.com
Signed-off-by: Li zeming <zeming@nfschina.com>
Reviewed-by: Andrew Morton <akpm@linux-foudation.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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All the users of vmemmap_remap_range() will hold the mmap lock and release
it once it returns, it is naturally to move the lock to
vmemmap_remap_range() to simplify the code and the users.
Link: https://lkml.kernel.org/r/20231205030853.3921-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The compiler will optimize the code as much as possible if we add the
check of CONFIG_MEMORY_HOTPLUG back.
Link: https://lkml.kernel.org/r/20231205030530.3802-1-songmuchun@bytedance.com
Signed-off-by: Muchun Song <songmuchun@bytedance.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The ret variable can be defined without assigning a value, as it is
assigned before use.
Link: https://lkml.kernel.org/r/20231205022954.101045-1-zeming@nfschina.com
Signed-off-by: Li zeming <zeming@nfschina.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Currently enabling THP support (CONFIG_TRANSPARENT_HUGEPAGE) requires
enabling either CONFIG_TRANSPARENT_HUGEPAGE_ALWAYS or
CONFIG_TRANSPARENT_HUGEPAGE_MADVISE, which both cause khugepaged starting
by default at kernel bootup. Add the third choice
CONFIG_TRANSPARENT_HUGEPAGE_NEVER, in line with the existing kernel
command line setting transparent_hugepage=never, to disable THP by default
(in particular, to prevent starting khugepaged by default) but still allow
enabling it at runtime via sysfs.
Rationale: khugepaged has its own non-negligible memory cost even if it is
not used by any applications, since it bumps up vm.min_free_kbytes to its
own required minimum in set_recommended_min_free_kbytes(). For example,
on a machine with 4GB RAM, with 3 mm zones and pageblock_order ==
MAX_ORDER, starting khugepaged causes vm.min_free_kbytes increase from 8MB
to 132MB.
So if we use THP on machines with e.g. >=8GB of memory for better
performance, but avoid using it on lower-memory machines to avoid its
memory overhead, then for the same reason we also want to avoid even
starting khugepaged on those <8GB machines. So with
CONFIG_TRANSPARENT_HUGEPAGE_NEVER we can use the same kernel image on both
>=8GB and <8GB machines, with THP support enabled but khugepaged not
started by default. The userspace can then decide to enable THP via sysfs
if needed, based on the total amount of memory.
This could also be achieved with the existing transparent_hugepage=never
setting in the kernel command line instead. But it seems cleaner to avoid
tweaking the command line for such a basic setting.
P.S. I see that CONFIG_TRANSPARENT_HUGEPAGE_NEVER was already proposed
in the past [1] but without an explanation of the purpose.
[1] https://lore.kernel.org/all/202211301651462590168@zte.com.cn/
Link: https://lkml.kernel.org/r/20231205170244.2746210-1-dmaluka@chromium.org
Link: https://lore.kernel.org/all/20231204163254.2636289-1-dmaluka@chromium.org/
Signed-off-by: Dmytro Maluka <dmaluka@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Use more folio APIs to save six compound_head() calls in
__split_huge_page_tail().
Link: https://lkml.kernel.org/r/20231110033324.2455523-5-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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On systems with large number of CPUs, the following soft lockup splat
might sometimes happen:
[ 2656.001617] watchdog: BUG: soft lockup - CPU#364 stuck for 21s! [ksoftirqd/364:2206]
:
[ 2656.141194] RIP: 0010:_raw_spin_unlock_irqrestore+0x3d/0x70
:
2656.241214] Call Trace:
[ 2656.243971] <IRQ>
[ 2656.246237] ? show_trace_log_lvl+0x1c4/0x2df
[ 2656.251152] ? show_trace_log_lvl+0x1c4/0x2df
[ 2656.256066] ? kmemleak_free_percpu+0x11f/0x1f0
[ 2656.261173] ? watchdog_timer_fn+0x379/0x470
[ 2656.265984] ? __pfx_watchdog_timer_fn+0x10/0x10
[ 2656.271179] ? __hrtimer_run_queues+0x5f3/0xd00
[ 2656.276283] ? __pfx___hrtimer_run_queues+0x10/0x10
[ 2656.281783] ? ktime_get_update_offsets_now+0x95/0x2c0
[ 2656.287573] ? ktime_get_update_offsets_now+0xdd/0x2c0
[ 2656.293380] ? hrtimer_interrupt+0x2e9/0x780
[ 2656.298221] ? __sysvec_apic_timer_interrupt+0x184/0x640
[ 2656.304211] ? sysvec_apic_timer_interrupt+0x8e/0xc0
[ 2656.309807] </IRQ>
[ 2656.312169] <TASK>
[ 2656.326110] kmemleak_free_percpu+0x11f/0x1f0
[ 2656.331015] free_percpu.part.0+0x1b/0xe70
[ 2656.335635] free_vfsmnt+0xb9/0x100
[ 2656.339567] rcu_do_batch+0x3c8/0xe30
[ 2656.363693] rcu_core+0x3de/0x5a0
[ 2656.367433] __do_softirq+0x2d0/0x9a8
[ 2656.381119] run_ksoftirqd+0x36/0x60
[ 2656.385145] smpboot_thread_fn+0x556/0x910
[ 2656.394971] kthread+0x2a4/0x350
[ 2656.402826] ret_from_fork+0x29/0x50
[ 2656.406861] </TASK>
The issue is caused by kmemleak registering each per_cpu_ptr()
corresponding to the __percpu pointer. This is unnecessary since such
individual per-CPU pointers are not tracked anyway. Create a new
object_percpu_tree_root rbtree that stores a single __percpu pointer
together with an OBJECT_PERCPU flag for the kmemleak metadata. Scanning
needs to be done for all per_cpu_ptr() pointers with a cond_resched()
between each CPU iteration to avoid RCU stalls.
[catalin.marinas@arm.com: update comment]
Link: https://lkml.kernel.org/r/20231206114414.2085824-1-catalin.marinas@arm.com
Link: https://lore.kernel.org/r/20231127194153.289626-1-longman@redhat.comLink: https://lkml.kernel.org/r/20231201190829.825856-1-catalin.marinas@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Waiman Long <longman@redhat.com>
Closes: https://lore.kernel.org/r/20231127194153.289626-1-longman@redhat.com
Reviewed-by: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Running my yearly branch profiler to see where likely/unlikely annotation
may be added or removed, I discovered this:
correct incorrect % Function File Line
------- --------- - -------- ---- ----
0 457918 100 page_try_dup_anon_rmap rmap.h 264
[..]
458021 0 0 page_try_dup_anon_rmap rmap.h 265
I thought it was interesting that line 264 of rmap.h had a 100% incorrect
annotation, but the line directly below it was 100% correct. Looking at the
code:
if (likely(!is_device_private_page(page) &&
unlikely(page_needs_cow_for_dma(vma, page))))
It didn't make sense. The "likely()" was around the entire if statement
(not just the "!is_device_private_page(page)"), which also included the
"unlikely()" portion of that if condition.
If the unlikely portion is unlikely to be true, that would make the entire
if condition unlikely to be true, so it made no sense at all to say the
entire if condition is true.
What is more likely to be likely is just the first part of the if statement
before the && operation. It's likely to be a misplaced parenthesis. And
after making the if condition broken into a likely() && unlikely(), both
now appear to be correct!
Link: https://lkml.kernel.org/r/20231201145936.5ddfdb50@gandalf.local.home
Fixes:fb3d824d1a46c ("mm/rmap: split page_dup_rmap() into page_dup_file_rmap() and page_try_dup_anon_rmap()")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
The THP machinery does not support order-1 folios because it requires meta
data spanning the first 3 `struct page`s. So order-2 is the smallest
large folio that we can safely create.
There was a theoretical bug whereby if ra->size was 2 or 3 pages (due to
the device-specific bdi->ra_pages being set that way), we could end up
with order = 1. Fix this by unconditionally checking if the preferred
order is 1 and if so, set it to 0. Previously this was done in a few
specific places, but with this refactoring it is done just once,
unconditionally, at the end of the calculation.
This is a theoretical bug found during review of the code; I have no
evidence to suggest this manifests in the real world (I expect all
device-specific ra_pages values are much bigger than 3).
Link: https://lkml.kernel.org/r/20231201161045.3962614-1-ryan.roberts@arm.com
Signed-off-by: Ryan Roberts <ryan.roberts@arm.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Use folio_prealloc() helper to simplify code a bit.
Link: https://lkml.kernel.org/r/20231118023232.1409103-6-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Use folio_prealloc() helper and convert to use a folio in do_cow_fault(),
which save five compound_head() calls.
Link: https://lkml.kernel.org/r/20231118023232.1409103-5-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Let's rename page_copy_prealloc() to folio_prealloc(), which could be
reused in more functons, as it maybe zero the new page, pass a new
need_zero to it, and call the vma_alloc_zeroed_movable_folio() if
need_zero is true.
Link: https://lkml.kernel.org/r/20231118023232.1409103-4-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Reviewed-by: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Use a folio in validate_page_before_insert() to save two compound_head()
calls.
Link: https://lkml.kernel.org/r/20231118023232.1409103-3-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Reviewed-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm: cleanup and use more folio in page fault", v3.
Rename page_copy_prealloc() to folio_prealloc(), which is used by more
functions, also do more folio conversion in page fault.
This patch (of 5):
Since ksm only support normal page, no swapout/in for ksm large folio too,
add large folio check in ksm_might_need_to_copy(), also convert
page->index to folio->index as page->index is going away.
Then convert ksm_might_need_to_copy() to use more folio api to save nine
compound_head() calls, short 'address' to reduce max-line-length.
Link: https://lkml.kernel.org/r/20231118023232.1409103-1-wangkefeng.wang@huawei.com
Link: https://lkml.kernel.org/r/20231118023232.1409103-2-wangkefeng.wang@huawei.com
Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Update DAMON sysfs usage for newly added DAMOS quota goals interface.
Link: https://lkml.kernel.org/r/20231130023652.50284-10-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Update DAMON ABI document for the newly added DAMON sysfs files and inputs
for DAMOS quota goals.
Link: https://lkml.kernel.org/r/20231130023652.50284-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Document the DAMOS quota auto tuning feature on the design document.
Link: https://lkml.kernel.org/r/20231130023652.50284-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Add DAMON selftests for testing creation/existence of quota goals
directories and files, and simple valid input writes.
Link: https://lkml.kernel.org/r/20231130023652.50284-7-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Implement a simple kunit test for testing the behavior of the feedback
loop algorithm for the aim-oriented feedback-friven DAMOS aggressiveness
auto tuning.
Link: https://lkml.kernel.org/r/20231130023652.50284-6-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
To update DAMOS quota goals, users need to enter 'commit' command to the
'state' file of the kdamond, which applies not only the goals but entire
inputs. It is inefficient. Implement yet another 'state' file input
command for reading and committing only the scheme quota goals, namely
'commit_schemes_quota_goals'.
Link: https://lkml.kernel.org/r/20231130023652.50284-5-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Make DAMON sysfs interface to read the user inputs for DAMOS quota goals
and pass those to DAMOS, so that the users can use the quota auto-tuning
feature. It uses the DAMON sysfs interface's user input commit mechanism,
which applies all user inputs for initial starting of DAMON and online
input updates, which can be done by writing 'on' and 'commit' to the
kdamond's 'state' file, respectively. In other words, the user should
periodically write appropriate value to 'current_value' files and 'commit'
command to the 'state' file. 'target_value' files could also be similarly
updated at any time.
Note that the interface is supporting multiple goals while the core logic
supports only one goal. DAMON sysfs interface passes only best feedback
among the given inputs, to avoid making DAMOS too aggressive.
Link: https://lkml.kernel.org/r/20231130023652.50284-4-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Implement DAMON sysfs directories and files for the goals of DAMOS quota.
Those allow users set multiple goals for their aim, with target values.
Users can further enter the current score value for each goal as feedback
for DAMOS.
Note that this commit is implementing only the basic file operations, and
not connecting the files with the DAMOS core logic. Hence writing
something to the files makes no real effect. The following commit will
connect the file operations and the core logic.
Link: https://lkml.kernel.org/r/20231130023652.50284-3-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Patch series "mm/damon: let users feed and tame/auto-tune DAMOS".
Introduce Aim-oriented Feedback-driven DAMOS Aggressiveness Auto-tuning.
It makes DAMOS self-tuned with periodic simple user feedback.
Background: DAMOS Control Difficulty
====================================
DAMOS helps users easily implement access pattern aware system operations.
However, controlling DAMOS in the wild is not that easy.
The basic way for DAMOS control is specifying the target access pattern.
In this approach, the user is assumed to well understand the access
pattern and the characteristics of the system and the workloads. Though
there are useful tools for that, it takes time and effort depending on the
complexity and the dynamicity of the system and the workloads. After all,
the access pattern consists of three ranges, namely the size, the access
rate, and the age of the regions. It means users need to tune six
parameters, which is anyway not a simple task.
One of the worst cases would be DAMOS being too aggressive like a
berserker, and therefore consuming too much system resource and making
unwanted radical system operations. To let users avoid such cases, DAMOS
allows users to set the upper-limit of the schemes' aggressiveness, namely
DAMOS quota. DAMOS further provides its best-effort under the limit by
prioritizing regions based on the access pattern of the regions. For
example, users can ask DAMOS to page out up to 100 MiB of memory regions
per second. Then DAMOS pages out regions that are not accessed for a
longer time (colder) first under the limit. This allows users to set the
target access pattern a bit naive with wider ranges, and focus on tuning
only one parameter, the quota. In other words, the number of parameters
to tune can be reduced from six to one.
Still, however, the optimum value for the quota depends on the system and
the workloads' characteristics, so not that simple. The number of
parameters to tune can also increase again if the user needs to run
multiple schemes.
Aim-oriented Feedback-driven DAMOS Aggressiveness Auto Tuning
=============================================================
Users would use DAMOS since they want to achieve something with it. They
will likely have measurable metrics representing the achievement and the
target number of the metric like SLO, and continuously measure that
anyway. While the additional cost of getting the information is nearly
zero, it could be useful for DAMOS to understand how appropriate its
current aggressiveness is set, and adjust it on its own to make the metric
value more close to the target.
Based on this idea, we introduce a new way of tuning DAMOS with nearly
zero additional effort, namely Aim-oriented Feedback-driven DAMOS
Aggressiveness Auto Tuning. It asks users to provide feedback
representing how well DAMOS is doing relative to the users' aim. Then
DAMOS adjusts its aggressiveness, specifically the quota that provides
the best effort result under the limit, based on the current level of
the aggressiveness and the users' feedback.
Implementation
==============
The implementation asks users to represent the feedback with score
numbers. The scores could be anything including user-space specific
metrics including latency and throughput of special user-space workloads,
and system metrics including free memory ratio, memory pressure stall time
(PSI), and active to inactive LRU lists size ratio. The feedback scores
and the aggressiveness of the given DAMOS scheme are assumed to be
positively proportional, though. Selecting metrics of the assumption is
the users' responsibility.
The core logic uses the below simple feedback loop algorithm to calculate
the next aggressiveness level of the scheme from the current
aggressiveness level and the current feedback (target_score and
current_score). It calculates the compensation for next aggressiveness as
a proportion of current aggressiveness and distance to the target score.
As a result, it arrives at the near-goal state in a short time using big
steps when it's far from the goal, but avoids making unnecessarily radical
changes that could turn out to be a bad decision using small steps when
its near to the goal.
f(n) = max(1, f(n - 1) * ((target_score - current_score) / target_score + 1))
Note that the compensation value becomes negative when it's over
achieving the goal. That's why the feedback metric and the
aggressiveness of the scheme should be positively proportional. The
distance-adaptive speed manipulation is simply applied.
Example Use Cases
=================
If users want to reduce the memory footprint of the system as much as
possible as long as the time spent for handling the resulting memory
pressure is within a threshold, they could use DAMOS scheme that reclaims
cold memory regions aiming for a little level of memory pressure stall
time.
If users want the active/inactive LRU lists well balanced to reduce the
performance impact due to possible future memory pressure, they could use
two schemes. The first one would be set to locate hot pages in the active
LRU list, aiming for a specific active-to-inactive LRU list size ratio,
say, 70%. The second one would be to locate cold pages in the inactive
LRU list, aiming for a specific inactive-to-active LRU list size ratio,
say, 30%. Then, DAMOS will balance the two schemes based on the goal and
feedback.
This aim-oriented auto tuning could also be useful for general
balancing-required access aware system operations such as system memory
auto scaling[3] and tiered memory management[4]. These two example usages
are not what current DAMOS implementation is already supporting, but
require additional DAMOS action developments, though.
Evaluation: subtle memory pressure aiming proactive reclamation
===============================================================
To show if the implementation works as expected, we prepare four different
system configurations on AWS i3.metal instances. The first setup
(original) runs the workload without any DAMOS scheme. The second setup
(not-tuned) runs the workload with a virtual address space-based proactive
reclamation scheme that pages out memory regions that are not accessed for
five seconds or more. The third setup (offline-tuned) runs the same
proactive reclamation DAMOS scheme, but after making it tuned for each
workload offline, using our previous user-space driven automatic tuning
approach, namely DAMOOS[1]. The fourth and final setup (AFDAA) runs the
scheme that is the same as that of 'not-tuned' setup, but aims to keep
0.5% of 'some' memory pressure stall time (PSI) for the last 10 seconds
using the aiming-oriented auto tuning.
For each setup, we run realistic workloads from PARSEC3 and SPLASH-2X
benchmark suites. For each run, we measure RSS and runtime of the
workload, and 'some' memory pressure stall time (PSI) of the system. We
repeat the runs five times and use averaged measurements.
For simple comparison of the results, we normalize the measurements to
those of 'original'. In the case of the PSI, though, the measurement for
'original' was zero, so we normalize the value to that of 'not-tuned'
scheme's result. The normalized results are shown below.
Not-tuned Offline-tuned AFDAA
RSS 0.622688178226118 0.787950678944904 0.740093483278979
runtime 1.11767826657912 1.0564674983585 1.0910833880499
PSI 1 0.727521443794069 0.308498846350299
The 'not-tuned' scheme achieves about 38.7% memory saving but incur about
11.7% runtime slowdown. The 'offline-tuned' scheme achieves about 22.2%
memory saving with about 5.5% runtime slowdown. It also achieves about
28.2% memory pressure stall time saving. AFDAA achieves about 26% memory
saving with about 9.1% runtime slowdown. It also achieves about 69.1%
memory pressure stall time saving. We repeat this test multiple times,
and get consistent results. AFDAA is now integrated in our daily DAMON
performance test setup.
Apparently the aggressiveness of 'AFDAA' setup is somewhere between those
of 'not-tuned' and 'offline-tuned' setup, since its memory saving and
runtime overhead are between those of the other two setups. Actually we
set the memory pressure stall time goal aiming for this middle
aggressiveness. The difference in the two metrics are not significant,
though. However, it shows significant saving of the memory pressure stall
time, which was the goal of the auto-tuning, over the two variants.
Hence, we conclude the automatic tuning is working as expected.
Please note that the AFDAA setup is only for the evaluation, and
therefore intentionally set a bit aggressive. It might not be
appropriate for production environments.
The test code is also available[2], so you could reproduce it on your
system and workloads.
Patches Sequence
================
The first four patches implement the core logic and user interfaces for
the auto tuning. The first patch implements the core logic for the auto
tuning, and the API for DAMOS users in the kernel space. The second
patch implements basic file operations of DAMON sysfs directories and
files that will be used for setting the goals and providing the
feedback. The third patch connects the quota goals files inputs to the
DAMOS core logic. Finally the fourth patch implements a dedicated DAMOS
sysfs command for efficiently committing the quota goals feedback.
Two patches for simple tests of the logic and interfaces follow. The
fifth patch implements the core logic unit test. The sixth patch
implements a selftest for the DAMON Sysfs interface for the goals.
Finally, three patches for documentation follows. The seventh patch
documents the design of the feature. The eighth patch updates the API
doc for the new sysfs files. The final eighth patch updates the usage
document for the features.
References
==========
[1] DAOS paper:
https://www.amazon.science/publications/daos-data-access-aware-operating-system
[2] Evaluation code:
https://github.com/damonitor/damon-tests/commit/3f884e61193f0166b8724554b6d06b0c449a712d
[3] Memory auto scaling RFC idea:
https://lore.kernel.org/damon/20231112195114.61474-1-sj@kernel.org/
[4] DAMON-based tiered memory management RFC idea:
https://lore.kernel.org/damon/20231112195602.61525-1-sj@kernel.org/
This patch (of 9)
Users can effectively control the upper-limit aggressiveness of DAMOS
schemes using the quota feature. The quota provides best result under the
limit by prioritizing regions based on the access pattern. That said,
finding the best value, which could depend on dynamic characteristics of
the system and the workloads, is still challenging.
Implement a simple feedback-driven tuning mechanism and use it for
automatic tuning of DAMOS quota. The implementation allows users to
provide the feedback by setting a feedback score returning callback
function. Then DAMOS periodically calls the function back and adjusts the
quota based on the return value of the callback and current quota value.
Note that the absolute-value based time/size quotas still work as the
maximum hard limits of the scheme's aggressiveness. The feedback-driven
auto-tuned quota is applied only if it is not exceeding the manually set
maximum limits. Same for the scheme-target access pattern and filters
like other features.
[sj@kernel.org: document get_score_arg field of struct damos_quota]
Link: https://lkml.kernel.org/r/20231204170106.60992-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20231130023652.50284-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20231130023652.50284-2-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Brendan Higgins <brendanhiggins@google.com>
Cc: David Gow <davidgow@google.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
ksm functional test is already being run. Remove the duplicate call to
./ksm_functional_tests.
Link: https://lkml.kernel.org/r/20231129221140.614713-1-npache@redhat.com
Fixes: 93fb70aa5904 ("selftests/vm: add KSM unmerge tests")
Signed-off-by: Nico Pache <npache@redhat.com>
Acked-by: Joel Savitz <jsavitz@redhat.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
Currently, we only shrink the zswap pool when the user-defined limit is
hit. This means that if we set the limit too high, cold data that are
unlikely to be used again will reside in the pool, wasting precious
memory. It is hard to predict how much zswap space will be needed ahead
of time, as this depends on the workload (specifically, on factors such as
memory access patterns and compressibility of the memory pages).
This patch implements a memcg- and NUMA-aware shrinker for zswap, that is
initiated when there is memory pressure. The shrinker does not have any
parameter that must be tuned by the user, and can be opted in or out on a
per-memcg basis.
Furthermore, to make it more robust for many workloads and prevent
overshrinking (i.e evicting warm pages that might be refaulted into
memory), we build in the following heuristics:
* Estimate the number of warm pages residing in zswap, and attempt to
protect this region of the zswap LRU.
* Scale the number of freeable objects by an estimate of the memory
saving factor. The better zswap compresses the data, the fewer pages
we will evict to swap (as we will otherwise incur IO for relatively
small memory saving).
* During reclaim, if the shrinker encounters a page that is also being
brought into memory, the shrinker will cautiously terminate its
shrinking action, as this is a sign that it is touching the warmer
region of the zswap LRU.
As a proof of concept, we ran the following synthetic benchmark: build the
linux kernel in a memory-limited cgroup, and allocate some cold data in
tmpfs to see if the shrinker could write them out and improved the overall
performance. Depending on the amount of cold data generated, we observe
from 14% to 35% reduction in kernel CPU time used in the kernel builds.
[nphamcs@gmail.com: check shrinker enablement early, use less costly stat flushing]
Link: https://lkml.kernel.org/r/20231206194456.3234203-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20231130194023.4102148-7-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Cc: Chengming Zhou <chengming.zhou@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The memcg-zswap self test is updated to adjust to the behavior change
implemented by commit 87730b165089 ("zswap: make shrinking memcg-aware"),
where zswap performs writeback for specific memcg.
Link: https://lkml.kernel.org/r/20231130194023.4102148-6-nphamcs@gmail.com
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Acked-by: Chris Li <chrisl@kernel.org> (Google)
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Since zswap now writes back pages from memcg-specific LRUs, we now need a
new stat to show writebacks count for each memcg.
[nphamcs@gmail.com: rename ZSWP_WB to ZSWPWB]
Link: https://lkml.kernel.org/r/20231205193307.2432803-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20231130194023.4102148-5-nphamcs@gmail.com
Suggested-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Currently, we only have a single global LRU for zswap. This makes it
impossible to perform worload-specific shrinking - an memcg cannot
determine which pages in the pool it owns, and often ends up writing pages
from other memcgs. This issue has been previously observed in practice
and mitigated by simply disabling memcg-initiated shrinking:
https://lore.kernel.org/all/20230530232435.3097106-1-nphamcs@gmail.com/T/#u
This patch fully resolves the issue by replacing the global zswap LRU
with memcg- and NUMA-specific LRUs, and modify the reclaim logic:
a) When a store attempt hits an memcg limit, it now triggers a
synchronous reclaim attempt that, if successful, allows the new
hotter page to be accepted by zswap.
b) If the store attempt instead hits the global zswap limit, it will
trigger an asynchronous reclaim attempt, in which an memcg is
selected for reclaim in a round-robin-like fashion.
[nphamcs@gmail.com: use correct function for the onlineness check, use mem_cgroup_iter_break()]
Link: https://lkml.kernel.org/r/20231205195419.2563217-1-nphamcs@gmail.com
[nphamcs@gmail.com: drop the pool's reference at the end of the writeback step]
Link: https://lkml.kernel.org/r/20231206030627.4155634-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20231130194023.4102148-4-nphamcs@gmail.com
Signed-off-by: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Co-developed-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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This patch implements a helper function that try to get a reference to an
memcg's css, as well as checking if it is online. This new function is
almost exactly the same as the existing mem_cgroup_tryget(), except for
the onlineness check. In the !CONFIG_MEMCG case, it always returns true,
analogous to mem_cgroup_tryget(). This is useful for e.g to the new zswap
writeback scheme, where we need to select the next online memcg as a
candidate for the global limit reclaim.
Link: https://lkml.kernel.org/r/20231130194023.4102148-3-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Reviewed-by: Yosry Ahmed <yosryahmed@google.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "workload-specific and memory pressure-driven zswap
writeback", v8.
There are currently several issues with zswap writeback:
1. There is only a single global LRU for zswap, making it impossible to
perform worload-specific shrinking - an memcg under memory pressure
cannot determine which pages in the pool it owns, and often ends up
writing pages from other memcgs. This issue has been previously
observed in practice and mitigated by simply disabling
memcg-initiated shrinking:
https://lore.kernel.org/all/20230530232435.3097106-1-nphamcs@gmail.com/T/#u
But this solution leaves a lot to be desired, as we still do not
have an avenue for an memcg to free up its own memory locked up in
the zswap pool.
2. We only shrink the zswap pool when the user-defined limit is hit.
This means that if we set the limit too high, cold data that are
unlikely to be used again will reside in the pool, wasting precious
memory. It is hard to predict how much zswap space will be needed
ahead of time, as this depends on the workload (specifically, on
factors such as memory access patterns and compressibility of the
memory pages).
This patch series solves these issues by separating the global zswap LRU
into per-memcg and per-NUMA LRUs, and performs workload-specific (i.e
memcg- and NUMA-aware) zswap writeback under memory pressure. The new
shrinker does not have any parameter that must be tuned by the user, and
can be opted in or out on a per-memcg basis.
As a proof of concept, we ran the following synthetic benchmark: build the
linux kernel in a memory-limited cgroup, and allocate some cold data in
tmpfs to see if the shrinker could write them out and improved the overall
performance. Depending on the amount of cold data generated, we observe
from 14% to 35% reduction in kernel CPU time used in the kernel builds.
This patch (of 6):
The interface of list_lru is based on the assumption that the list node
and the data it represents belong to the same allocated on the correct
node/memcg. While this assumption is valid for existing slab objects LRU
such as dentries and inodes, it is undocumented, and rather inflexible for
certain potential list_lru users (such as the upcoming zswap shrinker and
the THP shrinker). It has caused us a lot of issues during our
development.
This patch changes list_lru interface so that the caller must explicitly
specify numa node and memcg when adding and removing objects. The old
list_lru_add() and list_lru_del() are renamed to list_lru_add_obj() and
list_lru_del_obj(), respectively.
It also extends the list_lru API with a new function, list_lru_putback,
which undoes a previous list_lru_isolate call. Unlike list_lru_add, it
does not increment the LRU node count (as list_lru_isolate does not
decrement the node count). list_lru_putback also allows for explicit
memcg and NUMA node selection.
Link: https://lkml.kernel.org/r/20231130194023.4102148-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20231130194023.4102148-2-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Now it seems that the incoming 'end' is already pointing to the last item,
so we can simplify this function, considering only whether the last slot
is being used. This has passed the maple tree test suite.
Link: https://lkml.kernel.org/r/20231120070937.35481-6-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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There are two identical checks, delete one of them.
Link: https://lkml.kernel.org/r/20231120070937.35481-5-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The parameter maple_type is not used, so remove it.
Link: https://lkml.kernel.org/r/20231120070937.35481-4-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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When the child node is the first child of its parent node, mas->min does
not need to be updated. This can reduce the number of ascending times
in some cases.
Link: https://lkml.kernel.org/r/20231120070937.35481-3-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Dan Carpenter <dan.carpenter@linaro.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Patch series "Some cleanups of maple tree", v2.
These are some small cleanups of maple tree.
This patch (of 5):
Put the check for gap before its reference to avoid Smatch static check
warnings. This is not a bug, it's just a validation program. Even with
this change, Smatch may still generate warnings because MT_BUG_ON()
doesn't necessarily stop the program. It may require fixing Smatch itself
to avoid these warnings.
Link: https://lkml.kernel.org/r/20231120070937.35481-1-zhangpeng.00@bytedance.com
Link: https://lkml.kernel.org/r/20231120070937.35481-2-zhangpeng.00@bytedance.com
Signed-off-by: Peng Zhang <zhangpeng.00@bytedance.com>
Reported-by: Dan Carpenter <dan.carpenter@linaro.org>
Closes: http://lists.infradead.org/pipermail/maple-tree/2023-November/003046.html
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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The function are defined in the maple_tree.c file, but not called
elsewhere, so delete the unused function.
lib/maple_tree.c:689:29: warning: unused function 'mas_pivot'.
Link: https://lkml.kernel.org/r/20231027084944.24888-1-jiapeng.chong@linux.alibaba.com
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Closes: https://bugzilla.openanolis.cn/show_bug.cgi?id=7064
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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mtree_range_walk() needed to be updated to avoid checking if there was a
pivot value. On closer examination, the code could avoid setting min or
max in certain scenarios. The commit removes the extra check for
pivot[offset] before setting max and only sets max when necessary. It
also only sets min if it is necessary by checking offset 0 prior to the
loop (as it has always done).
The commit also drops a dead node check since the end of the node will
return the array size when the last slot is occupied (by a potential reuse
in a dead node). The data will be discarded later if the node is marked
dead.
Benchmarking these changes results in an increase in performance of 5.45%
using the BENCH_WALK in the maple tree test code.
Link: https://lkml.kernel.org/r/20231101171629.3612299-13-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Since the pivot being set is now reliable, the optimized loop no longer
needs to find the node end. The redundant check for a dead node can also
be avoided as there is no danger of using the wrong pivot since the
results will be thrown out in the case of a dead node by the later check.
This patch also adds a benchmark test for the function to the maple tree
test framework. The benchmark shows an average increase performance of
5.98% over 3 runs with this commit.
Link: https://lkml.kernel.org/r/20231101171629.3612299-12-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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ma_wr_state was previously tracking the end of the node for writing.
Since the implementation of the ma_state end tracking, this is duplicated
work. This patch removes the maple write state tracking of the end of the
node and uses the maple state end instead.
Link: https://lkml.kernel.org/r/20231101171629.3612299-11-Liam.Howlett@oracle.com
Signed-off-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Peng Zhang <zhangpeng.00@bytedance.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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