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[ Upstream commit 190a8c48ff623c3d67cb295b4536a660db2012aa ]
During futex_key_to_node_opt() execution, vma->vm_policy is read under
speculative mmap lock and RCU. Concurrently, mbind() may call
vma_replace_policy() which frees the old mempolicy immediately via
kmem_cache_free().
This creates a race where __futex_key_to_node() dereferences a freed
mempolicy pointer, causing a use-after-free read of mpol->mode.
[ 151.412631] BUG: KASAN: slab-use-after-free in __futex_key_to_node (kernel/futex/core.c:349)
[ 151.414046] Read of size 2 at addr ffff888001c49634 by task e/87
[ 151.415969] Call Trace:
[ 151.416732] __asan_load2 (mm/kasan/generic.c:271)
[ 151.416777] __futex_key_to_node (kernel/futex/core.c:349)
[ 151.416822] get_futex_key (kernel/futex/core.c:374 kernel/futex/core.c:386 kernel/futex/core.c:593)
Fix by adding rcu to __mpol_put().
Fixes: c042c505210d ("futex: Implement FUTEX2_MPOL")
Reported-by: Hao-Yu Yang <naup96721@gmail.com>
Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Hao-Yu Yang <naup96721@gmail.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Link: https://patch.msgid.link/20260324174418.GB1850007@noisy.programming.kicks-ass.net
Signed-off-by: Sasha Levin <sashal@kernel.org>
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commit 26f775a054c3cda86ad465a64141894a90a9e145 upstream.
One major usage of damon_call() is online DAMON parameters update. It is
done by calling damon_commit_ctx() inside the damon_call() callback
function. damon_commit_ctx() can fail for two reasons: 1) invalid
parameters and 2) internal memory allocation failures. In case of
failures, the damon_ctx that attempted to be updated (commit destination)
can be partially updated (or, corrupted from a perspective), and therefore
shouldn't be used anymore. The function only ensures the damon_ctx object
can safely deallocated using damon_destroy_ctx().
The API callers are, however, calling damon_commit_ctx() only after
asserting the parameters are valid, to avoid damon_commit_ctx() fails due
to invalid input parameters. But it can still theoretically fail if the
internal memory allocation fails. In the case, DAMON may run with the
partially updated damon_ctx. This can result in unexpected behaviors
including even NULL pointer dereference in case of damos_commit_dests()
failure [1]. Such allocation failure is arguably too small to fail, so
the real world impact would be rare. But, given the bad consequence, this
needs to be fixed.
Avoid such partially-committed (maybe-corrupted) damon_ctx use by saving
the damon_commit_ctx() failure on the damon_ctx object. For this,
introduce damon_ctx->maybe_corrupted field. damon_commit_ctx() sets it
when it is failed. kdamond_call() checks if the field is set after each
damon_call_control->fn() is executed. If it is set, ignore remaining
callback requests and return. All kdamond_call() callers including
kdamond_fn() also check the maybe_corrupted field right after
kdamond_call() invocations. If the field is set, break the kdamond_fn()
main loop so that DAMON sill doesn't use the context that might be
corrupted.
[sj@kernel.org: let kdamond_call() with cancel regardless of maybe_corrupted]
Link: https://lkml.kernel.org/r/20260320031553.2479-1-sj@kernel.org
Link: https://sashiko.dev/#/patchset/20260319145218.86197-1-sj%40kernel.org
Link: https://lkml.kernel.org/r/20260319145218.86197-1-sj@kernel.org
Link: https://lore.kernel.org/20260319043309.97966-1-sj@kernel.org [1]
Fixes: 3301f1861d34 ("mm/damon/sysfs: handle commit command using damon_call()")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [6.15+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 3b89863c3fa482912911cd65a12a3aeef662c250 upstream.
The splitting of a PUD entry in walk_pud_range() can race with a
concurrent thread refaulting the PUD leaf entry causing it to try walking
a PMD range that has disappeared.
An example and reproduction of this is to try reading numa_maps of a
process while VFIO-PCI is setting up DMA (specifically the
vfio_pin_pages_remote call) on a large BAR for that process.
This will trigger a kernel BUG:
vfio-pci 0000:03:00.0: enabling device (0000 -> 0002)
BUG: unable to handle page fault for address: ffffa23980000000
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP NOPTI
...
RIP: 0010:walk_pgd_range+0x3b5/0x7a0
Code: 8d 43 ff 48 89 44 24 28 4d 89 ce 4d 8d a7 00 00 20 00 48 8b 4c 24
28 49 81 e4 00 00 e0 ff 49 8d 44 24 ff 48 39 c8 4c 0f 43 e3 <49> f7 06
9f ff ff ff 75 3b 48 8b 44 24 20 48 8b 40 28 48 85 c0 74
RSP: 0018:ffffac23e1ecf808 EFLAGS: 00010287
RAX: 00007f44c01fffff RBX: 00007f4500000000 RCX: 00007f44ffffffff
RDX: 0000000000000000 RSI: 000ffffffffff000 RDI: ffffffff93378fe0
RBP: ffffac23e1ecf918 R08: 0000000000000004 R09: ffffa23980000000
R10: 0000000000000020 R11: 0000000000000004 R12: 00007f44c0200000
R13: 00007f44c0000000 R14: ffffa23980000000 R15: 00007f44c0000000
FS: 00007fe884739580(0000) GS:ffff9b7d7a9c0000(0000)
knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: ffffa23980000000 CR3: 000000c0650e2005 CR4: 0000000000770ef0
PKRU: 55555554
Call Trace:
<TASK>
__walk_page_range+0x195/0x1b0
walk_page_vma+0x62/0xc0
show_numa_map+0x12b/0x3b0
seq_read_iter+0x297/0x440
seq_read+0x11d/0x140
vfs_read+0xc2/0x340
ksys_read+0x5f/0xe0
do_syscall_64+0x68/0x130
? get_page_from_freelist+0x5c2/0x17e0
? mas_store_prealloc+0x17e/0x360
? vma_set_page_prot+0x4c/0xa0
? __alloc_pages_noprof+0x14e/0x2d0
? __mod_memcg_lruvec_state+0x8d/0x140
? __lruvec_stat_mod_folio+0x76/0xb0
? __folio_mod_stat+0x26/0x80
? do_anonymous_page+0x705/0x900
? __handle_mm_fault+0xa8d/0x1000
? __count_memcg_events+0x53/0xf0
? handle_mm_fault+0xa5/0x360
? do_user_addr_fault+0x342/0x640
? arch_exit_to_user_mode_prepare.constprop.0+0x16/0xa0
? irqentry_exit_to_user_mode+0x24/0x100
entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0033:0x7fe88464f47e
Code: c0 e9 b6 fe ff ff 50 48 8d 3d be 07 0b 00 e8 69 01 02 00 66 0f 1f
84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 0f 05 <48> 3d 00
f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28
RSP: 002b:00007ffe6cd9a9b8 EFLAGS: 00000246 ORIG_RAX: 0000000000000000
RAX: ffffffffffffffda RBX: 0000000000020000 RCX: 00007fe88464f47e
RDX: 0000000000020000 RSI: 00007fe884543000 RDI: 0000000000000003
RBP: 00007fe884543000 R08: 00007fe884542010 R09: 0000000000000000
R10: fffffffffffffbc5 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000003 R14: 0000000000020000 R15: 0000000000020000
</TASK>
Fix this by validating the PUD entry in walk_pmd_range() using a stable
snapshot (pudp_get()). If the PUD is not present or is a leaf, retry the
walk via ACTION_AGAIN instead of descending further. This mirrors the
retry logic in walk_pte_range(), which lets walk_pmd_range() retry if the
PTE is not being got by pte_offset_map_lock().
Link: https://lkml.kernel.org/r/20260325-pagewalk-check-pmd-refault-v2-1-707bff33bc60@akamai.com
Fixes: f9e54c3a2f5b ("vfio/pci: implement huge_fault support")
Co-developed-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Signed-off-by: Max Boone <mboone@akamai.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 6557004a8b59c7701e695f02be03c7e20ed1cc15 upstream.
damon_sysfs_repeat_call_fn() calls damon_sysfs_upd_tuned_intervals(),
damon_sysfs_upd_schemes_stats(), and
damon_sysfs_upd_schemes_effective_quotas() without checking contexts->nr.
If nr_contexts is set to 0 via sysfs while DAMON is running, these
functions dereference contexts_arr[0] and cause a NULL pointer
dereference. Add the missing check.
For example, the issue can be reproduced using DAMON sysfs interface and
DAMON user-space tool (damo) [1] like below.
$ sudo damo start --refresh_interval 1s
$ echo 0 | sudo tee \
/sys/kernel/mm/damon/admin/kdamonds/0/contexts/nr_contexts
Link: https://patch.msgid.link/20260320163559.178101-3-objecting@objecting.org
Link: https://lkml.kernel.org/r/20260321175427.86000-4-sj@kernel.org
Link: https://github.com/damonitor/damo [1]
Fixes: d809a7c64ba8 ("mm/damon/sysfs: implement refresh_ms file internal work")
Signed-off-by: Josh Law <objecting@objecting.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [6.17+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 1bfe9fb5ed2667fb075682408b776b5273162615 upstream.
Multiple sysfs command paths dereference contexts_arr[0] without first
verifying that kdamond->contexts->nr == 1. A user can set nr_contexts to
0 via sysfs while DAMON is running, causing NULL pointer dereferences.
In more detail, the issue can be triggered by privileged users like
below.
First, start DAMON and make contexts directory empty
(kdamond->contexts->nr == 0).
# damo start
# cd /sys/kernel/mm/damon/admin/kdamonds/0
# echo 0 > contexts/nr_contexts
Then, each of below commands will cause the NULL pointer dereference.
# echo update_schemes_stats > state
# echo update_schemes_tried_regions > state
# echo update_schemes_tried_bytes > state
# echo update_schemes_effective_quotas > state
# echo update_tuned_intervals > state
Guard all commands (except OFF) at the entry point of
damon_sysfs_handle_cmd().
Link: https://lkml.kernel.org/r/20260321175427.86000-3-sj@kernel.org
Fixes: 0ac32b8affb5 ("mm/damon/sysfs: support DAMOS stats")
Signed-off-by: Josh Law <objecting@objecting.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [5.18+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 7fe000eb32904758a85e62f6ea9483f89d5dabfc upstream.
Patch series "mm/damon/sysfs: fix memory leak and NULL dereference
issues", v4.
DAMON_SYSFS can leak memory under allocation failure, and do NULL pointer
dereference when a privileged user make wrong sequences of control. Fix
those.
This patch (of 3):
When damon_sysfs_new_test_ctx() fails in damon_sysfs_commit_input(),
param_ctx is leaked because the early return skips the cleanup at the out
label. Destroy param_ctx before returning.
Link: https://lkml.kernel.org/r/20260321175427.86000-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20260321175427.86000-2-sj@kernel.org
Fixes: f0c5118ebb0e ("mm/damon/sysfs: catch commit test ctx alloc failure")
Signed-off-by: Josh Law <objecting@objecting.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [6.18+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 2697dd8ae721db4f6a53d4f4cbd438212a80f8dc upstream.
Previously we stored the end of the current VMA in curr_end, and then upon
iterating to the next VMA updated curr_start to curr_end to advance to the
next VMA.
However, this doesn't take into account the fact that a VMA might be
updated due to a merge by vma_modify_flags(), which can result in curr_end
being stale and thus, upon setting curr_start to curr_end, ending up with
an incorrect curr_start on the next iteration.
Resolve the issue by setting curr_end to vma->vm_end unconditionally to
ensure this value remains updated should this occur.
While we're here, eliminate this entire class of bug by simply setting
const curr_[start/end] to be clamped to the input range and VMAs, which
also happens to simplify the logic.
Link: https://lkml.kernel.org/r/20260327173104.322405-1-ljs@kernel.org
Fixes: 6c2da14ae1e0 ("mm/mseal: rework mseal apply logic")
Signed-off-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Reported-by: Antonius <antonius@bluedragonsec.com>
Closes: https://lore.kernel.org/linux-mm/CAK8a0jwWGj9-SgFk0yKFh7i8jMkwKm5b0ao9=kmXWjO54veX2g@mail.gmail.com/
Suggested-by: David Hildenbrand (ARM) <david@kernel.org>
Acked-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Reviewed-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Jann Horn <jannh@google.com>
Cc: Jeff Xu <jeffxu@chromium.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit ffef67b93aa352b34e6aeba3d52c19a63885409a upstream.
follow_pfnmap_start() suffers from two problems:
(1) We are not re-fetching the pmd/pud after taking the PTL
Therefore, we are not properly stabilizing what the lock actually
protects. If there is concurrent zapping, we would indicate to the
caller that we found an entry, however, that entry might already have
been invalidated, or contain a different PFN after taking the lock.
Properly use pmdp_get() / pudp_get() after taking the lock.
(2) pmd_leaf() / pud_leaf() are not well defined on non-present entries
pmd_leaf()/pud_leaf() could wrongly trigger on non-present entries.
There is no real guarantee that pmd_leaf()/pud_leaf() returns something
reasonable on non-present entries. Most architectures indeed either
perform a present check or make it work by smart use of flags.
However, for example loongarch checks the _PAGE_HUGE flag in pmd_leaf(),
and always sets the _PAGE_HUGE flag in __swp_entry_to_pmd(). Whereby
pmd_trans_huge() explicitly checks pmd_present(), pmd_leaf() does not do
that.
Let's check pmd_present()/pud_present() before assuming "the is a present
PMD leaf" when spotting pmd_leaf()/pud_leaf(), like other page table
handling code that traverses user page tables does.
Given that non-present PMD entries are likely rare in VM_IO|VM_PFNMAP, (1)
is likely more relevant than (2). It is questionable how often (1) would
actually trigger, but let's CC stable to be sure.
This was found by code inspection.
Link: https://lkml.kernel.org/r/20260323-follow_pfnmap_fix-v1-1-5b0ec10872b3@kernel.org
Fixes: 6da8e9634bb7 ("mm: new follow_pfnmap API")
Signed-off-by: David Hildenbrand (Arm) <david@kernel.org>
Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 84481e705ab07ed46e56587fe846af194acacafe upstream.
DAMON_STAT usage document (Documentation/admin-guide/mm/damon/stat.rst)
says it monitors the system's entire physical memory. But, it is
monitoring only the biggest System RAM resource of the system. When there
are multiple System RAM resources, this results in monitoring only an
unexpectedly small fraction of the physical memory. For example, suppose
the system has a 500 GiB System RAM, 10 MiB non-System RAM, and 500 GiB
System RAM resources in order on the physical address space. DAMON_STAT
will monitor only the first 500 GiB System RAM. This situation is
particularly common on NUMA systems.
Select a physical address range that covers all System RAM areas of the
system, to fix this issue and make it work as documented.
[sj@kernel.org: return error if monitoring target region is invalid]
Link: https://lkml.kernel.org/r/20260317053631.87907-1-sj@kernel.org
Link: https://lkml.kernel.org/r/20260316235118.873-1-sj@kernel.org
Fixes: 369c415e6073 ("mm/damon: introduce DAMON_STAT module")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [6.17+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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shared THP
commit 939080834fef3ce42fdbcfef33fd29c9ffe5bbed upstream.
Commit 60fbb14396d5 ("mm/huge_memory: adjust try_to_migrate_one() and
split_huge_pmd_locked()") return false unconditionally after
split_huge_pmd_locked(). This may fail try_to_migrate() early when
TTU_SPLIT_HUGE_PMD is specified.
The reason is the above commit adjusted try_to_migrate_one() to, when a
PMD-mapped THP entry is found, and TTU_SPLIT_HUGE_PMD is specified (for
example, via unmap_folio()), return false unconditionally. This breaks
the rmap walk and fail try_to_migrate() early, if this PMD-mapped THP is
mapped in multiple processes.
The user sensible impact of this bug could be:
* On memory pressure, shrink_folio_list() may split partially mapped
folio with split_folio_to_list(). Then free unmapped pages without IO.
If failed, it may not be reclaimed.
* On memory failure, memory_failure() would call try_to_split_thp_page()
to split folio contains the bad page. If succeed, the PG_has_hwpoisoned
bit is only set in the after-split folio contains @split_at. By doing
so, we limit bad memory. If failed to split, the whole folios is not
usable.
One way to reproduce:
Create an anonymous THP range and fork 512 children, so we have a
THP shared mapped in 513 processes. Then trigger folio split with
/sys/kernel/debug/split_huge_pages debugfs to split the THP folio to
order 0.
Without the above commit, we can successfully split to order 0. With the
above commit, the folio is still a large folio.
And currently there are two core users of TTU_SPLIT_HUGE_PMD:
* try_to_unmap_one()
* try_to_migrate_one()
try_to_unmap_one() would restart the rmap walk, so only
try_to_migrate_one() is affected.
We can't simply revert commit 60fbb14396d5 ("mm/huge_memory: adjust
try_to_migrate_one() and split_huge_pmd_locked()"), since it removed some
duplicated check covered by page_vma_mapped_walk().
This patch fixes this by restart page_vma_mapped_walk() after
split_huge_pmd_locked(). Since we cannot simply return "true" to fix the
problem, as that would affect another case:
When invoking folio_try_share_anon_rmap_pmd() from
split_huge_pmd_locked(), the latter can fail and leave a large folio
mapped through PTEs, in which case we ought to return true from
try_to_migrate_one(). This might result in unnecessary walking of the
rmap but is relatively harmless.
Link: https://lkml.kernel.org/r/20260305015006.27343-1-richard.weiyang@gmail.com
Fixes: 60fbb14396d5 ("mm/huge_memory: adjust try_to_migrate_one() and split_huge_pmd_locked()")
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Reviewed-by: Zi Yan <ziy@nvidia.com>
Tested-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Gavin Guo <gavinguo@igalia.com>
Acked-by: David Hildenbrand (arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes (Oracle) <ljs@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit fae654083bfa409bb2244f390232e2be47f05bfc upstream.
move_pages_huge_pmd() handles UFFDIO_MOVE for both normal THPs and huge
zero pages. For the huge zero page path, src_folio is explicitly set to
NULL, and is used as a sentinel to skip folio operations like lock and
rmap.
In the huge zero page branch, src_folio is NULL, so folio_mk_pmd(NULL,
pgprot) passes NULL through folio_pfn() and page_to_pfn(). With
SPARSEMEM_VMEMMAP this silently produces a bogus PFN, installing a PMD
pointing to non-existent physical memory. On other memory models it is a
NULL dereference.
Use page_folio(src_page) to obtain the valid huge zero folio from the
page, which was obtained from pmd_page() and remains valid throughout.
After commit d82d09e48219 ("mm/huge_memory: mark PMD mappings of the huge
zero folio special"), moved huge zero PMDs must remain special so
vm_normal_page_pmd() continues to treat them as special mappings.
move_pages_huge_pmd() currently reconstructs the destination PMD in the
huge zero page branch, which drops PMD state such as pmd_special() on
architectures with CONFIG_ARCH_HAS_PTE_SPECIAL. As a result,
vm_normal_page_pmd() can treat the moved huge zero PMD as a normal page
and corrupt its refcount.
Instead of reconstructing the PMD from the folio, derive the destination
entry from src_pmdval after pmdp_huge_clear_flush(), then handle the PMD
metadata the same way move_huge_pmd() does for moved entries by marking it
soft-dirty and clearing uffd-wp.
Link: https://lkml.kernel.org/r/a1e787dd-b911-474d-8570-f37685357d86@lucifer.local
Fixes: e3981db444a0 ("mm: add folio_mk_pmd()")
Signed-off-by: Chris Down <chris@chrisdown.name>
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Tested-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 29f40594a28114b9a9bc87f6cf7bbee9609628f2 upstream.
We batch unmap anonymous lazyfree folios by folio_unmap_pte_batch. If the
batch has a mix of writable and non-writable bits, we may end up setting
the entire batch writable. Fix this by respecting writable bit during
batching.
Although on a successful unmap of a lazyfree folio, the soft-dirty bit is
lost, preserve it on pte restoration by respecting the bit during
batching, to make the fix consistent w.r.t both writable bit and
soft-dirty bit.
I was able to write the below reproducer and crash the kernel.
Explanation of reproducer (set 64K mTHP to always):
Fault in a 64K large folio. Split the VMA at mid-point with
MADV_DONTFORK. fork() - parent points to the folio with 8 writable ptes
and 8 non-writable ptes. Merge the VMAs with MADV_DOFORK so that
folio_unmap_pte_batch() can determine all the 16 ptes as a batch. Do
MADV_FREE on the range to mark the folio as lazyfree. Write to the memory
to dirty the pte, eventually rmap will dirty the folio. Then trigger
reclaim, we will hit the pte restoration path, and the kernel will crash
with the trace given below.
The BUG happens at:
BUG_ON(atomic_inc_return(&ptc->anon_map_count) > 1 && rw);
The code path is asking for anonymous page to be mapped writable into the
pagetable. The BUG_ON() firing implies that such a writable page has been
mapped into the pagetables of more than one process, which breaks
anonymous memory/CoW semantics.
[ 21.134473] kernel BUG at mm/page_table_check.c:118!
[ 21.134497] Internal error: Oops - BUG: 00000000f2000800 [#1] SMP
[ 21.135917] Modules linked in:
[ 21.136085] CPU: 1 UID: 0 PID: 1735 Comm: dup-lazyfree Not tainted 7.0.0-rc1-00116-g018018a17770 #1028 PREEMPT
[ 21.136858] Hardware name: linux,dummy-virt (DT)
[ 21.137019] pstate: 21400005 (nzCv daif +PAN -UAO -TCO +DIT -SSBS BTYPE=--)
[ 21.137308] pc : page_table_check_set+0x28c/0x2a8
[ 21.137607] lr : page_table_check_set+0x134/0x2a8
[ 21.137885] sp : ffff80008a3b3340
[ 21.138124] x29: ffff80008a3b3340 x28: fffffdffc3d14400 x27: ffffd1a55e03d000
[ 21.138623] x26: 0040000000000040 x25: ffffd1a55f7dd000 x24: 0000000000000001
[ 21.139045] x23: 0000000000000001 x22: 0000000000000001 x21: ffffd1a55f217f30
[ 21.139629] x20: 0000000000134521 x19: 0000000000134519 x18: 005c43e000040000
[ 21.140027] x17: 0001400000000000 x16: 0001700000000000 x15: 000000000000ffff
[ 21.140578] x14: 000000000000000c x13: 005c006000000000 x12: 0000000000000020
[ 21.140828] x11: 0000000000000000 x10: 005c000000000000 x9 : ffffd1a55c079ee0
[ 21.141077] x8 : 0000000000000001 x7 : 005c03e000040000 x6 : 000000004000ffff
[ 21.141490] x5 : ffff00017fffce00 x4 : 0000000000000001 x3 : 0000000000000002
[ 21.141741] x2 : 0000000000134510 x1 : 0000000000000000 x0 : ffff0000c08228c0
[ 21.141991] Call trace:
[ 21.142093] page_table_check_set+0x28c/0x2a8 (P)
[ 21.142265] __page_table_check_ptes_set+0x144/0x1e8
[ 21.142441] __set_ptes_anysz.constprop.0+0x160/0x1a8
[ 21.142766] contpte_set_ptes+0xe8/0x140
[ 21.142907] try_to_unmap_one+0x10c4/0x10d0
[ 21.143177] rmap_walk_anon+0x100/0x250
[ 21.143315] try_to_unmap+0xa0/0xc8
[ 21.143441] shrink_folio_list+0x59c/0x18a8
[ 21.143759] shrink_lruvec+0x664/0xbf0
[ 21.144043] shrink_node+0x218/0x878
[ 21.144285] __node_reclaim.constprop.0+0x98/0x338
[ 21.144763] user_proactive_reclaim+0x2a4/0x340
[ 21.145056] reclaim_store+0x3c/0x60
[ 21.145216] dev_attr_store+0x20/0x40
[ 21.145585] sysfs_kf_write+0x84/0xa8
[ 21.145835] kernfs_fop_write_iter+0x130/0x1c8
[ 21.145994] vfs_write+0x2b8/0x368
[ 21.146119] ksys_write+0x70/0x110
[ 21.146240] __arm64_sys_write+0x24/0x38
[ 21.146380] invoke_syscall+0x50/0x120
[ 21.146513] el0_svc_common.constprop.0+0x48/0xf8
[ 21.146679] do_el0_svc+0x28/0x40
[ 21.146798] el0_svc+0x34/0x110
[ 21.146926] el0t_64_sync_handler+0xa0/0xe8
[ 21.147074] el0t_64_sync+0x198/0x1a0
[ 21.147225] Code: f9400441 b4fff241 17ffff94 d4210000 (d4210000)
[ 21.147440] ---[ end trace 0000000000000000 ]---
#define _GNU_SOURCE
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/mman.h>
#include <string.h>
#include <sys/wait.h>
#include <sched.h>
#include <fcntl.h>
void write_to_reclaim() {
const char *path = "/sys/devices/system/node/node0/reclaim";
const char *value = "409600000000";
int fd = open(path, O_WRONLY);
if (fd == -1) {
perror("open");
exit(EXIT_FAILURE);
}
if (write(fd, value, sizeof("409600000000") - 1) == -1) {
perror("write");
close(fd);
exit(EXIT_FAILURE);
}
printf("Successfully wrote %s to %s\n", value, path);
close(fd);
}
int main()
{
char *ptr = mmap((void *)(1UL << 30), 1UL << 16, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if ((unsigned long)ptr != (1UL << 30)) {
perror("mmap");
return 1;
}
/* a 64K folio gets faulted in */
memset(ptr, 0, 1UL << 16);
/* 32K half will not be shared into child */
if (madvise(ptr, 1UL << 15, MADV_DONTFORK)) {
perror("madvise madv dontfork");
return 1;
}
pid_t pid = fork();
if (pid < 0) {
perror("fork");
return 1;
} else if (pid == 0) {
sleep(15);
} else {
/* merge VMAs. now first half of the 16 ptes are writable, the other half not. */
if (madvise(ptr, 1UL << 15, MADV_DOFORK)) {
perror("madvise madv fork");
return 1;
}
if (madvise(ptr, (1UL << 16), MADV_FREE)) {
perror("madvise madv free");
return 1;
}
/* dirty the large folio */
(*ptr) += 10;
write_to_reclaim();
// sleep(10);
waitpid(pid, NULL, 0);
}
}
Link: https://lkml.kernel.org/r/20260303061528.2429162-1-dev.jain@arm.com
Fixes: 354dffd29575 ("mm: support batched unmap for lazyfree large folios during reclamation")
Signed-off-by: Dev Jain <dev.jain@arm.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Tested-by: Lance Yang <lance.yang@linux.dev>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Harry Yoo <harry.yoo@oracle.com>
Cc: Jann Horn <jannh@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit c80f46ac228b48403866d65391ad09bdf0e8562a ]
DAMON core uses min_region_sz parameter value as the DAMON region
alignment. The alignment is made using ALIGN() and ALIGN_DOWN(), which
support only the power of two alignments. But DAMON core API callers can
set min_region_sz to an arbitrary number. Users can also set it
indirectly, using addr_unit.
When the alignment is not properly set, DAMON behavior becomes difficult
to expect and understand, makes it effectively broken. It doesn't cause a
kernel crash-like significant issue, though.
Fix the issue by disallowing min_region_sz input that is not a power of
two. Add the check to damon_commit_ctx(), as all DAMON API callers who
set min_region_sz uses the function.
This can be a sort of behavioral change, but it does not break users, for
the following reasons. As the symptom is making DAMON effectively broken,
it is not reasonable to believe there are real use cases of non-power of
two min_region_sz. There is no known use case or issue reports from the
setup, either.
In future, if we find real use cases of non-power of two alignments and we
can support it with low enough overhead, we can consider moving the
restriction. But, for now, simply disallowing the corner case should be
good enough as a hot fix.
Link: https://lkml.kernel.org/r/20260214214124.87689-1-sj@kernel.org
Fixes: d8f867fa0825 ("mm/damon: add damon_ctx->min_sz_region")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Quanmin Yan <yanquanmin1@huawei.com>
Cc: <stable@vger.kernel.org> [6.18+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit cc1db8dff8e751ec3ab352483de366b7f23aefe2 ]
'min_sz_region' field of 'struct damon_ctx' represents the minimum size of
each DAMON region for the context. 'struct damos_access_pattern' has a
field of the same name. It confuses readers and makes 'grep' less optimal
for them. Rename it to 'min_region_sz'.
Link: https://lkml.kernel.org/r/20260117175256.82826-9-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: c80f46ac228b ("mm/damon/core: disallow non-power of two min_region_sz")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit dfb1b0c9dc0d61e422905640e1e7334b3cf6f384 ]
The macro is for the default minimum size of each DAMON region. There was
a case that a reader was confused if it is the minimum number of total
DAMON regions, which is set on damon_attrs->min_nr_regions. Make the name
more explicit.
Link: https://lkml.kernel.org/r/20260117175256.82826-8-sj@kernel.org
Signed-off-by: SeongJae Park <sj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Stable-dep-of: c80f46ac228b ("mm/damon/core: disallow non-power of two min_region_sz")
Signed-off-by: Sasha Levin <sashal@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit dccd5ee2625d50239510bcd73ed78559005e00a3 upstream.
In the trylock path of refill_obj_stock(), mod_objcg_mlstate() should use
the real alloc/free bytes (i.e., nr_acct) for accounting, rather than
nr_bytes.
The user-visible impact is that the NR_SLAB_RECLAIMABLE_B and
NR_SLAB_UNRECLAIMABLE_B stats can end up being incorrect.
For example, if a user allocates a 6144-byte object, then before this
fix efill_obj_stock() calls mod_objcg_mlstate(..., nr_bytes=2048), even
though it should account for 6144 bytes (i.e., nr_acct).
When the user later frees the same object with kfree(),
refill_obj_stock() calls mod_objcg_mlstate(..., nr_bytes=6144). This
ends up adding 6144 to the stats, but it should be applying -6144
(i.e., nr_acct) since the object is being freed.
Link: https://lkml.kernel.org/r/20260226115145.62903-1-hao.li@linux.dev
Fixes: 200577f69f29 ("memcg: objcg stock trylock without irq disabling")
Signed-off-by: Hao Li <hao.li@linux.dev>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Acked-by: 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: Vlastimil Babka <vbabka@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 48647d3f9a644d1e81af6558102d43cdb260597b upstream.
sheaf_flush_main() can be called from __pcs_replace_full_main() where
it's fine if the trylock fails, and pcs_flush_all() where it's not
expected to and for some flush callers (when destroying the cache or
memory hotremove) it would be actually a problem if it failed and left
the main sheaf not flushed. The flush callers can however safely use
local_lock() instead of trylock.
The trylock failure should not happen in practice on !PREEMPT_RT, but
can happen on PREEMPT_RT. The impact is limited in practice because when
a trylock fails in the kmem_cache_destroy() path, it means someone is
using the cache while destroying it, which is a bug on its own. The memory
hotremove path is unlikely to be employed in a production RT config, but
it's possible.
To fix this, split the function into sheaf_flush_main() (using
local_lock()) and sheaf_try_flush_main() (using local_trylock()) where
both call __sheaf_flush_main_batch() to flush a single batch of objects.
This will also allow lockdep to verify our context assumptions.
The problem was raised in an off-list question by Marcelo.
Fixes: 2d517aa09bbc ("slab: add opt-in caching layer of percpu sheaves")
Cc: stable@vger.kernel.org
Reported-by: Marcelo Tosatti <mtosatti@redhat.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Hao Li <hao.li@linux.dev>
Link: https://patch.msgid.link/20260211-b4-sheaf-flush-v1-1-4e7f492f0055@suse.cz
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 8dafa9f5900c4855a65dbfee51e3bd00636deee1 upstream.
obj_exts_alloc_size() prevents recursive allocation of slabobj_ext
array from the same cache, to avoid creating slabs that are never freed.
There is one mistake that returns the original size when memory
allocation profiling is disabled. The assumption was that
memcg-triggered slabobj_ext allocation is always served from
KMALLOC_CGROUP type. But this is wrong [1]: when the caller specifies
both __GFP_RECLAIMABLE and __GFP_ACCOUNT with SLUB_TINY enabled, the
allocation is served from normal kmalloc. This is because kmalloc_type()
prioritizes __GFP_RECLAIMABLE over __GFP_ACCOUNT, and SLUB_TINY aliases
KMALLOC_RECLAIM with KMALLOC_NORMAL.
As a result, the recursion guard is bypassed and the problematic slabs
can be created. Fix this by removing the mem_alloc_profiling_enabled()
check entirely. The remaining is_kmalloc_normal() check is still
sufficient to detect whether the cache is of KMALLOC_NORMAL type and
avoid bumping the size if it's not.
Without SLUB_TINY, no functional change intended.
With SLUB_TINY, allocations with __GFP_ACCOUNT|__GFP_RECLAIMABLE
now allocate a larger array if the sizes equal.
Reported-by: Zw Tang <shicenci@gmail.com>
Fixes: 280ea9c3154b ("mm/slab: avoid allocating slabobj_ext array from its own slab")
Closes: https://lore.kernel.org/linux-mm/CAPHJ_VKuMKSke8b11AZQw1PTSFN4n2C0gFxC6xGOG0ZLHgPmnA@mail.gmail.com [1]
Cc: stable@vger.kernel.org
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20260309072219.22653-1-harry.yoo@oracle.com
Tested-by: Zw Tang <shicenci@gmail.com>
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit d210fdcac9c0d1380eab448aebc93f602c1cd4e6 upstream.
damos_walk() sets ctx->walk_control to the caller-provided control
structure before checking whether the context is running. If the context
is inactive (damon_is_running() returns false), the function returns
-EINVAL without clearing ctx->walk_control. This leaves a dangling
pointer to a stack-allocated structure that will be freed when the caller
returns.
This is structurally identical to the bug fixed in commit f9132fbc2e83
("mm/damon/core: remove call_control in inactive contexts") for
damon_call(), which had the same pattern of linking a control object and
returning an error without unlinking it.
The dangling walk_control pointer can cause:
1. Use-after-free if the context is later started and kdamond
dereferences ctx->walk_control (e.g., in damos_walk_cancel()
which writes to control->canceled and calls complete())
2. Permanent -EBUSY from subsequent damos_walk() calls, since the
stale pointer is non-NULL
Nonetheless, the real user impact is quite restrictive. The
use-after-free is impossible because there is no damos_walk() callers who
starts the context later. The permanent -EBUSY can actually confuse
users, as DAMON is not running. But the symptom is kept only while the
context is turned off. Turning it on again will make DAMON internally
uses a newly generated damon_ctx object that doesn't have the invalid
damos_walk_control pointer, so everything will work fine again.
Fix this by clearing ctx->walk_control under walk_control_lock before
returning -EINVAL, mirroring the fix pattern from f9132fbc2e83.
Link: https://lkml.kernel.org/r/20260224011102.56033-1-sj@kernel.org
Fixes: bf0eaba0ff9c ("mm/damon/core: implement damos_walk()")
Reported-by: Raul Pazemecxas De Andrade <raul_pazemecxas@hotmail.com>
Closes: https://lore.kernel.org/CPUPR80MB8171025468965E583EF2490F956CA@CPUPR80MB8171.lamprd80.prod.outlook.com
Signed-off-by: Raul Pazemecxas De Andrade <raul_pazemecxas@hotmail.com>
Signed-off-by: SeongJae Park <sj@kernel.org>
Reviewed-by: SeongJae Park <sj@kernel.org>
Cc: <stable@vger.kernel.org> [6.14+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 577a1f495fd78d8fb61b67ac3d3b595b01f6fcb0 upstream.
During a pagecache folio split, the values in the related xarray should
not be changed from the original folio at xarray split time until all
after-split folios are well formed and stored in the xarray. Current use
of xas_try_split() in __split_unmapped_folio() lets some after-split
folios show up at wrong indices in the xarray. When these misplaced
after-split folios are unfrozen, before correct folios are stored via
__xa_store(), and grabbed by folio_try_get(), they are returned to
userspace at wrong file indices, causing data corruption. More detailed
explanation is at the bottom.
The reproducer is at: https://github.com/dfinity/thp-madv-remove-test
It
1. creates a memfd,
2. forks,
3. in the child process, maps the file with large folios (via shmem code
path) and reads the mapped file continuously with 16 threads,
4. in the parent process, uses madvise(MADV_REMOVE) to punch poles in the
large folio.
Data corruption can be observed without the fix. Basically, data from a
wrong page->index is returned.
Fix it by using the original folio in xas_try_split() calls, so that
folio_try_get() can get the right after-split folios after the original
folio is unfrozen.
Uniform split, split_huge_page*(), is not affected, since it uses
xas_split_alloc() and xas_split() only once and stores the original folio
in the xarray. Change xas_split() used in uniform split branch to use the
original folio to avoid confusion.
Fixes below points to the commit introduces the code, but folio_split() is
used in a later commit 7460b470a131f ("mm/truncate: use folio_split() in
truncate operation").
More details:
For example, a folio f is split non-uniformly into f, f2, f3, f4 like
below:
+----------------+---------+----+----+
| f | f2 | f3 | f4 |
+----------------+---------+----+----+
but the xarray would look like below after __split_unmapped_folio() is
done:
+----------------+---------+----+----+
| f | f2 | f3 | f3 |
+----------------+---------+----+----+
After __split_unmapped_folio(), the code changes the xarray and unfreezes
after-split folios:
1. unfreezes f2, __xa_store(f2)
2. unfreezes f3, __xa_store(f3)
3. unfreezes f4, __xa_store(f4), which overwrites the second f3 to f4.
4. unfreezes f.
Meanwhile, a parallel filemap_get_entry() can read the second f3 from the
xarray and use folio_try_get() on it at step 2 when f3 is unfrozen. Then,
f3 is wrongly returned to user.
After the fix, the xarray looks like below after __split_unmapped_folio():
+----------------+---------+----+----+
| f | f | f | f |
+----------------+---------+----+----+
so that the race window no longer exists.
[ziy@nvidia.com: move comment, per David]
Link: https://lkml.kernel.org/r/5C9FA053-A4C6-4615-BE05-74E47A6462B3@nvidia.com
Link: https://lkml.kernel.org/r/20260302203159.3208341-1-ziy@nvidia.com
Fixes: 00527733d0dc ("mm/huge_memory: add two new (not yet used) functions for folio_split()")
Signed-off-by: Zi Yan <ziy@nvidia.com>
Reported-by: Bas van Dijk <bas@dfinity.org>
Closes: https://lore.kernel.org/all/CAKNNEtw5_kZomhkugedKMPOG-sxs5Q5OLumWJdiWXv+C9Yct0w@mail.gmail.com/
Tested-by: Lance Yang <lance.yang@linux.dev>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Reviewed-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Barry Song <baohua@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 7e04bf1f33151a30e06a65b74b5f2c19fc2be128 upstream.
A dirty folio is one which has been written to. A clean folio is its
opposite. Since a clean folio has no user data, it can be freed under
memory pressure.
memfd preservation with LUO saves the flag at preserve(). This is
problematic. The folio might get dirtied later. Saving it at freeze()
also doesn't work, since the dirty bit from PTE is normally synced at
unmap and there might still be mappings of the file at freeze().
To see why this is a problem, say a folio is clean at preserve, but gets
dirtied later. The serialized state of the folio will mark it as clean.
After retrieve, the next kernel will see the folio as clean and might try
to reclaim it under memory pressure. This will result in losing user
data.
Mark all folios of the file as dirty, and always set the
MEMFD_LUO_FOLIO_DIRTY flag. This comes with the side effect of making all
clean folios un-reclaimable. This is a cost that has to be paid for
participants of live update. It is not expected to be a common use case
to preserve a lot of clean folios anyway.
Since the value of pfolio->flags is a constant now, drop the flags
variable and set it directly.
Link: https://lkml.kernel.org/r/20260223173931.2221759-3-pratyush@kernel.org
Fixes: b3749f174d68 ("mm: memfd_luo: allow preserving memfd")
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 50d7b4332f27762d24641970fc34bb68a2621926 upstream.
Patch series "mm: memfd_luo: fixes for folio flag preservation".
This series contains a couple fixes for flag preservation for memfd live
update.
The first patch fixes memfd preservation when fallocate() was used to
pre-allocate some pages. For these memfds, all the writes to fallocated
pages touched after preserve were lost.
The second patch fixes dirty flag tracking. If the dirty flag is not
tracked correctly, the next kernel might incorrectly reclaim some folios
under memory pressure, losing user data. This is a theoretical bug that I
observed when reading the code, and haven't been able to reproduce it.
This patch (of 2):
When a folio is added to a shmem file via fallocate, it is not zeroed on
allocation. This is done as a performance optimization since it is
possible the folio will never end up being used at all. When the folio is
used, shmem checks for the uptodate flag, and if absent, zeroes the folio
(and sets the flag) before returning to user.
With LUO, the flags of each folio are saved at preserve time. It is
possible to have a memfd with some folios fallocated but not uptodate.
For those, the uptodate flag doesn't get saved. The folios might later
end up being used and become uptodate. They would get passed to the next
kernel via KHO correctly since they did get preserved. But they won't
have the MEMFD_LUO_FOLIO_UPTODATE flag.
This means that when the memfd is retrieved, the folios will be added to
the shmem file without the uptodate flag. They will be zeroed before
first use, losing the data in those folios.
Since we take a big performance hit in allocating, zeroing, and pinning
all folios at prepare time anyway, take some more and zero all
non-uptodate ones too.
Later when there is a stronger need to make prepare faster, this can be
optimized.
To avoid racing with another uptodate operation, take the folio lock.
Link: https://lkml.kernel.org/r/20260223173931.2221759-2-pratyush@kernel.org
Fixes: b3749f174d68 ("mm: memfd_luo: allow preserving memfd")
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit f85b1c6af5bc3872f994df0a5688c1162de07a62 upstream.
LUO keeps track of successful retrieve attempts on a LUO file. It does so
to avoid multiple retrievals of the same file. Multiple retrievals cause
problems because once the file is retrieved, the serialized data
structures are likely freed and the file is likely in a very different
state from what the code expects.
The retrieve boolean in struct luo_file keeps track of this, and is passed
to the finish callback so it knows what work was already done and what it
has left to do.
All this works well when retrieve succeeds. When it fails,
luo_retrieve_file() returns the error immediately, without ever storing
anywhere that a retrieve was attempted or what its error code was. This
results in an errored LIVEUPDATE_SESSION_RETRIEVE_FD ioctl to userspace,
but nothing prevents it from trying this again.
The retry is problematic for much of the same reasons listed above. The
file is likely in a very different state than what the retrieve logic
normally expects, and it might even have freed some serialization data
structures. Attempting to access them or free them again is going to
break things.
For example, if memfd managed to restore 8 of its 10 folios, but fails on
the 9th, a subsequent retrieve attempt will try to call
kho_restore_folio() on the first folio again, and that will fail with a
warning since it is an invalid operation.
Apart from the retry, finish() also breaks. Since on failure the
retrieved bool in luo_file is never touched, the finish() call on session
close will tell the file handler that retrieve was never attempted, and it
will try to access or free the data structures that might not exist, much
in the same way as the retry attempt.
There is no sane way of attempting the retrieve again. Remember the error
retrieve returned and directly return it on a retry. Also pass this
status code to finish() so it can make the right decision on the work it
needs to do.
This is done by changing the bool to an integer. A value of 0 means
retrieve was never attempted, a positive value means it succeeded, and a
negative value means it failed and the error code is the value.
Link: https://lkml.kernel.org/r/20260216132221.987987-1-pratyush@kernel.org
Fixes: 7c722a7f44e0 ("liveupdate: luo_file: implement file systems callbacks")
Signed-off-by: Pratyush Yadav (Google) <pratyush@kernel.org>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Pasha Tatashin <pasha.tatashin@soleen.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit b570f37a2ce480be26c665345c5514686a8a0274 upstream.
If hmm_range_fault() fails a folio_trylock() in do_swap_page,
trying to acquire the lock of a device-private folio for migration,
to ram, the function will spin until it succeeds grabbing the lock.
However, if the process holding the lock is depending on a work
item to be completed, which is scheduled on the same CPU as the
spinning hmm_range_fault(), that work item might be starved and
we end up in a livelock / starvation situation which is never
resolved.
This can happen, for example if the process holding the
device-private folio lock is stuck in
migrate_device_unmap()->lru_add_drain_all()
sinc lru_add_drain_all() requires a short work-item
to be run on all online cpus to complete.
A prerequisite for this to happen is:
a) Both zone device and system memory folios are considered in
migrate_device_unmap(), so that there is a reason to call
lru_add_drain_all() for a system memory folio while a
folio lock is held on a zone device folio.
b) The zone device folio has an initial mapcount > 1 which causes
at least one migration PTE entry insertion to be deferred to
try_to_migrate(), which can happen after the call to
lru_add_drain_all().
c) No or voluntary only preemption.
This all seems pretty unlikely to happen, but indeed is hit by
the "xe_exec_system_allocator" igt test.
Resolve this by waiting for the folio to be unlocked if the
folio_trylock() fails in do_swap_page().
Rename migration_entry_wait_on_locked() to
softleaf_entry_wait_unlock() and update its documentation to
indicate the new use-case.
Future code improvements might consider moving
the lru_add_drain_all() call in migrate_device_unmap() to be
called *after* all pages have migration entries inserted.
That would eliminate also b) above.
v2:
- Instead of a cond_resched() in hmm_range_fault(),
eliminate the problem by waiting for the folio to be unlocked
in do_swap_page() (Alistair Popple, Andrew Morton)
v3:
- Add a stub migration_entry_wait_on_locked() for the
!CONFIG_MIGRATION case. (Kernel Test Robot)
v4:
- Rename migrate_entry_wait_on_locked() to
softleaf_entry_wait_on_locked() and update docs (Alistair Popple)
v5:
- Add a WARN_ON_ONCE() for the !CONFIG_MIGRATION
version of softleaf_entry_wait_on_locked().
- Modify wording around function names in the commit message
(Andrew Morton)
Suggested-by: Alistair Popple <apopple@nvidia.com>
Fixes: 1afaeb8293c9 ("mm/migrate: Trylock device page in do_swap_page")
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Jason Gunthorpe <jgg@mellanox.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: John Hubbard <jhubbard@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: linux-mm@kvack.org
Cc: <dri-devel@lists.freedesktop.org>
Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: <stable@vger.kernel.org> # v6.15+
Reviewed-by: John Hubbard <jhubbard@nvidia.com> #v3
Reviewed-by: Alistair Popple <apopple@nvidia.com>
Link: https://patch.msgid.link/20260210115653.92413-1-thomas.hellstrom@linux.intel.com
(cherry picked from commit a69d1ab971a624c6f112cea61536569d579c3215)
Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit 09833d99db36d74456a4d13eb29c32d56ff8f2b6 upstream.
KFENCE does not currently support KASAN hardware tags. As a result, the
two features are incompatible when enabled simultaneously.
Given that MTE provides deterministic protection and KFENCE is a
sampling-based debugging tool, prioritize the stronger hardware
protections. Disable KFENCE initialization and free the pre-allocated
pool if KASAN hardware tags are detected to ensure the system maintains
the security guarantees provided by MTE.
Link: https://lkml.kernel.org/r/20260213095410.1862978-1-glider@google.com
Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Marco Elver <elver@google.com>
Reviewed-by: Marco Elver <elver@google.com>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Ernesto Martinez Garcia <ernesto.martinezgarcia@tugraz.at>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Kees Cook <kees@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit d155aab90fffa00f93cea1f107aef0a3d548b2ff upstream.
When KASAN hardware tags are enabled, re-enabling KFENCE late (via
/sys/module/kfence/parameters/sample_interval) causes KASAN faults.
This happens because the KFENCE pool and metadata are allocated via the
page allocator, which tags the memory, while KFENCE continues to access it
using untagged pointers during initialization.
Use __GFP_SKIP_KASAN for late KFENCE pool and metadata allocations to
ensure the memory remains untagged, consistent with early allocations from
memblock. To support this, add __GFP_SKIP_KASAN to the allowlist in
__alloc_contig_verify_gfp_mask().
Link: https://lkml.kernel.org/r/20260220144940.2779209-1-glider@google.com
Fixes: 0ce20dd84089 ("mm: add Kernel Electric-Fence infrastructure")
Signed-off-by: Alexander Potapenko <glider@google.com>
Suggested-by: Ernesto Martinez Garcia <ernesto.martinezgarcia@tugraz.at>
Cc: Andrey Konovalov <andreyknvl@gmail.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Greg KH <gregkh@linuxfoundation.org>
Cc: Kees Cook <kees@kernel.org>
Cc: Marco Elver <elver@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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commit dd085fe9a8ebfc5d10314c60452db38d2b75e609 upstream.
file_thp_enabled() incorrectly allows THP for files on anonymous inodes
(e.g. guest_memfd and secretmem). These files are created via
alloc_file_pseudo(), which does not call get_write_access() and leaves
inode->i_writecount at 0. Combined with S_ISREG(inode->i_mode) being
true, they appear as read-only regular files when
CONFIG_READ_ONLY_THP_FOR_FS is enabled, making them eligible for THP
collapse.
Anonymous inodes can never pass the inode_is_open_for_write() check
since their i_writecount is never incremented through the normal VFS
open path. The right thing to do is to exclude them from THP eligibility
altogether, since CONFIG_READ_ONLY_THP_FOR_FS was designed for real
filesystem files (e.g. shared libraries), not for pseudo-filesystem
inodes.
For guest_memfd, this allows khugepaged and MADV_COLLAPSE to create
large folios in the page cache via the collapse path, but the
guest_memfd fault handler does not support large folios. This triggers
WARN_ON_ONCE(folio_test_large(folio)) in kvm_gmem_fault_user_mapping().
For secretmem, collapse_file() tries to copy page contents through the
direct map, but secretmem pages are removed from the direct map. This
can result in a kernel crash:
BUG: unable to handle page fault for address: ffff88810284d000
RIP: 0010:memcpy_orig+0x16/0x130
Call Trace:
collapse_file
hpage_collapse_scan_file
madvise_collapse
Secretmem is not affected by the crash on upstream as the memory failure
recovery handles the failed copy gracefully, but it still triggers
confusing false memory failure reports:
Memory failure: 0x106d96f: recovery action for clean unevictable
LRU page: Recovered
Check IS_ANON_FILE(inode) in file_thp_enabled() to deny THP for all
anonymous inode files.
Link: https://syzkaller.appspot.com/bug?extid=33a04338019ac7e43a44
Link: https://lore.kernel.org/linux-mm/CAEvNRgHegcz3ro35ixkDw39ES8=U6rs6S7iP0gkR9enr7HoGtA@mail.gmail.com
Link: https://lkml.kernel.org/r/20260214001535.435626-1-kartikey406@gmail.com
Fixes: 7fbb5e188248 ("mm: remove VM_EXEC requirement for THP eligibility")
Signed-off-by: Deepanshu Kartikey <Kartikey406@gmail.com>
Reported-by: syzbot+33a04338019ac7e43a44@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=33a04338019ac7e43a44
Tested-by: syzbot+33a04338019ac7e43a44@syzkaller.appspotmail.com
Tested-by: Lance Yang <lance.yang@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Barry Song <baohua@kernel.org>
Reviewed-by: Ackerley Tng <ackerleytng@google.com>
Tested-by: Ackerley Tng <ackerleytng@google.com>
Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Fangrui Song <i@maskray.me>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Yang Shi <shy828301@gmail.com>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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[ Upstream commit 021ca6b670bebebc409d43845efcfe8c11c1dd54 ]
When refill_sheaf() is called, failing to refill the sheaf doesn't
necessarily mean the allocation will fail because a fallback path
might be available and serve the allocation request.
Suppress spurious warnings by passing __GFP_NOWARN along with
__GFP_NOMEMALLOC whenever a fallback path is available.
When the caller is alloc_full_sheaf() or __pcs_replace_empty_main(),
the kernel always falls back to the slowpath (__slab_alloc_node()).
For __prefill_sheaf_pfmemalloc(), the fallback path is available
only when gfp_pfmemalloc_allowed() returns true.
Reported-and-tested-by: Chris Bainbridge <chris.bainbridge@gmail.com>
Closes: https://lore.kernel.org/linux-mm/aZt2-oS9lkmwT7Ch@debian.local
Fixes: 1ce20c28eafd ("slab: handle pfmemalloc slabs properly with sheaves")
Link: https://lore.kernel.org/linux-mm/aZwSreGj9-HHdD-j@hyeyoo
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20260223133322.16705-1-harry.yoo@oracle.com
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit f043a93fff9e3e3e648b6525483f59104b0819fa ]
In some physical memory layout designs, the address space of CFMW (CXL
Fixed Memory Window) resides between multiple segments of system memory
belonging to the same NUMA node. In numa_cleanup_meminfo, these multiple
segments of system memory are merged into a larger numa_memblk. When
identifying which NUMA node the CFMW belongs to, it may be incorrectly
assigned to the NUMA node of the merged system memory.
When a CXL RAM region is created in userspace, the memory capacity of
the newly created region is not added to the CFMW-dedicated NUMA node.
Instead, it is accumulated into an existing NUMA node (e.g., NUMA0
containing RAM). This makes it impossible to clearly distinguish
between the two types of memory, which may affect memory-tiering
applications.
Example memory layout:
Physical address space:
0x00000000 - 0x1FFFFFFF System RAM (node0)
0x20000000 - 0x2FFFFFFF CXL CFMW (node2)
0x40000000 - 0x5FFFFFFF System RAM (node0)
0x60000000 - 0x7FFFFFFF System RAM (node1)
After numa_cleanup_meminfo, the two node0 segments are merged into one:
0x00000000 - 0x5FFFFFFF System RAM (node0) // CFMW is inside the range
0x60000000 - 0x7FFFFFFF System RAM (node1)
So the CFMW (0x20000000-0x2FFFFFFF) will be incorrectly assigned to node0.
To address this scenario, accurately identifying the correct NUMA node
can be achieved by checking whether the region belongs to both
numa_meminfo and numa_reserved_meminfo.
While this issue is only observed in a QEMU configuration, and no known
end users are impacted by this problem, it is likely that some firmware
implementation is leaving memory map holes in a CXL Fixed Memory Window.
CXL hotplug depends on mapping free window capacity, and it seems to be
only a coincidence to have not hit this problem yet.
Fixes: 779dd20cfb56 ("cxl/region: Add region creation support")
Signed-off-by: Cui Chao <cuichao1753@phytium.com.cn>
Cc: stable@vger.kernel.org
Reviewed-by: Jonathan Cameron <jonathan.cameron@huawei.com>
Reviewed-by: Gregory Price <gourry@gourry.net>
Reviewed-by: Dan Williams <dan.j.williams@intel.com>
Link: https://patch.msgid.link/20260213060347.2389818-2-cuichao1753@phytium.com.cn
Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit ac1ea219590c09572ed5992dc233bbf7bb70fef9 ]
Several subsystems (slub, shmem, ttm, etc.) use page->private but don't
clear it before freeing pages. When these pages are later allocated as
high-order pages and split via split_page(), tail pages retain stale
page->private values.
This causes a use-after-free in the swap subsystem. The swap code uses
page->private to track swap count continuations, assuming freshly
allocated pages have page->private == 0. When stale values are present,
swap_count_continued() incorrectly assumes the continuation list is valid
and iterates over uninitialized page->lru containing LIST_POISON values,
causing a crash:
KASAN: maybe wild-memory-access in range [0xdead000000000100-0xdead000000000107]
RIP: 0010:__do_sys_swapoff+0x1151/0x1860
Fix this by clearing page->private in free_pages_prepare(), ensuring all
freed pages have clean state regardless of previous use.
Link: https://lkml.kernel.org/r/20260207173615.146159-1-mikhail.v.gavrilov@gmail.com
Fixes: 3b8000ae185c ("mm/vmalloc: huge vmalloc backing pages should be split rather than compound")
Signed-off-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Suggested-by: Zi Yan <ziy@nvidia.com>
Acked-by: Zi Yan <ziy@nvidia.com>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Kairui Song <ryncsn@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 1aceed565ff172fc0331dd1d5e7e65139b711139 ]
Patch series "mm/vmscan: fix demotion targets checks in reclaim/demotion",
v9.
This patch series addresses two issues in demote_folio_list(),
can_demote(), and next_demotion_node() in reclaim/demotion.
1. demote_folio_list() and can_demote() do not correctly check
demotion target against cpuset.mems_effective, which will cause (a)
pages to be demoted to not-allowed nodes and (b) pages fail demotion
even if the system still has allowed demotion nodes.
Patch 1 fixes this bug by updating cpuset_node_allowed() and
mem_cgroup_node_allowed() to return effective_mems, allowing directly
logic-and operation against demotion targets.
2. next_demotion_node() returns a preferred demotion target, but it
does not check the node against allowed nodes.
Patch 2 ensures that next_demotion_node() filters against the allowed
node mask and selects the closest demotion target to the source node.
This patch (of 2):
Fix two bugs in demote_folio_list() and can_demote() due to incorrect
demotion target checks against cpuset.mems_effective in reclaim/demotion.
Commit 7d709f49babc ("vmscan,cgroup: apply mems_effective to reclaim")
introduces the cpuset.mems_effective check and applies it to can_demote().
However:
1. It does not apply this check in demote_folio_list(), which leads
to situations where pages are demoted to nodes that are
explicitly excluded from the task's cpuset.mems.
2. It checks only the nodes in the immediate next demotion hierarchy
and does not check all allowed demotion targets in can_demote().
This can cause pages to never be demoted if the nodes in the next
demotion hierarchy are not set in mems_effective.
These bugs break resource isolation provided by cpuset.mems. This is
visible from userspace because pages can either fail to be demoted
entirely or are demoted to nodes that are not allowed in multi-tier memory
systems.
To address these bugs, update cpuset_node_allowed() and
mem_cgroup_node_allowed() to return effective_mems, allowing directly
logic-and operation against demotion targets. Also update can_demote()
and demote_folio_list() accordingly.
Bug 1 reproduction:
Assume a system with 4 nodes, where nodes 0-1 are top-tier and
nodes 2-3 are far-tier memory. All nodes have equal capacity.
Test script:
echo 1 > /sys/kernel/mm/numa/demotion_enabled
mkdir /sys/fs/cgroup/test
echo +cpuset > /sys/fs/cgroup/cgroup.subtree_control
echo "0-2" > /sys/fs/cgroup/test/cpuset.mems
echo $$ > /sys/fs/cgroup/test/cgroup.procs
swapoff -a
# Expectation: Should respect node 0-2 limit.
# Observation: Node 3 shows significant allocation (MemFree drops)
stress-ng --oomable --vm 1 --vm-bytes 150% --mbind 0,1
Bug 2 reproduction:
Assume a system with 6 nodes, where nodes 0-2 are top-tier,
node 3 is a far-tier node, and nodes 4-5 are the farthest-tier nodes.
All nodes have equal capacity.
Test script:
echo 1 > /sys/kernel/mm/numa/demotion_enabled
mkdir /sys/fs/cgroup/test
echo +cpuset > /sys/fs/cgroup/cgroup.subtree_control
echo "0-2,4-5" > /sys/fs/cgroup/test/cpuset.mems
echo $$ > /sys/fs/cgroup/test/cgroup.procs
swapoff -a
# Expectation: Pages are demoted to Nodes 4-5
# Observation: No pages are demoted before oom.
stress-ng --oomable --vm 1 --vm-bytes 150% --mbind 0,1,2
Link: https://lkml.kernel.org/r/20260114205305.2869796-1-bingjiao@google.com
Link: https://lkml.kernel.org/r/20260114205305.2869796-2-bingjiao@google.com
Fixes: 7d709f49babc ("vmscan,cgroup: apply mems_effective to reclaim")
Signed-off-by: Bing Jiao <bingjiao@google.com>
Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Axel Rasmussen <axelrasmussen@google.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Gregory Price <gourry@gourry.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
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: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Waiman Long <longman@redhat.com>
Cc: Wei Xu <weixugc@google.com>
Cc: Yuanchu Xie <yuanchu@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
|
[ Upstream commit 338ad1e84d15078a9ae46d7dd7466329ae0bfa61 ]
When CONFIG_DEBUG_OBJECTS_FREE is enabled,
debug_check_no_{obj,locks}_freed() functions are called.
Since both of them spin on a lock, they are not safe to be called if the
FPI_TRYLOCK flag is specified. This leads to a lockdep splat:
================================
WARNING: inconsistent lock state
6.19.0-rc5-slab-for-next+ #326 Tainted: G N
--------------------------------
inconsistent {INITIAL USE} -> {IN-NMI} usage.
kunit_try_catch/9046 [HC2[2]:SC0[0]:HE0:SE1] takes:
ffffffff84ed6bf8 (&obj_hash[i].lock){-.-.}-{2:2}, at: __debug_check_no_obj_freed+0xe0/0x300
{INITIAL USE} state was registered at:
lock_acquire+0xd9/0x2f0
_raw_spin_lock_irqsave+0x4c/0x80
__debug_object_init+0x9d/0x1f0
debug_object_init+0x34/0x50
__init_work+0x28/0x40
init_cgroup_housekeeping+0x151/0x210
init_cgroup_root+0x3d/0x140
cgroup_init_early+0x30/0x240
start_kernel+0x3e/0xcd0
x86_64_start_reservations+0x18/0x30
x86_64_start_kernel+0xf3/0x140
common_startup_64+0x13e/0x148
irq event stamp: 2998
hardirqs last enabled at (2997): [<ffffffff8298b77a>] exc_nmi+0x11a/0x240
hardirqs last disabled at (2998): [<ffffffff8298b991>] sysvec_irq_work+0x11/0x110
softirqs last enabled at (1416): [<ffffffff813c1f72>] __irq_exit_rcu+0x132/0x1c0
softirqs last disabled at (1303): [<ffffffff813c1f72>] __irq_exit_rcu+0x132/0x1c0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&obj_hash[i].lock);
<Interrupt>
lock(&obj_hash[i].lock);
*** DEADLOCK ***
Rename free_pages_prepare() to __free_pages_prepare(), add an fpi_t
parameter, and skip those checks if FPI_TRYLOCK is set. To keep the fpi_t
definition in mm/page_alloc.c, add a wrapper function free_pages_prepare()
that always passes FPI_NONE and use it in mm/compaction.c.
Link: https://lkml.kernel.org/r/20260209062639.16577-1-harry.yoo@oracle.com
Fixes: 8c57b687e833 ("mm, bpf: Introduce free_pages_nolock()")
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
|
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[ Upstream commit 1d3f9bb4c8af70304d19c22e30f5d16a2d589bb5 ]
Commit a833a693a490 ("mm: hugetlb: fix incorrect fallback for subpool")
fixed an underflow error for hstate->resv_huge_pages caused by incorrectly
attributing globally requested pages to the subpool's reservation.
Unfortunately, this fix also introduced the opposite problem, which would
leave spool->used_hpages elevated if the globally requested pages could
not be acquired. This is because while a subpool's reserve pages only
accounts for what is requested and allocated from the subpool, its "used"
counter keeps track of what is consumed in total, both from the subpool
and globally. Thus, we need to adjust spool->used_hpages in the other
direction, and make sure that globally requested pages are uncharged from
the subpool's used counter.
Each failed allocation attempt increments the used_hpages counter by how
many pages were requested from the global pool. Ultimately, this renders
the subpool unusable, as used_hpages approaches the max limit.
The issue can be reproduced as follows:
1. Allocate 4 hugetlb pages
2. Create a hugetlb mount with max=4, min=2
3. Consume 2 pages globally
4. Request 3 pages from the subpool (2 from subpool + 1 from global)
4.1 hugepage_subpool_get_pages(spool, 3) succeeds.
used_hpages += 3
4.2 hugetlb_acct_memory(h, 1) fails: no global pages left
used_hpages -= 2
5. Subpool now has used_hpages = 1, despite not being able to
successfully allocate any hugepages. It believes it can now only
allocate 3 more hugepages, not 4.
With each failed allocation attempt incrementing the used counter, the
subpool eventually reaches a point where its used counter equals its
max counter. At that point, any future allocations that try to
allocate hugeTLB pages from the subpool will fail, despite the subpool
not having any of its hugeTLB pages consumed by any user.
Once this happens, there is no way to make the subpool usable again,
since there is no way to decrement the used counter as no process is
really consuming the hugeTLB pages.
The underflow issue that the original commit fixes still remains fixed
as well.
Without this fix, used_hpages would keep on leaking if
hugetlb_acct_memory() fails.
Link: https://lkml.kernel.org/r/20260116204037.2270096-1-joshua.hahnjy@gmail.com
Fixes: a833a693a490 ("mm: hugetlb: fix incorrect fallback for subpool")
Signed-off-by: Joshua Hahn <joshua.hahnjy@gmail.com>
Acked-by: Usama Arif <usama.arif@linux.dev>
Cc: David Hildenbrand <david@kernel.org>
Cc: "Liam R. Howlett" <Liam.Howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Ma Wupeng <mawupeng1@huawei.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Waiman Long <longman@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit a1e244a9f177894969c6cd5ebbc6d72c19fc4a7a ]
When CONFIG_SLAB_FREELIST_RANDOM is enabled and get_random_u32()
is called in an NMI context, lockdep complains because it acquires
a local_lock:
================================
WARNING: inconsistent lock state
6.19.0-rc5-slab-for-next+ #325 Tainted: G N
--------------------------------
inconsistent {INITIAL USE} -> {IN-NMI} usage.
kunit_try_catch/8312 [HC2[2]:SC0[0]:HE0:SE1] takes:
ffff88a02ec49cc0 (batched_entropy_u32.lock){-.-.}-{3:3}, at: get_random_u32+0x7f/0x2e0
{INITIAL USE} state was registered at:
lock_acquire+0xd9/0x2f0
get_random_u32+0x93/0x2e0
__get_random_u32_below+0x17/0x70
cache_random_seq_create+0x121/0x1c0
init_cache_random_seq+0x5d/0x110
do_kmem_cache_create+0x1e0/0xa30
__kmem_cache_create_args+0x4ec/0x830
create_kmalloc_caches+0xe6/0x130
kmem_cache_init+0x1b1/0x660
mm_core_init+0x1d8/0x4b0
start_kernel+0x620/0xcd0
x86_64_start_reservations+0x18/0x30
x86_64_start_kernel+0xf3/0x140
common_startup_64+0x13e/0x148
irq event stamp: 76
hardirqs last enabled at (75): [<ffffffff8298b77a>] exc_nmi+0x11a/0x240
hardirqs last disabled at (76): [<ffffffff8298b991>] sysvec_irq_work+0x11/0x110
softirqs last enabled at (0): [<ffffffff813b2dda>] copy_process+0xc7a/0x2350
softirqs last disabled at (0): [<0000000000000000>] 0x0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(batched_entropy_u32.lock);
<Interrupt>
lock(batched_entropy_u32.lock);
*** DEADLOCK ***
Fix this by using pseudo-random number generator if !allow_spin.
This means kmalloc_nolock() users won't get truly random numbers,
but there is not much we can do about it.
Note that an NMI handler might interrupt prandom_u32_state() and
change the random state, but that's safe.
Link: https://lore.kernel.org/all/0c33bdee-6de8-4d9f-92ca-4f72c1b6fb9f@suse.cz
Fixes: af92793e52c3 ("slab: Introduce kmalloc_nolock() and kfree_nolock().")
Cc: stable@vger.kernel.org
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20260210081900.329447-3-harry.yoo@oracle.com
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 144080a5823b2dbd635acb6decf7ab23182664f3 ]
Lockdep complains when get_from_any_partial() is called in an NMI
context, because current->mems_allowed_seq is seqcount_spinlock_t and
not NMI-safe:
================================
WARNING: inconsistent lock state
6.19.0-rc5-kfree-rcu+ #315 Tainted: G N
--------------------------------
inconsistent {INITIAL USE} -> {IN-NMI} usage.
kunit_try_catch/9989 [HC1[1]:SC0[0]:HE0:SE1] takes:
ffff889085799820 (&____s->seqcount#3){.-.-}-{0:0}, at: ___slab_alloc+0x58f/0xc00
{INITIAL USE} state was registered at:
lock_acquire+0x185/0x320
kernel_init_freeable+0x391/0x1150
kernel_init+0x1f/0x220
ret_from_fork+0x736/0x8f0
ret_from_fork_asm+0x1a/0x30
irq event stamp: 56
hardirqs last enabled at (55): [<ffffffff850a68d7>] _raw_spin_unlock_irq+0x27/0x70
hardirqs last disabled at (56): [<ffffffff850858ca>] __schedule+0x2a8a/0x6630
softirqs last enabled at (0): [<ffffffff81536711>] copy_process+0x1dc1/0x6a10
softirqs last disabled at (0): [<0000000000000000>] 0x0
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&____s->seqcount#3);
<Interrupt>
lock(&____s->seqcount#3);
*** DEADLOCK ***
According to Documentation/locking/seqlock.rst, seqcount_t is not
NMI-safe and seqcount_latch_t should be used when read path can interrupt
the write-side critical section. In this case, do not access
current->mems_allowed_seq and avoid retry.
Fixes: af92793e52c3 ("slab: Introduce kmalloc_nolock() and kfree_nolock().")
Cc: stable@vger.kernel.org
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20260210081900.329447-2-harry.yoo@oracle.com
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit b85f369b81aed457acbea4ad3314218254a72fd2 ]
When both KASAN and SLAB_STORE_USER are enabled, accesses to
struct kasan_alloc_meta fields can be misaligned on 64-bit architectures.
This occurs because orig_size is currently defined as unsigned int,
which only guarantees 4-byte alignment. When struct kasan_alloc_meta is
placed after orig_size, it may end up at a 4-byte boundary rather than
the required 8-byte boundary on 64-bit systems.
Note that 64-bit architectures without HAVE_EFFICIENT_UNALIGNED_ACCESS
are assumed to require 64-bit accesses to be 64-bit aligned.
See HAVE_64BIT_ALIGNED_ACCESS and commit adab66b71abf ("Revert:
"ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS"") for more details.
Change orig_size from unsigned int to unsigned long to ensure proper
alignment for any subsequent metadata. This should not waste additional
memory because kmalloc objects are already aligned to at least
ARCH_KMALLOC_MINALIGN.
Closes: https://lore.kernel.org/all/aPrLF0OUK651M4dk@hyeyoo
Suggested-by: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: stable@vger.kernel.org
Fixes: 6edf2576a6cc ("mm/slub: enable debugging memory wasting of kmalloc")
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Closes: https://lore.kernel.org/all/aPrLF0OUK651M4dk@hyeyoo/
Link: https://patch.msgid.link/20260113061845.159790-2-harry.yoo@oracle.com
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 280ea9c3154b2af7d841f992c9fc79e9d6534e03 ]
When allocating slabobj_ext array in alloc_slab_obj_exts(), the array
can be allocated from the same slab we're allocating the array for.
This led to obj_exts_in_slab() incorrectly returning true [1],
although the array is not allocated from wasted space of the slab.
Vlastimil Babka observed that this problem should be fixed even when
ignoring its incompatibility with obj_exts_in_slab(), because it creates
slabs that are never freed as there is always at least one allocated
object.
To avoid this, use the next kmalloc size or large kmalloc when
the array can be allocated from the same cache we're allocating
the array for.
In case of random kmalloc caches, there are multiple kmalloc caches
for the same size and the cache is selected based on the caller address.
Because it is fragile to ensure the same caller address is passed to
kmalloc_slab(), kmalloc_noprof(), and kmalloc_node_noprof(), bump the
size to (s->object_size + 1) when the sizes are equal, instead of
directly comparing the kmem_cache pointers.
Note that this doesn't happen when memory allocation profiling is
disabled, as when the allocation of the array is triggered by memory
cgroup (KMALLOC_CGROUP), the array is allocated from KMALLOC_NORMAL.
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202601231457.f7b31e09-lkp@intel.com [1]
Cc: stable@vger.kernel.org
Fixes: 4b8736964640 ("mm/slab: add allocation accounting into slab allocation and free paths")
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20260126125714.88008-1-harry.yoo@oracle.com
Reviewed-by: Hao Li <hao.li@linux.dev>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 94350fe6cad77b46c3dcb8c96543bef7647efbc0 ]
This changes fixes following build error which is a miss from ef6e06b2ef87
("highmem: fix kmap_to_page() for kmap_local_page() addresses").
mm/highmem.c:184:66: error: 'pteval' undeclared (first use in this
function); did you mean 'pte_val'?
184 | idx = arch_kmap_local_map_idx(i, pte_pfn(pteval));
In __kmap_to_page(), pteval is used but does not exist in the function.
(akpm: affects xtensa only)
Link: https://lkml.kernel.org/r/SJ0PR07MB86317E00EC0C59DA60935FDCD18DA@SJ0PR07MB8631.namprd07.prod.outlook.com
Fixes: ef6e06b2ef87 ("highmem: fix kmap_to_page() for kmap_local_page() addresses")
Signed-off-by: William Tambe <williamt@cadence.com>
Reviewed-by: Max Filippov <jcmvbkbc@gmail.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit b55b423e8518361124ff0a9e15df431b3682ee4f ]
After we submit the rcu_free sheaves to call_rcu() we need to make sure
the rcu callbacks complete. kvfree_rcu_barrier() does that via
flush_all_rcu_sheaves() but kvfree_rcu_barrier_on_cache() doesn't. Fix
that.
This currently causes no issues because the caches with sheaves we have
are never destroyed. The problem flagged by kernel test robot was
reported for a patch that enables sheaves for (almost) all caches, and
occurred only with CONFIG_KASAN. Harry Yoo found the root cause [1]:
It turns out the object freed by sheaf_flush_unused() was in KASAN
percpu quarantine list (confirmed by dumping the list) by the time
__kmem_cache_shutdown() returns an error.
Quarantined objects are supposed to be flushed by kasan_cache_shutdown(),
but things go wrong if the rcu callback (rcu_free_sheaf_nobarn()) is
processed after kasan_cache_shutdown() finishes.
That's why rcu_barrier() in __kmem_cache_shutdown() didn't help,
because it's called after kasan_cache_shutdown().
Calling rcu_barrier() in kvfree_rcu_barrier_on_cache() guarantees
that it'll be added to the quarantine list before kasan_cache_shutdown()
is called. So it's a valid fix!
[1] https://lore.kernel.org/all/aWd6f3jERlrB5yeF@hyeyoo/
Reported-by: kernel test robot <oliver.sang@intel.com>
Closes: https://lore.kernel.org/oe-lkp/202601121442.c530bed3-lkp@intel.com
Fixes: 0f35040de593 ("mm/slab: introduce kvfree_rcu_barrier_on_cache() for cache destruction")
Cc: stable@vger.kernel.org
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Tested-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 5747435e0fd474c24530ef1a6822f47e7d264b27 ]
When CONFIG_PAGE_OWNER is enabled, freeing KASAN shadow pages during
vmalloc cleanup triggers expensive stack unwinding that acquires RCU read
locks. Processing a large purge_list without rescheduling can cause the
task to hold CPU for extended periods (10+ seconds), leading to RCU stalls
and potential OOM conditions.
The issue manifests in purge_vmap_node() -> kasan_release_vmalloc_node()
where iterating through hundreds or thousands of vmap_area entries and
freeing their associated shadow pages causes:
rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P6229/1:b..l
...
task:kworker/0:17 state:R running task stack:28840 pid:6229
...
kasan_release_vmalloc_node+0x1ba/0xad0 mm/vmalloc.c:2299
purge_vmap_node+0x1ba/0xad0 mm/vmalloc.c:2299
Each call to kasan_release_vmalloc() can free many pages, and with
page_owner tracking, each free triggers save_stack() which performs stack
unwinding under RCU read lock. Without yielding, this creates an
unbounded RCU critical section.
Add periodic cond_resched() calls within the loop to allow:
- RCU grace periods to complete
- Other tasks to run
- Scheduler to preempt when needed
The fix uses need_resched() for immediate response under load, with a
batch count of 32 as a guaranteed upper bound to prevent worst-case stalls
even under light load.
Link: https://lkml.kernel.org/r/20260112103612.627247-1-kartikey406@gmail.com
Signed-off-by: Deepanshu Kartikey <kartikey406@gmail.com>
Reported-by: syzbot+d8d4c31d40f868eaea30@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=d8d4c31d40f868eaea30
Link: https://lore.kernel.org/all/20260112084723.622910-1-kartikey406@gmail.com/T/ [v1]
Suggested-by: Uladzislau Rezki <urezki@gmail.com>
Reviewed-by: Uladzislau Rezki (Sony) <urezki@gmail.com>
Cc: Hillf Danton <hdanton@sina.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit 9c9828d3ead69416d731b1238802af31760c823e ]
Since commit cc638f329ef6 ("mm, thp: tweak reclaim/compaction effort of
local-only and all-node allocations"), THP page fault allocations have
settled on the following scheme (from the commit log):
1. local node only THP allocation with no reclaim, just compaction.
2. for madvised VMA's or when synchronous compaction is enabled always - THP
allocation from any node with effort determined by global defrag setting
and VMA madvise
3. fallback to base pages on any node
Recent customer reports however revealed we have a gap in step 1 above.
What we have seen is excessive reclaim due to THP page faults on a NUMA
node that's close to its high watermark, while other nodes have plenty of
free memory.
The problem with step 1 is that it promises no reclaim after the
compaction attempt, however reclaim is only avoided for certain compaction
outcomes (deferred, or skipped due to insufficient free base pages), and
not e.g. when compaction is actually performed but fails (we did see
compact_fail vmstat counter increasing).
THP page faults can therefore exhibit a zone_reclaim_mode-like behavior,
which is not the intention.
Thus add a check for __GFP_THISNODE that corresponds to this exact
situation and prevents continuing with reclaim/compaction once the initial
compaction attempt isn't successful in allocating the page.
Note that commit cc638f329ef6 has not introduced this over-reclaim
possibility; it appears to exist in some form since commit 2f0799a0ffc0
("mm, thp: restore node-local hugepage allocations"). Followup commits
b39d0ee2632d ("mm, page_alloc: avoid expensive reclaim when compaction may
not succeed") and cc638f329ef6 have moved in the right direction, but left
the abovementioned gap.
Link: https://lkml.kernel.org/r/20251219-costly-noretry-thisnode-fix-v1-1-e1085a4a0c34@suse.cz
Fixes: 2f0799a0ffc0 ("mm, thp: restore node-local hugepage allocations")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Pedro Falcato <pfalcato@suse.de>
Acked-by: Zi Yan <ziy@nvidia.com>
Cc: Brendan Jackman <jackmanb@google.com>
Cc: "David Hildenbrand (Red Hat)" <david@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Liam Howlett <liam.howlett@oracle.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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[ Upstream commit f8b4cd2dad097e4ea5aed3511f42b9eb771e7b19 ]
kvfree_call_rcu() can be called while holding a raw_spinlock_t.
Since __kfree_rcu_sheaf() may acquire a spinlock_t (which becomes a
sleeping lock on PREEMPT_RT) and violate lock nesting rules,
kvfree_call_rcu() bypasses the sheaves layer entirely on PREEMPT_RT.
However, lockdep still complains about acquiring spinlock_t while holding
raw_spinlock_t, even on !PREEMPT_RT where spinlock_t is a spinning lock.
This causes a false lockdep warning [1]:
=============================
[ BUG: Invalid wait context ]
6.19.0-rc6-next-20260120 #21508 Not tainted
-----------------------------
migration/1/23 is trying to lock:
ffff8afd01054e98 (&barn->lock){..-.}-{3:3}, at: barn_get_empty_sheaf+0x1d/0xb0
other info that might help us debug this:
context-{5:5}
3 locks held by migration/1/23:
#0: ffff8afd01fd89a8 (&p->pi_lock){-.-.}-{2:2}, at: __balance_push_cpu_stop+0x3f/0x200
#1: ffffffff9f15c5c8 (rcu_read_lock){....}-{1:3}, at: cpuset_cpus_allowed_fallback+0x27/0x250
#2: ffff8afd1f470be0 ((local_lock_t *)&pcs->lock){+.+.}-{3:3}, at: __kfree_rcu_sheaf+0x52/0x3d0
stack backtrace:
CPU: 1 UID: 0 PID: 23 Comm: migration/1 Not tainted 6.19.0-rc6-next-20260120 #21508 PREEMPTLAZY
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Stopper: __balance_push_cpu_stop+0x0/0x200 <- balance_push+0x118/0x170
Call Trace:
<TASK>
__dump_stack+0x22/0x30
dump_stack_lvl+0x60/0x80
dump_stack+0x19/0x24
__lock_acquire+0xd3a/0x28e0
? __lock_acquire+0x5a9/0x28e0
? __lock_acquire+0x5a9/0x28e0
? barn_get_empty_sheaf+0x1d/0xb0
lock_acquire+0xc3/0x270
? barn_get_empty_sheaf+0x1d/0xb0
? __kfree_rcu_sheaf+0x52/0x3d0
_raw_spin_lock_irqsave+0x47/0x70
? barn_get_empty_sheaf+0x1d/0xb0
barn_get_empty_sheaf+0x1d/0xb0
? __kfree_rcu_sheaf+0x52/0x3d0
__kfree_rcu_sheaf+0x19f/0x3d0
kvfree_call_rcu+0xaf/0x390
set_cpus_allowed_force+0xc8/0xf0
[...]
</TASK>
This wasn't triggered until sheaves were enabled for all slab caches,
since kfree_rcu() wasn't being called with a raw spinlock held for
caches with sheaves (vma, maple node).
As suggested by Vlastimil Babka, fix this by using a lockdep map with
LD_WAIT_CONFIG wait type to tell lockdep that acquiring spinlock_t is valid
in this case, as those spinlocks won't be used on PREEMPT_RT.
Note that kfree_rcu_sheaf_map should be acquired using _try() variant,
otherwise the acquisition of the lockdep map itself will trigger an invalid
wait context warning.
Reported-by: Paul E. McKenney <paulmck@kernel.org>
Closes: https://lore.kernel.org/linux-mm/c858b9af-2510-448b-9ab3-058f7b80dd42@paulmck-laptop [1]
Fixes: ec66e0d59952 ("slab: add sheaf support for batching kfree_rcu() operations")
Suggested-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Sasha Levin <sashal@kernel.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull hotfixes from Andrew Morton:
"A couple of late-breaking MM fixes. One against a new-in-this-cycle
patch and the other addresses a locking issue which has been there for
over a year"
* tag 'mm-hotfixes-stable-2026-02-06-12-37' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
mm/memory-failure: reject unsupported non-folio compound page
procfs: avoid fetching build ID while holding VMA lock
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git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab
Pull slab fix from Vlastimil Babka:
"A stable fix for memory allocation profiling tag not being cleared
when aborting an allocation due to memcg charge failure (Hao Ge)"
* tag 'slab-for-6.19-rc8-fix' of git://git.kernel.org/pub/scm/linux/kernel/git/vbabka/slab:
mm/slab: Add alloc_tagging_slab_free_hook for memcg_alloc_abort_single
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|
When CONFIG_MEM_ALLOC_PROFILING_DEBUG is enabled, the following warning
may be noticed:
[ 3959.023862] ------------[ cut here ]------------
[ 3959.023891] alloc_tag was not cleared (got tag for lib/xarray.c:378)
[ 3959.023947] WARNING: ./include/linux/alloc_tag.h:155 at alloc_tag_add+0x128/0x178, CPU#6: mkfs.ntfs/113998
[ 3959.023978] Modules linked in: dns_resolver tun brd overlay exfat btrfs blake2b libblake2b xor xor_neon raid6_pq loop sctp ip6_udp_tunnel udp_tunnel ext4 crc16 mbcache jbd2 rfkill sunrpc vfat fat sg fuse nfnetlink sr_mod virtio_gpu cdrom drm_client_lib virtio_dma_buf drm_shmem_helper drm_kms_helper ghash_ce drm sm4 backlight virtio_net net_failover virtio_scsi failover virtio_console virtio_blk virtio_mmio dm_mirror dm_region_hash dm_log dm_multipath dm_mod i2c_dev aes_neon_bs aes_ce_blk [last unloaded: hwpoison_inject]
[ 3959.024170] CPU: 6 UID: 0 PID: 113998 Comm: mkfs.ntfs Kdump: loaded Tainted: G W 6.19.0-rc7+ #7 PREEMPT(voluntary)
[ 3959.024182] Tainted: [W]=WARN
[ 3959.024186] Hardware name: QEMU KVM Virtual Machine, BIOS unknown 2/2/2022
[ 3959.024192] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[ 3959.024199] pc : alloc_tag_add+0x128/0x178
[ 3959.024207] lr : alloc_tag_add+0x128/0x178
[ 3959.024214] sp : ffff80008b696d60
[ 3959.024219] x29: ffff80008b696d60 x28: 0000000000000000 x27: 0000000000000240
[ 3959.024232] x26: 0000000000000000 x25: 0000000000000240 x24: ffff800085d17860
[ 3959.024245] x23: 0000000000402800 x22: ffff0000c0012dc0 x21: 00000000000002d0
[ 3959.024257] x20: ffff0000e6ef3318 x19: ffff800085ae0410 x18: 0000000000000000
[ 3959.024269] x17: 0000000000000000 x16: 0000000000000000 x15: 0000000000000000
[ 3959.024281] x14: 0000000000000000 x13: 0000000000000001 x12: ffff600064101293
[ 3959.024292] x11: 1fffe00064101292 x10: ffff600064101292 x9 : dfff800000000000
[ 3959.024305] x8 : 00009fff9befed6e x7 : ffff000320809493 x6 : 0000000000000001
[ 3959.024316] x5 : ffff000320809490 x4 : ffff600064101293 x3 : ffff800080691838
[ 3959.024328] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff0000d5bcd640
[ 3959.024340] Call trace:
[ 3959.024346] alloc_tag_add+0x128/0x178 (P)
[ 3959.024355] __alloc_tagging_slab_alloc_hook+0x11c/0x1a8
[ 3959.024362] kmem_cache_alloc_lru_noprof+0x1b8/0x5e8
[ 3959.024369] xas_alloc+0x304/0x4f0
[ 3959.024381] xas_create+0x1e0/0x4a0
[ 3959.024388] xas_store+0x68/0xda8
[ 3959.024395] __filemap_add_folio+0x5b0/0xbd8
[ 3959.024409] filemap_add_folio+0x16c/0x7e0
[ 3959.024416] __filemap_get_folio_mpol+0x2dc/0x9e8
[ 3959.024424] iomap_get_folio+0xfc/0x180
[ 3959.024435] __iomap_get_folio+0x2f8/0x4b8
[ 3959.024441] iomap_write_begin+0x198/0xc18
[ 3959.024448] iomap_write_iter+0x2ec/0x8f8
[ 3959.024454] iomap_file_buffered_write+0x19c/0x290
[ 3959.024461] blkdev_write_iter+0x38c/0x978
[ 3959.024470] vfs_write+0x4d4/0x928
[ 3959.024482] ksys_write+0xfc/0x1f8
[ 3959.024489] __arm64_sys_write+0x74/0xb0
[ 3959.024496] invoke_syscall+0xd4/0x258
[ 3959.024507] el0_svc_common.constprop.0+0xb4/0x240
[ 3959.024514] do_el0_svc+0x48/0x68
[ 3959.024520] el0_svc+0x40/0xf8
[ 3959.024526] el0t_64_sync_handler+0xa0/0xe8
[ 3959.024533] el0t_64_sync+0x1ac/0x1b0
[ 3959.024540] ---[ end trace 0000000000000000 ]---
When __memcg_slab_post_alloc_hook() fails, there are two different
free paths depending on whether size == 1 or size != 1. In the
kmem_cache_free_bulk() path, we do call alloc_tagging_slab_free_hook().
However, in memcg_alloc_abort_single() we don't, the above warning will be
triggered on the next allocation.
Therefore, add alloc_tagging_slab_free_hook() to the
memcg_alloc_abort_single() path.
Fixes: 9f9796b413d3 ("mm, slab: move memcg charging to post-alloc hook")
Cc: stable@vger.kernel.org
Suggested-by: Hao Li <hao.li@linux.dev>
Signed-off-by: Hao Ge <hao.ge@linux.dev>
Reviewed-by: Hao Li <hao.li@linux.dev>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>
Link: https://patch.msgid.link/20260204101401.202762-1-hao.ge@linux.dev
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
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|
When !CONFIG_TRANSPARENT_HUGEPAGE, a non-folio compound page can appear in
a userspace mapping via either vm_insert_*() functions or
vm_operatios_struct->fault(). They are not folios, thus should not be
considered for folio operations like split. To reject these pages, make
sure get_hwpoison_page() is always called as HWPoisonHandlable() will do
the right work.
[Some commit log borrowed from Zi Yan. Thanks.]
Link: https://lkml.kernel.org/r/20260205075328.523211-1-linmiaohe@huawei.com
Fixes: 689b8986776c ("mm/memory-failure: improve large block size folio handling")
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reported-by: 是参差 <shicenci@gmail.com>
Closes: https://lore.kernel.org/all/PS1PPF7E1D7501F1E4F4441E7ECD056DEADAB98A@PS1PPF7E1D7501F.apcprd02.prod.outlook.com/
Reviewed-by: Zi Yan <ziy@nvidia.com>
Tested-by: Zi Yan <ziy@nvidia.com>
Cc: David Hildenbrand <david@kernel.org>
Cc: Jane Chu <jane.chu@oracle.com>
Cc: Miaohe Lin <linmiaohe@huawei.com>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
"Five hotfixes. Two are cc:stable, two are for MM.
All are singletons - please see the changelogs for details"
* tag 'mm-hotfixes-stable-2026-02-04-15-55' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
Documentation: document liveupdate cmdline parameter
mm, shmem: prevent infinite loop on truncate race
mailmap: update Alexander Mikhalitsyn's emails
liveupdate: luo_file: do not clear serialized_data on unfreeze
x86/kfence: fix booting on 32bit non-PAE systems
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When truncating a large swap entry, shmem_free_swap() returns 0 when the
entry's index doesn't match the given index due to lookup alignment. The
failure fallback path checks if the entry crosses the end border and
aborts when it happens, so truncate won't erase an unexpected entry or
range. But one scenario was ignored.
When `index` points to the middle of a large swap entry, and the large
swap entry doesn't go across the end border, find_get_entries() will
return that large swap entry as the first item in the batch with
`indices[0]` equal to `index`. The entry's base index will be smaller
than `indices[0]`, so shmem_free_swap() will fail and return 0 due to the
"base < index" check. The code will then call shmem_confirm_swap(), get
the order, check if it crosses the END boundary (which it doesn't), and
retry with the same index.
The next iteration will find the same entry again at the same index with
same indices, leading to an infinite loop.
Fix this by retrying with a round-down index, and abort if the index is
smaller than the truncate range.
Link: https://lkml.kernel.org/r/aXo6ltB5iqAKJzY8@KASONG-MC4
Fixes: 809bc86517cc ("mm: shmem: support large folio swap out")
Fixes: 8a1968bd997f ("mm/shmem, swap: fix race of truncate and swap entry split")
Signed-off-by: Kairui Song <kasong@tencent.com>
Reported-by: Chris Mason <clm@meta.com>
Closes: https://lore.kernel.org/linux-mm/20260128130336.727049-1-clm@meta.com/
Reviewed-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Chris Li <chrisl@kernel.org>
Cc: Hugh Dickins <hughd@google.com>
Cc: Kemeng Shi <shikemeng@huaweicloud.com>
Cc: Nhat Pham <nphamcs@gmail.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
|
|
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
"16 hotfixes. 9 are cc:stable, 12 are for MM.
There's a patch series from Pratyush Yadav which fixes a few things in
the new-in-6.19 LUO memfd code.
Plus the usual shower of singletons - please see the changelogs for
details"
* tag 'mm-hotfixes-stable-2026-01-29-09-41' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
vmcoreinfo: make hwerr_data visible for debugging
mm/zone_device: reinitialize large zone device private folios
mm/mm_init: don't cond_resched() in deferred_init_memmap_chunk() if called from deferred_grow_zone()
mm/kfence: randomize the freelist on initialization
kho: kho_preserve_vmalloc(): don't return 0 when ENOMEM
kho: init alloc tags when restoring pages from reserved memory
mm: memfd_luo: restore and free memfd_luo_ser on failure
mm: memfd_luo: use memfd_alloc_file() instead of shmem_file_setup()
memfd: export alloc_file()
flex_proportions: make fprop_new_period() hardirq safe
mailmap: add entry for Viacheslav Bocharov
mm/memory-failure: teach kill_accessing_process to accept hugetlb tail page pfn
mm/memory-failure: fix missing ->mf_stats count in hugetlb poison
mm, swap: restore swap_space attr aviod kernel panic
mm/kasan: fix KASAN poisoning in vrealloc()
mm/shmem, swap: fix race of truncate and swap entry split
|
|
Reinitialize metadata for large zone device private folios in
zone_device_page_init prior to creating a higher-order zone device private
folio. This step is necessary when the folio's order changes dynamically
between zone_device_page_init calls to avoid building a corrupt folio. As
part of the metadata reinitialization, the dev_pagemap must be passed in
from the caller because the pgmap stored in the folio page may have been
overwritten with a compound head.
Without this fix, individual pages could have invalid pgmap fields and
flags (with PG_locked being notably problematic) due to prior different
order allocations, which can, and will, result in kernel crashes.
Link: https://lkml.kernel.org/r/20260116111325.1736137-2-francois.dugast@intel.com
Fixes: d245f9b4ab80 ("mm/zone_device: support large zone device private folios")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Signed-off-by: Francois Dugast <francois.dugast@intel.com>
Acked-by: Felix Kuehling <felix.kuehling@amd.com>
Reviewed-by: Balbir Singh <balbirs@nvidia.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Christophe Leroy (CS GROUP)" <chleroy@kernel.org>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: David Airlie <airlied@gmail.com>
Cc: Simona Vetter <simona@ffwll.ch>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Maxime Ripard <mripard@kernel.org>
Cc: Thomas Zimmermann <tzimmermann@suse.de>
Cc: Lyude Paul <lyude@redhat.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: David Hildenbrand <david@kernel.org>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Leon Romanovsky <leon@kernel.org>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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