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c85507857b
23262 Commits
| Author | SHA1 | Message | Date | |
|---|---|---|---|---|
Qi Zheng
|
c85507857b |
mm: khugepaged: __collapse_huge_page_swapin() use pte_offset_map_ro_nolock()
In __collapse_huge_page_swapin(), we just use the ptl for pte_same() check in do_swap_page(). In other places, we directly use pte_offset_map_lock(), so convert it to using pte_offset_map_ro_nolock(). Link: https://lkml.kernel.org/r/dc97a6c3cb9ea80cab30c5626eeea79959d93258.1727332572.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Muchun Song <muchun.song@linux.dev> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Peter Xu <peterx@redhat.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Qi Zheng
|
bd6ad65ddc |
mm: filemap: filemap_fault_recheck_pte_none() use pte_offset_map_ro_nolock()
In filemap_fault_recheck_pte_none(), we just do pte_none() check, so convert it to using pte_offset_map_ro_nolock(). Link: https://lkml.kernel.org/r/9f7cbbaa772385ced1b8931b67a8b9d246c9b82d.1727332572.git.zhengqi.arch@bytedance.com Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Acked-by: David Hildenbrand <david@redhat.com> Reviewed-by: Muchun Song <muchun.song@linux.dev> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Peter Xu <peterx@redhat.com> Cc: Ryan Roberts <ryan.roberts@arm.com> Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Qi Zheng
|
66efef9b1a |
mm: pgtable: introduce pte_offset_map_{ro|rw}_nolock()
Patch series "introduce pte_offset_map_{ro|rw}_nolock()", v5.
As proposed by David Hildenbrand [1], this series introduces the following
two new helper functions to replace pte_offset_map_nolock().
1. pte_offset_map_ro_nolock()
2. pte_offset_map_rw_nolock()
As the name suggests, pte_offset_map_ro_nolock() is used for read-only
case. In this case, only read-only operations will be performed on PTE
page after the PTL is held. The RCU lock in pte_offset_map_nolock() will
ensure that the PTE page will not be freed, and there is no need to worry
about whether the pmd entry is modified. Therefore
pte_offset_map_ro_nolock() is just a renamed version of
pte_offset_map_nolock().
pte_offset_map_rw_nolock() is used for may-write case. In this case, the
pte or pmd entry may be modified after the PTL is held, so we need to
ensure that the pmd entry has not been modified concurrently. So in
addition to the name change, it also outputs the pmdval when successful.
The users should make sure the page table is stable like checking
pte_same() or checking pmd_same() by using the output pmdval before
performing the write operations.
This series will convert all pte_offset_map_nolock() into the above two
helper functions one by one, and finally completely delete it.
This also a preparation for reclaiming the empty user PTE page table
pages.
This patch (of 13):
Currently, the usage of pte_offset_map_nolock() can be divided into the
following two cases:
1) After acquiring PTL, only read-only operations are performed on the PTE
page. In this case, the RCU lock in pte_offset_map_nolock() will ensure
that the PTE page will not be freed, and there is no need to worry
about whether the pmd entry is modified.
2) After acquiring PTL, the pte or pmd entries may be modified. At this
time, we need to ensure that the pmd entry has not been modified
concurrently.
To more clearing distinguish between these two cases, this commit
introduces two new helper functions to replace pte_offset_map_nolock().
For 1), just rename it to pte_offset_map_ro_nolock(). For 2), in addition
to changing the name to pte_offset_map_rw_nolock(), it also outputs the
pmdval when successful. It is applicable for may-write cases where any
modification operations to the page table may happen after the
corresponding spinlock is held afterwards. But the users should make sure
the page table is stable like checking pte_same() or checking pmd_same()
by using the output pmdval before performing the write operations.
Note: "RO" / "RW" expresses the intended semantics, not that the *kmap*
will be read-only/read-write protected.
Subsequent commits will convert pte_offset_map_nolock() into the above
two functions one by one, and finally completely delete it.
Link: https://lkml.kernel.org/r/cover.1727332572.git.zhengqi.arch@bytedance.com
Link: https://lkml.kernel.org/r/5aeecfa131600a454b1f3a038a1a54282ca3b856.1727332572.git.zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: David Hildenbrand <david@redhat.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Cc: Peter Xu <peterx@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vishal Moola (Oracle) <vishal.moola@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
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Nanyong Sun
|
f2f484085e |
mm: move mm flags to mm_types.h
The types of mm flags are now far beyond the core dump related features. This patch moves mm flags from linux/sched/coredump.h to linux/mm_types.h. The linux/sched/coredump.h has include the mm_types.h, so the C files related to coredump does not need to change head file inclusion. In addition, the inclusion of sched/coredump.h now can be deleted from the C files that irrelevant to core dump. Link: https://lkml.kernel.org/r/20240926074922.2721274-1-sunnanyong@huawei.com Signed-off-by: Nanyong Sun <sunnanyong@huawei.com> Cc: Kefeng Wang <wangkefeng.wang@huawei.com> Cc: Masami Hiramatsu <mhiramat@kernel.org> Cc: Matthew Wilcox <willy@infradead.org> Cc: Oleg Nesterov <oleg@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Lorenzo Stoakes
|
021781b012 |
mm/madvise: unrestrict process_madvise() for current process
The process_madvise() call was introduced in commit |
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Tanya Agarwal
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1cd1a4e71b |
mm/mempolicy: fix comments for better documentation
Fix typo in mempolicy.h and Correct the number of allowed memory policy Link: https://lkml.kernel.org/r/20240926183516.4034-2-tanyaagarwal25699@gmail.com Signed-off-by: Tanya Agarwal <tanyaagarwal25699@gmail.com> Reviewed-by: Shuah Khan <skhan@linuxfoundation.org> Cc: Anup Sharma <anupnewsmail@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Zhiguo Jiang
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bbc251f30e |
mm: fix shrink nr.unqueued_dirty counter issue
It is needed to ensure sc->nr.unqueued_dirty > 0, which can avoid setting PGDAT_DIRTY flag when sc->nr.unqueued_dirty and sc->nr.file_taken are both zero. Link: https://lkml.kernel.org/r/20240112012353.1387-1-justinjiang@vivo.com Signed-off-by: Zhiguo Jiang <justinjiang@vivo.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Lorenzo Stoakes
|
cd3f8467af |
mm: refactor mm_access() to not return NULL
mm_access() can return NULL if the mm is not found, but this is handled the same as an error in all callers, with some translating this into an -ESRCH error. Only proc_mem_open() returns NULL if no mm is found, however in this case it is clearer and makes more sense to explicitly handle the error. Additionally we take the opportunity to refactor the function to eliminate unnecessary nesting. Simplify things by simply returning -ESRCH if no mm is found - this both eliminates confusing use of the IS_ERR_OR_NULL() macro, and simplifies callers which would return -ESRCH by returning this error directly. [lorenzo.stoakes@oracle.com: prefer neater pointer error comparison] Link: https://lkml.kernel.org/r/2fae1834-749a-45e1-8594-5e5979cf7103@lucifer.local Link: https://lkml.kernel.org/r/20240924201023.193135-1-lorenzo.stoakes@oracle.com Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Suggested-by: Arnd Bergmann <arnd@arndb.de> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Adrian Huang
|
9e9e085eff |
mm/vmalloc: combine all TLB flush operations of KASAN shadow virtual address into one operation
When compiling kernel source 'make -j $(nproc)' with the up-and-running
KASAN-enabled kernel on a 256-core machine, the following soft lockup is
shown:
watchdog: BUG: soft lockup - CPU#28 stuck for 22s! [kworker/28:1:1760]
CPU: 28 PID: 1760 Comm: kworker/28:1 Kdump: loaded Not tainted 6.10.0-rc5 #95
Workqueue: events drain_vmap_area_work
RIP: 0010:smp_call_function_many_cond+0x1d8/0xbb0
Code: 38 c8 7c 08 84 c9 0f 85 49 08 00 00 8b 45 08 a8 01 74 2e 48 89 f1 49 89 f7 48 c1 e9 03 41 83 e7 07 4c 01 e9 41 83 c7 03 f3 90 <0f> b6 01 41 38 c7 7c 08 84 c0 0f 85 d4 06 00 00 8b 45 08 a8 01 75
RSP: 0018:ffffc9000cb3fb60 EFLAGS: 00000202
RAX: 0000000000000011 RBX: ffff8883bc4469c0 RCX: ffffed10776e9949
RDX: 0000000000000002 RSI: ffff8883bb74ca48 RDI: ffffffff8434dc50
RBP: ffff8883bb74ca40 R08: ffff888103585dc0 R09: ffff8884533a1800
R10: 0000000000000004 R11: ffffffffffffffff R12: ffffed1077888d39
R13: dffffc0000000000 R14: ffffed1077888d38 R15: 0000000000000003
FS: 0000000000000000(0000) GS:ffff8883bc400000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00005577b5c8d158 CR3: 0000000004850000 CR4: 0000000000350ef0
Call Trace:
<IRQ>
? watchdog_timer_fn+0x2cd/0x390
? __pfx_watchdog_timer_fn+0x10/0x10
? __hrtimer_run_queues+0x300/0x6d0
? sched_clock_cpu+0x69/0x4e0
? __pfx___hrtimer_run_queues+0x10/0x10
? srso_return_thunk+0x5/0x5f
? ktime_get_update_offsets_now+0x7f/0x2a0
? srso_return_thunk+0x5/0x5f
? srso_return_thunk+0x5/0x5f
? hrtimer_interrupt+0x2ca/0x760
? __sysvec_apic_timer_interrupt+0x8c/0x2b0
? sysvec_apic_timer_interrupt+0x6a/0x90
</IRQ>
<TASK>
? asm_sysvec_apic_timer_interrupt+0x16/0x20
? smp_call_function_many_cond+0x1d8/0xbb0
? __pfx_do_kernel_range_flush+0x10/0x10
on_each_cpu_cond_mask+0x20/0x40
flush_tlb_kernel_range+0x19b/0x250
? srso_return_thunk+0x5/0x5f
? kasan_release_vmalloc+0xa7/0xc0
purge_vmap_node+0x357/0x820
? __pfx_purge_vmap_node+0x10/0x10
__purge_vmap_area_lazy+0x5b8/0xa10
drain_vmap_area_work+0x21/0x30
process_one_work+0x661/0x10b0
worker_thread+0x844/0x10e0
? srso_return_thunk+0x5/0x5f
? __kthread_parkme+0x82/0x140
? __pfx_worker_thread+0x10/0x10
kthread+0x2a5/0x370
? __pfx_kthread+0x10/0x10
ret_from_fork+0x30/0x70
? __pfx_kthread+0x10/0x10
ret_from_fork_asm+0x1a/0x30
</TASK>
Debugging Analysis:
1. The following ftrace log shows that the lockup CPU spends too much
time iterating vmap_nodes and flushing TLB when purging vm_area
structures. (Some info is trimmed).
kworker: funcgraph_entry: | drain_vmap_area_work() {
kworker: funcgraph_entry: | mutex_lock() {
kworker: funcgraph_entry: 1.092 us | __cond_resched();
kworker: funcgraph_exit: 3.306 us | }
... ...
kworker: funcgraph_entry: | flush_tlb_kernel_range() {
... ...
kworker: funcgraph_exit: # 7533.649 us | }
... ...
kworker: funcgraph_entry: 2.344 us | mutex_unlock();
kworker: funcgraph_exit: $ 23871554 us | }
The drain_vmap_area_work() spends over 23 seconds.
There are 2805 flush_tlb_kernel_range() calls in the ftrace log.
* One is called in __purge_vmap_area_lazy().
* Others are called by purge_vmap_node->kasan_release_vmalloc.
purge_vmap_node() iteratively releases kasan vmalloc
allocations and flushes TLB for each vmap_area.
- [Rough calculation] Each flush_tlb_kernel_range() runs
about 7.5ms.
-- 2804 * 7.5ms = 21.03 seconds.
-- That's why a soft lock is triggered.
2. Extending the soft lockup time can work around the issue (For example,
# echo 60 > /proc/sys/kernel/watchdog_thresh). This confirms the
above-mentioned speculation: drain_vmap_area_work() spends too much
time.
If we combine all TLB flush operations of the KASAN shadow virtual
address into one operation in the call path
'purge_vmap_node()->kasan_release_vmalloc()', the running time of
drain_vmap_area_work() can be saved greatly. The idea is from the
flush_tlb_kernel_range() call in __purge_vmap_area_lazy(). And, the
soft lockup won't be triggered.
Here is the test result based on 6.10:
[6.10 wo/ the patch]
1. ftrace latency profiling (record a trace if the latency > 20s).
echo 20000000 > /sys/kernel/debug/tracing/tracing_thresh
echo drain_vmap_area_work > /sys/kernel/debug/tracing/set_graph_function
echo function_graph > /sys/kernel/debug/tracing/current_tracer
echo 1 > /sys/kernel/debug/tracing/tracing_on
2. Run `make -j $(nproc)` to compile the kernel source
3. Once the soft lockup is reproduced, check the ftrace log:
cat /sys/kernel/debug/tracing/trace
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
76) $ 50412985 us | } /* __purge_vmap_area_lazy */
76) $ 50412997 us | } /* drain_vmap_area_work */
76) $ 29165911 us | } /* __purge_vmap_area_lazy */
76) $ 29165926 us | } /* drain_vmap_area_work */
91) $ 53629423 us | } /* __purge_vmap_area_lazy */
91) $ 53629434 us | } /* drain_vmap_area_work */
91) $ 28121014 us | } /* __purge_vmap_area_lazy */
91) $ 28121026 us | } /* drain_vmap_area_work */
[6.10 w/ the patch]
1. Repeat step 1-2 in "[6.10 wo/ the patch]"
2. The soft lockup is not triggered and ftrace log is empty.
cat /sys/kernel/debug/tracing/trace
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
3. Setting 'tracing_thresh' to 10/5 seconds does not get any ftrace
log.
4. Setting 'tracing_thresh' to 1 second gets ftrace log.
cat /sys/kernel/debug/tracing/trace
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
23) $ 1074942 us | } /* __purge_vmap_area_lazy */
23) $ 1074950 us | } /* drain_vmap_area_work */
The worst execution time of drain_vmap_area_work() is about 1 second.
Link: https://lore.kernel.org/lkml/ZqFlawuVnOMY2k3E@pc638.lan/
Link: https://lkml.kernel.org/r/20240726165246.31326-1-ahuang12@lenovo.com
Fixes:
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Jingxiang Zeng
|
15ff4d409e |
mm/memcontrol: add per-memcg pgpgin/pswpin counter
In proactive memory reclamation scenarios, it is necessary to estimate the pswpin and pswpout metrics of the cgroup to determine whether to continue reclaiming anonymous pages in the current batch. This patch will collect these metrics and expose them. [linuszeng@tencent.com: v2] Link: https://lkml.kernel.org/r/20240830082244.156923-1-jingxiangzeng.cas@gmail.com Li nk: https://lkml.kernel.org/r/20240913084453.3605621-1-jingxiangzeng.cas@gmail.com Link: https://lkml.kernel.org/r/20240830082244.156923-1-jingxiangzeng.cas@gmail.com Signed-off-by: Jingxiang Zeng <linuszeng@tencent.com> Acked-by: Nhat Pham <nphamcs@gmail.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: Muchun Song <muchun.song@linux.dev> Cc: Roman Gushchin <roman.gushchin@linux.dev> Cc: Shakeel Butt <shakeel.butt@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Leo Stone
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ba7196e566 |
mm/damon: fix sparse warning for zero initializer
sparse warns about zero initializing an array with {0,}, change it to
the equivalent {0}.
Fixes the sparse warning:
mm/damon/tests/vaddr-kunit.h:69:47: warning: missing braces around initializer
Link: https://lkml.kernel.org/r/xriwklcwjpwcz7eiavo6f7envdar4jychhsk6sfkj5klaznb6b@j6vrvr2sxjht
Fixes:
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Baolin Wang
|
d2d243df44 |
mm: shmem: fix khugepaged activation policy for shmem
Shmem has a separate interface (different from anonymous pages) to control huge page allocation, that means shmem THP can be enabled while anonymous THP is disabled. However, in this case, khugepaged will not start to collapse shmem THP, which is unreasonable. To fix this issue, we should call start_stop_khugepaged() to activate or deactivate the khugepaged thread when setting shmem mTHP interfaces. Moreover, add a new helper shmem_hpage_pmd_enabled() to help to check whether shmem THP is enabled, which will determine if khugepaged should be activated. Link: https://lkml.kernel.org/r/9b9c6cbc4499bf44c6455367fd9e0f6036525680.1726978977.git.baolin.wang@linux.alibaba.com Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com> Reported-by: Ryan Roberts <ryan.roberts@arm.com> Reviewed-by: Ryan Roberts <ryan.roberts@arm.com> Cc: David Hildenbrand <david@redhat.com> Cc: Hugh Dickins <hughd@google.com> Cc: Matthew Wilcox <willy@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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Lorenzo Stoakes
|
5de195060b |
mm: resolve faulty mmap_region() error path behaviour
The mmap_region() function is somewhat terrifying, with spaghetti-like
control flow and numerous means by which issues can arise and incomplete
state, memory leaks and other unpleasantness can occur.
A large amount of the complexity arises from trying to handle errors late
in the process of mapping a VMA, which forms the basis of recently
observed issues with resource leaks and observable inconsistent state.
Taking advantage of previous patches in this series we move a number of
checks earlier in the code, simplifying things by moving the core of the
logic into a static internal function __mmap_region().
Doing this allows us to perform a number of checks up front before we do
any real work, and allows us to unwind the writable unmap check
unconditionally as required and to perform a CONFIG_DEBUG_VM_MAPLE_TREE
validation unconditionally also.
We move a number of things here:
1. We preallocate memory for the iterator before we call the file-backed
memory hook, allowing us to exit early and avoid having to perform
complicated and error-prone close/free logic. We carefully free
iterator state on both success and error paths.
2. The enclosing mmap_region() function handles the mapping_map_writable()
logic early. Previously the logic had the mapping_map_writable() at the
point of mapping a newly allocated file-backed VMA, and a matching
mapping_unmap_writable() on success and error paths.
We now do this unconditionally if this is a file-backed, shared writable
mapping. If a driver changes the flags to eliminate VM_MAYWRITE, however
doing so does not invalidate the seal check we just performed, and we in
any case always decrement the counter in the wrapper.
We perform a debug assert to ensure a driver does not attempt to do the
opposite.
3. We also move arch_validate_flags() up into the mmap_region()
function. This is only relevant on arm64 and sparc64, and the check is
only meaningful for SPARC with ADI enabled. We explicitly add a warning
for this arch if a driver invalidates this check, though the code ought
eventually to be fixed to eliminate the need for this.
With all of these measures in place, we no longer need to explicitly close
the VMA on error paths, as we place all checks which might fail prior to a
call to any driver mmap hook.
This eliminates an entire class of errors, makes the code easier to reason
about and more robust.
Link: https://lkml.kernel.org/r/6e0becb36d2f5472053ac5d544c0edfe9b899e25.1730224667.git.lorenzo.stoakes@oracle.com
Fixes:
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Lorenzo Stoakes
|
5baf8b037d |
mm: refactor arch_calc_vm_flag_bits() and arm64 MTE handling
Currently MTE is permitted in two circumstances (desiring to use MTE
having been specified by the VM_MTE flag) - where MAP_ANONYMOUS is
specified, as checked by arch_calc_vm_flag_bits() and actualised by
setting the VM_MTE_ALLOWED flag, or if the file backing the mapping is
shmem, in which case we set VM_MTE_ALLOWED in shmem_mmap() when the mmap
hook is activated in mmap_region().
The function that checks that, if VM_MTE is set, VM_MTE_ALLOWED is also
set is the arm64 implementation of arch_validate_flags().
Unfortunately, we intend to refactor mmap_region() to perform this check
earlier, meaning that in the case of a shmem backing we will not have
invoked shmem_mmap() yet, causing the mapping to fail spuriously.
It is inappropriate to set this architecture-specific flag in general mm
code anyway, so a sensible resolution of this issue is to instead move the
check somewhere else.
We resolve this by setting VM_MTE_ALLOWED much earlier in do_mmap(), via
the arch_calc_vm_flag_bits() call.
This is an appropriate place to do this as we already check for the
MAP_ANONYMOUS case here, and the shmem file case is simply a variant of
the same idea - we permit RAM-backed memory.
This requires a modification to the arch_calc_vm_flag_bits() signature to
pass in a pointer to the struct file associated with the mapping, however
this is not too egregious as this is only used by two architectures anyway
- arm64 and parisc.
So this patch performs this adjustment and removes the unnecessary
assignment of VM_MTE_ALLOWED in shmem_mmap().
[akpm@linux-foundation.org: fix whitespace, per Catalin]
Link: https://lkml.kernel.org/r/ec251b20ba1964fb64cf1607d2ad80c47f3873df.1730224667.git.lorenzo.stoakes@oracle.com
Fixes:
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Lorenzo Stoakes
|
0fb4a7ad27 |
mm: refactor map_deny_write_exec()
Refactor the map_deny_write_exec() to not unnecessarily require a VMA
parameter but rather to accept VMA flags parameters, which allows us to
use this function early in mmap_region() in a subsequent commit.
While we're here, we refactor the function to be more readable and add
some additional documentation.
Link: https://lkml.kernel.org/r/6be8bb59cd7c68006ebb006eb9d8dc27104b1f70.1730224667.git.lorenzo.stoakes@oracle.com
Fixes:
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Lorenzo Stoakes
|
4080ef1579 |
mm: unconditionally close VMAs on error
Incorrect invocation of VMA callbacks when the VMA is no longer in a
consistent state is bug prone and risky to perform.
With regards to the important vm_ops->close() callback We have gone to
great lengths to try to track whether or not we ought to close VMAs.
Rather than doing so and risking making a mistake somewhere, instead
unconditionally close and reset vma->vm_ops to an empty dummy operations
set with a NULL .close operator.
We introduce a new function to do so - vma_close() - and simplify existing
vms logic which tracked whether we needed to close or not.
This simplifies the logic, avoids incorrect double-calling of the .close()
callback and allows us to update error paths to simply call vma_close()
unconditionally - making VMA closure idempotent.
Link: https://lkml.kernel.org/r/28e89dda96f68c505cb6f8e9fc9b57c3e9f74b42.1730224667.git.lorenzo.stoakes@oracle.com
Fixes:
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Lorenzo Stoakes
|
3dd6ed34ce |
mm: avoid unsafe VMA hook invocation when error arises on mmap hook
Patch series "fix error handling in mmap_region() and refactor
(hotfixes)", v4.
mmap_region() is somewhat terrifying, with spaghetti-like control flow and
numerous means by which issues can arise and incomplete state, memory
leaks and other unpleasantness can occur.
A large amount of the complexity arises from trying to handle errors late
in the process of mapping a VMA, which forms the basis of recently
observed issues with resource leaks and observable inconsistent state.
This series goes to great lengths to simplify how mmap_region() works and
to avoid unwinding errors late on in the process of setting up the VMA for
the new mapping, and equally avoids such operations occurring while the
VMA is in an inconsistent state.
The patches in this series comprise the minimal changes required to
resolve existing issues in mmap_region() error handling, in order that
they can be hotfixed and backported. There is additionally a follow up
series which goes further, separated out from the v1 series and sent and
updated separately.
This patch (of 5):
After an attempted mmap() fails, we are no longer in a situation where we
can safely interact with VMA hooks. This is currently not enforced,
meaning that we need complicated handling to ensure we do not incorrectly
call these hooks.
We can avoid the whole issue by treating the VMA as suspect the moment
that the file->f_ops->mmap() function reports an error by replacing
whatever VMA operations were installed with a dummy empty set of VMA
operations.
We do so through a new helper function internal to mm - mmap_file() -
which is both more logically named than the existing call_mmap() function
and correctly isolates handling of the vm_op reassignment to mm.
All the existing invocations of call_mmap() outside of mm are ultimately
nested within the call_mmap() from mm, which we now replace.
It is therefore safe to leave call_mmap() in place as a convenience
function (and to avoid churn). The invokers are:
ovl_file_operations -> mmap -> ovl_mmap() -> backing_file_mmap()
coda_file_operations -> mmap -> coda_file_mmap()
shm_file_operations -> shm_mmap()
shm_file_operations_huge -> shm_mmap()
dma_buf_fops -> dma_buf_mmap_internal -> i915_dmabuf_ops
-> i915_gem_dmabuf_mmap()
None of these callers interact with vm_ops or mappings in a problematic
way on error, quickly exiting out.
Link: https://lkml.kernel.org/r/cover.1730224667.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/d41fd763496fd0048a962f3fd9407dc72dd4fd86.1730224667.git.lorenzo.stoakes@oracle.com
Fixes:
|
||
|
Hugh Dickins
|
f8f931bba0 |
mm/thp: fix deferred split unqueue naming and locking
Recent changes are putting more pressure on THP deferred split queues: under load revealing long-standing races, causing list_del corruptions, "Bad page state"s and worse (I keep BUGs in both of those, so usually don't get to see how badly they end up without). The relevant recent changes being 6.8's mTHP, 6.10's mTHP swapout, and 6.12's mTHP swapin, improved swap allocation, and underused THP splitting. Before fixing locking: rename misleading folio_undo_large_rmappable(), which does not undo large_rmappable, to folio_unqueue_deferred_split(), which is what it does. But that and its out-of-line __callee are mm internals of very limited usability: add comment and WARN_ON_ONCEs to check usage; and return a bool to say if a deferred split was unqueued, which can then be used in WARN_ON_ONCEs around safety checks (sparing callers the arcane conditionals in __folio_unqueue_deferred_split()). Just omit the folio_unqueue_deferred_split() from free_unref_folios(), all of whose callers now call it beforehand (and if any forget then bad_page() will tell) - except for its caller put_pages_list(), which itself no longer has any callers (and will be deleted separately). Swapout: mem_cgroup_swapout() has been resetting folio->memcg_data 0 without checking and unqueueing a THP folio from deferred split list; which is unfortunate, since the split_queue_lock depends on the memcg (when memcg is enabled); so swapout has been unqueueing such THPs later, when freeing the folio, using the pgdat's lock instead: potentially corrupting the memcg's list. __remove_mapping() has frozen refcount to 0 here, so no problem with calling folio_unqueue_deferred_split() before resetting memcg_data. That goes back to 5.4 commit |
||
|
Hugh Dickins
|
e66f3185fa |
mm/thp: fix deferred split queue not partially_mapped
Recent changes are putting more pressure on THP deferred split queues:
under load revealing long-standing races, causing list_del corruptions,
"Bad page state"s and worse (I keep BUGs in both of those, so usually
don't get to see how badly they end up without). The relevant recent
changes being 6.8's mTHP, 6.10's mTHP swapout, and 6.12's mTHP swapin,
improved swap allocation, and underused THP splitting.
The new unlocked list_del_init() in deferred_split_scan() is buggy. I
gave bad advice, it looks plausible since that's a local on-stack list,
but the fact is that it can race with a third party freeing or migrating
the preceding folio (properly unqueueing it with refcount 0 while holding
split_queue_lock), thereby corrupting the list linkage.
The obvious answer would be to take split_queue_lock there: but it has a
long history of contention, so I'm reluctant to add to that. Instead,
make sure that there is always one safe (raised refcount) folio before, by
delaying its folio_put(). (And of course I was wrong to suggest updating
split_queue_len without the lock: leave that until the splice.)
And remove two over-eager partially_mapped checks, restoring those tests
to how they were before: if uncharge_folio() or free_tail_page_prepare()
finds _deferred_list non-empty, it's in trouble whether or not that folio
is partially_mapped (and the flag was already cleared in the latter case).
Link: https://lkml.kernel.org/r/81e34a8b-113a-0701-740e-2135c97eb1d7@google.com
Fixes:
|
||
|
Linus Torvalds
|
a8cc743272 |
17 hotfixes. 9 are cc:stable. 13 are MM and 4 are non-MM.
The usual collection of singletons - please see the changelogs.
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Merge tag 'mm-hotfixes-stable-2024-11-03-10-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
Pull misc fixes from Andrew Morton:
"17 hotfixes. 9 are cc:stable. 13 are MM and 4 are non-MM.
The usual collection of singletons - please see the changelogs"
* tag 'mm-hotfixes-stable-2024-11-03-10-50' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
mm: multi-gen LRU: use {ptep,pmdp}_clear_young_notify()
mm: multi-gen LRU: remove MM_LEAF_OLD and MM_NONLEAF_TOTAL stats
mm, mmap: limit THP alignment of anonymous mappings to PMD-aligned sizes
mm: shrinker: avoid memleak in alloc_shrinker_info
.mailmap: update e-mail address for Eugen Hristev
vmscan,migrate: fix page count imbalance on node stats when demoting pages
mailmap: update Jarkko's email addresses
mm: allow set/clear page_type again
nilfs2: fix potential deadlock with newly created symlinks
Squashfs: fix variable overflow in squashfs_readpage_block
kasan: remove vmalloc_percpu test
tools/mm: -Werror fixes in page-types/slabinfo
mm, swap: avoid over reclaim of full clusters
mm: fix PSWPIN counter for large folios swap-in
mm: avoid VM_BUG_ON when try to map an anon large folio to zero page.
mm/codetag: fix null pointer check logic for ref and tag
mm/gup: stop leaking pinned pages in low memory conditions
|
||
|
Yu Zhao
|
1d4832becd |
mm: multi-gen LRU: use {ptep,pmdp}_clear_young_notify()
When the MM_WALK capability is enabled, memory that is mostly accessed by
a VM appears younger than it really is, therefore this memory will be less
likely to be evicted. Therefore, the presence of a running VM can
significantly increase swap-outs for non-VM memory, regressing the
performance for the rest of the system.
Fix this regression by always calling {ptep,pmdp}_clear_young_notify()
whenever we clear the young bits on PMDs/PTEs.
[jthoughton@google.com: fix link-time error]
Link: https://lkml.kernel.org/r/20241019012940.3656292-3-jthoughton@google.com
Fixes:
|
||
|
Yu Zhao
|
ddd6d8e975 |
mm: multi-gen LRU: remove MM_LEAF_OLD and MM_NONLEAF_TOTAL stats
Patch series "mm: multi-gen LRU: Have secondary MMUs participate in
MM_WALK".
Today, the MM_WALK capability causes MGLRU to clear the young bit from
PMDs and PTEs during the page table walk before eviction, but MGLRU does
not call the clear_young() MMU notifier in this case. By not calling this
notifier, the MM walk takes less time/CPU, but it causes pages that are
accessed mostly through KVM / secondary MMUs to appear younger than they
should be.
We do call the clear_young() notifier today, but only when attempting to
evict the page, so we end up clearing young/accessed information less
frequently for secondary MMUs than for mm PTEs, and therefore they appear
younger and are less likely to be evicted. Therefore, memory that is
*not* being accessed mostly by KVM will be evicted *more* frequently,
worsening performance.
ChromeOS observed a tab-open latency regression when enabling MGLRU with a
setup that involved running a VM:
Tab-open latency histogram (ms)
Version p50 mean p95 p99 max
base 1315 1198 2347 3454 10319
mglru 2559 1311 7399 12060 43758
fix 1119 926 2470 4211 6947
This series replaces the final non-selftest patchs from this series[1],
which introduced a similar change (and a new MMU notifier) with KVM
optimizations. I'll send a separate series (to Sean and Paolo) for the
KVM optimizations.
This series also makes proactive reclaim with MGLRU possible for KVM
memory. I have verified that this functions correctly with the selftest
from [1], but given that that test is a KVM selftest, I'll send it with
the rest of the KVM optimizations later. Andrew, let me know if you'd
like to take the test now anyway.
[1]: https://lore.kernel.org/linux-mm/20240926013506.860253-18-jthoughton@google.com/
This patch (of 2):
The removed stats, MM_LEAF_OLD and MM_NONLEAF_TOTAL, are not very helpful
and become more complicated to properly compute when adding
test/clear_young() notifiers in MGLRU's mm walk.
Link: https://lkml.kernel.org/r/20241019012940.3656292-1-jthoughton@google.com
Link: https://lkml.kernel.org/r/20241019012940.3656292-2-jthoughton@google.com
Fixes:
|
||
|
Vlastimil Babka
|
d4148aeab4 |
mm, mmap: limit THP alignment of anonymous mappings to PMD-aligned sizes
Since commit |
||
|
Chen Ridong
|
15e8156713 |
mm: shrinker: avoid memleak in alloc_shrinker_info
A memleak was found as below:
unreferenced object 0xffff8881010d2a80 (size 32):
comm "mkdir", pid 1559, jiffies 4294932666
hex dump (first 32 bytes):
00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................
40 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 @...............
backtrace (crc 2e7ef6fa):
[<ffffffff81372754>] __kmalloc_node_noprof+0x394/0x470
[<ffffffff813024ab>] alloc_shrinker_info+0x7b/0x1a0
[<ffffffff813b526a>] mem_cgroup_css_online+0x11a/0x3b0
[<ffffffff81198dd9>] online_css+0x29/0xa0
[<ffffffff811a243d>] cgroup_apply_control_enable+0x20d/0x360
[<ffffffff811a5728>] cgroup_mkdir+0x168/0x5f0
[<ffffffff8148543e>] kernfs_iop_mkdir+0x5e/0x90
[<ffffffff813dbb24>] vfs_mkdir+0x144/0x220
[<ffffffff813e1c97>] do_mkdirat+0x87/0x130
[<ffffffff813e1de9>] __x64_sys_mkdir+0x49/0x70
[<ffffffff81f8c928>] do_syscall_64+0x68/0x140
[<ffffffff8200012f>] entry_SYSCALL_64_after_hwframe+0x76/0x7e
alloc_shrinker_info(), when shrinker_unit_alloc() returns an errer, the
info won't be freed. Just fix it.
Link: https://lkml.kernel.org/r/20241025060942.1049263-1-chenridong@huaweicloud.com
Fixes:
|
||
|
Gregory Price
|
35e41024c4 |
vmscan,migrate: fix page count imbalance on node stats when demoting pages
When numa balancing is enabled with demotion, vmscan will call
migrate_pages when shrinking LRUs. migrate_pages will decrement the
the node's isolated page count, leading to an imbalanced count when
invoked from (MG)LRU code.
The result is dmesg output like such:
$ cat /proc/sys/vm/stat_refresh
[77383.088417] vmstat_refresh: nr_isolated_anon -103212
[77383.088417] vmstat_refresh: nr_isolated_file -899642
This negative value may impact compaction and reclaim throttling.
The following path produces the decrement:
shrink_folio_list
demote_folio_list
migrate_pages
migrate_pages_batch
migrate_folio_move
migrate_folio_done
mod_node_page_state(-ve) <- decrement
This path happens for SUCCESSFUL migrations, not failures. Typically
callers to migrate_pages are required to handle putback/accounting for
failures, but this is already handled in the shrink code.
When accounting for migrations, instead do not decrement the count when
the migration reason is MR_DEMOTION. As of v6.11, this demotion logic
is the only source of MR_DEMOTION.
Link: https://lkml.kernel.org/r/20241025141724.17927-1-gourry@gourry.net
Fixes:
|
||
|
Andrey Konovalov
|
330d8df81f |
kasan: remove vmalloc_percpu test
Commit |
||
|
Kairui Song
|
5168a68eb7 |
mm, swap: avoid over reclaim of full clusters
When running low on usable slots, cluster allocator will try to reclaim
the full clusters aggressively to reclaim HAS_CACHE slots. This
guarantees that as long as there are any usable slots, HAS_CACHE or not,
the swap device will be usable and workload won't go OOM early.
Before the cluster allocator, swap allocator fails easily if device is
filled up with reclaimable HAS_CACHE slots. Which can be easily
reproduced with following simple program:
#include <stdio.h>
#include <string.h>
#include <linux/mman.h>
#include <sys/mman.h>
#define SIZE 8192UL * 1024UL * 1024UL
int main(int argc, char **argv) {
long tmp;
char *p = mmap(NULL, SIZE, PROT_READ | PROT_WRITE,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
memset(p, 0, SIZE);
madvise(p, SIZE, MADV_PAGEOUT);
for (unsigned long i = 0; i < SIZE; ++i)
tmp += p[i];
getchar(); /* Pause */
return 0;
}
Setup an 8G non ramdisk swap, the first run of the program will swapout 8G
ram successfully. But run same program again after the first run paused,
the second run can't swapout all 8G memory as now half of the swap device
is pinned by HAS_CACHE. There was a random scan in the old allocator that
may reclaim part of the HAS_CACHE by luck, but it's unreliable.
The new allocator's added reclaim of full clusters when device is low on
usable slots. But when multiple CPUs are seeing the device is low on
usable slots at the same time, they ran into a thundering herd problem.
This is an observable problem on large machine with mass parallel
workload, as full cluster reclaim is slower on large swap device and
higher number of CPUs will also make things worse.
Testing using a 128G ZRAM on a 48c96t system. When the swap device is
very close to full (eg. 124G / 128G), running build linux kernel with
make -j96 in a 1G memory cgroup will hung (not a softlockup though)
spinning in full cluster reclaim for about ~5min before go OOM.
To solve this, split the full reclaim into two parts:
- Instead of do a synchronous aggressively reclaim when device is low,
do only one aggressively reclaim when device is strictly full with a
kworker. This still ensures in worst case the device won't be unusable
because of HAS_CACHE slots.
- To avoid allocation (especially higher order) suffer from HAS_CACHE
filling up clusters and kworker not responsive enough, do one synchronous
scan every time the free list is drained, and only scan one cluster. This
is kind of similar to the random reclaim before, keeps the full clusters
rotated and has a minimal latency. This should provide a fair reclaim
strategy suitable for most workloads.
Link: https://lkml.kernel.org/r/20241022175512.10398-1-ryncsn@gmail.com
Fixes:
|
||
|
Barry Song
|
b54e1bfecc |
mm: fix PSWPIN counter for large folios swap-in
Similar to PSWPOUT, we should count the number of base pages instead of
large folios.
Link: https://lkml.kernel.org/r/20241023210201.2798-1-21cnbao@gmail.com
Fixes:
|
||
|
Zi Yan
|
e0fc203748 |
mm: avoid VM_BUG_ON when try to map an anon large folio to zero page.
An anonymous large folio can be split into non order-0 folios,
try_to_map_unused_to_zeropage() should not VM_BUG_ON compound pages but
just return false. This fixes the crash when splitting anonymous large
folios to non order-0 folios.
Link: https://lkml.kernel.org/r/20241023171236.1122535-1-ziy@nvidia.com
Fixes:
|
||
|
John Hubbard
|
aa6f8b2593 |
mm/gup: stop leaking pinned pages in low memory conditions
If a driver tries to call any of the pin_user_pages*(FOLL_LONGTERM) family
of functions, and requests "too many" pages, then the call will
erroneously leave pages pinned. This is visible in user space as an
actual memory leak.
Repro is trivial: just make enough pin_user_pages(FOLL_LONGTERM) calls to
exhaust memory.
The root cause of the problem is this sequence, within
__gup_longterm_locked():
__get_user_pages_locked()
rc = check_and_migrate_movable_pages()
...which gets retried in a loop. The loop error handling is incomplete,
clearly due to a somewhat unusual and complicated tri-state error API.
But anyway, if -ENOMEM, or in fact, any unexpected error is returned from
check_and_migrate_movable_pages(), then __gup_longterm_locked() happily
returns the error, while leaving the pages pinned.
In the failed case, which is an app that requests (via a device driver)
30720000000 bytes to be pinned, and then exits, I see this:
$ grep foll /proc/vmstat
nr_foll_pin_acquired 7502048
nr_foll_pin_released 2048
And after applying this patch, it returns to balanced pins:
$ grep foll /proc/vmstat
nr_foll_pin_acquired 7502048
nr_foll_pin_released 7502048
Note that the child routine, check_and_migrate_movable_folios(), avoids
this problem, by unpinning any folios in the **folios argument, before
returning an error.
Fix this by making check_and_migrate_movable_pages() behave in exactly the
same way as check_and_migrate_movable_folios(): unpin all pages in
**pages, before returning an error.
Also, documentation was an aggravating factor, so:
1) Consolidate the documentation for these two routines, now that they
have identical external behavior.
2) Rewrite the consolidated documentation:
a) Clearly list the three return code cases, and what happens in
each case.
b) Mention that one of the cases unpins the pages or folios, before
returning an error code.
Link: https://lkml.kernel.org/r/20241018223411.310331-1-jhubbard@nvidia.com
Fixes:
|
||
|
Linus Torvalds
|
7fbaacafbc |
slab fixes for 6.12-rc6
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||
|
Qun-Wei Lin
|
704573851b |
mm: krealloc: Fix MTE false alarm in __do_krealloc
This patch addresses an issue introduced by commit |
||
|
Barry Song
|
01626a1823 |
mm: avoid unconditional one-tick sleep when swapcache_prepare fails
Commit |
||
|
Kirill A. Shutemov
|
58a039e679 |
mm: split critical region in remap_file_pages() and invoke LSMs in between
Commit |
||
|
Lorenzo Stoakes
|
c4d91e225f |
mm/vma: add expand-only VMA merge mode and optimise do_brk_flags()
Patch series "introduce VMA merge mode to improve brk() performance".
A ~5% performance regression was discovered on the
aim9.brk_test.ops_per_sec by the linux kernel test bot [0].
In the past to satisfy brk() performance we duplicated VMA expansion code
and special-cased do_brk_flags(). This is however horrid and undoes work
to abstract this logic, so in resolving the issue I have endeavoured to
avoid this.
Investigating further I was able to observe that the use of a
vma_iter_next_range() and vma_prev() pair, causing an unnecessary maple
tree walk. In addition there is work that we do that is simply
unnecessary for brk().
Therefore, add a special VMA merge mode VMG_FLAG_JUST_EXPAND to avoid
doing any of this - it assumes the VMA iterator is pointing at the
previous VMA and which skips logic that brk() does not require.
This mostly eliminates the performance regression reducing it to ~2% which
is in the realm of noise. In addition, the will-it-scale test brk2,
written to be more representative of real-world brk() usage, shows a
modest performance improvement - which gives me confidence that we are not
meaningfully regressing real workloads here.
This series includes a test asserting that the 'just expand' mode works as
expected.
With many thanks to Oliver Sang for helping with performance testing of
candidate patch sets!
[0]:https://lore.kernel.org/linux-mm/202409301043.629bea78-oliver.sang@intel.com
This patch (of 2):
We know in advance that do_brk_flags() wants only to perform a VMA
expansion (if the prior VMA is compatible), and that we assume no
mergeable VMA follows it.
These are the semantics of this function prior to the recent rewrite of
the VMA merging logic, however we are now doing more work than necessary -
positioning the VMA iterator at the prior VMA and performing tasks that
are not required.
Add a new field to the vmg struct to permit merge flags and add a new
merge flag VMG_FLAG_JUST_EXPAND which implies this behaviour, and have
do_brk_flags() use this.
This fixes a reported performance regression in a brk() benchmarking suite.
Link: https://lkml.kernel.org/r/cover.1729174352.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/4e65d4395e5841c5acf8470dbcb714016364fd39.1729174352.git.lorenzo.stoakes@oracle.com
Fixes:
|
||
|
Nobuhiro Iwamatsu
|
d95fb348f0 |
mm: numa_clear_kernel_node_hotplug: Add NUMA_NO_NODE check for node id
The acquired memory blocks for reserved may include blocks outside of
memory management. In this case, the nid variable is set to NUMA_NO_NODE
(-1), so an error occurs in node_set(). This adds a check using
numa_valid_node() to numa_clear_kernel_node_hotplug() that skips
node_set() when nid is set to NUMA_NO_NODE.
Link: https://lkml.kernel.org/r/1729070461-13576-1-git-send-email-nobuhiro1.iwamatsu@toshiba.co.jp
Fixes:
|
||
|
Jeongjun Park
|
d949d1d14f |
mm: shmem: fix data-race in shmem_getattr()
I got the following KCSAN report during syzbot testing:
==================================================================
BUG: KCSAN: data-race in generic_fillattr / inode_set_ctime_current
write to 0xffff888102eb3260 of 4 bytes by task 6565 on cpu 1:
inode_set_ctime_to_ts include/linux/fs.h:1638 [inline]
inode_set_ctime_current+0x169/0x1d0 fs/inode.c:2626
shmem_mknod+0x117/0x180 mm/shmem.c:3443
shmem_create+0x34/0x40 mm/shmem.c:3497
lookup_open fs/namei.c:3578 [inline]
open_last_lookups fs/namei.c:3647 [inline]
path_openat+0xdbc/0x1f00 fs/namei.c:3883
do_filp_open+0xf7/0x200 fs/namei.c:3913
do_sys_openat2+0xab/0x120 fs/open.c:1416
do_sys_open fs/open.c:1431 [inline]
__do_sys_openat fs/open.c:1447 [inline]
__se_sys_openat fs/open.c:1442 [inline]
__x64_sys_openat+0xf3/0x120 fs/open.c:1442
x64_sys_call+0x1025/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:258
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x76/0x7e
read to 0xffff888102eb3260 of 4 bytes by task 3498 on cpu 0:
inode_get_ctime_nsec include/linux/fs.h:1623 [inline]
inode_get_ctime include/linux/fs.h:1629 [inline]
generic_fillattr+0x1dd/0x2f0 fs/stat.c:62
shmem_getattr+0x17b/0x200 mm/shmem.c:1157
vfs_getattr_nosec fs/stat.c:166 [inline]
vfs_getattr+0x19b/0x1e0 fs/stat.c:207
vfs_statx_path fs/stat.c:251 [inline]
vfs_statx+0x134/0x2f0 fs/stat.c:315
vfs_fstatat+0xec/0x110 fs/stat.c:341
__do_sys_newfstatat fs/stat.c:505 [inline]
__se_sys_newfstatat+0x58/0x260 fs/stat.c:499
__x64_sys_newfstatat+0x55/0x70 fs/stat.c:499
x64_sys_call+0x141f/0x2d60 arch/x86/include/generated/asm/syscalls_64.h:263
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0x54/0x120 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x76/0x7e
value changed: 0x2755ae53 -> 0x27ee44d3
Reported by Kernel Concurrency Sanitizer on:
CPU: 0 UID: 0 PID: 3498 Comm: udevd Not tainted 6.11.0-rc6-syzkaller-00326-gd1f2d51b711a-dirty #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/06/2024
==================================================================
When calling generic_fillattr(), if you don't hold read lock, data-race
will occur in inode member variables, which can cause unexpected
behavior.
Since there is no special protection when shmem_getattr() calls
generic_fillattr(), data-race occurs by functions such as shmem_unlink()
or shmem_mknod(). This can cause unexpected results, so commenting it out
is not enough.
Therefore, when calling generic_fillattr() from shmem_getattr(), it is
appropriate to protect the inode using inode_lock_shared() and
inode_unlock_shared() to prevent data-race.
Link: https://lkml.kernel.org/r/20240909123558.70229-1-aha310510@gmail.com
Fixes:
|
||
|
Jann Horn
|
14611508cb |
mm: mark mas allocation in vms_abort_munmap_vmas as __GFP_NOFAIL
vms_abort_munmap_vmas() is a recovery path where, on entry, some VMAs have
already been torn down halfway (in a way we can't undo) but are still
present in the maple tree.
At this point, we *must* remove the VMAs from the VMA tree, otherwise we
get UAF.
Because removing VMA tree nodes can require memory allocation, the
existing code has an error path which tries to handle this by reattaching
the VMAs; but that can't be done safely.
A nicer way to fix it would probably be to preallocate enough maple tree
nodes for the removal before the point of no return, or something like
that; but for now, fix it the easy and kinda ugly way, by marking this
allocation __GFP_NOFAIL.
Link: https://lkml.kernel.org/r/20241016-fix-munmap-abort-v1-1-601c94b2240d@google.com
Fixes:
|
||
|
Huang Ying
|
b7c5f9a1fb |
resource: remove dependency on SPARSEMEM from GET_FREE_REGION
We want to use the functions (get_free_mem_region()) configured via GET_FREE_REGION in resource kunit tests. However, GET_FREE_REGION depends on SPARSEMEM now. This makes resource kunit tests cannot be built on some architectures lacking SPARSEMEM, or causes config warning as follows, WARNING: unmet direct dependencies detected for GET_FREE_REGION Depends on [n]: SPARSEMEM [=n] Selected by [y]: - RESOURCE_KUNIT_TEST [=y] && RUNTIME_TESTING_MENU [=y] && KUNIT [=y] When get_free_mem_region() was introduced the only consumers were those looking to pass the address range to memremap_pages(). That address range needed to be mindful of the maximum addressable platform physical address which at the time only SPARSMEM defined via MAX_PHYSMEM_BITS. Given that memremap_pages() also depended on SPARSEMEM via ZONE_DEVICE, it was easier to just depend on that definition than invent a general MAX_PHYSMEM_BITS concept outside of SPARSEMEM. Turns out that decision was buggy and did not account for KASAN consumption of physical address space. That problem was resolved recently with commit |
||
|
Liam R. Howlett
|
79f3d123ca |
mm/mmap: fix race in mmap_region() with ftruncate()
Avoiding the zeroing of the vma tree in mmap_region() introduced a race
with truncate in the page table walk. To avoid any races, create a hole
in the rmap during the operation by clearing the pagetable entries earlier
under the mmap write lock and (critically) before the new vma is installed
into the vma tree. The result is that the old vma(s) are left in the vma
tree, but free_pgtables() removes them from the rmap and clears the ptes
while holding the necessary locks.
This change extends the fix required for hugetblfs and the call_mmap()
function by moving the cleanup higher in the function and running it
unconditionally.
Link: https://lkml.kernel.org/r/20241016013455.2241533-1-Liam.Howlett@oracle.com
Fixes:
|
||
|
Matt Fleming
|
281dd25c1a |
mm/page_alloc: let GFP_ATOMIC order-0 allocs access highatomic reserves
Under memory pressure it's possible for GFP_ATOMIC order-0 allocations to
fail even though free pages are available in the highatomic reserves.
GFP_ATOMIC allocations cannot trigger unreserve_highatomic_pageblock()
since it's only run from reclaim.
Given that such allocations will pass the watermarks in
__zone_watermark_unusable_free(), it makes sense to fallback to highatomic
reserves the same way that ALLOC_OOM can.
This fixes order-0 page allocation failures observed on Cloudflare's fleet
when handling network packets:
kswapd1: page allocation failure: order:0, mode:0x820(GFP_ATOMIC),
nodemask=(null),cpuset=/,mems_allowed=0-7
CPU: 10 PID: 696 Comm: kswapd1 Kdump: loaded Tainted: G O 6.6.43-CUSTOM #1
Hardware name: MACHINE
Call Trace:
<IRQ>
dump_stack_lvl+0x3c/0x50
warn_alloc+0x13a/0x1c0
__alloc_pages_slowpath.constprop.0+0xc9d/0xd10
__alloc_pages+0x327/0x340
__napi_alloc_skb+0x16d/0x1f0
bnxt_rx_page_skb+0x96/0x1b0 [bnxt_en]
bnxt_rx_pkt+0x201/0x15e0 [bnxt_en]
__bnxt_poll_work+0x156/0x2b0 [bnxt_en]
bnxt_poll+0xd9/0x1c0 [bnxt_en]
__napi_poll+0x2b/0x1b0
bpf_trampoline_6442524138+0x7d/0x1000
__napi_poll+0x5/0x1b0
net_rx_action+0x342/0x740
handle_softirqs+0xcf/0x2b0
irq_exit_rcu+0x6c/0x90
sysvec_apic_timer_interrupt+0x72/0x90
</IRQ>
[mfleming@cloudflare.com: update comment]
Link: https://lkml.kernel.org/r/20241015125158.3597702-1-matt@readmodwrite.com
Link: https://lkml.kernel.org/r/20241011120737.3300370-1-matt@readmodwrite.com
Link: https://lore.kernel.org/all/CAGis_TWzSu=P7QJmjD58WWiu3zjMTVKSzdOwWE8ORaGytzWJwQ@mail.gmail.com/
Fixes:
|
||
|
David Hildenbrand
|
7c18d48110 |
mm/pagewalk: fix usage of pmd_leaf()/pud_leaf() without present check
pmd_leaf()/pud_leaf() only implies a pmd_present()/pud_present() check on
some architectures. We really should check for
pmd_present()/pud_present() first.
This should explain the report we got on ppc64 (which has
CONFIG_PGTABLE_HAS_HUGE_LEAVES set in the config) that triggered:
VM_WARN_ON_ONCE(pmd_leaf(pmdp_get_lockless(pmdp)));
Likely we had a PMD migration entry for which pmd_leaf() did not trigger.
We raced with restoring the PMD migration entry, and suddenly saw a
pmd_leaf(). In this case, pte_offset_map_lock() saved us from more
trouble, because it rechecks the PMD value, but we would not have
processed the migration entry -- which is not too bad because the only
user of FW_MIGRATION is KSM for unsharing, and KSM only applies to small
folios.
Further, we shouldn't re-read the PMD/PUD value for our warning, the
primary purpose of the VM_WARN_ON_ONCE() is to find spurious use of
pmd_leaf()/pud_leaf() without CONFIG_PGTABLE_HAS_HUGE_LEAVES.
As a side note, we are currently not implementing FW_MIGRATION support for
PUD migration entries, which likely should exist due to hugetlb. Add a
TODO so this won't fall through the cracks if more FW_MIGRATION users get
added.
Was able to write a quick reproducer and verify that the issue no longer triggers with this fix.
https://gitlab.com/davidhildenbrand/scratchspace/-/blob/main/reproducers/move-pages-pmd-leaf.c
Without this fix after a couple of seconds in a VM with 2 NUMA nodes:
[ 54.333753] ------------[ cut here ]------------
[ 54.334901] WARNING: CPU: 20 PID: 1704 at mm/pagewalk.c:815 folio_walk_start+0x48f/0x6e0
[ 54.336455] Modules linked in: ...
[ 54.345009] CPU: 20 UID: 0 PID: 1704 Comm: move-pages-pmd- Not tainted 6.12.0-rc2+ #81
[ 54.346529] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-2.fc40 04/01/2014
[ 54.348191] RIP: 0010:folio_walk_start+0x48f/0x6e0
[ 54.349134] Code: b5 ad 48 8d 35 00 00 00 00 e8 6d 59 d7 ff e8 08 74 da ff e9 9c fe ff ff 4c 8b 7c 24 08 4c 89 ff e8 26 2b be 00 e9 8a fe ff ff <0f> 0b e9 ec fe ff ff f7 c2 ff 0f 00 00 0f 85 81 fe ff ff 48 8b 02
[ 54.352660] RSP: 0018:ffffb7e4c430bc78 EFLAGS: 00010282
[ 54.353679] RAX: 80000002a3e008e7 RBX: ffff9946039aa580 RCX: ffff994380000000
[ 54.355056] RDX: ffff994606aec000 RSI: 00007f004b000000 RDI: 0000000000000000
[ 54.356440] RBP: 00007f004b000000 R08: 0000000000000591 R09: 0000000000000001
[ 54.357820] R10: 0000000000000200 R11: 0000000000000001 R12: ffffb7e4c430bd10
[ 54.359198] R13: ffff994606aec2c0 R14: 0000000000000002 R15: ffff994604a89b00
[ 54.360564] FS: 00007f004ae006c0(0000) GS:ffff9947f7400000(0000) knlGS:0000000000000000
[ 54.362111] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 54.363242] CR2: 00007f004adffe58 CR3: 0000000281e12005 CR4: 0000000000770ef0
[ 54.364615] PKRU: 55555554
[ 54.365153] Call Trace:
[ 54.365646] <TASK>
[ 54.366073] ? __warn.cold+0xb7/0x14d
[ 54.366796] ? folio_walk_start+0x48f/0x6e0
[ 54.367628] ? report_bug+0xff/0x140
[ 54.368324] ? handle_bug+0x58/0x90
[ 54.369019] ? exc_invalid_op+0x17/0x70
[ 54.369771] ? asm_exc_invalid_op+0x1a/0x20
[ 54.370606] ? folio_walk_start+0x48f/0x6e0
[ 54.371415] ? folio_walk_start+0x9e/0x6e0
[ 54.372227] do_pages_move+0x1c5/0x680
[ 54.372972] kernel_move_pages+0x1a1/0x2b0
[ 54.373804] __x64_sys_move_pages+0x25/0x30
Link: https://lkml.kernel.org/r/20241015111236.1290921-1-david@redhat.com
Fixes:
|
||
|
Bibo Mao
|
d2f8671045 |
LoongArch: Set initial pte entry with PAGE_GLOBAL for kernel space
There are two pages in one TLB entry on LoongArch system. For kernel space, it requires both two pte entries (buddies) with PAGE_GLOBAL bit set, otherwise HW treats it as non-global tlb, there will be potential problems if tlb entry for kernel space is not global. Such as fail to flush kernel tlb with the function local_flush_tlb_kernel_range() which supposed only flush tlb with global bit. Kernel address space areas include percpu, vmalloc, vmemmap, fixmap and kasan areas. For these areas both two consecutive page table entries should be enabled with PAGE_GLOBAL bit. So with function set_pte() and pte_clear(), pte buddy entry is checked and set besides its own pte entry. However it is not atomic operation to set both two pte entries, there is problem with test_vmalloc test case. So function kernel_pte_init() is added to init a pte table when it is created for kernel address space, and the default initial pte value is PAGE_GLOBAL rather than zero at beginning. Then only its own pte entry need update with function set_pte() and pte_clear(), nothing to do with the pte buddy entry. Signed-off-by: Bibo Mao <maobibo@loongson.cn> Signed-off-by: Huacai Chen <chenhuacai@loongson.cn> |
||
|
Linus Torvalds
|
b1b4675167 |
mm: fix follow_pfnmap API lockdep assert
The lockdep asserts for the new follow_pfnmap() API "knows" that a
pfnmap always has a vma->vm_file, since that's the only way to create
such a mapping.
And that's actually true for all the normal cases. But not for the mmap
failure case, where the incomplete mapping is torn down and we have
cleared vma->vm_file because the failure occured before the file was
linked to the vma.
So this codepath does actually need to check for vm_file being NULL.
Reported-by: Jann Horn <jannh@google.com>
Fixes:
|
||
|
Wei Xu
|
b130ba4a62 |
mm/mglru: only clear kswapd_failures if reclaimable
lru_gen_shrink_node() unconditionally clears kswapd_failures, which can
prevent kswapd from sleeping and cause 100% kswapd cpu usage even when
kswapd repeatedly fails to make progress in reclaim.
Only clear kswap_failures in lru_gen_shrink_node() if reclaim makes some
progress, similar to shrink_node().
I happened to run into this problem in one of my tests recently. It
requires a combination of several conditions: The allocator needs to
allocate a right amount of pages such that it can wake up kswapd
without itself being OOM killed; there is no memory for kswapd to
reclaim (My test disables swap and cleans page cache first); no other
process frees enough memory at the same time.
Link: https://lkml.kernel.org/r/20241014221211.832591-1-weixugc@google.com
Fixes:
|
||
|
Liu Shixin
|
7528c4fb12 |
mm/swapfile: skip HugeTLB pages for unuse_vma
I got a bad pud error and lost a 1GB HugeTLB when calling swapoff. The
problem can be reproduced by the following steps:
1. Allocate an anonymous 1GB HugeTLB and some other anonymous memory.
2. Swapout the above anonymous memory.
3. run swapoff and we will get a bad pud error in kernel message:
mm/pgtable-generic.c:42: bad pud 00000000743d215d(84000001400000e7)
We can tell that pud_clear_bad is called by pud_none_or_clear_bad in
unuse_pud_range() by ftrace. And therefore the HugeTLB pages will never
be freed because we lost it from page table. We can skip HugeTLB pages
for unuse_vma to fix it.
Link: https://lkml.kernel.org/r/20241015014521.570237-1-liushixin2@huawei.com
Fixes:
|
||
|
Jeongjun Park
|
818f916e3a |
mm: swap: prevent possible data-race in __try_to_reclaim_swap
A report [1] was uploaded from syzbot. In the previous commit |
||
|
Baolin Wang
|
d60fcaf00d |
mm: khugepaged: fix the incorrect statistics when collapsing large file folios
Khugepaged already supports collapsing file large folios (including shmem mTHP) by commit |
||
|
David Hildenbrand
|
2b0f922323 |
mm: don't install PMD mappings when THPs are disabled by the hw/process/vma
We (or rather, readahead logic :) ) might be allocating a THP in the
pagecache and then try mapping it into a process that explicitly disabled
THP: we might end up installing PMD mappings.
This is a problem for s390x KVM, which explicitly remaps all PMD-mapped
THPs to be PTE-mapped in s390_enable_sie()->thp_split_mm(), before
starting the VM.
For example, starting a VM backed on a file system with large folios
supported makes the VM crash when the VM tries accessing such a mapping
using KVM.
Is it also a problem when the HW disabled THP using
TRANSPARENT_HUGEPAGE_UNSUPPORTED? At least on x86 this would be the case
without X86_FEATURE_PSE.
In the future, we might be able to do better on s390x and only disallow
PMD mappings -- what s390x and likely TRANSPARENT_HUGEPAGE_UNSUPPORTED
really wants. For now, fix it by essentially performing the same check as
would be done in __thp_vma_allowable_orders() or in shmem code, where this
works as expected, and disallow PMD mappings, making us fallback to PTE
mappings.
Link: https://lkml.kernel.org/r/20241011102445.934409-3-david@redhat.com
Fixes:
|
||
|
Kefeng Wang
|
963756aac1 |
mm: huge_memory: add vma_thp_disabled() and thp_disabled_by_hw()
Patch series "mm: don't install PMD mappings when THPs are disabled by the
hw/process/vma".
During testing, it was found that we can get PMD mappings in processes
where THP (and more precisely, PMD mappings) are supposed to be disabled.
While it works as expected for anon+shmem, the pagecache is the
problematic bit.
For s390 KVM this currently means that a VM backed by a file located on
filesystem with large folio support can crash when KVM tries accessing the
problematic page, because the readahead logic might decide to use a
PMD-sized THP and faulting it into the page tables will install a PMD
mapping, something that s390 KVM cannot tolerate.
This might also be a problem with HW that does not support PMD mappings,
but I did not try reproducing it.
Fix it by respecting the ways to disable THPs when deciding whether we can
install a PMD mapping. khugepaged should already be taking care of not
collapsing if THPs are effectively disabled for the hw/process/vma.
This patch (of 2):
Add vma_thp_disabled() and thp_disabled_by_hw() helpers to be shared by
shmem_allowable_huge_orders() and __thp_vma_allowable_orders().
[david@redhat.com: rename to vma_thp_disabled(), split out thp_disabled_by_hw() ]
Link: https://lkml.kernel.org/r/20241011102445.934409-2-david@redhat.com
Fixes:
|