linux.git/mm, branch v6.8 Linux kernel source tree Merge tag 'mm-hotfixes-stable-2024-03-07-16-17' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 2024-03-08T01:16:38+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-03-08T01:16:38+00:00 3aaa8ce7a3350d95b241046ae2401103a4384ba2 Pull misc fixes from Andrew Morton: "6 hotfixes. 4 are cc:stable and the remainder pertain to post-6.7 issues or aren't considered to be needed in earlier kernel versions" * tag 'mm-hotfixes-stable-2024-03-07-16-17' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: scripts/gdb/symbols: fix invalid escape sequence warning mailmap: fix Kishon's email init/Kconfig: lower GCC version check for -Warray-bounds mm, mmap: fix vma_merge() case 7 with vma_ops->close mm: userfaultfd: fix unexpected change to src_folio when UFFDIO_MOVE fails mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations 
Pull misc fixes from Andrew Morton:
 "6 hotfixes. 4 are cc:stable and the remainder pertain to post-6.7
  issues or aren't considered to be needed in earlier kernel versions"

* tag 'mm-hotfixes-stable-2024-03-07-16-17' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  scripts/gdb/symbols: fix invalid escape sequence warning
  mailmap: fix Kishon's email
  init/Kconfig: lower GCC version check for -Warray-bounds
  mm, mmap: fix vma_merge() case 7 with vma_ops->close
  mm: userfaultfd: fix unexpected change to src_folio when UFFDIO_MOVE fails
  mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations
mm, mmap: fix vma_merge() case 7 with vma_ops->close 2024-03-05T00:40:33+00:00 Vlastimil Babka vbabka@suse.cz 2024-02-22T21:59:31+00:00 fc0c8f9089c20d198d8fe51ddc28bfa1af588dce When debugging issues with a workload using SysV shmem, Michal Hocko has come up with a reproducer that shows how a series of mprotect() operations can result in an elevated shm_nattch and thus leak of the resource. The problem is caused by wrong assumptions in vma_merge() commit 714965ca8252 ("mm/mmap: start distinguishing if vma can be removed in mergeability test"). The shmem vmas have a vma_ops->close callback that decrements shm_nattch, and we remove the vma without calling it. vma_merge() has thus historically avoided merging vma's with vma_ops->close and commit 714965ca8252 was supposed to keep it that way. It relaxed the checks for vma_ops->close in can_vma_merge_after() assuming that it is never called on a vma that would be a candidate for removal. However, the vma_merge() code does also use the result of this check in the decision to remove a different vma in the merge case 7. A robust solution would be to refactor vma_merge() code in a way that the vma_ops->close check is only done for vma's that are actually going to be removed, and not as part of the preliminary checks. That would both solve the existing bug, and also allow additional merges that the checks currently prevent unnecessarily in some cases. However to fix the existing bug first with a minimized risk, and for easier stable backports, this patch only adds a vma_ops->close check to the buggy case 7 specifically. All other cases of vma removal are covered by the can_vma_merge_before() check that includes the test for vma_ops->close. The reproducer code, adapted from Michal Hocko's code: int main(int argc, char *argv[]) { int segment_id; size_t segment_size = 20 * PAGE_SIZE; char * sh_mem; struct shmid_ds shmid_ds; key_t key = 0x1234; segment_id = shmget(key, segment_size, IPC_CREAT | IPC_EXCL | S_IRUSR | S_IWUSR); sh_mem = (char *)shmat(segment_id, NULL, 0); mprotect(sh_mem + 2*PAGE_SIZE, PAGE_SIZE, PROT_NONE); mprotect(sh_mem + PAGE_SIZE, PAGE_SIZE, PROT_WRITE); mprotect(sh_mem + 2*PAGE_SIZE, PAGE_SIZE, PROT_WRITE); shmdt(sh_mem); shmctl(segment_id, IPC_STAT, &shmid_ds); printf("nattch after shmdt(): %lu (expected: 0)\n", shmid_ds.shm_nattch); if (shmctl(segment_id, IPC_RMID, 0)) printf("IPCRM failed %d\n", errno); return (shmid_ds.shm_nattch) ? 1 : 0; } Link: https://lkml.kernel.org/r/20240222215930.14637-2-vbabka@suse.cz Fixes: 714965ca8252 ("mm/mmap: start distinguishing if vma can be removed in mergeability test") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Michal Hocko <mhocko@suse.com> Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com> Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
When debugging issues with a workload using SysV shmem, Michal Hocko has
come up with a reproducer that shows how a series of mprotect() operations
can result in an elevated shm_nattch and thus leak of the resource.

The problem is caused by wrong assumptions in vma_merge() commit
714965ca8252 ("mm/mmap: start distinguishing if vma can be removed in
mergeability test").  The shmem vmas have a vma_ops->close callback that
decrements shm_nattch, and we remove the vma without calling it.

vma_merge() has thus historically avoided merging vma's with
vma_ops->close and commit 714965ca8252 was supposed to keep it that way. 
It relaxed the checks for vma_ops->close in can_vma_merge_after() assuming
that it is never called on a vma that would be a candidate for removal. 
However, the vma_merge() code does also use the result of this check in
the decision to remove a different vma in the merge case 7.

A robust solution would be to refactor vma_merge() code in a way that the
vma_ops->close check is only done for vma's that are actually going to be
removed, and not as part of the preliminary checks.  That would both solve
the existing bug, and also allow additional merges that the checks
currently prevent unnecessarily in some cases.

However to fix the existing bug first with a minimized risk, and for
easier stable backports, this patch only adds a vma_ops->close check to
the buggy case 7 specifically.  All other cases of vma removal are covered
by the can_vma_merge_before() check that includes the test for
vma_ops->close.

The reproducer code, adapted from Michal Hocko's code:

int main(int argc, char *argv[]) {
  int segment_id;
  size_t segment_size = 20 * PAGE_SIZE;
  char * sh_mem;
  struct shmid_ds shmid_ds;

  key_t key = 0x1234;
  segment_id = shmget(key, segment_size,
                      IPC_CREAT | IPC_EXCL | S_IRUSR | S_IWUSR);
  sh_mem = (char *)shmat(segment_id, NULL, 0);

  mprotect(sh_mem + 2*PAGE_SIZE, PAGE_SIZE, PROT_NONE);

  mprotect(sh_mem + PAGE_SIZE, PAGE_SIZE, PROT_WRITE);

  mprotect(sh_mem + 2*PAGE_SIZE, PAGE_SIZE, PROT_WRITE);

  shmdt(sh_mem);

  shmctl(segment_id, IPC_STAT, &shmid_ds);
  printf("nattch after shmdt(): %lu (expected: 0)\n", shmid_ds.shm_nattch);

  if (shmctl(segment_id, IPC_RMID, 0))
          printf("IPCRM failed %d\n", errno);
  return (shmid_ds.shm_nattch) ? 1 : 0;
}

Link: https://lkml.kernel.org/r/20240222215930.14637-2-vbabka@suse.cz
Fixes: 714965ca8252 ("mm/mmap: start distinguishing if vma can be removed in mergeability test")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Lorenzo Stoakes <lstoakes@gmail.com>
Reviewed-by: Liam R. Howlett <Liam.Howlett@oracle.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: userfaultfd: fix unexpected change to src_folio when UFFDIO_MOVE fails 2024-03-05T00:40:33+00:00 Qi Zheng zhengqi.arch@bytedance.com 2024-02-22T08:08:15+00:00 d7a08838ab74652f2b53fee9763f0178278c3a4b After ptep_clear_flush(), if we find that src_folio is pinned we will fail UFFDIO_MOVE and put src_folio back to src_pte entry, but the change to src_folio->{mapping,index} is not restored in this process. This is not what we expected, so fix it. This can cause the rmap for that page to be invalid, possibly resulting in memory corruption. At least swapout+migration would no longer work, because we might fail to locate the mappings of that folio. Link: https://lkml.kernel.org/r/20240222080815.46291-1-zhengqi.arch@bytedance.com Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI") Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com> Reviewed-by: David Hildenbrand <david@redhat.com> Reviewed-by: Suren Baghdasaryan <surenb@google.com> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
After ptep_clear_flush(), if we find that src_folio is pinned we will fail
UFFDIO_MOVE and put src_folio back to src_pte entry, but the change to
src_folio->{mapping,index} is not restored in this process. This is not
what we expected, so fix it.

This can cause the rmap for that page to be invalid, possibly resulting
in memory corruption.  At least swapout+migration would no longer work,
because we might fail to locate the mappings of that folio.

Link: https://lkml.kernel.org/r/20240222080815.46291-1-zhengqi.arch@bytedance.com
Fixes: adef440691ba ("userfaultfd: UFFDIO_MOVE uABI")
Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Suren Baghdasaryan <surenb@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm, vmscan: prevent infinite loop for costly GFP_NOIO | __GFP_RETRY_MAYFAIL allocations 2024-03-05T00:40:32+00:00 Vlastimil Babka vbabka@suse.cz 2024-02-21T11:43:58+00:00 803de9000f334b771afacb6ff3e78622916668b0 Sven reports an infinite loop in __alloc_pages_slowpath() for costly order __GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO. Such combination can happen in a suspend/resume context where a GFP_KERNEL allocation can have __GFP_IO masked out via gfp_allowed_mask. Quoting Sven: 1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER) with __GFP_RETRY_MAYFAIL set. 2. page alloc's __alloc_pages_slowpath tries to get a page from the freelist. This fails because there is nothing free of that costly order. 3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim, which bails out because a zone is ready to be compacted; it pretends to have made a single page of progress. 4. page alloc tries to compact, but this always bails out early because __GFP_IO is not set (it's not passed by the snd allocator, and even if it were, we are suspending so the __GFP_IO flag would be cleared anyway). 5. page alloc believes reclaim progress was made (because of the pretense in item 3) and so it checks whether it should retry compaction. The compaction retry logic thinks it should try again, because: a) reclaim is needed because of the early bail-out in item 4 b) a zonelist is suitable for compaction 6. goto 2. indefinite stall. (end quote) The immediate root cause is confusing the COMPACT_SKIPPED returned from __alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be indicating a lack of order-0 pages, and in step 5 evaluating that in should_compact_retry() as a reason to retry, before incrementing and limiting the number of retries. There are however other places that wrongly assume that compaction can happen while we lack __GFP_IO. To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO evaluation and switch the open-coded test in try_to_compact_pages() to use it. Also use the new helper in: - compaction_ready(), which will make reclaim not bail out in step 3, so there's at least one attempt to actually reclaim, even if chances are small for a costly order - in_reclaim_compaction() which will make should_continue_reclaim() return false and we don't over-reclaim unnecessarily - in __alloc_pages_slowpath() to set a local variable can_compact, which is then used to avoid retrying reclaim/compaction for costly allocations (step 5) if we can't compact and also to skip the early compaction attempt that we do in some cases Link: https://lkml.kernel.org/r/20240221114357.13655-2-vbabka@suse.cz Fixes: 3250845d0526 ("Revert "mm, oom: prevent premature OOM killer invocation for high order request"") Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Reported-by: Sven van Ashbrook <svenva@chromium.org> Closes: https://lore.kernel.org/all/CAG-rBihs_xMKb3wrMO1%2B-%2Bp4fowP9oy1pa_OTkfxBzPUVOZF%2Bg@mail.gmail.com/ Tested-by: Karthikeyan Ramasubramanian <kramasub@chromium.org> Cc: Brian Geffon <bgeffon@google.com> Cc: Curtis Malainey <cujomalainey@chromium.org> Cc: Jaroslav Kysela <perex@perex.cz> Cc: Mel Gorman <mgorman@techsingularity.net> Cc: Michal Hocko <mhocko@kernel.org> Cc: Takashi Iwai <tiwai@suse.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Sven reports an infinite loop in __alloc_pages_slowpath() for costly order
__GFP_RETRY_MAYFAIL allocations that are also GFP_NOIO.  Such combination
can happen in a suspend/resume context where a GFP_KERNEL allocation can
have __GFP_IO masked out via gfp_allowed_mask.

Quoting Sven:

1. try to do a "costly" allocation (order > PAGE_ALLOC_COSTLY_ORDER)
   with __GFP_RETRY_MAYFAIL set.

2. page alloc's __alloc_pages_slowpath tries to get a page from the
   freelist. This fails because there is nothing free of that costly
   order.

3. page alloc tries to reclaim by calling __alloc_pages_direct_reclaim,
   which bails out because a zone is ready to be compacted; it pretends
   to have made a single page of progress.

4. page alloc tries to compact, but this always bails out early because
   __GFP_IO is not set (it's not passed by the snd allocator, and even
   if it were, we are suspending so the __GFP_IO flag would be cleared
   anyway).

5. page alloc believes reclaim progress was made (because of the
   pretense in item 3) and so it checks whether it should retry
   compaction. The compaction retry logic thinks it should try again,
   because:
    a) reclaim is needed because of the early bail-out in item 4
    b) a zonelist is suitable for compaction

6. goto 2. indefinite stall.

(end quote)

The immediate root cause is confusing the COMPACT_SKIPPED returned from
__alloc_pages_direct_compact() (step 4) due to lack of __GFP_IO to be
indicating a lack of order-0 pages, and in step 5 evaluating that in
should_compact_retry() as a reason to retry, before incrementing and
limiting the number of retries.  There are however other places that
wrongly assume that compaction can happen while we lack __GFP_IO.

To fix this, introduce gfp_compaction_allowed() to abstract the __GFP_IO
evaluation and switch the open-coded test in try_to_compact_pages() to use
it.

Also use the new helper in:
- compaction_ready(), which will make reclaim not bail out in step 3, so
  there's at least one attempt to actually reclaim, even if chances are
  small for a costly order
- in_reclaim_compaction() which will make should_continue_reclaim()
  return false and we don't over-reclaim unnecessarily
- in __alloc_pages_slowpath() to set a local variable can_compact,
  which is then used to avoid retrying reclaim/compaction for costly
  allocations (step 5) if we can't compact and also to skip the early
  compaction attempt that we do in some cases

Link: https://lkml.kernel.org/r/20240221114357.13655-2-vbabka@suse.cz
Fixes: 3250845d0526 ("Revert "mm, oom: prevent premature OOM killer invocation for high order request"")
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Reported-by: Sven van Ashbrook <svenva@chromium.org>
Closes: https://lore.kernel.org/all/CAG-rBihs_xMKb3wrMO1%2B-%2Bp4fowP9oy1pa_OTkfxBzPUVOZF%2Bg@mail.gmail.com/
Tested-by: Karthikeyan Ramasubramanian <kramasub@chromium.org>
Cc: Brian Geffon <bgeffon@google.com>
Cc: Curtis Malainey <cujomalainey@chromium.org>
Cc: Jaroslav Kysela <perex@perex.cz>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Takashi Iwai <tiwai@suse.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Merge tag 'mm-hotfixes-stable-2024-02-27-14-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm 2024-02-28T00:44:15+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-02-28T00:44:15+00:00 5e10bf6cb4cdcc0ede9a83a0d986899dff219bc0 Pull misc fixes from Andrew Morton: "Six hotfixes. Three are cc:stable and the remainder address post-6.7 issues or aren't considered appropriate for backporting" * tag 'mm-hotfixes-stable-2024-02-27-14-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: mm/debug_vm_pgtable: fix BUG_ON with pud advanced test mm: cachestat: fix folio read-after-free in cache walk MAINTAINERS: add memory mapping entry with reviewers mm/vmscan: fix a bug calling wakeup_kswapd() with a wrong zone index kasan: revert eviction of stack traces in generic mode stackdepot: use variable size records for non-evictable entries 
Pull misc fixes from Andrew Morton:
 "Six hotfixes. Three are cc:stable and the remainder address post-6.7
  issues or aren't considered appropriate for backporting"

* tag 'mm-hotfixes-stable-2024-02-27-14-52' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm:
  mm/debug_vm_pgtable: fix BUG_ON with pud advanced test
  mm: cachestat: fix folio read-after-free in cache walk
  MAINTAINERS: add memory mapping entry with reviewers
  mm/vmscan: fix a bug calling wakeup_kswapd() with a wrong zone index
  kasan: revert eviction of stack traces in generic mode
  stackdepot: use variable size records for non-evictable entries
Merge tag 'cxl-fixes-6.8-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl 2024-02-24T23:53:40+00:00 Linus Torvalds torvalds@linux-foundation.org 2024-02-24T23:53:40+00:00 ac389bc0ca56e1a2f92b2a17e58298390a3879a8 Pull cxl fixes from Dan Williams: "A collection of significant fixes for the CXL subsystem. The largest change in this set, that bordered on "new development", is the fix for the fact that the location of the new qos_class attribute did not match the Documentation. The fix ends up deleting more code than it added, and it has a new unit test to backstop basic errors in this interface going forward. So the "red-diff" and unit test saved the "rip it out and try again" response. In contrast, the new notification path for firmware reported CXL errors (CXL CPER notifications) has a locking context bug that can not be fixed with a red-diff. Given where the release cycle stands, it is not comfortable to squeeze in that fix in these waning days. So, that receives the "back it out and try again later" treatment. There is a regression fix in the code that establishes memory NUMA nodes for platform CXL regions. That has an ack from x86 folks. There are a couple more fixups for Linux to understand (reassemble) CXL regions instantiated by platform firmware. The policy around platforms that do not match host-physical-address with system-physical-address (i.e. systems that have an address translation mechanism between the address range reported in the ACPI CEDT.CFMWS and endpoint decoders) has been softened to abort driver load rather than teardown the memory range (can cause system hangs). Lastly, there is a robustness / regression fix for cases where the driver would previously continue in the face of error, and a fixup for PCI error notification handling. Summary: - Fix NUMA initialization from ACPI CEDT.CFMWS - Fix region assembly failures due to async init order - Fix / simplify export of qos_class information - Fix cxl_acpi initialization vs single-window-init failures - Fix handling of repeated 'pci_channel_io_frozen' notifications - Workaround platforms that violate host-physical-address == system-physical address assumptions - Defer CXL CPER notification handling to v6.9" * tag 'cxl-fixes-6.8-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl: cxl/acpi: Fix load failures due to single window creation failure acpi/ghes: Remove CXL CPER notifications cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window cxl/test: Add support for qos_class checking cxl: Fix sysfs export of qos_class for memdev cxl: Remove unnecessary type cast in cxl_qos_class_verify() cxl: Change 'struct cxl_memdev_state' *_perf_list to single 'struct cxl_dpa_perf' cxl/region: Allow out of order assembly of autodiscovered regions cxl/region: Handle endpoint decoders in cxl_region_find_decoder() x86/numa: Fix the sort compare func used in numa_fill_memblks() x86/numa: Fix the address overlap check in numa_fill_memblks() cxl/pci: Skip to handle RAS errors if CXL.mem device is detached 
Pull cxl fixes from Dan Williams:
 "A collection of significant fixes for the CXL subsystem.

  The largest change in this set, that bordered on "new development", is
  the fix for the fact that the location of the new qos_class attribute
  did not match the Documentation. The fix ends up deleting more code
  than it added, and it has a new unit test to backstop basic errors in
  this interface going forward. So the "red-diff" and unit test saved
  the "rip it out and try again" response.

  In contrast, the new notification path for firmware reported CXL
  errors (CXL CPER notifications) has a locking context bug that can not
  be fixed with a red-diff. Given where the release cycle stands, it is
  not comfortable to squeeze in that fix in these waning days. So, that
  receives the "back it out and try again later" treatment.

  There is a regression fix in the code that establishes memory NUMA
  nodes for platform CXL regions. That has an ack from x86 folks. There
  are a couple more fixups for Linux to understand (reassemble) CXL
  regions instantiated by platform firmware. The policy around platforms
  that do not match host-physical-address with system-physical-address
  (i.e. systems that have an address translation mechanism between the
  address range reported in the ACPI CEDT.CFMWS and endpoint decoders)
  has been softened to abort driver load rather than teardown the memory
  range (can cause system hangs). Lastly, there is a robustness /
  regression fix for cases where the driver would previously continue in
  the face of error, and a fixup for PCI error notification handling.

  Summary:

   - Fix NUMA initialization from ACPI CEDT.CFMWS

   - Fix region assembly failures due to async init order

   - Fix / simplify export of qos_class information

   - Fix cxl_acpi initialization vs single-window-init failures

   - Fix handling of repeated 'pci_channel_io_frozen' notifications

   - Workaround platforms that violate host-physical-address ==
     system-physical address assumptions

   - Defer CXL CPER notification handling to v6.9"

* tag 'cxl-fixes-6.8-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/cxl/cxl:
  cxl/acpi: Fix load failures due to single window creation failure
  acpi/ghes: Remove CXL CPER notifications
  cxl/pci: Fix disabling memory if DVSEC CXL Range does not match a CFMWS window
  cxl/test: Add support for qos_class checking
  cxl: Fix sysfs export of qos_class for memdev
  cxl: Remove unnecessary type cast in cxl_qos_class_verify()
  cxl: Change 'struct cxl_memdev_state' *_perf_list to single 'struct cxl_dpa_perf'
  cxl/region: Allow out of order assembly of autodiscovered regions
  cxl/region: Handle endpoint decoders in cxl_region_find_decoder()
  x86/numa: Fix the sort compare func used in numa_fill_memblks()
  x86/numa: Fix the address overlap check in numa_fill_memblks()
  cxl/pci: Skip to handle RAS errors if CXL.mem device is detached
mm/debug_vm_pgtable: fix BUG_ON with pud advanced test 2024-02-24T01:27:13+00:00 Aneesh Kumar K.V (IBM) aneesh.kumar@kernel.org 2024-01-29T06:00:22+00:00 720da1e593b85a550593b415bf1d79a053133451 Architectures like powerpc add debug checks to ensure we find only devmap PUD pte entries. These debug checks are only done with CONFIG_DEBUG_VM. This patch marks the ptes used for PUD advanced test devmap pte entries so that we don't hit on debug checks on architecture like ppc64 as below. WARNING: CPU: 2 PID: 1 at arch/powerpc/mm/book3s64/radix_pgtable.c:1382 radix__pud_hugepage_update+0x38/0x138 .... NIP [c0000000000a7004] radix__pud_hugepage_update+0x38/0x138 LR [c0000000000a77a8] radix__pudp_huge_get_and_clear+0x28/0x60 Call Trace: [c000000004a2f950] [c000000004a2f9a0] 0xc000000004a2f9a0 (unreliable) [c000000004a2f980] [000d34c100000000] 0xd34c100000000 [c000000004a2f9a0] [c00000000206ba98] pud_advanced_tests+0x118/0x334 [c000000004a2fa40] [c00000000206db34] debug_vm_pgtable+0xcbc/0x1c48 [c000000004a2fc10] [c00000000000fd28] do_one_initcall+0x60/0x388 Also kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:202! .... NIP [c000000000096510] pudp_huge_get_and_clear_full+0x98/0x174 LR [c00000000206bb34] pud_advanced_tests+0x1b4/0x334 Call Trace: [c000000004a2f950] [000d34c100000000] 0xd34c100000000 (unreliable) [c000000004a2f9a0] [c00000000206bb34] pud_advanced_tests+0x1b4/0x334 [c000000004a2fa40] [c00000000206db34] debug_vm_pgtable+0xcbc/0x1c48 [c000000004a2fc10] [c00000000000fd28] do_one_initcall+0x60/0x388 Link: https://lkml.kernel.org/r/20240129060022.68044-1-aneesh.kumar@kernel.org Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage") Signed-off-by: Aneesh Kumar K.V (IBM) <aneesh.kumar@kernel.org> Cc: Anshuman Khandual <anshuman.khandual@arm.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
Architectures like powerpc add debug checks to ensure we find only devmap
PUD pte entries.  These debug checks are only done with CONFIG_DEBUG_VM. 
This patch marks the ptes used for PUD advanced test devmap pte entries so
that we don't hit on debug checks on architecture like ppc64 as below.

WARNING: CPU: 2 PID: 1 at arch/powerpc/mm/book3s64/radix_pgtable.c:1382 radix__pud_hugepage_update+0x38/0x138
....
NIP [c0000000000a7004] radix__pud_hugepage_update+0x38/0x138
LR [c0000000000a77a8] radix__pudp_huge_get_and_clear+0x28/0x60
Call Trace:
[c000000004a2f950] [c000000004a2f9a0] 0xc000000004a2f9a0 (unreliable)
[c000000004a2f980] [000d34c100000000] 0xd34c100000000
[c000000004a2f9a0] [c00000000206ba98] pud_advanced_tests+0x118/0x334
[c000000004a2fa40] [c00000000206db34] debug_vm_pgtable+0xcbc/0x1c48
[c000000004a2fc10] [c00000000000fd28] do_one_initcall+0x60/0x388

Also

 kernel BUG at arch/powerpc/mm/book3s64/pgtable.c:202!
 ....

 NIP [c000000000096510] pudp_huge_get_and_clear_full+0x98/0x174
 LR [c00000000206bb34] pud_advanced_tests+0x1b4/0x334
 Call Trace:
 [c000000004a2f950] [000d34c100000000] 0xd34c100000000 (unreliable)
 [c000000004a2f9a0] [c00000000206bb34] pud_advanced_tests+0x1b4/0x334
 [c000000004a2fa40] [c00000000206db34] debug_vm_pgtable+0xcbc/0x1c48
 [c000000004a2fc10] [c00000000000fd28] do_one_initcall+0x60/0x388

Link: https://lkml.kernel.org/r/20240129060022.68044-1-aneesh.kumar@kernel.org
Fixes: 27af67f35631 ("powerpc/book3s64/mm: enable transparent pud hugepage")
Signed-off-by: Aneesh Kumar K.V (IBM) <aneesh.kumar@kernel.org>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm: cachestat: fix folio read-after-free in cache walk 2024-02-24T01:27:13+00:00 Nhat Pham nphamcs@gmail.com 2024-02-20T03:01:21+00:00 3a75cb05d53f4a6823a32deb078de1366954a804 In cachestat, we access the folio from the page cache's xarray to compute its page offset, and check for its dirty and writeback flags. However, we do not hold a reference to the folio before performing these actions, which means the folio can concurrently be released and reused as another folio/page/slab. Get around this altogether by just using xarray's existing machinery for the folio page offsets and dirty/writeback states. This changes behavior for tmpfs files to now always report zeroes in their dirty and writeback counters. This is okay as tmpfs doesn't follow conventional writeback cache behavior: its pages get "cleaned" during swapout, after which they're no longer resident etc. Link: https://lkml.kernel.org/r/20240220153409.GA216065@cmpxchg.org Fixes: cf264e1329fb ("cachestat: implement cachestat syscall") Reported-by: Jann Horn <jannh@google.com> Suggested-by: Matthew Wilcox <willy@infradead.org> Signed-off-by: Nhat Pham <nphamcs@gmail.com> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Tested-by: Jann Horn <jannh@google.com> Cc: <stable@vger.kernel.org> [6.4+] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
In cachestat, we access the folio from the page cache's xarray to compute
its page offset, and check for its dirty and writeback flags.  However, we
do not hold a reference to the folio before performing these actions,
which means the folio can concurrently be released and reused as another
folio/page/slab.

Get around this altogether by just using xarray's existing machinery for
the folio page offsets and dirty/writeback states.

This changes behavior for tmpfs files to now always report zeroes in their
dirty and writeback counters.  This is okay as tmpfs doesn't follow
conventional writeback cache behavior: its pages get "cleaned" during
swapout, after which they're no longer resident etc.

Link: https://lkml.kernel.org/r/20240220153409.GA216065@cmpxchg.org
Fixes: cf264e1329fb ("cachestat: implement cachestat syscall")
Reported-by: Jann Horn <jannh@google.com>
Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Jann Horn <jannh@google.com>
Cc: <stable@vger.kernel.org>	[6.4+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
mm/vmscan: fix a bug calling wakeup_kswapd() with a wrong zone index 2024-02-24T01:27:13+00:00 Byungchul Park byungchul@sk.com 2024-02-16T11:15:02+00:00 2774f256e7c0219e2b0a0894af1c76bdabc4f974 With numa balancing on, when a numa system is running where a numa node doesn't have its local memory so it has no managed zones, the following oops has been observed. It's because wakeup_kswapd() is called with a wrong zone index, -1. Fixed it by checking the index before calling wakeup_kswapd(). > BUG: unable to handle page fault for address: 00000000000033f3 > #PF: supervisor read access in kernel mode > #PF: error_code(0x0000) - not-present page > PGD 0 P4D 0 > Oops: 0000 [#1] PREEMPT SMP NOPTI > CPU: 2 PID: 895 Comm: masim Not tainted 6.6.0-dirty #255 > Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS > rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014 > RIP: 0010:wakeup_kswapd (./linux/mm/vmscan.c:7812) > Code: (omitted) > RSP: 0000:ffffc90004257d58 EFLAGS: 00010286 > RAX: ffffffffffffffff RBX: ffff88883fff0480 RCX: 0000000000000003 > RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88883fff0480 > RBP: ffffffffffffffff R08: ff0003ffffffffff R09: ffffffffffffffff > R10: ffff888106c95540 R11: 0000000055555554 R12: 0000000000000003 > R13: 0000000000000000 R14: 0000000000000000 R15: ffff88883fff0940 > FS: 00007fc4b8124740(0000) GS:ffff888827c00000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00000000000033f3 CR3: 000000026cc08004 CR4: 0000000000770ee0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > PKRU: 55555554 > Call Trace: > <TASK> > ? __die > ? page_fault_oops > ? __pte_offset_map_lock > ? exc_page_fault > ? asm_exc_page_fault > ? wakeup_kswapd > migrate_misplaced_page > __handle_mm_fault > handle_mm_fault > do_user_addr_fault > exc_page_fault > asm_exc_page_fault > RIP: 0033:0x55b897ba0808 > Code: (omitted) > RSP: 002b:00007ffeefa821a0 EFLAGS: 00010287 > RAX: 000055b89983acd0 RBX: 00007ffeefa823f8 RCX: 000055b89983acd0 > RDX: 00007fc2f8122010 RSI: 0000000000020000 RDI: 000055b89983acd0 > RBP: 00007ffeefa821a0 R08: 0000000000000037 R09: 0000000000000075 > R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000 > R13: 00007ffeefa82410 R14: 000055b897ba5dd8 R15: 00007fc4b8340000 > </TASK> Link: https://lkml.kernel.org/r/20240216111502.79759-1-byungchul@sk.com Signed-off-by: Byungchul Park <byungchul@sk.com> Reported-by: Hyeongtak Ji <hyeongtak.ji@sk.com> Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system") Reviewed-by: Oscar Salvador <osalvador@suse.de> Cc: Baolin Wang <baolin.wang@linux.alibaba.com> Cc: "Huang, Ying" <ying.huang@intel.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
With numa balancing on, when a numa system is running where a numa node
doesn't have its local memory so it has no managed zones, the following
oops has been observed.  It's because wakeup_kswapd() is called with a
wrong zone index, -1.  Fixed it by checking the index before calling
wakeup_kswapd().

> BUG: unable to handle page fault for address: 00000000000033f3
> #PF: supervisor read access in kernel mode
> #PF: error_code(0x0000) - not-present page
> PGD 0 P4D 0
> Oops: 0000 [#1] PREEMPT SMP NOPTI
> CPU: 2 PID: 895 Comm: masim Not tainted 6.6.0-dirty #255
> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS
>    rel-1.16.0-0-gd239552ce722-prebuilt.qemu.org 04/01/2014
> RIP: 0010:wakeup_kswapd (./linux/mm/vmscan.c:7812)
> Code: (omitted)
> RSP: 0000:ffffc90004257d58 EFLAGS: 00010286
> RAX: ffffffffffffffff RBX: ffff88883fff0480 RCX: 0000000000000003
> RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88883fff0480
> RBP: ffffffffffffffff R08: ff0003ffffffffff R09: ffffffffffffffff
> R10: ffff888106c95540 R11: 0000000055555554 R12: 0000000000000003
> R13: 0000000000000000 R14: 0000000000000000 R15: ffff88883fff0940
> FS:  00007fc4b8124740(0000) GS:ffff888827c00000(0000) knlGS:0000000000000000
> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> CR2: 00000000000033f3 CR3: 000000026cc08004 CR4: 0000000000770ee0
> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> PKRU: 55555554
> Call Trace:
>  <TASK>
> ? __die
> ? page_fault_oops
> ? __pte_offset_map_lock
> ? exc_page_fault
> ? asm_exc_page_fault
> ? wakeup_kswapd
> migrate_misplaced_page
> __handle_mm_fault
> handle_mm_fault
> do_user_addr_fault
> exc_page_fault
> asm_exc_page_fault
> RIP: 0033:0x55b897ba0808
> Code: (omitted)
> RSP: 002b:00007ffeefa821a0 EFLAGS: 00010287
> RAX: 000055b89983acd0 RBX: 00007ffeefa823f8 RCX: 000055b89983acd0
> RDX: 00007fc2f8122010 RSI: 0000000000020000 RDI: 000055b89983acd0
> RBP: 00007ffeefa821a0 R08: 0000000000000037 R09: 0000000000000075
> R10: 0000000000000000 R11: 0000000000000202 R12: 0000000000000000
> R13: 00007ffeefa82410 R14: 000055b897ba5dd8 R15: 00007fc4b8340000
>  </TASK>

Link: https://lkml.kernel.org/r/20240216111502.79759-1-byungchul@sk.com
Signed-off-by: Byungchul Park <byungchul@sk.com>
Reported-by: Hyeongtak Ji <hyeongtak.ji@sk.com>
Fixes: c574bbe917036 ("NUMA balancing: optimize page placement for memory tiering system")
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
kasan: revert eviction of stack traces in generic mode 2024-02-24T01:27:12+00:00 Marco Elver elver@google.com 2024-01-29T10:07:02+00:00 711d349174fd5cf906955249dd0163635e144a1e This partially reverts commits cc478e0b6bdf, 63b85ac56a64, 08d7c94d9635, a414d4286f34, and 773688a6cb24 to make use of variable-sized stack depot records, since eviction of stack entries from stack depot forces fixed- sized stack records. Care was taken to retain the code cleanups by the above commits. Eviction was added to generic KASAN as a response to alleviating the additional memory usage from fixed-sized stack records, but this still uses more memory than previously. With the re-introduction of variable-sized records for stack depot, we can just switch back to non-evictable stack records again, and return back to the previous performance and memory usage baseline. Before (observed after a KASAN kernel boot): pools: 597 refcounted_allocations: 17547 refcounted_frees: 6477 refcounted_in_use: 11070 freelist_size: 3497 persistent_count: 12163 persistent_bytes: 1717008 After: pools: 319 refcounted_allocations: 0 refcounted_frees: 0 refcounted_in_use: 0 freelist_size: 0 persistent_count: 29397 persistent_bytes: 5183536 As can be seen from the counters, with a generic KASAN config, refcounted allocations and evictions are no longer used. Due to using variable-sized records, I observe a reduction of 278 stack depot pools (saving 4448 KiB) with my test setup. Link: https://lkml.kernel.org/r/20240129100708.39460-2-elver@google.com Fixes: cc478e0b6bdf ("kasan: avoid resetting aux_lock") Fixes: 63b85ac56a64 ("kasan: stop leaking stack trace handles") Fixes: 08d7c94d9635 ("kasan: memset free track in qlink_free") Fixes: a414d4286f34 ("kasan: handle concurrent kasan_record_aux_stack calls") Fixes: 773688a6cb24 ("kasan: use stack_depot_put for Generic mode") Signed-off-by: Marco Elver <elver@google.com> Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com> Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com> Cc: Alexander Potapenko <glider@google.com> Cc: Dmitry Vyukov <dvyukov@google.com> Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com> Cc: Vincenzo Frascino <vincenzo.frascino@arm.com> Cc: Vlastimil Babka <vbabka@suse.cz> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> 
This partially reverts commits cc478e0b6bdf, 63b85ac56a64, 08d7c94d9635,
a414d4286f34, and 773688a6cb24 to make use of variable-sized stack depot
records, since eviction of stack entries from stack depot forces fixed-
sized stack records.  Care was taken to retain the code cleanups by the
above commits.

Eviction was added to generic KASAN as a response to alleviating the
additional memory usage from fixed-sized stack records, but this still
uses more memory than previously.

With the re-introduction of variable-sized records for stack depot, we can
just switch back to non-evictable stack records again, and return back to
the previous performance and memory usage baseline.

Before (observed after a KASAN kernel boot):

  pools: 597
  refcounted_allocations: 17547
  refcounted_frees: 6477
  refcounted_in_use: 11070
  freelist_size: 3497
  persistent_count: 12163
  persistent_bytes: 1717008

After:

  pools: 319
  refcounted_allocations: 0
  refcounted_frees: 0
  refcounted_in_use: 0
  freelist_size: 0
  persistent_count: 29397
  persistent_bytes: 5183536

As can be seen from the counters, with a generic KASAN config, refcounted
allocations and evictions are no longer used.  Due to using variable-sized
records, I observe a reduction of 278 stack depot pools (saving 4448 KiB)
with my test setup.

Link: https://lkml.kernel.org/r/20240129100708.39460-2-elver@google.com
Fixes: cc478e0b6bdf ("kasan: avoid resetting aux_lock")
Fixes: 63b85ac56a64 ("kasan: stop leaking stack trace handles")
Fixes: 08d7c94d9635 ("kasan: memset free track in qlink_free")
Fixes: a414d4286f34 ("kasan: handle concurrent kasan_record_aux_stack calls")
Fixes: 773688a6cb24 ("kasan: use stack_depot_put for Generic mode")
Signed-off-by: Marco Elver <elver@google.com>
Reviewed-by: Andrey Konovalov <andreyknvl@gmail.com>
Tested-by: Mikhail Gavrilov <mikhail.v.gavrilov@gmail.com>
Cc: Alexander Potapenko <glider@google.com>
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrey Ryabinin <ryabinin.a.a@gmail.com>
Cc: Vincenzo Frascino <vincenzo.frascino@arm.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>