<feed xmlns='http://www.w3.org/2005/Atom'>
<title>linux/tools/testing/vma, branch v6.17</title>
<subtitle>Mirror of https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/
</subtitle>
<id>https://git.shady.money/linux/atom?h=v6.17</id>
<link rel='self' href='https://git.shady.money/linux/atom?h=v6.17'/>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/'/>
<updated>2025-08-05T13:02:07Z</updated>
<entry>
<title>Merge tag 'mm-stable-2025-08-03-12-35' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2025-08-05T13:02:07Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-08-05T13:02:07Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=da23ea194db94257123f1534d487f3cdc9b5626d'/>
<id>urn:sha1:da23ea194db94257123f1534d487f3cdc9b5626d</id>
<content type='text'>
Pull more MM updates from Andrew Morton:
 "Significant patch series in this pull request:

   - "mseal cleanups" (Lorenzo Stoakes)

     Some mseal cleaning with no intended functional change.

   - "Optimizations for khugepaged" (David Hildenbrand)

     Improve khugepaged throughput by batching PTE operations for large
     folios. This gain is mainly for arm64.

   - "x86: enable EXECMEM_ROX_CACHE for ftrace and kprobes" (Mike Rapoport)

     A bugfix, additional debug code and cleanups to the execmem code.

   - "mm/shmem, swap: bugfix and improvement of mTHP swap in" (Kairui Song)

     Bugfixes, cleanups and performance improvememnts to the mTHP swapin
     code"

* tag 'mm-stable-2025-08-03-12-35' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (38 commits)
  mm: mempool: fix crash in mempool_free() for zero-minimum pools
  mm: correct type for vmalloc vm_flags fields
  mm/shmem, swap: fix major fault counting
  mm/shmem, swap: rework swap entry and index calculation for large swapin
  mm/shmem, swap: simplify swapin path and result handling
  mm/shmem, swap: never use swap cache and readahead for SWP_SYNCHRONOUS_IO
  mm/shmem, swap: tidy up swap entry splitting
  mm/shmem, swap: tidy up THP swapin checks
  mm/shmem, swap: avoid redundant Xarray lookup during swapin
  x86/ftrace: enable EXECMEM_ROX_CACHE for ftrace allocations
  x86/kprobes: enable EXECMEM_ROX_CACHE for kprobes allocations
  execmem: drop writable parameter from execmem_fill_trapping_insns()
  execmem: add fallback for failures in vmalloc(VM_ALLOW_HUGE_VMAP)
  execmem: move execmem_force_rw() and execmem_restore_rox() before use
  execmem: rework execmem_cache_free()
  execmem: introduce execmem_alloc_rw()
  execmem: drop unused execmem_update_copy()
  mm: fix a UAF when vma-&gt;mm is freed after vma-&gt;vm_refcnt got dropped
  mm/rmap: add anon_vma lifetime debug check
  mm: remove mm/io-mapping.c
  ...
</content>
</entry>
<entry>
<title>mm/mseal: always define VM_SEALED</title>
<updated>2025-08-02T19:06:09Z</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2025-07-25T08:29:41Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=f225b34f1e6c81c50e48f6207ddb6d290be1b932'/>
<id>urn:sha1:f225b34f1e6c81c50e48f6207ddb6d290be1b932</id>
<content type='text'>
Patch series "mseal cleanups", v4.

Perform a number of cleanups to the mseal logic.  Firstly, VM_SEALED is
treated differently from every other VMA flag, it really doesn't make
sense to do this, so we start by making this consistent with everything
else.

Next we place the madvise logic where it belongs - in mm/madvise.c.  It
really makes no sense to abstract this elsewhere.  In doing so, we go to
great lengths to explain very clearly the previously very confusing logic
as to what sealed mappings are impacted here.

In doing so, we retain existing logic regarding treatment of madvise()
discard operations for a sealed, read-only MAP_PRIVATE file-backed
mapping.  This is something we likely need to revisit.

We then abstract out and explain the 'are there are any gaps in this range
in the mm?' check being performed as a prerequisite to mseal being
performed.

Finally, we simplify the actual mseal logic which is really quite
straightforward.

No functional change is intended.


This patch (of 4):

There is no reason to treat VM_SEALED in a special way, in each other case
in which a VMA flag is unavailable due to configuration, we simply assign
that flag to VM_NONE, so make VM_SEALED consistent with all other VMA
flags in this respect.

Additionally, use the next available bit for VM_SEALED, 42, rather than
arbitrarily putting it at 63 and update the declaration to match all other
VMA flags.

No functional change intended.

Link: https://lkml.kernel.org/r/cover.1753431105.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/aeb398a77029b6e7377cd944328bc9bbc3c90537.1753431105.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Reviewed-by: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Reviewed-by: Pedro Falcato &lt;pfalcato@suse.de&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Jeff Xu &lt;jeffxu@chromium.org&gt;
Cc: Kees Cook &lt;kees@kernel.org&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'mm-stable-2025-07-30-15-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2025-07-31T21:57:54Z</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-07-31T21:57:54Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=beace86e61e465dba204a268ab3f3377153a4973'/>
<id>urn:sha1:beace86e61e465dba204a268ab3f3377153a4973</id>
<content type='text'>
Pull MM updates from Andrew Morton:
 "As usual, many cleanups. The below blurbiage describes 42 patchsets.
  21 of those are partially or fully cleanup work. "cleans up",
  "cleanup", "maintainability", "rationalizes", etc.

  I never knew the MM code was so dirty.

  "mm: ksm: prevent KSM from breaking merging of new VMAs" (Lorenzo Stoakes)
     addresses an issue with KSM's PR_SET_MEMORY_MERGE mode: newly
     mapped VMAs were not eligible for merging with existing adjacent
     VMAs.

  "mm/damon: introduce DAMON_STAT for simple and practical access monitoring" (SeongJae Park)
     adds a new kernel module which simplifies the setup and usage of
     DAMON in production environments.

  "stop passing a writeback_control to swap/shmem writeout" (Christoph Hellwig)
     is a cleanup to the writeback code which removes a couple of
     pointers from struct writeback_control.

  "drivers/base/node.c: optimization and cleanups" (Donet Tom)
     contains largely uncorrelated cleanups to the NUMA node setup and
     management code.

  "mm: userfaultfd: assorted fixes and cleanups" (Tal Zussman)
     does some maintenance work on the userfaultfd code.

  "Readahead tweaks for larger folios" (Ryan Roberts)
     implements some tuneups for pagecache readahead when it is reading
     into order&gt;0 folios.

  "selftests/mm: Tweaks to the cow test" (Mark Brown)
     provides some cleanups and consistency improvements to the
     selftests code.

  "Optimize mremap() for large folios" (Dev Jain)
     does that. A 37% reduction in execution time was measured in a
     memset+mremap+munmap microbenchmark.

  "Remove zero_user()" (Matthew Wilcox)
     expunges zero_user() in favor of the more modern memzero_page().

  "mm/huge_memory: vmf_insert_folio_*() and vmf_insert_pfn_pud() fixes" (David Hildenbrand)
     addresses some warts which David noticed in the huge page code.
     These were not known to be causing any issues at this time.

  "mm/damon: use alloc_migrate_target() for DAMOS_MIGRATE_{HOT,COLD" (SeongJae Park)
     provides some cleanup and consolidation work in DAMON.

  "use vm_flags_t consistently" (Lorenzo Stoakes)
     uses vm_flags_t in places where we were inappropriately using other
     types.

  "mm/memfd: Reserve hugetlb folios before allocation" (Vivek Kasireddy)
     increases the reliability of large page allocation in the memfd
     code.

  "mm: Remove pXX_devmap page table bit and pfn_t type" (Alistair Popple)
     removes several now-unneeded PFN_* flags.

  "mm/damon: decouple sysfs from core" (SeongJae Park)
     implememnts some cleanup and maintainability work in the DAMON
     sysfs layer.

  "madvise cleanup" (Lorenzo Stoakes)
     does quite a lot of cleanup/maintenance work in the madvise() code.

  "madvise anon_name cleanups" (Vlastimil Babka)
     provides additional cleanups on top or Lorenzo's effort.

  "Implement numa node notifier" (Oscar Salvador)
     creates a standalone notifier for NUMA node memory state changes.
     Previously these were lumped under the more general memory
     on/offline notifier.

  "Make MIGRATE_ISOLATE a standalone bit" (Zi Yan)
     cleans up the pageblock isolation code and fixes a potential issue
     which doesn't seem to cause any problems in practice.

  "selftests/damon: add python and drgn based DAMON sysfs functionality tests" (SeongJae Park)
     adds additional drgn- and python-based DAMON selftests which are
     more comprehensive than the existing selftest suite.

  "Misc rework on hugetlb faulting path" (Oscar Salvador)
     fixes a rather obscure deadlock in the hugetlb fault code and
     follows that fix with a series of cleanups.

  "cma: factor out allocation logic from __cma_declare_contiguous_nid" (Mike Rapoport)
     rationalizes and cleans up the highmem-specific code in the CMA
     allocator.

  "mm/migration: rework movable_ops page migration (part 1)" (David Hildenbrand)
     provides cleanups and future-preparedness to the migration code.

  "mm/damon: add trace events for auto-tuned monitoring intervals and DAMOS quota" (SeongJae Park)
     adds some tracepoints to some DAMON auto-tuning code.

  "mm/damon: fix misc bugs in DAMON modules" (SeongJae Park)
     does that.

  "mm/damon: misc cleanups" (SeongJae Park)
     also does what it claims.

  "mm: folio_pte_batch() improvements" (David Hildenbrand)
     cleans up the large folio PTE batching code.

  "mm/damon/vaddr: Allow interleaving in migrate_{hot,cold} actions" (SeongJae Park)
     facilitates dynamic alteration of DAMON's inter-node allocation
     policy.

  "Remove unmap_and_put_page()" (Vishal Moola)
     provides a couple of page-&gt;folio conversions.

  "mm: per-node proactive reclaim" (Davidlohr Bueso)
     implements a per-node control of proactive reclaim - beyond the
     current memcg-based implementation.

  "mm/damon: remove damon_callback" (SeongJae Park)
     replaces the damon_callback interface with a more general and
     powerful damon_call()+damos_walk() interface.

  "mm/mremap: permit mremap() move of multiple VMAs" (Lorenzo Stoakes)
     implements a number of mremap cleanups (of course) in preparation
     for adding new mremap() functionality: newly permit the remapping
     of multiple VMAs when the user is specifying MREMAP_FIXED. It still
     excludes some specialized situations where this cannot be performed
     reliably.

  "drop hugetlb_free_pgd_range()" (Anthony Yznaga)
     switches some sparc hugetlb code over to the generic version and
     removes the thus-unneeded hugetlb_free_pgd_range().

  "mm/damon/sysfs: support periodic and automated stats update" (SeongJae Park)
     augments the present userspace-requested update of DAMON sysfs
     monitoring files. Automatic update is now provided, along with a
     tunable to control the update interval.

  "Some randome fixes and cleanups to swapfile" (Kemeng Shi)
     does what is claims.

  "mm: introduce snapshot_page" (Luiz Capitulino and David Hildenbrand)
     provides (and uses) a means by which debug-style functions can grab
     a copy of a pageframe and inspect it locklessly without tripping
     over the races inherent in operating on the live pageframe
     directly.

  "use per-vma locks for /proc/pid/maps reads" (Suren Baghdasaryan)
     addresses the large contention issues which can be triggered by
     reads from that procfs file. Latencies are reduced by more than
     half in some situations. The series also introduces several new
     selftests for the /proc/pid/maps interface.

  "__folio_split() clean up" (Zi Yan)
     cleans up __folio_split()!

  "Optimize mprotect() for large folios" (Dev Jain)
     provides some quite large (&gt;3x) speedups to mprotect() when dealing
     with large folios.

  "selftests/mm: reuse FORCE_READ to replace "asm volatile("" : "+r" (XXX));" and some cleanup" (wang lian)
     does some cleanup work in the selftests code.

  "tools/testing: expand mremap testing" (Lorenzo Stoakes)
     extends the mremap() selftest in several ways, including adding
     more checking of Lorenzo's recently added "permit mremap() move of
     multiple VMAs" feature.

  "selftests/damon/sysfs.py: test all parameters" (SeongJae Park)
     extends the DAMON sysfs interface selftest so that it tests all
     possible user-requested parameters. Rather than the present minimal
     subset"

* tag 'mm-stable-2025-07-30-15-25' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (370 commits)
  MAINTAINERS: add missing headers to mempory policy &amp; migration section
  MAINTAINERS: add missing file to cgroup section
  MAINTAINERS: add MM MISC section, add missing files to MISC and CORE
  MAINTAINERS: add missing zsmalloc file
  MAINTAINERS: add missing files to page alloc section
  MAINTAINERS: add missing shrinker files
  MAINTAINERS: move memremap.[ch] to hotplug section
  MAINTAINERS: add missing mm_slot.h file THP section
  MAINTAINERS: add missing interval_tree.c to memory mapping section
  MAINTAINERS: add missing percpu-internal.h file to per-cpu section
  mm/page_alloc: remove trace_mm_alloc_contig_migrate_range_info()
  selftests/damon: introduce _common.sh to host shared function
  selftests/damon/sysfs.py: test runtime reduction of DAMON parameters
  selftests/damon/sysfs.py: test non-default parameters runtime commit
  selftests/damon/sysfs.py: generalize DAMON context commit assertion
  selftests/damon/sysfs.py: generalize monitoring attributes commit assertion
  selftests/damon/sysfs.py: generalize DAMOS schemes commit assertion
  selftests/damon/sysfs.py: test DAMOS filters commitment
  selftests/damon/sysfs.py: generalize DAMOS scheme commit assertion
  selftests/damon/sysfs.py: test DAMOS destinations commitment
  ...
</content>
</entry>
<entry>
<title>mm: update architecture and driver code to use vm_flags_t</title>
<updated>2025-07-10T05:42:14Z</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2025-06-18T19:42:54Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=d75fa3c9475048356e50357e8a71745e5c1bd740'/>
<id>urn:sha1:d75fa3c9475048356e50357e8a71745e5c1bd740</id>
<content type='text'>
In future we intend to change the vm_flags_t type, so it isn't correct for
architecture and driver code to assume it is unsigned long.  Correct this
assumption across the board.

Overall, this patch does not introduce any functional change.

Link: https://lkml.kernel.org/r/b6eb1894abc5555ece80bb08af5c022ef780c8bc.1750274467.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Acked-by: Mike Rapoport (Microsoft) &lt;rppt@kernel.org&gt;
Acked-by: Christian Brauner &lt;brauner@kernel.org&gt;
Reviewed-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Reviewed-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Reviewed-by: Pedro Falcato &lt;pfalcato@suse.de&gt;
Acked-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;	[arm64]
Acked-by: Zi Yan &lt;ziy@nvidia.com&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Reviewed-by: Anshuman Khandual &lt;anshuman.khandual@arm.com&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Kees Cook &lt;kees@kernel.org&gt;
Cc: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>mm: update core kernel code to use vm_flags_t consistently</title>
<updated>2025-07-10T05:42:13Z</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2025-06-18T19:42:53Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=bfbe71109fa40e8cc05a0f99e6734b7d76ee00b0'/>
<id>urn:sha1:bfbe71109fa40e8cc05a0f99e6734b7d76ee00b0</id>
<content type='text'>
The core kernel code is currently very inconsistent in its use of
vm_flags_t vs.  unsigned long.  This prevents us from changing the type of
vm_flags_t in the future and is simply not correct, so correct this.

While this results in rather a lot of churn, it is a critical
pre-requisite for a future planned change to VMA flag type.

Additionally, update VMA userland tests to account for the changes.

To make review easier and to break things into smaller parts, driver and
architecture-specific changes is left for a subsequent commit.

The code has been adjusted to cascade the changes across all calling code
as far as is needed.

We will adjust architecture-specific and driver code in a subsequent patch.

Overall, this patch does not introduce any functional change.

Link: https://lkml.kernel.org/r/d1588e7bb96d1ea3fe7b9df2c699d5b4592d901d.1750274467.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Acked-by: Kees Cook &lt;kees@kernel.org&gt;
Acked-by: Mike Rapoport (Microsoft) &lt;rppt@kernel.org&gt;
Acked-by: Jan Kara &lt;jack@suse.cz&gt;
Acked-by: Christian Brauner &lt;brauner@kernel.org&gt;
Reviewed-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Acked-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Reviewed-by: Pedro Falcato &lt;pfalcato@suse.de&gt;
Acked-by: Zi Yan &lt;ziy@nvidia.com&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Anshuman Khandual &lt;anshuman.khandual@arm.com&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Cc: Catalin Marinas &lt;catalin.marinas@arm.com&gt;
Cc: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>mm: change vm_get_page_prot() to accept vm_flags_t argument</title>
<updated>2025-07-10T05:42:13Z</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2025-06-18T19:42:52Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=78ddaa358ec4cdd60bd0e243ced1c83a52c30241'/>
<id>urn:sha1:78ddaa358ec4cdd60bd0e243ced1c83a52c30241</id>
<content type='text'>
Patch series "use vm_flags_t consistently".

The VMA flags field vma-&gt;vm_flags is of type vm_flags_t.  Right now this
is exactly equivalent to unsigned long, but it should not be assumed to
be.

Much code that references vma-&gt;vm_flags already correctly uses vm_flags_t,
but a fairly large chunk of code simply uses unsigned long and assumes
that the two are equivalent.

This series corrects that and has us use vm_flags_t consistently.

This series is motivated by the desire to, in a future series, adjust
vm_flags_t to be a u64 regardless of whether the kernel is 32-bit or
64-bit in order to deal with the VMA flag exhaustion issue and avoid all
the various problems that arise from it (being unable to use certain
features in 32-bit, being unable to add new flags except for 64-bit, etc.)

This is therefore a critical first step towards that goal.  At any rate,
using the correct type is of value regardless.

We additionally take the opportunity to refer to VMA flags as vm_flags
where possible to make clear what we're referring to.

Overall, this series does not introduce any functional change.


This patch (of 3):

We abstract the type of the VMA flags to vm_flags_t, however in may places
it is simply assumed this is unsigned long, which is simply incorrect.

At the moment this is simply an incongruity, however in future we plan to
change this type and therefore this change is a critical requirement for
doing so.

Overall, this patch does not introduce any functional change.

[lorenzo.stoakes@oracle.com: add missing vm_get_page_prot() instance, remove include]
  Link: https://lkml.kernel.org/r/552f88e1-2df8-4e95-92b8-812f7c8db829@lucifer.local
Link: https://lkml.kernel.org/r/cover.1750274467.git.lorenzo.stoakes@oracle.com
Link: https://lkml.kernel.org/r/a12769720a2743f235643b158c4f4f0a9911daf0.1750274467.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Acked-by: Mike Rapoport (Microsoft) &lt;rppt@kernel.org&gt;
Acked-by: Christian Brauner &lt;brauner@kernel.org&gt;
Reviewed-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Reviewed-by: Oscar Salvador &lt;osalvador@suse.de&gt;
Reviewed-by: Pedro Falcato &lt;pfalcato@suse.de&gt;
Acked-by: Catalin Marinas &lt;catalin.marinas@arm.com&gt;	[arm64]
Acked-by: Zi Yan &lt;ziy@nvidia.com&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Anshuman Khandual &lt;anshuman.khandual@arm.com&gt;
Cc: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Cc: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Kees Cook &lt;kees@kernel.org&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Cc: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>mm/vma: use vmg-&gt;target to specify target VMA for new VMA merge</title>
<updated>2025-07-10T05:42:11Z</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2025-06-13T18:48:07Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=4535cb331cfbdbc73d42887330e46e87a4589e6d'/>
<id>urn:sha1:4535cb331cfbdbc73d42887330e46e87a4589e6d</id>
<content type='text'>
In commit 3a75ccba047b ("mm: simplify vma merge structure and expand
comments") we introduced the vmg-&gt;target field to make the merging of
existing VMAs simpler - clarifying precisely which VMA would eventually
become the merged VMA once the merge operation was complete.

New VMA merging did not get quite the same treatment, retaining the rather
confusing convention of storing the target VMA in vmg-&gt;middle.

This patch corrects this state of affairs, utilising vmg-&gt;target for this
purpose for both vma_merge_new_range() and also for vma_expand().

We retain the WARN_ON for vmg-&gt;middle being specified in
vma_merge_new_range() as doing so would make no sense, but add an
additional debug assert for setting vmg-&gt;target.

This patch additionally updates VMA userland testing to account for this
change.

[lorenzo.stoakes@oracle.com: make comment consistent in vma_expand()]
  Link: https://lkml.kernel.org/r/c54f45e3-a6ac-4749-93c0-cc9e3080ee37@lucifer.local
Link: https://lkml.kernel.org/r/20250613184807.108089-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Reviewed-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Kees Cook &lt;kees@kernel.org&gt;
Cc: Liam Howlett &lt;liam.howlett@oracle.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>mm: prevent KSM from breaking VMA merging for new VMAs</title>
<updated>2025-07-10T05:41:54Z</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2025-05-29T17:15:47Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=cf7e7a3503df0b71afd68ee84e9a09d4514cc2dd'/>
<id>urn:sha1:cf7e7a3503df0b71afd68ee84e9a09d4514cc2dd</id>
<content type='text'>
If a user wishes to enable KSM mergeability for an entire process and all
fork/exec'd processes that come after it, they use the prctl()
PR_SET_MEMORY_MERGE operation.

This defaults all newly mapped VMAs to have the VM_MERGEABLE VMA flag set
(in order to indicate they are KSM mergeable), as well as setting this
flag for all existing VMAs and propagating this across fork/exec.

However it also breaks VMA merging for new VMAs, both in the process and
all forked (and fork/exec'd) child processes.

This is because when a new mapping is proposed, the flags specified will
never have VM_MERGEABLE set.  However all adjacent VMAs will already have
VM_MERGEABLE set, rendering VMAs unmergeable by default.

To work around this, we try to set the VM_MERGEABLE flag prior to
attempting a merge.  In the case of brk() this can always be done.

However on mmap() things are more complicated - while KSM is not supported
for MAP_SHARED file-backed mappings, it is supported for MAP_PRIVATE
file-backed mappings.

These mappings may have deprecated .mmap() callbacks specified which
could, in theory, adjust flags and thus KSM eligibility.

So we check to determine whether this is possible.  If not, we set
VM_MERGEABLE prior to the merge attempt on mmap(), otherwise we retain the
previous behaviour.

This fixes VMA merging for all new anonymous mappings, which covers the
majority of real-world cases, so we should see a significant improvement
in VMA mergeability.

For MAP_PRIVATE file-backed mappings, those which implement the
.mmap_prepare() hook and shmem are both known to be safe, so we allow
these, disallowing all other cases.

Also add stubs for newly introduced function invocations to VMA userland
testing.

[lorenzo.stoakes@oracle.com: correctly invoke late KSM check after mmap hook]
  Link: https://lkml.kernel.org/r/5861f8f6-cf5a-4d82-a062-139fb3f9cddb@lucifer.local
Link: https://lkml.kernel.org/r/3ba660af716d87a18ca5b4e635f2101edeb56340.1748537921.git.lorenzo.stoakes@oracle.com
Fixes: d7597f59d1d3 ("mm: add new api to enable ksm per process") # please no backport!
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Reviewed-by: Chengming Zhou &lt;chengming.zhou@linux.dev&gt;
Acked-by: David Hildenbrand &lt;david@redhat.com&gt;
Reviewed-by: Liam R. Howlett &lt;Liam.Howlett@oracle.com&gt;
Reviewed-by: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Reviewed-by: Xu Xin &lt;xu.xin16@zte.com.cn&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Christian Brauner &lt;brauner@kernel.org&gt;
Cc: Jan Kara &lt;jack@suse.cz&gt;
Cc: Jann Horn &lt;jannh@google.com&gt;
Cc: Stefan Roesch &lt;shr@devkernel.io&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>fs: consistently use can_mmap_file() helper</title>
<updated>2025-06-17T11:47:22Z</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2025-06-16T19:33:22Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=b013ed403197f3f8c30ddb3ce66fe05a632b3493'/>
<id>urn:sha1:b013ed403197f3f8c30ddb3ce66fe05a632b3493</id>
<content type='text'>
Since commit c84bf6dd2b83 ("mm: introduce new .mmap_prepare() file
callback"), the f_op-&gt;mmap() hook has been deprecated in favour of
f_op-&gt;mmap_prepare().

Additionally, commit bb666b7c2707 ("mm: add mmap_prepare() compatibility
layer for nested file systems") permits the use of the .mmap_prepare() hook
even in nested filesystems like overlayfs.

There are a number of places where we check only for f_op-&gt;mmap - this is
incorrect now mmap_prepare exists, so update all of these to use the
general helper can_mmap_file().

Most notably, this updates the elf logic to allow for the ability to
execute binaries on filesystems which have the .mmap_prepare hook, but
additionally we update nested filesystems.

Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Link: https://lore.kernel.org/b68145b609532e62bab603dd9686faa6562046ec.1750099179.git.lorenzo.stoakes@oracle.com
Acked-by: Kees Cook &lt;kees@kernel.org&gt;
Signed-off-by: Christian Brauner &lt;brauner@kernel.org&gt;
</content>
</entry>
<entry>
<title>mm: rename call_mmap/mmap_prepare to vfs_mmap/mmap_prepare</title>
<updated>2025-06-17T11:35:23Z</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2025-06-16T19:33:20Z</published>
<link rel='alternate' type='text/html' href='https://git.shady.money/linux/commit/?id=20ca475d9860e14cf389f5a7d5ba9c6437d74613'/>
<id>urn:sha1:20ca475d9860e14cf389f5a7d5ba9c6437d74613</id>
<content type='text'>
The call_mmap() function violates the existing convention in
include/linux/fs.h whereby invocations of virtual file system hooks is
performed by functions prefixed with vfs_xxx().

Correct this by renaming call_mmap() to vfs_mmap(). This also avoids
confusion as to the fact that f_op-&gt;mmap_prepare may be invoked here.

Also rename __call_mmap_prepare() function to vfs_mmap_prepare() and adjust
to accept a file parameter, this is useful later for nested file systems.

Finally, fix up the VMA userland tests and ensure the mmap_prepare -&gt; mmap
shim is implemented there.

Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Link: https://lore.kernel.org/8d389f4994fa736aa8f9172bef8533c10a9e9011.1750099179.git.lorenzo.stoakes@oracle.com
Signed-off-by: Christian Brauner &lt;brauner@kernel.org&gt;
</content>
</entry>
</feed>
