<feed xmlns='http://www.w3.org/2005/Atom'>
<title>kernel/git/stable/linux.git/fs/ramfs, branch master</title>
<subtitle>Linux kernel stable tree</subtitle>
<id>https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/atom?h=master</id>
<link rel='self' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/atom?h=master'/>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/'/>
<updated>2026-08-27T16:17:06+00:00</updated>
<entry>
<title>Merge tag 'mm-stable-2026-08-26-15-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm</title>
<updated>2026-08-27T16:17:06+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2026-08-27T16:17:06+00:00</published>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=18fbf5151d2c0bfe433c7428eef03cabf5fdb2fa'/>
<id>urn:sha1:18fbf5151d2c0bfe433c7428eef03cabf5fdb2fa</id>
<content type='text'>
Pull more MM updates from Andrew Morton:

 - "mm/rmap: index MAP_PRIVATE file-backed folios by anonymous pgoff"
   (Lorenzo Stoakes)

   Index MAP_PRIVATE file-backed folios by their anonymous page offset
   to resolve confusion around reverse mapping for zeroed and CoW'd
   file-backed memory.

   Use this new VMA anonymous page offset tracking to eliminate index
   conflicts and lay the foundation for scalable CoW performance
   improvements.

 - "promote mapped executable folios after first usage for MGLRU"
   (Baolin Wang)

   Make MGLRU's protection of mapped executable file folios more
   reliable. Follow the classical LRU's logic, promoting mapped
   executable file folios after their first usage to give executable
   code a better chance to stay in memory and improve workload
   performance.

 - "mm: vmscan: fix node reclaim ignoring swappiness parameter" (Ridong
   Chen)

   Fix per-node proactive reclaim interface's ignoring the swappiness
   parameter when CONFIG_MEMCG is disabled by consolidating
   sc_swappiness() into a single function that checks
   proactive_swappiness regardless of kernel configuration.

 - "mm/vmscan: reduce lru_lock contention via vmstat-derived
   scan-balance cost" (Usama Arif)

   Reduce lru_lock contention in the reclaim path by deriving
   scan-balance costs from vmstat counters rather than lock-acquired
   producer updates.

   Read and decay these cost signals on the reclaim side under a
   dedicated per-lruvec lock, reducing total LRU lock wait time by over
   60% without impacting scan throughput.

 - "zram: fix zram issues reported by sashiko" (Sergey Senozhatsky)

   Fix two low-risk zram bugs which Sashiko spotted in drive-by review.

 - "Honor XA_FLAGS_ACCOUNT in xas_split_alloc() and charge to folio's
   memcg" (Zi Yan)

   Fix xas_split_alloc() by enabling target folio memcg charging during
   splits and adding the missing __GFP_ACCOUNT flag for proper XArray
   node memory accounting.

 - "selftests/mm: use pattern matching in .gitignore" (Pratyush Mallick)

   Replace hardcoded binary names in selftests/mm/.gitignore with a
   generic pattern-matching rule to automatically ignore generated test
   files and avoid manual updates when adding new tests.

 - "mm/page_ext: remove pgdat_page_ext_init()" (Sang-Heon Jeon)

   Make the incompatibility between FLATMEM and NUMA explicit in
   mm/Kconfig and remove the unused pgdat_page_ext_init() function.

 - "zram: fix zstd error paths and add parameter validation" (Haoqin
   Huang)

   Clean up zram compression backends by removing redundant error
   cleanup, adding parameter and dictionary validation, auto-prefixing
   algorithm error logs, and resetting parameters prior to
   reinitialization.

 - "zram: fix stale scan bounds after reinitialization" (Longlong Xia)

   Prevent out-of-bounds slot accesses during concurrent zram resets by
   moving table scan bound calculations under dev_lock in
   writeback_store() and read_block_state().

 - "add anon mTHP collapse test cases" (Baolin Wang)

   Extend selftests helper functions to support arbitrary page orders
   and add new test cases and options for mTHP collapse in khugepaged.

 - "selftests/mm: Handle unsupported and transient test conditions"
   (Muhammad Usama Anjum)

   Update MM selftests to report a SKIP status instead of a failure when
   required kernel or filesystem features are unsupported, while adding
   retry logic for transient page migration errors.

 - "mm/zswap: Fixes and improves the zswap shrink" (Hao Jia)

   Fix the missing zswap global shrinker when CONFIG_MEMCG is disabled
   and extend shrink_memcg() to support batch writeback for improved
   writeback efficiency.

 - "alloc_tag: introduce IOCTL-based filtering for MAP" (Suren
   Baghdasaryan)

   Introduce an IOCTL-based binary interface for memory allocation
   profiling that enables kernel-side filtering before per-CPU counter
   aggregation.

   This eliminates the text-parsing overhead of /proc/allocinfo and
   provides up to a 20x speedup by transferring only filtered allocation
   data to userspace.

 - "better block swap batching and a different take on swap_ops v5"
   (Christoph Hellwig)

   Refactor block swap I/O to use swap_iocb for batching instead of
   single-bio requests and rebase the swap_ops interface, achieving
   faster swap throughput during kernel builds.

 - "mm: kmemleak: reduce transient false positives by confirming leaks"
   (Catalin Marinas)

   Reduce false-positive kmemleak reports by combining two kmemleak
   enhancements that add a second confirmation scan and a configurable
   minimum unreferenced scan count module parameter.

 - "mm: kmemleak: default min_unref_scans to 2 for verbose kernels"
   (Breno Leitao)

   Auto-scanning kernels can generate false-positive memory leak reports
   on single scans, so this patch defaults min_unref_scans to 2 when
   CONFIG_DEBUG_KMEMLEAK_VERBOSE is enabled to require a second
   confirming scan.

 - "swap_ops updates" (Christoph Hellwig)

   Batching I/O for synchronous swap devices causes performance
   regressions and filesystem-based swap suffers from double-indirection
   overhead. This series resolves both issues by reintroducing per-folio
   writes for synchronous swap and allowing filesystems to directly
   export their own swap_ops.

 - "mm/khugepaged: several cleanups" (Nico Pache)

   khugepaged accumulated redundant state-checking patterns and outdated
   comments following mTHP integration. Introduce dedicated helpers for
   PTE validation and event counting while refreshing the internal
   documentation.

 - "maple_tree: lock checking and clean ups" (Liam Howlett)

   Syzbot reports incorrectly blame memory management exit paths for
   locking bugs, maple tree erase operations risk allocation failures
   without gfp flags and internal documentation lacks clarity.

   Improve lock error detection, update docs, fix race and allocation
   edge cases and optimize erase allocations using a fallback to
   GFP_KERNEL | GFP_NOFAIL.

* tag 'mm-stable-2026-08-26-15-22' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (172 commits)
  selftests/proc: make proc-maps-race work with READ_IMPLIES_EXEC
  memcg: move LRU size accounting on reparenting instead of copying it
  mm/vmscan: fix comment logic in balance_pgdat
  maple_tree: add helper mas_make_walkable()
  maple_tree: avoid extra gap calculation
  maple_tree: fix argument name in header
  maple_tree: change two GFP flags in tests
  maple_tree: document erase and allocations better
  maple_tree: avoid mas_erase() and mtree_erase() failures
  maple_tree: document that erase may use GFP_KERNEL for allocations
  maple_tree: catch race in mas_alloc_cyclic()
  maple_tree: add bulk parent set helper
  maple_tree: micro optimisation of mas_wr_store_type()
  maple_tree: optimise mas_wr_node_store() when not in rcu mode
  maple_tree: use prefetched value in mas_wr_store_type()
  maple_tree: clarify comments on mas_nomem()
  maple_tree: drop MAPLE_ALLOC_SLOTS
  maple_tree: drop dead code from mas_extend_spanning_null()
  maple_tree: documentation fix
  maple_tree: add write lock checking with lockdep sequence numbers
  ...
</content>
</entry>
<entry>
<title>tmpfs/ramfs: let memfd_create() work on nommu</title>
<updated>2026-08-25T01:43:01+00:00</updated>
<author>
<name>Daniel Palmer</name>
<email>daniel@thingy.jp</email>
</author>
<published>2026-05-23T13:04:45+00:00</published>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=32c9625638c2fda23b9301be5184b8abf84c92a7'/>
<id>urn:sha1:32c9625638c2fda23b9301be5184b8abf84c92a7</id>
<content type='text'>
Currently trying to use memfd_create() on nommu returns an error with
errno set to EFBIG.  The manpage memfd_create() doesn't have EFBIG as a
possible error value.

Doing some digging this is coming from 0 getting passed as newsize to
ramfs_nommu_expand_for_mapping() and that getting into get_order() and
there "The result is undefined if the size is 0".

Whatever comes out of get_order() is then used in the following logic and
that results in the EFBIG that causes the syscall to fail and the errno in
userspace.

If newsize is 0 there is nothing to do so just return.

Roughly tested on m68k nommu by creating a process, creating an memfd,
forking another process, mmap()ing the memfd in the child, writing into
the mapping, then mmap()ing in the parent and checking that the right data
is there.

Link: https://lore.kernel.org/20260523130445.1101818-1-daniel@thingy.jp
Signed-off-by: Daniel Palmer &lt;daniel@thingy.jp&gt;
Acked-by: Lorenzo Stoakes &lt;ljs@kernel.org&gt;
Cc: "Liam R. Howlett" &lt;liam@infradead.org&gt;
Cc: Al Viro &lt;viro@zeniv.linux.org.uk&gt;
Cc: Christian Brauner &lt;brauner@kernel.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'vfs-7.3-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs</title>
<updated>2026-08-17T19:56:12+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2026-08-17T19:56:12+00:00</published>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=1c3e8cef79ea5f1415cff0d3c507e2e07b71ade8'/>
<id>urn:sha1:1c3e8cef79ea5f1415cff0d3c507e2e07b71ade8</id>
<content type='text'>
Pull misc vfs updates from Christian Brauner:
 "Bigger cleanups:

   - The lockref dead-count handling is tidied up.

     The open-coded check for a count below zero as the dead marker
     relies on information the caller should not have.

   - make put_mnt_ns() leave mounts connected. Destroying a mount
     namespace disconnected its mounts from their mount points. So a
     file descriptor still open on the parent of a mount point could be
     used to peek under it.

     Locked mounts were already kept connected to prevent exactly that.
     But a mount is only locked when its tree is copied across a user
     namespace boundary. So a mount namespace set up by a privileged
     component had no locked mounts and its mounts were disconnected.
     Passing UMOUNT_CONNECTED keeps every mount connected and prevents
     that bug.

   - vfs_prepare_mode() passes S_IFDIR for directories. I meant to fix
     that ago but didn't get to it. So now someone finally did it.

     This kills the exception where the mode could be 0 when a directory
     was created whereas every other creation operation passed it
     explicitly already.

   - move long delayed work for ufs, jffs2, hfsplus, hfs and affs from
     the per-cpu system_long_wq to the new unbound system_dfl_long_wq.

     None of that work relies on per-cpu state and the work item is
     enqueued with queue_delayed_work() whose timer is global anyway. So
     it may as well benefit from scheduler task placement.

  Smaller fixes and cleanups:

   - unlock_buffer() and journal_end_buffer_io_sync() use
     clear_and_wake_up_bit()

   - the pipe page pools are unified into a single per-pipe pool and the
     extra wake_up(rd_wait) is limited to EPOLLET consumers

   - eventpoll now computes its timer slack lazily in ep_poll()

   - shrink_dcache_for_umount() keeps making progress on busy roots

   - excess xarray nodes are freed in clear_inode()

   - romfs detects hard link cycles

   - the user path of nested backing files is fixed

   - pidfd holds exec_update_lock around the namespace ioctl

   - non-memcg-aware nr_cached_objects is skipped during memcg slab
     shrink

   - iomap_write_iter() always returns status

   - mangle_path() is renamed to seq_mangle_path()

   - inode timestamp accessors are annotated

   - new regression test for pipe-&gt;poll_usage.

   - a few documentation, kernel-doc and selftest fixes"

* tag 'vfs-7.3-rc1.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (67 commits)
  selftests/namespaces: Fix racy pipe handshake in timens and pidns_separate
  selftests/epoll: add a regression test for pipe-&gt;poll_usage
  pipe: only enable the extra wake_up(rd_wait) for EPOLLET consumers
  pidfd: hold exec_update_lock around namespace ioctl
  fs: fix user path of nested backing files
  fs: remove stale inode_insert5() kernel-doc parameter
  fs: fix switch/case indentation in sysfs() syscall
  fs: document semantics of kstat::{uid,gid} fields
  dcache: keep shrink_dcache_for_umount() making progress on busy roots
  seq_file: rename mangle_path to seq_mangle_path
  nstree: add/fix struct ns_id_req kernel-doc member fields
  dcache: use lockref routines for dead count checks
  lockref: tidy up dead count handling
  initramfs: fix typo in reserve_initrd_mem comment
  fs/pipe: unify the page pools into a single per-pipe pool
  fs: annotate inode timestamp accessors
  eventpoll: compute timer slack lazily in ep_poll()
  selftests/filesystems: add mntns cleanup test
  put_mnt_ns(): leave mounts connected
  affs: Move long delayed work on system_dfl_long_wq
  ...
</content>
</entry>
<entry>
<title>Remove excl arg to -&gt;create inode_operation</title>
<updated>2026-07-31T08:18:30+00:00</updated>
<author>
<name>NeilBrown</name>
<email>neil@brown.name</email>
</author>
<published>2026-07-01T11:51:55+00:00</published>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=b2f1e6301efa4a80becdb0715416c3cbc693fbb4'/>
<id>urn:sha1:b2f1e6301efa4a80becdb0715416c3cbc693fbb4</id>
<content type='text'>
The only time that 'false' is passed as the 'excl' arg to the -&gt;create
inode_operation is in lookup_open() when -&gt;atomic_open is not provided
by the parent directory.
*all* directory inode_operations which do not have -&gt;atomic_open
completely ignore the 'excl' arg.

Therefore we don't need the 'excl' arg.  Those few -&gt;create operations
which pay attention to the arg are only ever called with a value of
'true'.

We remove that arg and change all -&gt;create operations to behave as those
thhe arg were 'true'.

Signed-off-by: NeilBrown &lt;neil@brown.name&gt;
Link: https://patch.msgid.link/178290671516.27465.15984496764174914338@noble.neil.brown.name
Reviewed-by: Jori Koolstra &lt;jkoolstra@xs4all.nl&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Christian Brauner (Amutable) &lt;brauner@kernel.org&gt;
</content>
</entry>
<entry>
<title>ramfs: drop redundant S_IFDIR from mkdir</title>
<updated>2026-07-01T10:51:01+00:00</updated>
<author>
<name>Jori Koolstra</name>
<email>jkoolstra@xs4all.nl</email>
</author>
<published>2026-06-30T10:53:54+00:00</published>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=0ffe991d6ccc6787f68c5ddecc4c13eb4bd0fe4a'/>
<id>urn:sha1:0ffe991d6ccc6787f68c5ddecc4c13eb4bd0fe4a</id>
<content type='text'>
vfs_mkdir() now sets the S_IFDIR type bit in the mode it passes to
-&gt;mkdir(), so OR-ing S_IFDIR into the mode again in ramfs_mkdir() is
redundant. Drop it.

Assisted-by: LLM
Signed-off-by: Jori Koolstra &lt;jkoolstra@xs4all.nl&gt;
Link: https://patch.msgid.link/20260630105400.68459-26-jkoolstra@xs4all.nl
Reviewed-by: NeilBrown &lt;neil@brown.name&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Signed-off-by: Christian Brauner (Amutable) &lt;brauner@kernel.org&gt;
</content>
</entry>
<entry>
<title>folio_batch: rename pagevec.h to folio_batch.h</title>
<updated>2026-04-05T20:53:07+00:00</updated>
<author>
<name>Tal Zussman</name>
<email>tz2294@columbia.edu</email>
</author>
<published>2026-02-25T23:44:27+00:00</published>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=4e1d77a8f382a0ef4dd7732bb1986c8143600def'/>
<id>urn:sha1:4e1d77a8f382a0ef4dd7732bb1986c8143600def</id>
<content type='text'>
struct pagevec was removed in commit 1e0877d58b1e ("mm: remove struct
pagevec").  Rename include/linux/pagevec.h to reflect reality and update
includes tree-wide.  Add the new filename to MAINTAINERS explicitly, as it
no longer matches the "include/linux/page[-_]*" pattern in MEMORY
MANAGEMENT - CORE.

Link: https://lkml.kernel.org/r/20260225-pagevec_cleanup-v2-3-716868cc2d11@columbia.edu
Signed-off-by: Tal Zussman &lt;tz2294@columbia.edu&gt;
Acked-by: David Hildenbrand (Arm) &lt;david@kernel.org&gt;
Reviewed-by: Jan Kara &lt;jack@suse.cz&gt;
Acked-by: Zi Yan &lt;ziy@nvidia.com&gt;
Reviewed-by: Lorenzo Stoakes (Oracle) &lt;ljs@kernel.org&gt;
Cc: Chris Li &lt;chrisl@kernel.org&gt;
Cc: Christian Brauner &lt;brauner@kernel.org&gt;
Cc: Matthew Wilcox (Oracle) &lt;willy@infradead.org&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Convert 'alloc_obj' family to use the new default GFP_KERNEL argument</title>
<updated>2026-02-22T01:09:51+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2026-02-22T00:37:42+00:00</published>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=bf4afc53b77aeaa48b5409da5c8da6bb4eff7f43'/>
<id>urn:sha1:bf4afc53b77aeaa48b5409da5c8da6bb4eff7f43</id>
<content type='text'>
This was done entirely with mindless brute force, using

    git grep -l '\&lt;k[vmz]*alloc_objs*(.*, GFP_KERNEL)' |
        xargs sed -i 's/\(alloc_objs*(.*\), GFP_KERNEL)/\1)/'

to convert the new alloc_obj() users that had a simple GFP_KERNEL
argument to just drop that argument.

Note that due to the extreme simplicity of the scripting, any slightly
more complex cases spread over multiple lines would not be triggered:
they definitely exist, but this covers the vast bulk of the cases, and
the resulting diff is also then easier to check automatically.

For the same reason the 'flex' versions will be done as a separate
conversion.

Signed-off-by: Linus Torvalds &lt;torvalds@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>treewide: Replace kmalloc with kmalloc_obj for non-scalar types</title>
<updated>2026-02-21T09:02:28+00:00</updated>
<author>
<name>Kees Cook</name>
<email>kees@kernel.org</email>
</author>
<published>2026-02-21T07:49:23+00:00</published>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=69050f8d6d075dc01af7a5f2f550a8067510366f'/>
<id>urn:sha1:69050f8d6d075dc01af7a5f2f550a8067510366f</id>
<content type='text'>
This is the result of running the Coccinelle script from
scripts/coccinelle/api/kmalloc_objs.cocci. The script is designed to
avoid scalar types (which need careful case-by-case checking), and
instead replace kmalloc-family calls that allocate struct or union
object instances:

Single allocations:	kmalloc(sizeof(TYPE), ...)
are replaced with:	kmalloc_obj(TYPE, ...)

Array allocations:	kmalloc_array(COUNT, sizeof(TYPE), ...)
are replaced with:	kmalloc_objs(TYPE, COUNT, ...)

Flex array allocations:	kmalloc(struct_size(PTR, FAM, COUNT), ...)
are replaced with:	kmalloc_flex(*PTR, FAM, COUNT, ...)

(where TYPE may also be *VAR)

The resulting allocations no longer return "void *", instead returning
"TYPE *".

Signed-off-by: Kees Cook &lt;kees@kernel.org&gt;
</content>
</entry>
<entry>
<title>mm: update all remaining mmap_prepare users to use vma_flags_t</title>
<updated>2026-02-12T23:42:58+00:00</updated>
<author>
<name>Lorenzo Stoakes</name>
<email>lorenzo.stoakes@oracle.com</email>
</author>
<published>2026-01-22T16:06:18+00:00</published>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=5bd2c0650a9030007af5c2cf2a01dccdc67a6991'/>
<id>urn:sha1:5bd2c0650a9030007af5c2cf2a01dccdc67a6991</id>
<content type='text'>
We will be shortly removing the vm_flags_t field from vm_area_desc so we
need to update all mmap_prepare users to only use the dessc-&gt;vma_flags
field.

This patch achieves that and makes all ancillary changes required to make
this possible.

This lays the groundwork for future work to eliminate the use of
vm_flags_t in vm_area_desc altogether and more broadly throughout the
kernel.

While we're here, we take the opportunity to replace VM_REMAP_FLAGS with
VMA_REMAP_FLAGS, the vma_flags_t equivalent.

No functional changes intended.

Link: https://lkml.kernel.org/r/fb1f55323799f09fe6a36865b31550c9ec67c225.1769097829.git.lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes &lt;lorenzo.stoakes@oracle.com&gt;
Acked-by: Damien Le Moal &lt;dlemoal@kernel.org&gt;	[zonefs]
Acked-by: "Darrick J. Wong" &lt;djwong@kernel.org&gt;
Acked-by: Pedro Falcato &lt;pfalcato@suse.de&gt;
Cc: Baolin Wang &lt;baolin.wang@linux.alibaba.com&gt;
Cc: Barry Song &lt;baohua@kernel.org&gt;
Cc: David Hildenbrand &lt;david@kernel.org&gt;
Cc: Dev Jain &lt;dev.jain@arm.com&gt;
Cc: Jason Gunthorpe &lt;jgg@nvidia.com&gt;
Cc: Liam Howlett &lt;liam.howlett@oracle.com&gt;
Cc: Suren Baghdasaryan &lt;surenb@google.com&gt;
Cc: Vlastimil Babka &lt;vbabka@suse.cz&gt;
Cc: Zi Yan &lt;ziy@nvidia.com&gt;
Cc: Jarkko Sakkinen &lt;jarkko@kernel.org&gt;
Cc: Yury Norov &lt;ynorov@nvidia.com&gt;
Cc: Chris Mason &lt;clm@fb.com&gt;
Signed-off-by: Andrew Morton &lt;akpm@linux-foundation.org&gt;
</content>
</entry>
<entry>
<title>Merge tag 'pull-persistency' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs</title>
<updated>2025-12-05T22:36:21+00:00</updated>
<author>
<name>Linus Torvalds</name>
<email>torvalds@linux-foundation.org</email>
</author>
<published>2025-12-05T22:36:21+00:00</published>
<link rel='alternate' type='text/html' href='https://git.rulkc.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=7cd122b55283d3ceef71a5b723ccaa03a72284b4'/>
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Pull persistent dentry infrastructure and conversion from Al Viro:
 "Some filesystems use a kinda-sorta controlled dentry refcount leak to
  pin dentries of created objects in dcache (and undo it when removing
  those). A reference is grabbed and not released, but it's not actually
  _stored_ anywhere.

  That works, but it's hard to follow and verify; among other things, we
  have no way to tell _which_ of the increments is intended to be an
  unpaired one. Worse, on removal we need to decide whether the
  reference had already been dropped, which can be non-trivial if that
  removal is on umount and we need to figure out if this dentry is
  pinned due to e.g. unlink() not done. Usually that is handled by using
  kill_litter_super() as -&gt;kill_sb(), but there are open-coded special
  cases of the same (consider e.g. /proc/self).

  Things get simpler if we introduce a new dentry flag
  (DCACHE_PERSISTENT) marking those "leaked" dentries. Having it set
  claims responsibility for +1 in refcount.

  The end result this series is aiming for:

   - get these unbalanced dget() and dput() replaced with new primitives
     that would, in addition to adjusting refcount, set and clear
     persistency flag.

   - instead of having kill_litter_super() mess with removing the
     remaining "leaked" references (e.g. for all tmpfs files that hadn't
     been removed prior to umount), have the regular
     shrink_dcache_for_umount() strip DCACHE_PERSISTENT of all dentries,
     dropping the corresponding reference if it had been set. After that
     kill_litter_super() becomes an equivalent of kill_anon_super().

  Doing that in a single step is not feasible - it would affect too many
  places in too many filesystems. It has to be split into a series.

  This work has really started early in 2024; quite a few preliminary
  pieces have already gone into mainline. This chunk is finally getting
  to the meat of that stuff - infrastructure and most of the conversions
  to it.

  Some pieces are still sitting in the local branches, but the bulk of
  that stuff is here"

* tag 'pull-persistency' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs: (54 commits)
  d_make_discardable(): warn if given a non-persistent dentry
  kill securityfs_recursive_remove()
  convert securityfs
  get rid of kill_litter_super()
  convert rust_binderfs
  convert nfsctl
  convert rpc_pipefs
  convert hypfs
  hypfs: swich hypfs_create_u64() to returning int
  hypfs: switch hypfs_create_str() to returning int
  hypfs: don't pin dentries twice
  convert gadgetfs
  gadgetfs: switch to simple_remove_by_name()
  convert functionfs
  functionfs: switch to simple_remove_by_name()
  functionfs: fix the open/removal races
  functionfs: need to cancel -&gt;reset_work in -&gt;kill_sb()
  functionfs: don't bother with ffs-&gt;ref in ffs_data_{opened,closed}()
  functionfs: don't abuse ffs_data_closed() on fs shutdown
  convert selinuxfs
  ...
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