Pull MM updates from Andrew Morton:
 "Many singleton patches against the MM code. The patch series which are
  included in this merge do the following:

   - Kemeng Shi has contributed some compation maintenance work in the
     series 'Fixes and cleanups to compaction'

   - Joel Fernandes has a patchset ('Optimize mremap during mutual
     alignment within PMD') which fixes an obscure issue with mremap()'s
     pagetable handling during a subsequent exec(), based upon an
     implementation which Linus suggested

   - More DAMON/DAMOS maintenance and feature work from SeongJae Park i
     the following patch series:

	mm/damon: misc fixups for documents, comments and its tracepoint
	mm/damon: add a tracepoint for damos apply target regions
	mm/damon: provide pseudo-moving sum based access rate
	mm/damon: implement DAMOS apply intervals
	mm/damon/core-test: Fix memory leaks in core-test
	mm/damon/sysfs-schemes: Do DAMOS tried regions update for only one apply interval

   - In the series 'Do not try to access unaccepted memory' Adrian
     Hunter provides some fixups for the recently-added 'unaccepted
     memory' feature. To increase the feature's checking coverage. 'Plug
     a few gaps where RAM is exposed without checking if it is
     unaccepted memory'

   - In the series 'cleanups for lockless slab shrink' Qi Zheng has done
     some maintenance work which is preparation for the lockless slab
     shrinking code

   - Qi Zheng has redone the earlier (and reverted) attempt to make slab
     shrinking lockless in the series 'use refcount+RCU method to
     implement lockless slab shrink'

   - David Hildenbrand contributes some maintenance work for the rmap
     code in the series 'Anon rmap cleanups'

   - Kefeng Wang does more folio conversions and some maintenance work
     in the migration code. Series 'mm: migrate: more folio conversion
     and unification'

   - Matthew Wilcox has fixed an issue in the buffer_head code which was
     causing long stalls under some heavy memory/IO loads. Some cleanups
     were added on the way. Series 'Add and use bdev_getblk()'

   - In the series 'Use nth_page() in place of direct struct page
     manipulation' Zi Yan has fixed a potential issue with the direct
     manipulation of hugetlb page frames

   - In the series 'mm: hugetlb: Skip initialization of gigantic tail
     struct pages if freed by HVO' has improved our handling of gigantic
     pages in the hugetlb vmmemmep optimizaton code. This provides
     significant boot time improvements when significant amounts of
     gigantic pages are in use

   - Matthew Wilcox has sent the series 'Small hugetlb cleanups' - code
     rationalization and folio conversions in the hugetlb code

   - Yin Fengwei has improved mlock()'s handling of large folios in the
     series 'support large folio for mlock'

   - In the series 'Expose swapcache stat for memcg v1' Liu Shixin has
     added statistics for memcg v1 users which are available (and
     useful) under memcg v2

   - Florent Revest has enhanced the MDWE (Memory-Deny-Write-Executable)
     prctl so that userspace may direct the kernel to not automatically
     propagate the denial to child processes. The series is named 'MDWE
     without inheritance'

   - Kefeng Wang has provided the series 'mm: convert numa balancing
     functions to use a folio' which does what it says

   - In the series 'mm/ksm: add fork-exec support for prctl' Stefan
     Roesch makes is possible for a process to propagate KSM treatment
     across exec()

   - Huang Ying has enhanced memory tiering's calculation of memory
     distances. This is used to permit the dax/kmem driver to use 'high
     bandwidth memory' in addition to Optane Data Center Persistent
     Memory Modules (DCPMM). The series is named 'memory tiering:
     calculate abstract distance based on ACPI HMAT'

   - In the series 'Smart scanning mode for KSM' Stefan Roesch has
     optimized KSM by teaching it to retain and use some historical
     information from previous scans

   - Yosry Ahmed has fixed some inconsistencies in memcg statistics in
     the series 'mm: memcg: fix tracking of pending stats updates
     values'

   - In the series 'Implement IOCTL to get and optionally clear info
     about PTEs' Peter Xu has added an ioctl to /proc/<pid>/pagemap
     which permits us to atomically read-then-clear page softdirty
     state. This is mainly used by CRIU

   - Hugh Dickins contributed the series 'shmem,tmpfs: general
     maintenance', a bunch of relatively minor maintenance tweaks to
     this code

   - Matthew Wilcox has increased the use of the VMA lock over
     file-backed page faults in the series 'Handle more faults under the
     VMA lock'. Some rationalizations of the fault path became possible
     as a result

   - In the series 'mm/rmap: convert page_move_anon_rmap() to
     folio_move_anon_rmap()' David Hildenbrand has implemented some
     cleanups and folio conversions

   - In the series 'various improvements to the GUP interface' Lorenzo
     Stoakes has simplified and improved the GUP interface with an eye
     to providing groundwork for future improvements

   - Andrey Konovalov has sent along the series 'kasan: assorted fixes
     and improvements' which does those things

   - Some page allocator maintenance work from Kemeng Shi in the series
     'Two minor cleanups to break_down_buddy_pages'

   - In thes series 'New selftest for mm' Breno Leitao has developed
     another MM self test which tickles a race we had between madvise()
     and page faults

   - In the series 'Add folio_end_read' Matthew Wilcox provides cleanups
     and an optimization to the core pagecache code

   - Nhat Pham has added memcg accounting for hugetlb memory in the
     series 'hugetlb memcg accounting'

   - Cleanups and rationalizations to the pagemap code from Lorenzo
     Stoakes, in the series 'Abstract vma_merge() and split_vma()'

   - Audra Mitchell has fixed issues in the procfs page_owner code's new
     timestamping feature which was causing some misbehaviours. In the
     series 'Fix page_owner's use of free timestamps'

   - Lorenzo Stoakes has fixed the handling of new mappings of sealed
     files in the series 'permit write-sealed memfd read-only shared
     mappings'

   - Mike Kravetz has optimized the hugetlb vmemmap optimization in the
     series 'Batch hugetlb vmemmap modification operations'

   - Some buffer_head folio conversions and cleanups from Matthew Wilcox
     in the series 'Finish the create_empty_buffers() transition'

   - As a page allocator performance optimization Huang Ying has added
     automatic tuning to the allocator's per-cpu-pages feature, in the
     series 'mm: PCP high auto-tuning'

   - Roman Gushchin has contributed the patchset 'mm: improve
     performance of accounted kernel memory allocations' which improves
     their performance by ~30% as measured by a micro-benchmark

   - folio conversions from Kefeng Wang in the series 'mm: convert page
     cpupid functions to folios'

   - Some kmemleak fixups in Liu Shixin's series 'Some bugfix about
     kmemleak'

   - Qi Zheng has improved our handling of memoryless nodes by keeping
     them off the allocation fallback list. This is done in the series
     'handle memoryless nodes more appropriately'

   - khugepaged conversions from Vishal Moola in the series 'Some
     khugepaged folio conversions'"

[ bcachefs conflicts with the dynamically allocated shrinkers have been
  resolved as per Stephen Rothwell in

     https://lore.kernel.org/all/20230913093553.4290421e@canb.auug.org.au/

  with help from Qi Zheng.

  The clone3 test filtering conflict was half-arsed by yours truly ]

* tag 'mm-stable-2023-11-01-14-33' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (406 commits)
  mm/damon/sysfs: update monitoring target regions for online input commit
  mm/damon/sysfs: remove requested targets when online-commit inputs
  selftests: add a sanity check for zswap
  Documentation: maple_tree: fix word spelling error
  mm/vmalloc: fix the unchecked dereference warning in vread_iter()
  zswap: export compression failure stats
  Documentation: ubsan: drop "the" from article title
  mempolicy: migration attempt to match interleave nodes
  mempolicy: mmap_lock is not needed while migrating folios
  mempolicy: alloc_pages_mpol() for NUMA policy without vma
  mm: add page_rmappable_folio() wrapper
  mempolicy: remove confusing MPOL_MF_LAZY dead code
  mempolicy: mpol_shared_policy_init() without pseudo-vma
  mempolicy trivia: use pgoff_t in shared mempolicy tree
  mempolicy trivia: slightly more consistent naming
  mempolicy trivia: delete those ancient pr_debug()s
  mempolicy: fix migrate_pages(2) syscall return nr_failed
  kernfs: drop shared NUMA mempolicy hooks
  hugetlbfs: drop shared NUMA mempolicy pretence
  mm/damon/sysfs-test: add a unit test for damon_sysfs_set_targets()
  ...

Pull LSM updates from Paul Moore:

 - Add new credential functions, get_cred_many() and put_cred_many() to
   save some atomic_t operations for a few operations.

   While not strictly LSM related, this patchset had been rotting on the
   mailing lists for some time and since the LSMs do care a lot about
   credentials I thought it reasonable to give this patch a home.

 - Five patches to constify different LSM hook parameters.

 - Fix a spelling mistake.

* tag 'lsm-pr-20231030' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/lsm:
  lsm: fix a spelling mistake
  cred: add get_cred_many and put_cred_many
  lsm: constify 'sb' parameter in security_sb_kern_mount()
  lsm: constify 'bprm' parameter in security_bprm_committed_creds()
  lsm: constify 'bprm' parameter in security_bprm_committing_creds()
  lsm: constify 'file' parameter in security_bprm_creds_from_file()
  lsm: constify 'sb' parameter in security_quotactl()

Pull fscrypt updates from Eric Biggers:
 "This update adds support for configuring the crypto data unit size
  (i.e. the granularity of file contents encryption) to be less than the
  filesystem block size. This can allow users to use inline encryption
  hardware in some cases when it wouldn't otherwise be possible.

  In addition, there are two commits that are prerequisites for the
  extent-based encryption support that the btrfs folks are working on"

* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/linux:
  fscrypt: track master key presence separately from secret
  fscrypt: rename fscrypt_info => fscrypt_inode_info
  fscrypt: support crypto data unit size less than filesystem block size
  fscrypt: replace get_ino_and_lblk_bits with just has_32bit_inodes
  fscrypt: compute max_lblk_bits from s_maxbytes and block size
  fscrypt: make the bounce page pool opt-in instead of opt-out
  fscrypt: make it clearer that key_prefix is deprecated

Pull vfs inode time accessor updates from Christian Brauner:
 "This finishes the conversion of all inode time fields to accessor
  functions as discussed on list. Changing timestamps manually as we
  used to do before is error prone. Using accessors function makes this
  robust.

  It does not contain the switch of the time fields to discrete 64 bit
  integers to replace struct timespec and free up space in struct inode.
  But after this, the switch can be trivially made and the patch should
  only affect the vfs if we decide to do it"

* tag 'vfs-6.7.ctime' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (86 commits)
  fs: rename inode i_atime and i_mtime fields
  security: convert to new timestamp accessors
  selinux: convert to new timestamp accessors
  apparmor: convert to new timestamp accessors
  sunrpc: convert to new timestamp accessors
  mm: convert to new timestamp accessors
  bpf: convert to new timestamp accessors
  ipc: convert to new timestamp accessors
  linux: convert to new timestamp accessors
  zonefs: convert to new timestamp accessors
  xfs: convert to new timestamp accessors
  vboxsf: convert to new timestamp accessors
  ufs: convert to new timestamp accessors
  udf: convert to new timestamp accessors
  ubifs: convert to new timestamp accessors
  tracefs: convert to new timestamp accessors
  sysv: convert to new timestamp accessors
  squashfs: convert to new timestamp accessors
  server: convert to new timestamp accessors
  client: convert to new timestamp accessors
  ...

Pull vfs xattr updates from Christian Brauner:
 "The 's_xattr' field of 'struct super_block' currently requires a
  mutable table of 'struct xattr_handler' entries (although each handler
  itself is const). However, no code in vfs actually modifies the
  tables.

  This changes the type of 's_xattr' to allow const tables, and modifies
  existing file systems to move their tables to .rodata. This is
  desirable because these tables contain entries with function pointers
  in them; moving them to .rodata makes it considerably less likely to
  be modified accidentally or maliciously at runtime"

* tag 'vfs-6.7.xattr' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (30 commits)
  const_structs.checkpatch: add xattr_handler
  net: move sockfs_xattr_handlers to .rodata
  shmem: move shmem_xattr_handlers to .rodata
  overlayfs: move xattr tables to .rodata
  xfs: move xfs_xattr_handlers to .rodata
  ubifs: move ubifs_xattr_handlers to .rodata
  squashfs: move squashfs_xattr_handlers to .rodata
  smb: move cifs_xattr_handlers to .rodata
  reiserfs: move reiserfs_xattr_handlers to .rodata
  orangefs: move orangefs_xattr_handlers to .rodata
  ocfs2: move ocfs2_xattr_handlers and ocfs2_xattr_handler_map to .rodata
  ntfs3: move ntfs_xattr_handlers to .rodata
  nfs: move nfs4_xattr_handlers to .rodata
  kernfs: move kernfs_xattr_handlers to .rodata
  jfs: move jfs_xattr_handlers to .rodata
  jffs2: move jffs2_xattr_handlers to .rodata
  hfsplus: move hfsplus_xattr_handlers to .rodata
  hfs: move hfs_xattr_handlers to .rodata
  gfs2: move gfs2_xattr_handlers_max to .rodata
  fuse: move fuse_xattr_handlers to .rodata
  ...

Pull misc vfs updates from Christian Brauner:
 "This contains the usual miscellaneous features, cleanups, and fixes
  for vfs and individual fses.

  Features:

   - Rename and export helpers that get write access to a mount. They
     are used in overlayfs to get write access to the upper mount.

   - Print the pretty name of the root device on boot failure. This
     helps in scenarios where we would usually only print
     "unknown-block(1,2)".

   - Add an internal SB_I_NOUMASK flag. This is another part in the
     endless POSIX ACL saga in a way.

     When POSIX ACLs are enabled via SB_POSIXACL the vfs cannot strip
     the umask because if the relevant inode has POSIX ACLs set it might
     take the umask from there. But if the inode doesn't have any POSIX
     ACLs set then we apply the umask in the filesytem itself. So we end
     up with:

      (1) no SB_POSIXACL -> strip umask in vfs
      (2) SB_POSIXACL    -> strip umask in filesystem

     The umask semantics associated with SB_POSIXACL allowed filesystems
     that don't even support POSIX ACLs at all to raise SB_POSIXACL
     purely to avoid umask stripping. That specifically means NFS v4 and
     Overlayfs. NFS v4 does it because it delegates this to the server
     and Overlayfs because it needs to delegate umask stripping to the
     upper filesystem, i.e., the filesystem used as the writable layer.

     This went so far that SB_POSIXACL is raised eve on kernels that
     don't even have POSIX ACL support at all.

     Stop this blatant abuse and add SB_I_NOUMASK which is an internal
     superblock flag that filesystems can raise to opt out of umask
     handling. That should really only be the two mentioned above. It's
     not that we want any filesystems to do this. Ideally we have all
     umask handling always in the vfs.

   - Make overlayfs use SB_I_NOUMASK too.

   - Now that we have SB_I_NOUMASK, stop checking for SB_POSIXACL in
     IS_POSIXACL() if the kernel doesn't have support for it. This is a
     very old patch but it's only possible to do this now with the wider
     cleanup that was done.

   - Follow-up work on fake path handling from last cycle. Citing mostly
     from Amir:

     When overlayfs was first merged, overlayfs files of regular files
     and directories, the ones that are installed in file table, had a
     "fake" path, namely, f_path is the overlayfs path and f_inode is
     the "real" inode on the underlying filesystem.

     In v6.5, we took another small step by introducing of the
     backing_file container and the file_real_path() helper. This change
     allowed vfs and filesystem code to get the "real" path of an
     overlayfs backing file. With this change, we were able to make
     fsnotify work correctly and report events on the "real" filesystem
     objects that were accessed via overlayfs.

     This method works fine, but it still leaves the vfs vulnerable to
     new code that is not aware of files with fake path. A recent
     example is commit db1d1e8b9867 ("IMA: use vfs_getattr_nosec to get
     the i_version"). This commit uses direct referencing to f_path in
     IMA code that otherwise uses file_inode() and file_dentry() to
     reference the filesystem objects that it is measuring.

     This contains work to switch things around: instead of having
     filesystem code opt-in to get the "real" path, have generic code
     opt-in for the "fake" path in the few places that it is needed.

     Is it far more likely that new filesystems code that does not use
     the file_dentry() and file_real_path() helpers will end up causing
     crashes or averting LSM/audit rules if we keep the "fake" path
     exposed by default.

     This change already makes file_dentry() moot, but for now we did
     not change this helper just added a WARN_ON() in ovl_d_real() to
     catch if we have made any wrong assumptions.

     After the dust settles on this change, we can make file_dentry() a
     plain accessor and we can drop the inode argument to ->d_real().

   - Switch struct file to SLAB_TYPESAFE_BY_RCU. This looks like a small
     change but it really isn't and I would like to see everyone on
     their tippie toes for any possible bugs from this work.

     Essentially we've been doing most of what SLAB_TYPESAFE_BY_RCU for
     files since a very long time because of the nasty interactions
     between the SCM_RIGHTS file descriptor garbage collection. So
     extending it makes a lot of sense but it is a subtle change. There
     are almost no places that fiddle with file rcu semantics directly
     and the ones that did mess around with struct file internal under
     rcu have been made to stop doing that because it really was always
     dodgy.

     I forgot to put in the link tag for this change and the discussion
     in the commit so adding it into the merge message:

       https://lore.kernel.org/r/20230926162228.68666-1-mjguzik@gmail.com

  Cleanups:

   - Various smaller pipe cleanups including the removal of a spin lock
     that was only used to protect against writes without pipe_lock()
     from O_NOTIFICATION_PIPE aka watch queues. As that was never
     implemented remove the additional locking from pipe_write().

   - Annotate struct watch_filter with the new __counted_by attribute.

   - Clarify do_unlinkat() cleanup so that it doesn't look like an extra
     iput() is done that would cause issues.

   - Simplify file cleanup when the file has never been opened.

   - Use module helper instead of open-coding it.

   - Predict error unlikely for stale retry.

   - Use WRITE_ONCE() for mount expiry field instead of just commenting
     that one hopes the compiler doesn't get smart.

  Fixes:

   - Fix readahead on block devices.

   - Fix writeback when layztime is enabled and inodes whose timestamp
     is the only thing that changed reside on wb->b_dirty_time. This
     caused excessively large zombie memory cgroup when lazytime was
     enabled as such inodes weren't handled fast enough.

   - Convert BUG_ON() to WARN_ON_ONCE() in open_last_lookups()"

* tag 'vfs-6.7.misc' of gitolite.kernel.org:pub/scm/linux/kernel/git/vfs/vfs: (26 commits)
  file, i915: fix file reference for mmap_singleton()
  vfs: Convert BUG_ON to WARN_ON_ONCE in open_last_lookups
  writeback, cgroup: switch inodes with dirty timestamps to release dying cgwbs
  chardev: Simplify usage of try_module_get()
  ovl: rely on SB_I_NOUMASK
  fs: fix umask on NFS with CONFIG_FS_POSIX_ACL=n
  fs: store real path instead of fake path in backing file f_path
  fs: create helper file_user_path() for user displayed mapped file path
  fs: get mnt_writers count for an open backing file's real path
  vfs: stop counting on gcc not messing with mnt_expiry_mark if not asked
  vfs: predict the error in retry_estale as unlikely
  backing file: free directly
  vfs: fix readahead(2) on block devices
  io_uring: use files_lookup_fd_locked()
  file: convert to SLAB_TYPESAFE_BY_RCU
  vfs: shave work on failed file open
  fs: simplify misleading code to remove ambiguity regarding ihold()/iput()
  watch_queue: Annotate struct watch_filter with __counted_by
  fs/pipe: use spinlock in pipe_read() only if there is a watch_queue
  fs/pipe: remove unnecessary spinlock from pipe_write()
  ...

Convert mount code to use bdev_open_by_dev() and propagate the handle
around to bdev_release().

Acked-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Jan Kara <jack@suse.cz>
Link: https://lore.kernel.org/r/20230927093442.25915-19-jack@suse.cz
Signed-off-by: Christian Brauner <brauner@kernel.org>

Today we got a report at [1] for rcu stalls on the i915 testsuite in [2]
due to the conversion of files to SLAB_TYPSSAFE_BY_RCU. Afaict,
get_file_rcu() goes into an infinite loop trying to carefully verify
that i915->gem.mmap_singleton hasn't changed - see the splat below.

So I stared at this code to figure out what it actually does. It seems
that the i915->gem.mmap_singleton pointer itself never had rcu semantics.

The i915->gem.mmap_singleton is replaced in
file->f_op->release::singleton_release():

        static int singleton_release(struct inode *inode, struct file *file)
        {
                struct drm_i915_private *i915 = file->private_data;

                cmpxchg(&i915->gem.mmap_singleton, file, NULL);
                drm_dev_put(&i915->drm);

                return 0;
        }

The cmpxchg() is ordered against a concurrent update of
i915->gem.mmap_singleton from mmap_singleton(). IOW, when
mmap_singleton() fails to get a reference on i915->gem.mmap_singleton:

While mmap_singleton() does

        rcu_read_lock();
        file = get_file_rcu(&i915->gem.mmap_singleton);
        rcu_read_unlock();

it allocates a new file via anon_inode_getfile() and does

        smp_store_mb(i915->gem.mmap_singleton, file);

So, then what happens in the case of this bug is that at some point
fput() is called and drops the file->f_count to zero leaving the pointer
in i915->gem.mmap_singleton in tact.

Now, there might be delays until
file->f_op->release::singleton_release() is called and
i915->gem.mmap_singleton is set to NULL.

Say concurrently another task hits mmap_singleton() and does:

        rcu_read_lock();
        file = get_file_rcu(&i915->gem.mmap_singleton);
        rcu_read_unlock();

When get_file_rcu() fails to get a reference via atomic_inc_not_zero()
it will try the reload from i915->gem.mmap_singleton expecting it to be
NULL, assuming it has comparable semantics as we expect in
__fget_files_rcu().

But it hasn't so it reloads the same pointer again, trying the same
atomic_inc_not_zero() again and doing so until
file->f_op->release::singleton_release() of the old file has been
called.

So, in contrast to __fget_files_rcu() here we want to not retry when
atomic_inc_not_zero() has failed. We only want to retry in case we
managed to get a reference but the pointer did change on reload.

<3> [511.395679] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
<3> [511.395716] rcu:   Tasks blocked on level-1 rcu_node (CPUs 0-9): P6238
<3> [511.395934] rcu:   (detected by 16, t=65002 jiffies, g=123977, q=439 ncpus=20)
<6> [511.395944] task:i915_selftest   state:R  running task     stack:10568 pid:6238  tgid:6238  ppid:1001   flags:0x00004002
<6> [511.395962] Call Trace:
<6> [511.395966]  <TASK>
<6> [511.395974]  ? __schedule+0x3a8/0xd70
<6> [511.395995]  ? asm_sysvec_apic_timer_interrupt+0x1a/0x20
<6> [511.396003]  ? lockdep_hardirqs_on+0xc3/0x140
<6> [511.396013]  ? asm_sysvec_apic_timer_interrupt+0x1a/0x20
<6> [511.396029]  ? get_file_rcu+0x10/0x30
<6> [511.396039]  ? get_file_rcu+0x10/0x30
<6> [511.396046]  ? i915_gem_object_mmap+0xbc/0x450 [i915]
<6> [511.396509]  ? i915_gem_mmap+0x272/0x480 [i915]
<6> [511.396903]  ? mmap_region+0x253/0xb60
<6> [511.396925]  ? do_mmap+0x334/0x5c0
<6> [511.396939]  ? vm_mmap_pgoff+0x9f/0x1c0
<6> [511.396949]  ? rcu_is_watching+0x11/0x50
<6> [511.396962]  ? igt_mmap_offset+0xfc/0x110 [i915]
<6> [511.397376]  ? __igt_mmap+0xb3/0x570 [i915]
<6> [511.397762]  ? igt_mmap+0x11e/0x150 [i915]
<6> [511.398139]  ? __trace_bprintk+0x76/0x90
<6> [511.398156]  ? __i915_subtests+0xbf/0x240 [i915]
<6> [511.398586]  ? __pfx___i915_live_setup+0x10/0x10 [i915]
<6> [511.399001]  ? __pfx___i915_live_teardown+0x10/0x10 [i915]
<6> [511.399433]  ? __run_selftests+0xbc/0x1a0 [i915]
<6> [511.399875]  ? i915_live_selftests+0x4b/0x90 [i915]
<6> [511.400308]  ? i915_pci_probe+0x106/0x200 [i915]
<6> [511.400692]  ? pci_device_probe+0x95/0x120
<6> [511.400704]  ? really_probe+0x164/0x3c0
<6> [511.400715]  ? __pfx___driver_attach+0x10/0x10
<6> [511.400722]  ? __driver_probe_device+0x73/0x160
<6> [511.400731]  ? driver_probe_device+0x19/0xa0
<6> [511.400741]  ? __driver_attach+0xb6/0x180
<6> [511.400749]  ? __pfx___driver_attach+0x10/0x10
<6> [511.400756]  ? bus_for_each_dev+0x77/0xd0
<6> [511.400770]  ? bus_add_driver+0x114/0x210
<6> [511.400781]  ? driver_register+0x5b/0x110
<6> [511.400791]  ? i915_init+0x23/0xc0 [i915]
<6> [511.401153]  ? __pfx_i915_init+0x10/0x10 [i915]
<6> [511.401503]  ? do_one_initcall+0x57/0x270
<6> [511.401515]  ? rcu_is_watching+0x11/0x50
<6> [511.401521]  ? kmalloc_trace+0xa3/0xb0
<6> [511.401532]  ? do_init_module+0x5f/0x210
<6> [511.401544]  ? load_module+0x1d00/0x1f60
<6> [511.401581]  ? init_module_from_file+0x86/0xd0
<6> [511.401590]  ? init_module_from_file+0x86/0xd0
<6> [511.401613]  ? idempotent_init_module+0x17c/0x230
<6> [511.401639]  ? __x64_sys_finit_module+0x56/0xb0
<6> [511.401650]  ? do_syscall_64+0x3c/0x90
<6> [511.401659]  ? entry_SYSCALL_64_after_hwframe+0x6e/0xd8
<6> [511.401684]  </TASK>

Link: [1]: https://lore.kernel.org/intel-gfx/SJ1PR11MB6129CB39EED831784C331BAFB9DEA@SJ1PR11MB6129.namprd11.prod.outlook.com
Link: [2]: https://intel-gfx-ci.01.org/tree/linux-next/next-20231013/bat-dg2-11/igt@i915_selftest@live@mman.html#dmesg-warnings10963
Cc: Jann Horn <jannh@google.com>,
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/r/20231025-formfrage-watscheln-84526cd3bd7d@brauner
Signed-off-by: Christian Brauner <brauner@kernel.org>

Make IS_POSIXACL() return false if POSIX ACL support is disabled.

Never skip applying the umask in namei.c and never bother to do any
ACL specific checks if the filesystem falsely indicates it has ACLs
enabled when the feature is completely disabled in the kernel.

This fixes a problem where the umask is always ignored in the NFS
client when compiled without CONFIG_FS_POSIX_ACL.  This is a 4 year
old regression caused by commit 013cdf1088d723 which itself was not
completely wrong, but failed to consider all the side effects by
misdesigned VFS code.

Prior to that commit, there were two places where the umask could be
applied, for example when creating a directory:

 1. in the VFS layer in SYSCALL_DEFINE3(mkdirat), but only if
    !IS_POSIXACL()

 2. again (unconditionally) in nfs3_proc_mkdir()

The first one does not apply, because even without
CONFIG_FS_POSIX_ACL, the NFS client sets SB_POSIXACL in
nfs_fill_super().

After that commit, (2.) was replaced by:

 2b. in posix_acl_create(), called by nfs3_proc_mkdir()

There's one branch in posix_acl_create() which applies the umask;
however, without CONFIG_FS_POSIX_ACL, posix_acl_create() is an empty
dummy function which does not apply the umask.

The approach chosen by this patch is to make IS_POSIXACL() always
return false when POSIX ACL support is disabled, so the umask always
gets applied by the VFS layer.  This is consistent with the (regular)
behavior of posix_acl_create(): that function returns early if
IS_POSIXACL() is false, before applying the umask.

Therefore, posix_acl_create() is responsible for applying the umask if
there is ACL support enabled in the file system (SB_POSIXACL), and the
VFS layer is responsible for all other cases (no SB_POSIXACL or no
CONFIG_FS_POSIX_ACL).

Signed-off-by: Max Kellermann <mk@cm4all.com>
Link: https://lore.kernel.org/r/151603744662.29035.4910161264124875658.stgit@rabbit.intern.cm-ag
Signed-off-by: Christian Brauner <brauner@kernel.org>

A backing file struct stores two path's, one "real" path that is referring
to f_inode and one "fake" path, which should be displayed to users in
/proc/<pid>/maps.

There is a lot more potential code that needs to know the "real" path, then
code that needs to know the "fake" path.

Instead of code having to request the "real" path with file_real_path(),
store the "real" path in f_path and require code that needs to know the
"fake" path request it with file_user_path().
Replace the file_real_path() helper with a simple const accessor f_path().

After this change, file_dentry() is not expected to observe any files
with overlayfs f_path and real f_inode, so the call to ->d_real() should
not be needed.  Leave the ->d_real() call for now and add an assertion
in ovl_d_real() to catch if we made wrong assumptions.

Suggested-by: Miklos Szeredi <miklos@szeredi.hu>
Link: https://lore.kernel.org/r/CAJfpegtt48eXhhjDFA1ojcHPNKj3Go6joryCPtEFAKpocyBsnw@mail.gmail.com/
Signed-off-by: Amir Goldstein <amir73il@gmail.com>
Link: https://lore.kernel.org/r/20231009153712.1566422-4-amir73il@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>