Commit Graph

534 Commits

Author SHA1 Message Date
Linus Torvalds
5c00ff742b - The series "zram: optimal post-processing target selection" from
Sergey Senozhatsky improves zram's post-processing selection algorithm.
   This leads to improved memory savings.
 
 - Wei Yang has gone to town on the mapletree code, contributing several
   series which clean up the implementation:
 
 	- "refine mas_mab_cp()"
 	- "Reduce the space to be cleared for maple_big_node"
 	- "maple_tree: simplify mas_push_node()"
 	- "Following cleanup after introduce mas_wr_store_type()"
 	- "refine storing null"
 
 - The series "selftests/mm: hugetlb_fault_after_madv improvements" from
   David Hildenbrand fixes this selftest for s390.
 
 - The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
   implements some rationaizations and cleanups in the page mapping code.
 
 - The series "mm: optimize shadow entries removal" from Shakeel Butt
   optimizes the file truncation code by speeding up the handling of shadow
   entries.
 
 - The series "Remove PageKsm()" from Matthew Wilcox completes the
   migration of this flag over to being a folio-based flag.
 
 - The series "Unify hugetlb into arch_get_unmapped_area functions" from
   Oscar Salvador implements a bunch of consolidations and cleanups in the
   hugetlb code.
 
 - The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
   takes away the wp-fault time practice of turning a huge zero page into
   small pages.  Instead we replace the whole thing with a THP.  More
   consistent cleaner and potentiall saves a large number of pagefaults.
 
 - The series "percpu: Add a test case and fix for clang" from Andy
   Shevchenko enhances and fixes the kernel's built in percpu test code.
 
 - The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
   optimizes mremap() by avoiding doing things which we didn't need to do.
 
 - The series "Improve the tmpfs large folio read performance" from
   Baolin Wang teaches tmpfs to copy data into userspace at the folio size
   rather than as individual pages.  A 20% speedup was observed.
 
 - The series "mm/damon/vaddr: Fix issue in
   damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON splitting.
 
 - The series "memcg-v1: fully deprecate charge moving" from Shakeel Butt
   removes the long-deprecated memcgv2 charge moving feature.
 
 - The series "fix error handling in mmap_region() and refactor" from
   Lorenzo Stoakes cleanup up some of the mmap() error handling and
   addresses some potential performance issues.
 
 - The series "x86/module: use large ROX pages for text allocations" from
   Mike Rapoport teaches x86 to use large pages for read-only-execute
   module text.
 
 - The series "page allocation tag compression" from Suren Baghdasaryan
   is followon maintenance work for the new page allocation profiling
   feature.
 
 - The series "page->index removals in mm" from Matthew Wilcox remove
   most references to page->index in mm/.  A slow march towards shrinking
   struct page.
 
 - The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
   interface tests" from Andrew Paniakin performs maintenance work for
   DAMON's self testing code.
 
 - The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
   improves zswap's batching of compression and decompression.  It is a
   step along the way towards using Intel IAA hardware acceleration for
   this zswap operation.
 
 - The series "kasan: migrate the last module test to kunit" from
   Sabyrzhan Tasbolatov completes the migration of the KASAN built-in tests
   over to the KUnit framework.
 
 - The series "implement lightweight guard pages" from Lorenzo Stoakes
   permits userapace to place fault-generating guard pages within a single
   VMA, rather than requiring that multiple VMAs be created for this.
   Improved efficiencies for userspace memory allocators are expected.
 
 - The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
   tracepoints to provide increased visibility into memcg stats flushing
   activity.
 
 - The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
   fixes a zram buglet which potentially affected performance.
 
 - The series "mm: add more kernel parameters to control mTHP" from
   Maíra Canal enhances our ability to control/configuremultisize THP from
   the kernel boot command line.
 
 - The series "kasan: few improvements on kunit tests" from Sabyrzhan
   Tasbolatov has a couple of fixups for the KASAN KUnit tests.
 
 - The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
   from Kairui Song optimizes list_lru memory utilization when lockdep is
   enabled.
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Merge tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

Pull MM updates from Andrew Morton:

 - The series "zram: optimal post-processing target selection" from
   Sergey Senozhatsky improves zram's post-processing selection
   algorithm. This leads to improved memory savings.

 - Wei Yang has gone to town on the mapletree code, contributing several
   series which clean up the implementation:
	- "refine mas_mab_cp()"
	- "Reduce the space to be cleared for maple_big_node"
	- "maple_tree: simplify mas_push_node()"
	- "Following cleanup after introduce mas_wr_store_type()"
	- "refine storing null"

 - The series "selftests/mm: hugetlb_fault_after_madv improvements" from
   David Hildenbrand fixes this selftest for s390.

 - The series "introduce pte_offset_map_{ro|rw}_nolock()" from Qi Zheng
   implements some rationaizations and cleanups in the page mapping
   code.

 - The series "mm: optimize shadow entries removal" from Shakeel Butt
   optimizes the file truncation code by speeding up the handling of
   shadow entries.

 - The series "Remove PageKsm()" from Matthew Wilcox completes the
   migration of this flag over to being a folio-based flag.

 - The series "Unify hugetlb into arch_get_unmapped_area functions" from
   Oscar Salvador implements a bunch of consolidations and cleanups in
   the hugetlb code.

 - The series "Do not shatter hugezeropage on wp-fault" from Dev Jain
   takes away the wp-fault time practice of turning a huge zero page
   into small pages. Instead we replace the whole thing with a THP. More
   consistent cleaner and potentiall saves a large number of pagefaults.

 - The series "percpu: Add a test case and fix for clang" from Andy
   Shevchenko enhances and fixes the kernel's built in percpu test code.

 - The series "mm/mremap: Remove extra vma tree walk" from Liam Howlett
   optimizes mremap() by avoiding doing things which we didn't need to
   do.

 - The series "Improve the tmpfs large folio read performance" from
   Baolin Wang teaches tmpfs to copy data into userspace at the folio
   size rather than as individual pages. A 20% speedup was observed.

 - The series "mm/damon/vaddr: Fix issue in
   damon_va_evenly_split_region()" fro Zheng Yejian fixes DAMON
   splitting.

 - The series "memcg-v1: fully deprecate charge moving" from Shakeel
   Butt removes the long-deprecated memcgv2 charge moving feature.

 - The series "fix error handling in mmap_region() and refactor" from
   Lorenzo Stoakes cleanup up some of the mmap() error handling and
   addresses some potential performance issues.

 - The series "x86/module: use large ROX pages for text allocations"
   from Mike Rapoport teaches x86 to use large pages for
   read-only-execute module text.

 - The series "page allocation tag compression" from Suren Baghdasaryan
   is followon maintenance work for the new page allocation profiling
   feature.

 - The series "page->index removals in mm" from Matthew Wilcox remove
   most references to page->index in mm/. A slow march towards shrinking
   struct page.

 - The series "damon/{self,kunit}tests: minor fixups for DAMON debugfs
   interface tests" from Andrew Paniakin performs maintenance work for
   DAMON's self testing code.

 - The series "mm: zswap swap-out of large folios" from Kanchana Sridhar
   improves zswap's batching of compression and decompression. It is a
   step along the way towards using Intel IAA hardware acceleration for
   this zswap operation.

 - The series "kasan: migrate the last module test to kunit" from
   Sabyrzhan Tasbolatov completes the migration of the KASAN built-in
   tests over to the KUnit framework.

 - The series "implement lightweight guard pages" from Lorenzo Stoakes
   permits userapace to place fault-generating guard pages within a
   single VMA, rather than requiring that multiple VMAs be created for
   this. Improved efficiencies for userspace memory allocators are
   expected.

 - The series "memcg: tracepoint for flushing stats" from JP Kobryn uses
   tracepoints to provide increased visibility into memcg stats flushing
   activity.

 - The series "zram: IDLE flag handling fixes" from Sergey Senozhatsky
   fixes a zram buglet which potentially affected performance.

 - The series "mm: add more kernel parameters to control mTHP" from
   Maíra Canal enhances our ability to control/configuremultisize THP
   from the kernel boot command line.

 - The series "kasan: few improvements on kunit tests" from Sabyrzhan
   Tasbolatov has a couple of fixups for the KASAN KUnit tests.

 - The series "mm/list_lru: Split list_lru lock into per-cgroup scope"
   from Kairui Song optimizes list_lru memory utilization when lockdep
   is enabled.

* tag 'mm-stable-2024-11-18-19-27' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (215 commits)
  cma: enforce non-zero pageblock_order during cma_init_reserved_mem()
  mm/kfence: add a new kunit test test_use_after_free_read_nofault()
  zram: fix NULL pointer in comp_algorithm_show()
  memcg/hugetlb: add hugeTLB counters to memcg
  vmstat: call fold_vm_zone_numa_events() before show per zone NUMA event
  mm: mmap_lock: check trace_mmap_lock_$type_enabled() instead of regcount
  zram: ZRAM_DEF_COMP should depend on ZRAM
  MAINTAINERS/MEMORY MANAGEMENT: add document files for mm
  Docs/mm/damon: recommend academic papers to read and/or cite
  mm: define general function pXd_init()
  kmemleak: iommu/iova: fix transient kmemleak false positive
  mm/list_lru: simplify the list_lru walk callback function
  mm/list_lru: split the lock to per-cgroup scope
  mm/list_lru: simplify reparenting and initial allocation
  mm/list_lru: code clean up for reparenting
  mm/list_lru: don't export list_lru_add
  mm/list_lru: don't pass unnecessary key parameters
  kasan: add kunit tests for kmalloc_track_caller, kmalloc_node_track_caller
  kasan: change kasan_atomics kunit test as KUNIT_CASE_SLOW
  kasan: use EXPORT_SYMBOL_IF_KUNIT to export symbols
  ...
2024-11-23 09:58:07 -08:00
Linus Torvalds
70e7730c2a vfs-6.13.misc
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Merge tag 'vfs-6.13.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull misc vfs updates from Christian Brauner:
 "Features:

   - Fixup and improve NLM and kNFSD file lock callbacks

     Last year both GFS2 and OCFS2 had some work done to make their
     locking more robust when exported over NFS. Unfortunately, part of
     that work caused both NLM (for NFS v3 exports) and kNFSD (for
     NFSv4.1+ exports) to no longer send lock notifications to clients

     This in itself is not a huge problem because most NFS clients will
     still poll the server in order to acquire a conflicted lock

     It's important for NLM and kNFSD that they do not block their
     kernel threads inside filesystem's file_lock implementations
     because that can produce deadlocks. We used to make sure of this by
     only trusting that posix_lock_file() can correctly handle blocking
     lock calls asynchronously, so the lock managers would only setup
     their file_lock requests for async callbacks if the filesystem did
     not define its own lock() file operation

     However, when GFS2 and OCFS2 grew the capability to correctly
     handle blocking lock requests asynchronously, they started
     signalling this behavior with EXPORT_OP_ASYNC_LOCK, and the check
     for also trusting posix_lock_file() was inadvertently dropped, so
     now most filesystems no longer produce lock notifications when
     exported over NFS

     Fix this by using an fop_flag which greatly simplifies the problem
     and grooms the way for future uses by both filesystems and lock
     managers alike

   - Add a sysctl to delete the dentry when a file is removed instead of
     making it a negative dentry

     Commit 681ce86235 ("vfs: Delete the associated dentry when
     deleting a file") introduced an unconditional deletion of the
     associated dentry when a file is removed. However, this led to
     performance regressions in specific benchmarks, such as
     ilebench.sum_operations/s, prompting a revert in commit
     4a4be1ad3a ("Revert "vfs: Delete the associated dentry when
     deleting a file""). This reintroduces the concept conditionally
     through a sysctl

   - Expand the statmount() system call:

       * Report the filesystem subtype in a new fs_subtype field to
         e.g., report fuse filesystem subtypes

       * Report the superblock source in a new sb_source field

       * Add a new way to return filesystem specific mount options in an
         option array that returns filesystem specific mount options
         separated by zero bytes and unescaped. This allows caller's to
         retrieve filesystem specific mount options and immediately pass
         them to e.g., fsconfig() without having to unescape or split
         them

       * Report security (LSM) specific mount options in a separate
         security option array. We don't lump them together with
         filesystem specific mount options as security mount options are
         generic and most users aren't interested in them

         The format is the same as for the filesystem specific mount
         option array

   - Support relative paths in fsconfig()'s FSCONFIG_SET_STRING command

   - Optimize acl_permission_check() to avoid costly {g,u}id ownership
     checks if possible

   - Use smp_mb__after_spinlock() to avoid full smp_mb() in evict()

   - Add synchronous wakeup support for ep_poll_callback.

     Currently, epoll only uses wake_up() to wake up task. But sometimes
     there are epoll users which want to use the synchronous wakeup flag
     to give a hint to the scheduler, e.g., the Android binder driver.
     So add a wake_up_sync() define, and use wake_up_sync() when sync is
     true in ep_poll_callback()

  Fixes:

   - Fix kernel documentation for inode_insert5() and iget5_locked()

   - Annotate racy epoll check on file->f_ep

   - Make F_DUPFD_QUERY associative

   - Avoid filename buffer overrun in initramfs

   - Don't let statmount() return empty strings

   - Add a cond_resched() to dump_user_range() to avoid hogging the CPU

   - Don't query the device logical blocksize multiple times for hfsplus

   - Make filemap_read() check that the offset is positive or zero

  Cleanups:

   - Various typo fixes

   - Cleanup wbc_attach_fdatawrite_inode()

   - Add __releases annotation to wbc_attach_and_unlock_inode()

   - Add hugetlbfs tracepoints

   - Fix various vfs kernel doc parameters

   - Remove obsolete TODO comment from io_cancel()

   - Convert wbc_account_cgroup_owner() to take a folio

   - Fix comments for BANDWITH_INTERVAL and wb_domain_writeout_add()

   - Reorder struct posix_acl to save 8 bytes

   - Annotate struct posix_acl with __counted_by()

   - Replace one-element array with flexible array member in freevxfs

   - Use idiomatic atomic64_inc_return() in alloc_mnt_ns()"

* tag 'vfs-6.13.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (35 commits)
  statmount: retrieve security mount options
  vfs: make evict() use smp_mb__after_spinlock instead of smp_mb
  statmount: add flag to retrieve unescaped options
  fs: add the ability for statmount() to report the sb_source
  writeback: wbc_attach_fdatawrite_inode out of line
  writeback: add a __releases annoation to wbc_attach_and_unlock_inode
  fs: add the ability for statmount() to report the fs_subtype
  fs: don't let statmount return empty strings
  fs:aio: Remove TODO comment suggesting hash or array usage in io_cancel()
  hfsplus: don't query the device logical block size multiple times
  freevxfs: Replace one-element array with flexible array member
  fs: optimize acl_permission_check()
  initramfs: avoid filename buffer overrun
  fs/writeback: convert wbc_account_cgroup_owner to take a folio
  acl: Annotate struct posix_acl with __counted_by()
  acl: Realign struct posix_acl to save 8 bytes
  epoll: Add synchronous wakeup support for ep_poll_callback
  coredump: add cond_resched() to dump_user_range
  mm/page-writeback.c: Fix comment of wb_domain_writeout_add()
  mm/page-writeback.c: Update comment for BANDWIDTH_INTERVAL
  ...
2024-11-18 09:35:30 -08:00
Linus Torvalds
6ac81fd55e vfs-6.13.mgtime
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Merge tag 'vfs-6.13.mgtime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs multigrain timestamps from Christian Brauner:
 "This is another try at implementing multigrain timestamps. This time
  with significant help from the timekeeping maintainers to reduce the
  performance impact.

  Thomas provided a base branch that contains the required timekeeping
  interfaces for the VFS. It serves as the base for the multi-grain
  timestamp work:

   - Multigrain timestamps allow the kernel to use fine-grained
     timestamps when an inode's attributes is being actively observed
     via ->getattr(). With this support, it's possible for a file to get
     a fine-grained timestamp, and another modified after it to get a
     coarse-grained stamp that is earlier than the fine-grained time. If
     this happens then the files can appear to have been modified in
     reverse order, which breaks VFS ordering guarantees.

     To prevent this, a floor value is maintained for multigrain
     timestamps. Whenever a fine-grained timestamp is handed out, record
     it, and when later coarse-grained stamps are handed out, ensure
     they are not earlier than that value. If the coarse-grained
     timestamp is earlier than the fine-grained floor, return the floor
     value instead.

     The timekeeper changes add a static singleton atomic64_t into
     timekeeper.c that is used to keep track of the latest fine-grained
     time ever handed out. This is tracked as a monotonic ktime_t value
     to ensure that it isn't affected by clock jumps. Because it is
     updated at different times than the rest of the timekeeper object,
     the floor value is managed independently of the timekeeper via a
     cmpxchg() operation, and sits on its own cacheline.

     Two new public timekeeper interfaces are added:

      (1) ktime_get_coarse_real_ts64_mg() fills a timespec64 with the
          later of the coarse-grained clock and the floor time

      (2) ktime_get_real_ts64_mg() gets the fine-grained clock value,
          and tries to swap it into the floor. A timespec64 is filled
          with the result.

   - The VFS has always used coarse-grained timestamps when updating the
     ctime and mtime after a change. This has the benefit of allowing
     filesystems to optimize away a lot metadata updates, down to around
     1 per jiffy, even when a file is under heavy writes.

     Unfortunately, this has always been an issue when we're exporting
     via NFSv3, which relies on timestamps to validate caches. A lot of
     changes can happen in a jiffy, so timestamps aren't sufficient to
     help the client decide when to invalidate the cache. Even with
     NFSv4, a lot of exported filesystems don't properly support a
     change attribute and are subject to the same problems with
     timestamp granularity. Other applications have similar issues with
     timestamps (e.g backup applications).

     If we were to always use fine-grained timestamps, that would
     improve the situation, but that becomes rather expensive, as the
     underlying filesystem would have to log a lot more metadata
     updates.

     This adds a way to only use fine-grained timestamps when they are
     being actively queried. Use the (unused) top bit in
     inode->i_ctime_nsec as a flag that indicates whether the current
     timestamps have been queried via stat() or the like. When it's set,
     we allow the kernel to use a fine-grained timestamp iff it's
     necessary to make the ctime show a different value.

     This solves the problem of being able to distinguish the timestamp
     between updates, but introduces a new problem: it's now possible
     for a file being changed to get a fine-grained timestamp. A file
     that is altered just a bit later can then get a coarse-grained one
     that appears older than the earlier fine-grained time. This
     violates timestamp ordering guarantees.

     This is where the earlier mentioned timkeeping interfaces help. A
     global monotonic atomic64_t value is kept that acts as a timestamp
     floor. When we go to stamp a file, we first get the latter of the
     current floor value and the current coarse-grained time. If the
     inode ctime hasn't been queried then we just attempt to stamp it
     with that value.

     If it has been queried, then first see whether the current coarse
     time is later than the existing ctime. If it is, then we accept
     that value. If it isn't, then we get a fine-grained time and try to
     swap that into the global floor. Whether that succeeds or fails, we
     take the resulting floor time, convert it to realtime and try to
     swap that into the ctime.

     We take the result of the ctime swap whether it succeeds or fails,
     since either is just as valid.

     Filesystems can opt into this by setting the FS_MGTIME fstype flag.
     Others should be unaffected (other than being subject to the same
     floor value as multigrain filesystems)"

* tag 'vfs-6.13.mgtime' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  fs: reduce pointer chasing in is_mgtime() test
  tmpfs: add support for multigrain timestamps
  btrfs: convert to multigrain timestamps
  ext4: switch to multigrain timestamps
  xfs: switch to multigrain timestamps
  Documentation: add a new file documenting multigrain timestamps
  fs: add percpu counters for significant multigrain timestamp events
  fs: tracepoints around multigrain timestamp events
  fs: handle delegated timestamps in setattr_copy_mgtime
  timekeeping: Add percpu counter for tracking floor swap events
  timekeeping: Add interfaces for handling timestamps with a floor value
  fs: have setattr_copy handle multigrain timestamps appropriately
  fs: add infrastructure for multigrain timestamps
2024-11-18 09:15:39 -08:00
Jeff Layton
9fed2c0f2f
fs: reduce pointer chasing in is_mgtime() test
The is_mgtime test checks whether the FS_MGTIME flag is set in the
fstype. To get there from the inode though, we have to dereference 3
pointers.

Add a new IOP_MGTIME flag, and have inode_init_always() set that flag
when the fstype flag is set. Then, make is_mgtime test for IOP_MGTIME
instead.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241113-mgtime-v1-1-84e256980e11@kernel.org
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-11-14 10:45:53 +01:00
Mateusz Guzik
45c9faf506
vfs: make evict() use smp_mb__after_spinlock instead of smp_mb
It literally directly follows a spin_lock() call.

This whacks an explicit barrier on x86-64.

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20241113155103.4194099-1-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-11-14 10:44:35 +01:00
Kairui Song
da0c02516c mm/list_lru: simplify the list_lru walk callback function
Now isolation no longer takes the list_lru global node lock, only use the
per-cgroup lock instead.  And this lock is inside the list_lru_one being
walked, no longer needed to pass the lock explicitly.

Link: https://lkml.kernel.org/r/20241104175257.60853-7-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-11 17:22:26 -08:00
Kairui Song
fb56fdf8b9 mm/list_lru: split the lock to per-cgroup scope
Currently, every list_lru has a per-node lock that protects adding,
deletion, isolation, and reparenting of all list_lru_one instances
belonging to this list_lru on this node.  This lock contention is heavy
when multiple cgroups modify the same list_lru.

This lock can be split into per-cgroup scope to reduce contention.

To achieve this, we need a stable list_lru_one for every cgroup.  This
commit adds a lock to each list_lru_one and introduced a helper function
lock_list_lru_of_memcg, making it possible to pin the list_lru of a memcg.
Then reworked the reparenting process.

Reparenting will switch the list_lru_one instances one by one.  By locking
each instance and marking it dead using the nr_items counter, reparenting
ensures that all items in the corresponding cgroup (on-list or not,
because items have a stable cgroup, see below) will see the list_lru_one
switch synchronously.

Objcg reparent is also moved after list_lru reparent so items will have a
stable mem cgroup until all list_lru_one instances are drained.

The only caller that doesn't work the *_obj interfaces are direct calls to
list_lru_{add,del}.  But it's only used by zswap and that's also based on
objcg, so it's fine.

This also changes the bahaviour of the isolation function when LRU_RETRY
or LRU_REMOVED_RETRY is returned, because now releasing the lock could
unblock reparenting and free the list_lru_one, isolation function will
have to return withoug re-lock the lru.

prepare() {
    mkdir /tmp/test-fs
    modprobe brd rd_nr=1 rd_size=33554432
    mkfs.xfs -f /dev/ram0
    mount -t xfs /dev/ram0 /tmp/test-fs
    for i in $(seq 1 512); do
        mkdir "/tmp/test-fs/$i"
        for j in $(seq 1 10240); do
            echo TEST-CONTENT > "/tmp/test-fs/$i/$j"
        done &
    done; wait
}

do_test() {
    read_worker() {
        sleep 1
        tar -cv "$1" &>/dev/null
    }
    read_in_all() {
        cd "/tmp/test-fs" && ls
        for i in $(seq 1 512); do
            (exec sh -c 'echo "$PPID"') > "/sys/fs/cgroup/benchmark/$i/cgroup.procs"
            read_worker "$i" &
        done; wait
    }
    for i in $(seq 1 512); do
        mkdir -p "/sys/fs/cgroup/benchmark/$i"
    done
    echo +memory > /sys/fs/cgroup/benchmark/cgroup.subtree_control
    echo 512M > /sys/fs/cgroup/benchmark/memory.max
    echo 3 > /proc/sys/vm/drop_caches
    time read_in_all
}

Above script simulates compression of small files in multiple cgroups
with memory pressure. Run prepare() then do_test for 6 times:

Before:
real      0m7.762s user      0m11.340s sys       3m11.224s
real      0m8.123s user      0m11.548s sys       3m2.549s
real      0m7.736s user      0m11.515s sys       3m11.171s
real      0m8.539s user      0m11.508s sys       3m7.618s
real      0m7.928s user      0m11.349s sys       3m13.063s
real      0m8.105s user      0m11.128s sys       3m14.313s

After this commit (about ~15% faster):
real      0m6.953s user      0m11.327s sys       2m42.912s
real      0m7.453s user      0m11.343s sys       2m51.942s
real      0m6.916s user      0m11.269s sys       2m43.957s
real      0m6.894s user      0m11.528s sys       2m45.346s
real      0m6.911s user      0m11.095s sys       2m43.168s
real      0m6.773s user      0m11.518s sys       2m40.774s

Link: https://lkml.kernel.org/r/20241104175257.60853-6-ryncsn@gmail.com
Signed-off-by: Kairui Song <kasong@tencent.com>
Cc: Chengming Zhou <zhouchengming@bytedance.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Qi Zheng <zhengqi.arch@bytedance.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Shakeel Butt <shakeel.butt@linux.dev>
Cc: Waiman Long <longman@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-11-11 17:22:26 -08:00
Andrew Kreimer
80d3ab2227
fs/inode: Fix a typo
Fix a typo in comments: wether v-> whether.

Signed-off-by: Andrew Kreimer <algonell@gmail.com>
Link: https://lore.kernel.org/r/20241008121602.16778-1-algonell@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-22 11:16:58 +02:00
Andreas Gruenbacher
c298638743
vfs: inode insertion kdoc corrections
Some minor corrections to the inode_insert5 and iget5_locked kernel
documentation.

Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
Link: https://lore.kernel.org/r/20241004115151.44834-1-agruenba@redhat.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-22 11:16:57 +02:00
Christian Brauner
b40508ca5d
Merge patch series "timekeeping/fs: multigrain timestamp redux"
Jeff Layton <jlayton@kernel.org> says:

The VFS has always used coarse-grained timestamps when updating the
ctime and mtime after a change. This has the benefit of allowing
filesystems to optimize away a lot metadata updates, down to around 1
per jiffy, even when a file is under heavy writes.

Unfortunately, this has always been an issue when we're exporting via
NFSv3, which relies on timestamps to validate caches. A lot of changes
can happen in a jiffy, so timestamps aren't sufficient to help the
client decide when to invalidate the cache. Even with NFSv4, a lot of
exported filesystems don't properly support a change attribute and are
subject to the same problems with timestamp granularity. Other
applications have similar issues with timestamps (e.g backup
applications).

If we were to always use fine-grained timestamps, that would improve the
situation, but that becomes rather expensive, as the underlying
filesystem would have to log a lot more metadata updates.

What we need is a way to only use fine-grained timestamps when they are
being actively queried. Use the (unused) top bit in inode->i_ctime_nsec
as a flag that indicates whether the current timestamps have been
queried via stat() or the like. When it's set, we allow the kernel to
use a fine-grained timestamp iff it's necessary to make the ctime show
a different value.

This solves the problem of being able to distinguish the timestamp
between updates, but introduces a new problem: it's now possible for a
file being changed to get a fine-grained timestamp. A file that is
altered just a bit later can then get a coarse-grained one that appears
older than the earlier fine-grained time. This violates timestamp
ordering guarantees.

To remedy this, keep a global monotonic atomic64_t value that acts as a
timestamp floor.  When we go to stamp a file, we first get the latter of
the current floor value and the current coarse-grained time. If the
inode ctime hasn't been queried then we just attempt to stamp it with
that value.

If it has been queried, then first see whether the current coarse time
is later than the existing ctime. If it is, then we accept that value.
If it isn't, then we get a fine-grained time and try to swap that into
the global floor. Whether that succeeds or fails, we take the resulting
floor time, convert it to realtime and try to swap that into the ctime.

We take the result of the ctime swap whether it succeeds or fails, since
either is just as valid.

Filesystems can opt into this by setting the FS_MGTIME fstype flag.
Others should be unaffected (other than being subject to the same floor
value as multigrain filesystems).

* patches from https://lore.kernel.org/r/20241002-mgtime-v10-0-d1c4717f5284@kernel.org:
  tmpfs: add support for multigrain timestamps
  btrfs: convert to multigrain timestamps
  ext4: switch to multigrain timestamps
  xfs: switch to multigrain timestamps
  Documentation: add a new file documenting multigrain timestamps
  fs: add percpu counters for significant multigrain timestamp events
  fs: tracepoints around multigrain timestamp events
  fs: handle delegated timestamps in setattr_copy_mgtime
  fs: have setattr_copy handle multigrain timestamps appropriately
  fs: add infrastructure for multigrain timestamps

Link: https://lore.kernel.org/r/20241002-mgtime-v10-0-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-10 10:20:57 +02:00
Jeff Layton
73a47cf40f
fs: add percpu counters for significant multigrain timestamp events
New percpu counters for counting various stats around multigrain
timestamp events, and a new debugfs file for displaying them when
CONFIG_DEBUG_FS is enabled:

- number of attempted ctime updates
- number of successful i_ctime_nsec swaps
- number of fine-grained timestamp fetches
- number of floor value swap events

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241002-mgtime-v10-7-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-10 10:20:52 +02:00
Jeff Layton
c86e3c4718
fs: tracepoints around multigrain timestamp events
Add some tracepoints around various multigrain timestamp events.

Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241002-mgtime-v10-6-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-10 10:20:52 +02:00
Jeff Layton
7f2c86cba3
fs: handle delegated timestamps in setattr_copy_mgtime
An update to the inode ctime typically requires the latest clock
value possible. The exception to this rule is when there is a nfsd write
delegation and the server is proxying timestamps from the client.

When nfsd gets a CB_GETATTR response, update the timestamp value in the
inode to the values that the client is tracking. The client doesn't send
a ctime value (since that's always determined by the exported
filesystem), but it can send a mtime value. In the case where it does,
update the ctime to a value commensurate with that instead of the
current time.

If ATTR_DELEG is set, then use ia_ctime value instead of setting the
timestamp to the current time.

With the addition of delegated timestamps, the server may receive a
request to update only the atime, which doesn't involve a ctime update.
Trust the ATTR_CTIME flag in the update and only update the ctime when
it's set.

Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241002-mgtime-v10-5-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-10 10:20:51 +02:00
Michal Hocko
9897713fe1 bcachefs: do not use PF_MEMALLOC_NORECLAIM
Patch series "remove PF_MEMALLOC_NORECLAIM" v3.


This patch (of 2):

bch2_new_inode relies on PF_MEMALLOC_NORECLAIM to try to allocate a new
inode to achieve GFP_NOWAIT semantic while holding locks. If this
allocation fails it will drop locks and use GFP_NOFS allocation context.

We would like to drop PF_MEMALLOC_NORECLAIM because it is really
dangerous to use if the caller doesn't control the full call chain with
this flag set. E.g. if any of the function down the chain needed
GFP_NOFAIL request the PF_MEMALLOC_NORECLAIM would override this and
cause unexpected failure.

While this is not the case in this particular case using the scoped gfp
semantic is not really needed bacause we can easily pus the allocation
context down the chain without too much clutter.

[akpm@linux-foundation.org: fix kerneldoc warnings]
Link: https://lkml.kernel.org/r/20240926172940.167084-1-mhocko@kernel.org
Link: https://lkml.kernel.org/r/20240926172940.167084-2-mhocko@kernel.org
Signed-off-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Jan Kara <jack@suse.cz> # For vfs changes
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: James Morris <jmorris@namei.org>
Cc: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Paul Moore <paul@paul-moore.com>
Cc: Serge E. Hallyn <serge@hallyn.com>
Cc: Yafang Shao <laoar.shao@gmail.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2024-10-09 12:47:18 -07:00
Jeff Layton
4e40eff0b5
fs: add infrastructure for multigrain timestamps
The VFS has always used coarse-grained timestamps when updating the
ctime and mtime after a change. This has the benefit of allowing
filesystems to optimize away a lot metadata updates, down to around 1
per jiffy, even when a file is under heavy writes.

Unfortunately, this has always been an issue when we're exporting via
NFSv3, which relies on timestamps to validate caches. A lot of changes
can happen in a jiffy, so timestamps aren't sufficient to help the
client decide when to invalidate the cache. Even with NFSv4, a lot of
exported filesystems don't properly support a change attribute and are
subject to the same problems with timestamp granularity. Other
applications have similar issues with timestamps (e.g backup
applications).

If fine-grained timestamps were always used, that would improve the
situation, but that becomes rather expensive, as the underlying
filesystem would have to log a lot more metadata updates.

What is needed is a way to only use fine-grained timestamps when they
are being actively queried. Use the (unused) top bit in
inode->i_ctime_nsec as a flag that indicates whether the current
timestamps have been queried via stat() or the like. When it's set,
allow the update to use a fine-grained timestamp iff it's necessary to
make the ctime show a different value.

If it has been queried, then first see whether the current coarse time
is later than the existing ctime. If it is, accept that value.  If it
isn't, then get a fine-grained timestamp and attempt to stamp the inode
ctime with that value. If that races with another concurrent stamp, then
abandon the update and take the new value without retrying.

Filesystems can opt into this by setting the FS_MGTIME fstype flag.
Others should be unaffected (other than being subject to the same floor
value as multigrain filesystems).

Tested-by: Randy Dunlap <rdunlap@infradead.org> # documentation bits
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Jeff Layton <jlayton@kernel.org>
Link: https://lore.kernel.org/r/20241002-mgtime-v10-3-d1c4717f5284@kernel.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-10-07 12:48:56 +02:00
Linus Torvalds
b3f391fddf bcachefs changes for 6.12-rc1
rcu_pending, btree key cache rework: this solves lock contenting in the
 key cache, eliminating the biggest source of the srcu lock hold time
 warnings, and drastically improving performance on some metadata heavy
 workloads - on multithreaded creates we're now 3-4x faster than xfs.
 
 We're now using an rhashtable instead of the system inode hash table;
 this is another significant performance improvement on multithreaded
 metadata workloads, eliminating more lock contention.
 
 for_each_btree_key_in_subvolume_upto(): new helper for iterating over
 keys within a specific subvolume, eliminating a lot of open coded
 "subvolume_get_snapshot()" and also fixing another source of srcu lock
 time warnings, by running each loop iteration in its own transaction (as
 the existing for_each_btree_key() does).
 
 More work on btree_trans locking asserts; we now assert that we don't
 hold btree node locks when trans->locked is false, which is important
 because we don't use lockdep for tracking individual btree node locks.
 
 Some cleanups and improvements in the bset.c btree node lookup code,
 from Alan.
 
 Rework of btree node pinning, which we use in backpointers fsck. The old
 hacky implementation, where the shrinker just skipped over nodes in the
 pinned range, was causing OOMs; instead we now use another shrinker with
 a much higher seeks number for pinned nodes.
 
 Rebalance now uses BCH_WRITE_ONLY_SPECIFIED_DEVS; this fixes an issue
 where rebalance would sometimes fall back to allocating from the full
 filesystem, which is not what we want when it's trying to move data to a
 specific target.
 
 Use __GFP_ACCOUNT, GFP_RECLAIMABLE for btree node, key cache
 allocations.
 
 Idmap mounts are now supported - Hongbo.
 
 Rename whiteouts are now supported - Hongbo.
 
 Erasure coding can now handle devices being marked as failed, or
 forcibly removed. We still need the evacuate path for erasure coding,
 but it's getting very close to ready for people to start using.
 
 Status, and when will we be taking off experimental:
 ----------------------------------------------------
 
 Going by critical, user facing bugs getting found and fixed, we're
 nearly there. There are a couple key items that need to be finished
 before we can take off the experimental label:
 
 - The end-user experience is still pretty painful when the root
   filesystem needs a fsck; we need some form of limited self healing so
   that necessary repair gets run automatically. Errors (by type) are
   recorded in the superblock, so what we need to do next is convert
   remaining inconsistent() errors to fsck() errors (so that all runtime
   inconsistencies are logged in the superblock), and we need to go
   through the list of fsck errors and classify them by which fsck passes
   are needed to repair them.
 
 - We need comprehensive torture testing for all our repair paths, to
   shake out remaining bugs there. Thomas has been working on the tooling
   for this, so this is coming soonish.
 
 Slightly less critical items:
 
 - We need to improve the end-user experience for degraded mounts: right
   now, a degraded root filesystem means dropping to an initramfs shell
   or somehow inputting mount options manually (we don't want to allow
   degraded mounts without some form of user input, except on unattended
   servers) - we need the mount helper to prompt the user to allow
   mounting degraded, and make sure this works with systemd.
 
 - Scalabiity: we have users running 100TB+ filesystems, and that's
   effectively the limit right now due to fsck times. We have some
   reworks in the pipeline to address this, we're aiming to make petabyte
   sized filesystems practical.
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Merge tag 'bcachefs-2024-09-21' of git://evilpiepirate.org/bcachefs

Pull bcachefs updates from Kent Overstreet:

 - rcu_pending, btree key cache rework: this solves lock contenting in
   the key cache, eliminating the biggest source of the srcu lock hold
   time warnings, and drastically improving performance on some metadata
   heavy workloads - on multithreaded creates we're now 3-4x faster than
   xfs.

 - We're now using an rhashtable instead of the system inode hash table;
   this is another significant performance improvement on multithreaded
   metadata workloads, eliminating more lock contention.

 - for_each_btree_key_in_subvolume_upto(): new helper for iterating over
   keys within a specific subvolume, eliminating a lot of open coded
   "subvolume_get_snapshot()" and also fixing another source of srcu
   lock time warnings, by running each loop iteration in its own
   transaction (as the existing for_each_btree_key() does).

 - More work on btree_trans locking asserts; we now assert that we don't
   hold btree node locks when trans->locked is false, which is important
   because we don't use lockdep for tracking individual btree node
   locks.

 - Some cleanups and improvements in the bset.c btree node lookup code,
   from Alan.

 - Rework of btree node pinning, which we use in backpointers fsck. The
   old hacky implementation, where the shrinker just skipped over nodes
   in the pinned range, was causing OOMs; instead we now use another
   shrinker with a much higher seeks number for pinned nodes.

 - Rebalance now uses BCH_WRITE_ONLY_SPECIFIED_DEVS; this fixes an issue
   where rebalance would sometimes fall back to allocating from the full
   filesystem, which is not what we want when it's trying to move data
   to a specific target.

 - Use __GFP_ACCOUNT, GFP_RECLAIMABLE for btree node, key cache
   allocations.

 - Idmap mounts are now supported (Hongbo Li)

 - Rename whiteouts are now supported (Hongbo Li)

 - Erasure coding can now handle devices being marked as failed, or
   forcibly removed. We still need the evacuate path for erasure coding,
   but it's getting very close to ready for people to start using.

* tag 'bcachefs-2024-09-21' of git://evilpiepirate.org/bcachefs: (99 commits)
  bcachefs: return err ptr instead of null in read sb clean
  bcachefs: Remove duplicated include in backpointers.c
  bcachefs: Don't drop devices with stripe pointers
  bcachefs: bch2_ec_stripe_head_get() now checks for change in rw devices
  bcachefs: bch_fs.rw_devs_change_count
  bcachefs: bch2_dev_remove_stripes()
  bcachefs: bch2_trigger_ptr() calculates sectors even when no device
  bcachefs: improve error messages in bch2_ec_read_extent()
  bcachefs: improve error message on too few devices for ec
  bcachefs: improve bch2_new_stripe_to_text()
  bcachefs: ec_stripe_head.nr_created
  bcachefs: bch_stripe.disk_label
  bcachefs: stripe_to_mem()
  bcachefs: EIO errcode cleanup
  bcachefs: Rework btree node pinning
  bcachefs: split up btree cache counters for live, freeable
  bcachefs: btree cache counters should be size_t
  bcachefs: Don't count "skipped access bit" as touched in btree cache scan
  bcachefs: Failed devices no longer require mounting in degraded mode
  bcachefs: bch2_dev_rcu_noerror()
  ...
2024-09-23 10:05:41 -07:00
Kent Overstreet
88d2ae0e6e inode: make __iget() a static inline
bcachefs is switching to an rhashtable for vfs inodes instead of the
standard inode.c hashtable, so we need this exported, or - a static
inline makes more sense for a single atomic_inc().

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
2024-09-09 09:41:47 -04:00
Li Zhijian
7f7b850689 fs/inode: Prevent dump_mapping() accessing invalid dentry.d_name.name
It's observed that a crash occurs during hot-remove a memory device,
in which user is accessing the hugetlb. See calltrace as following:

------------[ cut here ]------------
WARNING: CPU: 1 PID: 14045 at arch/x86/mm/fault.c:1278 do_user_addr_fault+0x2a0/0x790
Modules linked in: kmem device_dax cxl_mem cxl_pmem cxl_port cxl_pci dax_hmem dax_pmem nd_pmem cxl_acpi nd_btt cxl_core crc32c_intel nvme virtiofs fuse nvme_core nfit libnvdimm dm_multipath scsi_dh_rdac scsi_dh_emc s
mirror dm_region_hash dm_log dm_mod
CPU: 1 PID: 14045 Comm: daxctl Not tainted 6.10.0-rc2-lizhijian+ #492
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
RIP: 0010:do_user_addr_fault+0x2a0/0x790
Code: 48 8b 00 a8 04 0f 84 b5 fe ff ff e9 1c ff ff ff 4c 89 e9 4c 89 e2 be 01 00 00 00 bf 02 00 00 00 e8 b5 ef 24 00 e9 42 fe ff ff <0f> 0b 48 83 c4 08 4c 89 ea 48 89 ee 4c 89 e7 5b 5d 41 5c 41 5d 41
RSP: 0000:ffffc90000a575f0 EFLAGS: 00010046
RAX: ffff88800c303600 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000001000 RSI: ffffffff82504162 RDI: ffffffff824b2c36
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: ffffc90000a57658
R13: 0000000000001000 R14: ffff88800bc2e040 R15: 0000000000000000
FS:  00007f51cb57d880(0000) GS:ffff88807fd00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000001000 CR3: 00000000072e2004 CR4: 00000000001706f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 ? __warn+0x8d/0x190
 ? do_user_addr_fault+0x2a0/0x790
 ? report_bug+0x1c3/0x1d0
 ? handle_bug+0x3c/0x70
 ? exc_invalid_op+0x14/0x70
 ? asm_exc_invalid_op+0x16/0x20
 ? do_user_addr_fault+0x2a0/0x790
 ? exc_page_fault+0x31/0x200
 exc_page_fault+0x68/0x200
<...snip...>
BUG: unable to handle page fault for address: 0000000000001000
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 800000000ad92067 P4D 800000000ad92067 PUD 7677067 PMD 0
 Oops: Oops: 0000 [#1] PREEMPT SMP PTI
 ---[ end trace 0000000000000000 ]---
 BUG: unable to handle page fault for address: 0000000000001000
 #PF: supervisor read access in kernel mode
 #PF: error_code(0x0000) - not-present page
 PGD 800000000ad92067 P4D 800000000ad92067 PUD 7677067 PMD 0
 Oops: Oops: 0000 [#1] PREEMPT SMP PTI
 CPU: 1 PID: 14045 Comm: daxctl Kdump: loaded Tainted: G        W          6.10.0-rc2-lizhijian+ #492
 Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS rel-1.16.3-0-ga6ed6b701f0a-prebuilt.qemu.org 04/01/2014
 RIP: 0010:dentry_name+0x1f4/0x440
<...snip...>
? dentry_name+0x2fa/0x440
vsnprintf+0x1f3/0x4f0
vprintk_store+0x23a/0x540
vprintk_emit+0x6d/0x330
_printk+0x58/0x80
dump_mapping+0x10b/0x1a0
? __pfx_free_object_rcu+0x10/0x10
__dump_page+0x26b/0x3e0
? vprintk_emit+0xe0/0x330
? _printk+0x58/0x80
? dump_page+0x17/0x50
dump_page+0x17/0x50
do_migrate_range+0x2f7/0x7f0
? do_migrate_range+0x42/0x7f0
? offline_pages+0x2f4/0x8c0
offline_pages+0x60a/0x8c0
memory_subsys_offline+0x9f/0x1c0
? lockdep_hardirqs_on+0x77/0x100
? _raw_spin_unlock_irqrestore+0x38/0x60
device_offline+0xe3/0x110
state_store+0x6e/0xc0
kernfs_fop_write_iter+0x143/0x200
vfs_write+0x39f/0x560
ksys_write+0x65/0xf0
do_syscall_64+0x62/0x130

Previously, some sanity check have been done in dump_mapping() before
the print facility parsing '%pd' though, it's still possible to run into
an invalid dentry.d_name.name.

Since dump_mapping() only needs to dump the filename only, retrieve it
by itself in a safer way to prevent an unnecessary crash.

Note that either retrieving the filename with '%pd' or
strncpy_from_kernel_nofault(), the filename could be unreliable.

Signed-off-by: Li Zhijian <lizhijian@fujitsu.com>
Link: https://lore.kernel.org/r/20240826055503.1522320-1-lizhijian@fujitsu.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:41 +02:00
Christian Brauner
f469e6e6f5 inode: port __I_LRU_ISOLATING to var event
Port the __I_LRU_ISOLATING mechanism to use the new var event mechanism.

Link: https://lore.kernel.org/r/20240823-work-i_state-v3-5-5cd5fd207a57@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:40 +02:00
Christian Brauner
0fe340a98b inode: port __I_NEW to var event
Port the __I_NEW mechanism to use the new var event mechanism.

Link: https://lore.kernel.org/r/20240823-work-i_state-v3-4-5cd5fd207a57@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:39 +02:00
Christian Brauner
da18ecbf0f fs: add i_state helpers
The i_state member is an unsigned long so that it can be used with the
wait bit infrastructure which expects unsigned long. This wastes 4 bytes
which we're unlikely to ever use. Switch to using the var event wait
mechanism using the address of the bit. Thanks to Linus for the address
idea.

Link: https://lore.kernel.org/r/20240823-work-i_state-v3-1-5cd5fd207a57@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:39 +02:00
Julian Sun
88b1afbf0f vfs: fix race between evice_inodes() and find_inode()&iput()
Hi, all

Recently I noticed a bug[1] in btrfs, after digged it into
and I believe it'a race in vfs.

Let's assume there's a inode (ie ino 261) with i_count 1 is
called by iput(), and there's a concurrent thread calling
generic_shutdown_super().

cpu0:                              cpu1:
iput() // i_count is 1
  ->spin_lock(inode)
  ->dec i_count to 0
  ->iput_final()                    generic_shutdown_super()
    ->__inode_add_lru()               ->evict_inodes()
      // cause some reason[2]           ->if (atomic_read(inode->i_count)) continue;
      // return before                  // inode 261 passed the above check
      // list_lru_add_obj()             // and then schedule out
   ->spin_unlock()
// note here: the inode 261
// was still at sb list and hash list,
// and I_FREEING|I_WILL_FREE was not been set

btrfs_iget()
  // after some function calls
  ->find_inode()
    // found the above inode 261
    ->spin_lock(inode)
   // check I_FREEING|I_WILL_FREE
   // and passed
      ->__iget()
    ->spin_unlock(inode)                // schedule back
                                        ->spin_lock(inode)
                                        // check (I_NEW|I_FREEING|I_WILL_FREE) flags,
                                        // passed and set I_FREEING
iput()                                  ->spin_unlock(inode)
  ->spin_lock(inode)			  ->evict()
  // dec i_count to 0
  ->iput_final()
    ->spin_unlock()
    ->evict()

Now, we have two threads simultaneously evicting
the same inode, which may trigger the BUG(inode->i_state & I_CLEAR)
statement both within clear_inode() and iput().

To fix the bug, recheck the inode->i_count after holding i_lock.
Because in the most scenarios, the first check is valid, and
the overhead of spin_lock() can be reduced.

If there is any misunderstanding, please let me know, thanks.

[1]: https://lore.kernel.org/linux-btrfs/000000000000eabe1d0619c48986@google.com/
[2]: The reason might be 1. SB_ACTIVE was removed or 2. mapping_shrinkable()
return false when I reproduced the bug.

Reported-by: syzbot+67ba3c42bcbb4665d3ad@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=67ba3c42bcbb4665d3ad
CC: stable@vger.kernel.org
Fixes: 63997e98a3 ("split invalidate_inodes()")
Signed-off-by: Julian Sun <sunjunchao2870@gmail.com>
Link: https://lore.kernel.org/r/20240823130730.658881-1-sunjunchao2870@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:39 +02:00
Mateusz Guzik
57510c58b5 vfs: drop one lock trip in evict()
Most commonly neither I_LRU_ISOLATING nor I_SYNC are set, but the stock
kernel takes a back-to-back relock trip to check for them.

It probably can be avoided altogether, but for now massage things back
to just one lock acquire.

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240813143626.1573445-1-mjguzik@gmail.com
Reviewed-by: Zhihao Cheng <chengzhihao1@huawei.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:38 +02:00
Christian Brauner
1c48d44146 inode: remove __I_DIO_WAKEUP
Afaict, we can just rely on inode->i_dio_count for waiting instead of
this awkward indirection through __I_DIO_WAKEUP. This survives LTP dio
and xfstests dio tests.

Link: https://lore.kernel.org/r/20240816-vfs-misc-dio-v1-1-80fe21a2c710@kernel.org
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:37 +02:00
Mateusz Guzik
122381a469 vfs: use RCU in ilookup
A soft lockup in ilookup was reported when stress-testing a 512-way
system [1] (see [2] for full context) and it was verified that not
taking the lock shifts issues back to mm.

[1] https://lore.kernel.org/linux-mm/56865e57-c250-44da-9713-cf1404595bcc@amd.com/
[2] https://lore.kernel.org/linux-mm/d2841226-e27b-4d3d-a578-63587a3aa4f3@amd.com/

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240715071324.265879-1-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-30 08:22:36 +02:00
Zhihao Cheng
2a0629834c
vfs: Don't evict inode under the inode lru traversing context
The inode reclaiming process(See function prune_icache_sb) collects all
reclaimable inodes and mark them with I_FREEING flag at first, at that
time, other processes will be stuck if they try getting these inodes
(See function find_inode_fast), then the reclaiming process destroy the
inodes by function dispose_list(). Some filesystems(eg. ext4 with
ea_inode feature, ubifs with xattr) may do inode lookup in the inode
evicting callback function, if the inode lookup is operated under the
inode lru traversing context, deadlock problems may happen.

Case 1: In function ext4_evict_inode(), the ea inode lookup could happen
        if ea_inode feature is enabled, the lookup process will be stuck
	under the evicting context like this:

 1. File A has inode i_reg and an ea inode i_ea
 2. getfattr(A, xattr_buf) // i_ea is added into lru // lru->i_ea
 3. Then, following three processes running like this:

    PA                              PB
 echo 2 > /proc/sys/vm/drop_caches
  shrink_slab
   prune_dcache_sb
   // i_reg is added into lru, lru->i_ea->i_reg
   prune_icache_sb
    list_lru_walk_one
     inode_lru_isolate
      i_ea->i_state |= I_FREEING // set inode state
     inode_lru_isolate
      __iget(i_reg)
      spin_unlock(&i_reg->i_lock)
      spin_unlock(lru_lock)
                                     rm file A
                                      i_reg->nlink = 0
      iput(i_reg) // i_reg->nlink is 0, do evict
       ext4_evict_inode
        ext4_xattr_delete_inode
         ext4_xattr_inode_dec_ref_all
          ext4_xattr_inode_iget
           ext4_iget(i_ea->i_ino)
            iget_locked
             find_inode_fast
              __wait_on_freeing_inode(i_ea) ----→ AA deadlock
    dispose_list // cannot be executed by prune_icache_sb
     wake_up_bit(&i_ea->i_state)

Case 2: In deleted inode writing function ubifs_jnl_write_inode(), file
        deleting process holds BASEHD's wbuf->io_mutex while getting the
	xattr inode, which could race with inode reclaiming process(The
        reclaiming process could try locking BASEHD's wbuf->io_mutex in
	inode evicting function), then an ABBA deadlock problem would
	happen as following:

 1. File A has inode ia and a xattr(with inode ixa), regular file B has
    inode ib and a xattr.
 2. getfattr(A, xattr_buf) // ixa is added into lru // lru->ixa
 3. Then, following three processes running like this:

        PA                PB                        PC
                echo 2 > /proc/sys/vm/drop_caches
                 shrink_slab
                  prune_dcache_sb
                  // ib and ia are added into lru, lru->ixa->ib->ia
                  prune_icache_sb
                   list_lru_walk_one
                    inode_lru_isolate
                     ixa->i_state |= I_FREEING // set inode state
                    inode_lru_isolate
                     __iget(ib)
                     spin_unlock(&ib->i_lock)
                     spin_unlock(lru_lock)
                                                   rm file B
                                                    ib->nlink = 0
 rm file A
  iput(ia)
   ubifs_evict_inode(ia)
    ubifs_jnl_delete_inode(ia)
     ubifs_jnl_write_inode(ia)
      make_reservation(BASEHD) // Lock wbuf->io_mutex
      ubifs_iget(ixa->i_ino)
       iget_locked
        find_inode_fast
         __wait_on_freeing_inode(ixa)
          |          iput(ib) // ib->nlink is 0, do evict
          |           ubifs_evict_inode
          |            ubifs_jnl_delete_inode(ib)
          ↓             ubifs_jnl_write_inode
     ABBA deadlock ←-----make_reservation(BASEHD)
                   dispose_list // cannot be executed by prune_icache_sb
                    wake_up_bit(&ixa->i_state)

Fix the possible deadlock by using new inode state flag I_LRU_ISOLATING
to pin the inode in memory while inode_lru_isolate() reclaims its pages
instead of using ordinary inode reference. This way inode deletion
cannot be triggered from inode_lru_isolate() thus avoiding the deadlock.
evict() is made to wait for I_LRU_ISOLATING to be cleared before
proceeding with inode cleanup.

Link: https://lore.kernel.org/all/37c29c42-7685-d1f0-067d-63582ffac405@huaweicloud.com/
Link: https://bugzilla.kernel.org/show_bug.cgi?id=219022
Fixes: e50e5129f3 ("ext4: xattr-in-inode support")
Fixes: 7959cf3a75 ("ubifs: journal: Handle xattrs like files")
Cc: stable@vger.kernel.org
Signed-off-by: Zhihao Cheng <chengzhihao1@huawei.com>
Link: https://lore.kernel.org/r/20240809031628.1069873-1-chengzhihao@huaweicloud.com
Reviewed-by: Jan Kara <jack@suse.cz>
Suggested-by: Jan Kara <jack@suse.cz>
Suggested-by: Mateusz Guzik <mjguzik@gmail.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-08-13 13:52:16 +02:00
Joel Granados
78eb4ea25c sysctl: treewide: constify the ctl_table argument of proc_handlers
const qualify the struct ctl_table argument in the proc_handler function
signatures. This is a prerequisite to moving the static ctl_table
structs into .rodata data which will ensure that proc_handler function
pointers cannot be modified.

This patch has been generated by the following coccinelle script:

```
  virtual patch

  @r1@
  identifier ctl, write, buffer, lenp, ppos;
  identifier func !~ "appldata_(timer|interval)_handler|sched_(rt|rr)_handler|rds_tcp_skbuf_handler|proc_sctp_do_(hmac_alg|rto_min|rto_max|udp_port|alpha_beta|auth|probe_interval)";
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

  @r2@
  identifier func, ctl, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int write, void *buffer, size_t *lenp, loff_t *ppos)
  { ... }

  @r3@
  identifier func;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int , void *, size_t *, loff_t *);

  @r4@
  identifier func, ctl;
  @@

  int func(
  - struct ctl_table *ctl
  + const struct ctl_table *ctl
    ,int , void *, size_t *, loff_t *);

  @r5@
  identifier func, write, buffer, lenp, ppos;
  @@

  int func(
  - struct ctl_table *
  + const struct ctl_table *
    ,int write, void *buffer, size_t *lenp, loff_t *ppos);

```

* Code formatting was adjusted in xfs_sysctl.c to comply with code
  conventions. The xfs_stats_clear_proc_handler,
  xfs_panic_mask_proc_handler and xfs_deprecated_dointvec_minmax where
  adjusted.

* The ctl_table argument in proc_watchdog_common was const qualified.
  This is called from a proc_handler itself and is calling back into
  another proc_handler, making it necessary to change it as part of the
  proc_handler migration.

Co-developed-by: Thomas Weißschuh <linux@weissschuh.net>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Co-developed-by: Joel Granados <j.granados@samsung.com>
Signed-off-by: Joel Granados <j.granados@samsung.com>
2024-07-24 20:59:29 +02:00
Christian Brauner
f5e5e97c71
inode: clarify what's locked
In __wait_on_freeing_inode() we warn in case the inode_hash_lock is held
but the inode is unhashed. We then release the inode_lock. So using
"locked" as parameter name is confusing. Use is_inode_hash_locked as
parameter name instead.

Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-24 11:11:40 +02:00
Mateusz Guzik
5bc9ad78c2
vfs: handle __wait_on_freeing_inode() and evict() race
Lockless hash lookup can find and lock the inode after it gets the
I_FREEING flag set, at which point it blocks waiting for teardown in
evict() to finish.

However, the flag is still set even after evict() wakes up all waiters.

This results in a race where if the inode lock is taken late enough, it
can happen after both hash removal and wakeups, meaning there is nobody
to wake the racing thread up.

This worked prior to RCU-based lookup because the entire ordeal was
synchronized with the inode hash lock.

Since unhashing requires the inode lock, we can safely check whether it
happened after acquiring it.

Link: https://lore.kernel.org/v9fs/20240717102458.649b60be@kernel.org/
Reported-by: Dominique Martinet <asmadeus@codewreck.org>
Fixes: 7180f8d91f ("vfs: add rcu-based find_inode variants for iget ops")
Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240718151838.611807-1-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-07-24 10:52:58 +02:00
Linus Torvalds
2aae1d67fd vfs-6.11.inode
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Merge tag 'vfs-6.11.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull vfs inode / dentry updates from Christian Brauner:
 "This contains smaller performance improvements to inodes and dentries:

  inode:

   - Add rcu based inode lookup variants.

     They avoid one inode hash lock acquire in the common case thereby
     significantly reducing contention. We already support RCU-based
     operations but didn't take advantage of them during inode
     insertion.

     Callers of iget_locked() get the improvement without any code
     changes. Callers that need a custom callback can switch to
     iget5_locked_rcu() as e.g., did btrfs.

     With 20 threads each walking a dedicated 1000 dirs * 1000 files
     directory tree to stat(2) on a 32 core + 24GB ram vm:

        before: 3.54s user 892.30s system 1966% cpu 45.549 total
        after:  3.28s user 738.66s system 1955% cpu 37.932 total (-16.7%)

     Long-term we should pick up the effort to introduce more
     fine-grained locking and possibly improve on the currently used
     hash implementation.

   - Start zeroing i_state in inode_init_always() instead of doing it in
     individual filesystems.

     This allows us to remove an unneeded lock acquire in new_inode()
     and not burden individual filesystems with this.

  dcache:

   - Move d_lockref out of the area used by RCU lookup to avoid
     cacheline ping poing because the embedded name is sharing a
     cacheline with d_lockref.

   - Fix dentry size on 32bit with CONFIG_SMP=y so it does actually end
     up with 128 bytes in total"

* tag 'vfs-6.11.inode' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs:
  fs: fix dentry size
  vfs: move d_lockref out of the area used by RCU lookup
  bcachefs: remove now spurious i_state initialization
  xfs: remove now spurious i_state initialization in xfs_inode_alloc
  vfs: partially sanitize i_state zeroing on inode creation
  xfs: preserve i_state around inode_init_always in xfs_reinit_inode
  btrfs: use iget5_locked_rcu
  vfs: add rcu-based find_inode variants for iget ops
2024-07-15 11:39:44 -07:00
Youling Tang
9b6a14f08b
fs: Export in_group_or_capable()
Export in_group_or_capable() as a VFS helper function.

Signed-off-by: Youling Tang <tangyouling@kylinos.cn>
Link: https://lore.kernel.org/r/20240620032335.147136-1-youling.tang@linux.dev
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-25 11:15:48 +02:00
Mateusz Guzik
5a9b911b8a vfs: partially sanitize i_state zeroing on inode creation
new_inode used to have the following:
	spin_lock(&inode_lock);
	inodes_stat.nr_inodes++;
	list_add(&inode->i_list, &inode_in_use);
	list_add(&inode->i_sb_list, &sb->s_inodes);
	inode->i_ino = ++last_ino;
	inode->i_state = 0;
	spin_unlock(&inode_lock);

over time things disappeared, got moved around or got replaced (global
inode lock with a per-inode lock), eventually this got reduced to:
	spin_lock(&inode->i_lock);
	inode->i_state = 0;
	spin_unlock(&inode->i_lock);

But the lock acquire here does not synchronize against anyone.

Additionally iget5_locked performs i_state = 0 assignment without any
locks to begin with, the two combined look confusing at best.

It looks like the current state is a leftover which was not cleaned up.

Ideally it would be an invariant that i_state == 0 to begin with, but
achieving that would require dealing with all filesystem alloc handlers
one by one.

In the meantime drop the misleading locking and move i_state zeroing to
inode_init_always so that others don't need to deal with it by hand.

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240611120626.513952-3-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-13 13:40:40 +02:00
Mateusz Guzik
7180f8d91f vfs: add rcu-based find_inode variants for iget ops
This avoids one inode hash lock acquire in the common case on inode
creation, in effect significantly reducing contention.

On the stock kernel said lock is typically taken twice:
1. once to check if the inode happens to already be present
2. once to add it to the hash

The back-to-back lock/unlock pattern is known to degrade performance
significantly, which is further exacerbated if the hash is heavily
populated (long chains to walk, extending hold time). Arguably hash
sizing and hashing algo need to be revisited, but that's beyond the
scope of this patch.

With the acquire from step 1 eliminated with RCU lookup throughput
increases significantly at the scale of 20 cores (benchmark results at
the bottom).

So happens the hash already supports RCU-based operation, but lookups on
inode insertions didn't take advantage of it.

This of course has its limits as the global lock is still a bottleneck.
There was a patchset posted which introduced fine-grained locking[1] but
it appears staled. Apart from that doubt was expressed whether a
handrolled hash implementation is appropriate to begin with, suggesting
replacement with rhashtables. Nobody committed to carrying [1] across
the finish line or implementing anything better, thus the bandaid below.

iget_locked consumers (notably ext4) get away without any changes
because inode comparison method is built-in.

iget5_locked consumers pass a custom callback. Since removal of locking
adds more problems (inode can be changing) it's not safe to assume all
filesystems happen to cope.  Thus iget5_locked_rcu gets added, requiring
manual conversion of interested filesystems.

In order to reduce code duplication find_inode and find_inode_fast grow
an argument indicating whether inode hash lock is held, which is passed
down in case sleeping is necessary. They always rcu_read_lock, which is
redundant but harmless. Doing it conditionally reduces readability for
no real gain that I can see. RCU-alike restrictions were already put on
callbacks due to the hash spinlock being held.

Benchmarking:
There is a real cache-busting workload scanning millions of files in
parallel (it's a backup appliance), where the initial lookup is
guaranteed to fail resulting in the two lock acquires on stock kernel
(and one with the patch at hand).

Implemented below is a synthetic benchmark providing the same behavior.
[I shall note the workload is not running on Linux, instead it was
causing trouble elsewhere. Benchmark below was used while addressing
said problems and was found to adequately represent the real workload.]

Total real time fluctuates by 1-2s.

With 20 threads each walking a dedicated 1000 dirs * 1000 files
directory tree to stat(2) on a 32 core + 24GB RAM vm:

ext4 (needed mkfs.ext4 -N 24000000):
before: 3.77s user 890.90s system 1939% cpu 46.118 total
after:  3.24s user 397.73s system 1858% cpu 21.581 total (-53%)

That's 20 million files to visit, while the machine can only cache about
15 million at a time (obtained from ext4_inode_cache object count in
/proc/slabinfo). Since each terminal inode is only visited once per run
this amounts to 0% hit ratio for the dentry cache and the hash table
(there are however hits for the intermediate directories).

On repeated runs the kernel caches the last ~15 mln, meaning there is ~5
mln of uncached inodes which are going to be visited first, evicting the
previously cached state as it happens.

Lack of hits can be trivially verified with bpftrace, like so:
bpftrace -e 'kretprobe:find_inode_fast { @[kstack(), retval != 0] = count(); }'\
-c "/bin/sh walktrees /testfs 20"

Best ran more than once.

Expected results after "warmup":
[snip]
@[
    __ext4_iget+275
    ext4_lookup+224
    __lookup_slow+130
    walk_component+219
    link_path_walk.part.0.constprop.0+614
    path_lookupat+62
    filename_lookup+204
    vfs_statx+128
    vfs_fstatat+131
    __do_sys_newfstatat+38
    do_syscall_64+87
    entry_SYSCALL_64_after_hwframe+118
, 1]: 20000
@[
    __ext4_iget+275
    ext4_lookup+224
    __lookup_slow+130
    walk_component+219
    path_lookupat+106
    filename_lookup+204
    vfs_statx+128
    vfs_fstatat+131
    __do_sys_newfstatat+38
    do_syscall_64+87
    entry_SYSCALL_64_after_hwframe+118
, 1]: 20000000

That is 20 million calls for the initial lookup and 20 million after
allocating a new inode, all of them failing to return a value != 0
(i.e., they are returning NULL -- no match found).

Of course aborting the benchmark in the middle and starting it again (or
messing with the state in other ways) is going to alter these results.

Benchmark can be found here: https://people.freebsd.org/~mjg/fstree.tgz

[1] https://lore.kernel.org/all/20231206060629.2827226-1-david@fromorbit.com/

Signed-off-by: Mateusz Guzik <mjguzik@gmail.com>
Link: https://lore.kernel.org/r/20240611173824.535995-2-mjguzik@gmail.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-06-12 14:09:59 +02:00
Linus Torvalds
32a50540c3 bcachefs updates for 6.9
- Subvolume children btree; this is needed for providing a userspace
    interface for walking subvolumes, which will come later
  - Lots of improvements to directory structure checking
  - Improved journal pipelining, significantly improving performance on
    high iodepth write workloads
  - Discard path improvements: the discard path is more efficient, and no
    longer flushes the journal unnecessarily
  - Buffered write path can now avoid taking the inode lock
  - new mm helper: memalloc_flags_{save|restore}
  - mempool now does kvmalloc mempools
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Merge tag 'bcachefs-2024-03-13' of https://evilpiepirate.org/git/bcachefs

Pull bcachefs updates from Kent Overstreet:

 - Subvolume children btree; this is needed for providing a userspace
   interface for walking subvolumes, which will come later

 - Lots of improvements to directory structure checking

 - Improved journal pipelining, significantly improving performance on
   high iodepth write workloads

 - Discard path improvements: the discard path is more efficient, and no
   longer flushes the journal unnecessarily

 - Buffered write path can now avoid taking the inode lock

 - new mm helper: memalloc_flags_{save|restore}

 - mempool now does kvmalloc mempools

* tag 'bcachefs-2024-03-13' of https://evilpiepirate.org/git/bcachefs: (128 commits)
  bcachefs: time_stats: shrink time_stat_buffer for better alignment
  bcachefs: time_stats: split stats-with-quantiles into a separate structure
  bcachefs: mean_and_variance: put struct mean_and_variance_weighted on a diet
  bcachefs: time_stats: add larger units
  bcachefs: pull out time_stats.[ch]
  bcachefs: reconstruct_alloc cleanup
  bcachefs: fix bch_folio_sector padding
  bcachefs: Fix btree key cache coherency during replay
  bcachefs: Always flush write buffer in delete_dead_inodes()
  bcachefs: Fix order of gc_done passes
  bcachefs: fix deletion of indirect extents in btree_gc
  bcachefs: Prefer struct_size over open coded arithmetic
  bcachefs: Kill unused flags argument to btree_split()
  bcachefs: Check for writing superblocks with nonsense member seq fields
  bcachefs: fix bch2_journal_buf_to_text()
  lib/generic-radix-tree.c: Make nodes more reasonably sized
  bcachefs: copy_(to|from)_user_errcode()
  bcachefs: Split out bkey_types.h
  bcachefs: fix lost journal buf wakeup due to improved pipelining
  bcachefs: intercept mountoption value for bool type
  ...
2024-03-15 09:00:09 -07:00
Kent Overstreet
66a67c860c fs: file_remove_privs_flags()
Rename and export __file_remove_privs(); for a buffered write path that
doesn't take the inode lock we need to be able to check if the operation
needs to do work first.

Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
2024-03-13 21:22:25 -04:00
Linus Torvalds
54126fafea vfs-6.9.iomap
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Merge tag 'vfs-6.9.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

Pull iomap updates from Christian Brauner:

 - Restore read-write hints in struct bio through the bi_write_hint
   member for the sake of UFS devices in mobile applications. This can
   result in up to 40% lower write amplification in UFS devices. The
   patch series that builds on this will be coming in via the SCSI
   maintainers (Bart)

 - Overhaul the iomap writeback code. Afterwards ->map_blocks() is able
   to map multiple blocks at once as long as they're in the same folio.
   This reduces CPU usage for buffered write workloads on e.g., xfs on
   systems with lots of cores (Christoph)

 - Record processed bytes in iomap_iter() trace event (Kassey)

 - Extend iomap_writepage_map() trace event after Christoph's
   ->map_block() changes to map mutliple blocks at once (Zhang)

* tag 'vfs-6.9.iomap' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (22 commits)
  iomap: Add processed for iomap_iter
  iomap: add pos and dirty_len into trace_iomap_writepage_map
  block, fs: Restore the per-bio/request data lifetime fields
  fs: Propagate write hints to the struct block_device inode
  fs: Move enum rw_hint into a new header file
  fs: Split fcntl_rw_hint()
  fs: Verify write lifetime constants at compile time
  fs: Fix rw_hint validation
  iomap: pass the length of the dirty region to ->map_blocks
  iomap: map multiple blocks at a time
  iomap: submit ioends immediately
  iomap: factor out a iomap_writepage_map_block helper
  iomap: only call mapping_set_error once for each failed bio
  iomap: don't chain bios
  iomap: move the iomap_sector sector calculation out of iomap_add_to_ioend
  iomap: clean up the iomap_alloc_ioend calling convention
  iomap: move all remaining per-folio logic into iomap_writepage_map
  iomap: factor out a iomap_writepage_handle_eof helper
  iomap: move the PF_MEMALLOC check to iomap_writepages
  iomap: move the io_folios field out of struct iomap_ioend
  ...
2024-03-11 10:07:03 -07:00
Nguyen Dinh Phi
24a8b7bfb9
fs: use inode_set_ctime_to_ts to set inode ctime to current time
The function inode_set_ctime_current simply retrieves the current time
and assigns it to the field __i_ctime without any alterations. Therefore,
it is possible to set ctime to now directly using inode_set_ctime_to_ts

Signed-off-by: Nguyen Dinh Phi <phind.uet@gmail.com>
Link: https://lore.kernel.org/r/20240228173031.3208743-1-phind.uet@gmail.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-03-01 13:58:46 +01:00
Chengming Zhou
c997d683d9 vfs: remove SLAB_MEM_SPREAD flag usage
The SLAB_MEM_SPREAD flag used to be implemented in SLAB, which was
removed as of v6.8-rc1 (see [1]), so it became a dead flag since the
commit 16a1d96835 ("mm/slab: remove mm/slab.c and slab_def.h"). And
the series[1] went on to mark it obsolete explicitly to avoid confusion
for users. Here we can just remove all its users, which has no any
functional change.

Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com>
Link: https://lore.kernel.org/all/20240223-slab-cleanup-flags-v2-1-02f1753e8303@suse.cz [1]
Link: https://lore.kernel.org/r/20240224135315.830477-1-chengming.zhou@linux.dev
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-27 11:21:31 +01:00
Bart Van Assche
fe3944fb24
fs: Move enum rw_hint into a new header file
Move enum rw_hint into a new header file to prepare for using this data
type in the block layer. Add the attribute __packed to reduce the space
occupied by instances of this data type from four bytes to one byte.
Change the data type of i_write_hint from u8 into enum rw_hint.

Reviewed-by: Christoph Hellwig <hch@lst.de>
Acked-by: Chao Yu <chao@kernel.org> # for the F2FS part
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Link: https://lore.kernel.org/r/20240202203926.2478590-5-bvanassche@acm.org
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-02-06 14:30:48 +01:00
Baolin Wang
8b3d838139 fs: improve dump_mapping() robustness
We met a kernel crash issue when running stress-ng testing, and the
system crashes when printing the dentry name in dump_mapping().

Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
pc : dentry_name+0xd8/0x224
lr : pointer+0x22c/0x370
sp : ffff800025f134c0
......
Call trace:
  dentry_name+0xd8/0x224
  pointer+0x22c/0x370
  vsnprintf+0x1ec/0x730
  vscnprintf+0x2c/0x60
  vprintk_store+0x70/0x234
  vprintk_emit+0xe0/0x24c
  vprintk_default+0x3c/0x44
  vprintk_func+0x84/0x2d0
  printk+0x64/0x88
  __dump_page+0x52c/0x530
  dump_page+0x14/0x20
  set_migratetype_isolate+0x110/0x224
  start_isolate_page_range+0xc4/0x20c
  offline_pages+0x124/0x474
  memory_block_offline+0x44/0xf4
  memory_subsys_offline+0x3c/0x70
  device_offline+0xf0/0x120
  ......

The root cause is that, one thread is doing page migration, and we will
use the target page's ->mapping field to save 'anon_vma' pointer between
page unmap and page move, and now the target page is locked and refcount
is 1.

Currently, there is another stress-ng thread performing memory hotplug,
attempting to offline the target page that is being migrated. It discovers
that the refcount of this target page is 1, preventing the offline operation,
thus proceeding to dump the page. However, page_mapping() of the target
page may return an incorrect file mapping to crash the system in dump_mapping(),
since the target page->mapping only saves 'anon_vma' pointer without setting
PAGE_MAPPING_ANON flag.

The page migration issue has been fixed by commit d1adb25df7 ("mm: migrate:
fix getting incorrect page mapping during page migration"). In addition,
Matthew suggested we should also improve dump_mapping()'s robustness to
resilient against the kernel crash [1].

With checking the 'dentry.parent' and 'dentry.d_name.name' used by
dentry_name(), I can see dump_mapping() will output the invalid dentry
instead of crashing the system when this issue is reproduced again.

[12211.189128] page:fffff7de047741c0 refcount:1 mapcount:0 mapping:ffff989117f55ea0 index:0x1 pfn:0x211dd07
[12211.189144] aops:0x0 ino:1 invalid dentry:74786574206e6870
[12211.189148] flags: 0x57ffffc0000001(locked|node=1|zone=2|lastcpupid=0x1fffff)
[12211.189150] page_type: 0xffffffff()
[12211.189153] raw: 0057ffffc0000001 0000000000000000 dead000000000122 ffff989117f55ea0
[12211.189154] raw: 0000000000000001 0000000000000001 00000001ffffffff 0000000000000000
[12211.189155] page dumped because: unmovable page

[1] https://lore.kernel.org/all/ZXxn%2F0oixJxxAnpF@casper.infradead.org/

Suggested-by: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Baolin Wang <baolin.wang@linux.alibaba.com>
Link: https://lore.kernel.org/r/937ab1f87328516821d39be672b6bc18861d9d3e.1705391420.git.baolin.wang@linux.alibaba.com
Signed-off-by: Christian Brauner <brauner@kernel.org>
2024-01-22 15:33:37 +01:00
Linus Torvalds
bf4e7080ae fix directory locking scheme on rename
broken in 6.5; we really can't lock two unrelated directories
 without holding ->s_vfs_rename_mutex first and in case of
 same-parent rename of a subdirectory 6.5 ends up doing just
 that.
 
 Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
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Merge tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull rename updates from Al Viro:
 "Fix directory locking scheme on rename

  This was broken in 6.5; we really can't lock two unrelated directories
  without holding ->s_vfs_rename_mutex first and in case of same-parent
  rename of a subdirectory 6.5 ends up doing just that"

* tag 'pull-rename' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  rename(): avoid a deadlock in the case of parents having no common ancestor
  kill lock_two_inodes()
  rename(): fix the locking of subdirectories
  f2fs: Avoid reading renamed directory if parent does not change
  ext4: don't access the source subdirectory content on same-directory rename
  ext2: Avoid reading renamed directory if parent does not change
  udf_rename(): only access the child content on cross-directory rename
  ocfs2: Avoid touching renamed directory if parent does not change
  reiserfs: Avoid touching renamed directory if parent does not change
2024-01-11 20:00:22 -08:00
Linus Torvalds
a05aea98d4 sysctl-6.8-rc1
To help make the move of sysctls out of kernel/sysctl.c not incur a size
 penalty sysctl has been changed to allow us to not require the sentinel, the
 final empty element on the sysctl array. Joel Granados has been doing all this
 work. On the v6.6 kernel we got the major infrastructure changes required to
 support this. For v6.7 we had all arch/ and drivers/ modified to remove
 the sentinel. For v6.8-rc1 we get a few more updates for fs/ directory only.
 The kernel/ directory is left but we'll save that for v6.9-rc1 as those patches
 are still being reviewed. After that we then can expect also the removal of the
 no longer needed check for procname == NULL.
 
 Let us recap the purpose of this work:
 
   - this helps reduce the overall build time size of the kernel and run time
     memory consumed by the kernel by about ~64 bytes per array
   - the extra 64-byte penalty is no longer inncurred now when we move sysctls
     out from kernel/sysctl.c to their own files
 
 Thomas Weißschuh also sent a few cleanups, for v6.9-rc1 we expect to see further
 work by Thomas Weißschuh with the constificatin of the struct ctl_table.
 
 Due to Joel Granados's work, and to help bring in new blood, I have suggested
 for him to become a maintainer and he's accepted. So for v6.9-rc1 I look forward
 to seeing him sent you a pull request for further sysctl changes. This also
 removes Iurii Zaikin as a maintainer as he has moved on to other projects and
 has had no time to help at all.
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Merge tag 'sysctl-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux

Pull sysctl updates from Luis Chamberlain:
 "To help make the move of sysctls out of kernel/sysctl.c not incur a
  size penalty sysctl has been changed to allow us to not require the
  sentinel, the final empty element on the sysctl array. Joel Granados
  has been doing all this work.

  In the v6.6 kernel we got the major infrastructure changes required to
  support this. For v6.7 we had all arch/ and drivers/ modified to
  remove the sentinel. For v6.8-rc1 we get a few more updates for fs/
  directory only.

  The kernel/ directory is left but we'll save that for v6.9-rc1 as
  those patches are still being reviewed. After that we then can expect
  also the removal of the no longer needed check for procname == NULL.

  Let us recap the purpose of this work:

   - this helps reduce the overall build time size of the kernel and run
     time memory consumed by the kernel by about ~64 bytes per array

   - the extra 64-byte penalty is no longer inncurred now when we move
     sysctls out from kernel/sysctl.c to their own files

  Thomas Weißschuh also sent a few cleanups, for v6.9-rc1 we expect to
  see further work by Thomas Weißschuh with the constificatin of the
  struct ctl_table.

  Due to Joel Granados's work, and to help bring in new blood, I have
  suggested for him to become a maintainer and he's accepted. So for
  v6.9-rc1 I look forward to seeing him sent you a pull request for
  further sysctl changes. This also removes Iurii Zaikin as a maintainer
  as he has moved on to other projects and has had no time to help at
  all"

* tag 'sysctl-6.8-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/mcgrof/linux:
  sysctl: remove struct ctl_path
  sysctl: delete unused define SYSCTL_PERM_EMPTY_DIR
  coda: Remove the now superfluous sentinel elements from ctl_table array
  sysctl: Remove the now superfluous sentinel elements from ctl_table array
  fs: Remove the now superfluous sentinel elements from ctl_table array
  cachefiles: Remove the now superfluous sentinel element from ctl_table array
  sysclt: Clarify the results of selftest run
  sysctl: Add a selftest for handling empty dirs
  sysctl: Fix out of bounds access for empty sysctl registers
  MAINTAINERS: Add Joel Granados as co-maintainer for proc sysctl
  MAINTAINERS: remove Iurii Zaikin from proc sysctl
2024-01-10 17:44:36 -08:00
Linus Torvalds
fb46e22a9e Many singleton patches against the MM code. The patch series which
are included in this merge do the following:
 
 - Peng Zhang has done some mapletree maintainance work in the
   series
 
 	"maple_tree: add mt_free_one() and mt_attr() helpers"
 	"Some cleanups of maple tree"
 
 - In the series "mm: use memmap_on_memory semantics for dax/kmem"
   Vishal Verma has altered the interworking between memory-hotplug
   and dax/kmem so that newly added 'device memory' can more easily
   have its memmap placed within that newly added memory.
 
 - Matthew Wilcox continues folio-related work (including a few
   fixes) in the patch series
 
 	"Add folio_zero_tail() and folio_fill_tail()"
 	"Make folio_start_writeback return void"
 	"Fix fault handler's handling of poisoned tail pages"
 	"Convert aops->error_remove_page to ->error_remove_folio"
 	"Finish two folio conversions"
 	"More swap folio conversions"
 
 - Kefeng Wang has also contributed folio-related work in the series
 
 	"mm: cleanup and use more folio in page fault"
 
 - Jim Cromie has improved the kmemleak reporting output in the
   series "tweak kmemleak report format".
 
 - In the series "stackdepot: allow evicting stack traces" Andrey
   Konovalov to permits clients (in this case KASAN) to cause
   eviction of no longer needed stack traces.
 
 - Charan Teja Kalla has fixed some accounting issues in the page
   allocator's atomic reserve calculations in the series "mm:
   page_alloc: fixes for high atomic reserve caluculations".
 
 - Dmitry Rokosov has added to the samples/ dorectory some sample
   code for a userspace memcg event listener application.  See the
   series "samples: introduce cgroup events listeners".
 
 - Some mapletree maintanance work from Liam Howlett in the series
   "maple_tree: iterator state changes".
 
 - Nhat Pham has improved zswap's approach to writeback in the
   series "workload-specific and memory pressure-driven zswap
   writeback".
 
 - DAMON/DAMOS feature and maintenance work from SeongJae Park in
   the series
 
 	"mm/damon: let users feed and tame/auto-tune DAMOS"
 	"selftests/damon: add Python-written DAMON functionality tests"
 	"mm/damon: misc updates for 6.8"
 
 - Yosry Ahmed has improved memcg's stats flushing in the series
   "mm: memcg: subtree stats flushing and thresholds".
 
 - In the series "Multi-size THP for anonymous memory" Ryan Roberts
   has added a runtime opt-in feature to transparent hugepages which
   improves performance by allocating larger chunks of memory during
   anonymous page faults.
 
 - Matthew Wilcox has also contributed some cleanup and maintenance
   work against eh buffer_head code int he series "More buffer_head
   cleanups".
 
 - Suren Baghdasaryan has done work on Andrea Arcangeli's series
   "userfaultfd move option".  UFFDIO_MOVE permits userspace heap
   compaction algorithms to move userspace's pages around rather than
   UFFDIO_COPY'a alloc/copy/free.
 
 - Stefan Roesch has developed a "KSM Advisor", in the series
   "mm/ksm: Add ksm advisor".  This is a governor which tunes KSM's
   scanning aggressiveness in response to userspace's current needs.
 
 - Chengming Zhou has optimized zswap's temporary working memory
   use in the series "mm/zswap: dstmem reuse optimizations and
   cleanups".
 
 - Matthew Wilcox has performed some maintenance work on the
   writeback code, both code and within filesystems.  The series is
   "Clean up the writeback paths".
 
 - Andrey Konovalov has optimized KASAN's handling of alloc and
   free stack traces for secondary-level allocators, in the series
   "kasan: save mempool stack traces".
 
 - Andrey also performed some KASAN maintenance work in the series
   "kasan: assorted clean-ups".
 
 - David Hildenbrand has gone to town on the rmap code.  Cleanups,
   more pte batching, folio conversions and more.  See the series
   "mm/rmap: interface overhaul".
 
 - Kinsey Ho has contributed some maintenance work on the MGLRU
   code in the series "mm/mglru: Kconfig cleanup".
 
 - Matthew Wilcox has contributed lruvec page accounting code
   cleanups in the series "Remove some lruvec page accounting
   functions".
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Merge tag 'mm-stable-2024-01-08-15-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

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:

   - Peng Zhang has done some mapletree maintainance work in the series

	'maple_tree: add mt_free_one() and mt_attr() helpers'
	'Some cleanups of maple tree'

   - In the series 'mm: use memmap_on_memory semantics for dax/kmem'
     Vishal Verma has altered the interworking between memory-hotplug
     and dax/kmem so that newly added 'device memory' can more easily
     have its memmap placed within that newly added memory.

   - Matthew Wilcox continues folio-related work (including a few fixes)
     in the patch series

	'Add folio_zero_tail() and folio_fill_tail()'
	'Make folio_start_writeback return void'
	'Fix fault handler's handling of poisoned tail pages'
	'Convert aops->error_remove_page to ->error_remove_folio'
	'Finish two folio conversions'
	'More swap folio conversions'

   - Kefeng Wang has also contributed folio-related work in the series

	'mm: cleanup and use more folio in page fault'

   - Jim Cromie has improved the kmemleak reporting output in the series
     'tweak kmemleak report format'.

   - In the series 'stackdepot: allow evicting stack traces' Andrey
     Konovalov to permits clients (in this case KASAN) to cause eviction
     of no longer needed stack traces.

   - Charan Teja Kalla has fixed some accounting issues in the page
     allocator's atomic reserve calculations in the series 'mm:
     page_alloc: fixes for high atomic reserve caluculations'.

   - Dmitry Rokosov has added to the samples/ dorectory some sample code
     for a userspace memcg event listener application. See the series
     'samples: introduce cgroup events listeners'.

   - Some mapletree maintanance work from Liam Howlett in the series
     'maple_tree: iterator state changes'.

   - Nhat Pham has improved zswap's approach to writeback in the series
     'workload-specific and memory pressure-driven zswap writeback'.

   - DAMON/DAMOS feature and maintenance work from SeongJae Park in the
     series

	'mm/damon: let users feed and tame/auto-tune DAMOS'
	'selftests/damon: add Python-written DAMON functionality tests'
	'mm/damon: misc updates for 6.8'

   - Yosry Ahmed has improved memcg's stats flushing in the series 'mm:
     memcg: subtree stats flushing and thresholds'.

   - In the series 'Multi-size THP for anonymous memory' Ryan Roberts
     has added a runtime opt-in feature to transparent hugepages which
     improves performance by allocating larger chunks of memory during
     anonymous page faults.

   - Matthew Wilcox has also contributed some cleanup and maintenance
     work against eh buffer_head code int he series 'More buffer_head
     cleanups'.

   - Suren Baghdasaryan has done work on Andrea Arcangeli's series
     'userfaultfd move option'. UFFDIO_MOVE permits userspace heap
     compaction algorithms to move userspace's pages around rather than
     UFFDIO_COPY'a alloc/copy/free.

   - Stefan Roesch has developed a 'KSM Advisor', in the series 'mm/ksm:
     Add ksm advisor'. This is a governor which tunes KSM's scanning
     aggressiveness in response to userspace's current needs.

   - Chengming Zhou has optimized zswap's temporary working memory use
     in the series 'mm/zswap: dstmem reuse optimizations and cleanups'.

   - Matthew Wilcox has performed some maintenance work on the writeback
     code, both code and within filesystems. The series is 'Clean up the
     writeback paths'.

   - Andrey Konovalov has optimized KASAN's handling of alloc and free
     stack traces for secondary-level allocators, in the series 'kasan:
     save mempool stack traces'.

   - Andrey also performed some KASAN maintenance work in the series
     'kasan: assorted clean-ups'.

   - David Hildenbrand has gone to town on the rmap code. Cleanups, more
     pte batching, folio conversions and more. See the series 'mm/rmap:
     interface overhaul'.

   - Kinsey Ho has contributed some maintenance work on the MGLRU code
     in the series 'mm/mglru: Kconfig cleanup'.

   - Matthew Wilcox has contributed lruvec page accounting code cleanups
     in the series 'Remove some lruvec page accounting functions'"

* tag 'mm-stable-2024-01-08-15-31' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (361 commits)
  mm, treewide: rename MAX_ORDER to MAX_PAGE_ORDER
  mm, treewide: introduce NR_PAGE_ORDERS
  selftests/mm: add separate UFFDIO_MOVE test for PMD splitting
  selftests/mm: skip test if application doesn't has root privileges
  selftests/mm: conform test to TAP format output
  selftests: mm: hugepage-mmap: conform to TAP format output
  selftests/mm: gup_test: conform test to TAP format output
  mm/selftests: hugepage-mremap: conform test to TAP format output
  mm/vmstat: move pgdemote_* out of CONFIG_NUMA_BALANCING
  mm: zsmalloc: return -ENOSPC rather than -EINVAL in zs_malloc while size is too large
  mm/memcontrol: remove __mod_lruvec_page_state()
  mm/khugepaged: use a folio more in collapse_file()
  slub: use a folio in __kmalloc_large_node
  slub: use folio APIs in free_large_kmalloc()
  slub: use alloc_pages_node() in alloc_slab_page()
  mm: remove inc/dec lruvec page state functions
  mm: ratelimit stat flush from workingset shrinker
  kasan: stop leaking stack trace handles
  mm/mglru: remove CONFIG_TRANSPARENT_HUGEPAGE
  mm/mglru: add dummy pmd_dirty()
  ...
2024-01-09 11:18:47 -08:00
Linus Torvalds
c604110e66 vfs-6.8.misc
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Merge tag 'vfs-6.8.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs

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

  Features:

   - Add Jan Kara as VFS reviewer

   - Show correct device and inode numbers in proc/<pid>/maps for vma
     files on stacked filesystems. This is now easily doable thanks to
     the backing file work from the last cycles. This comes with
     selftests

  Cleanups:

   - Remove a redundant might_sleep() from wait_on_inode()

   - Initialize pointer with NULL, not 0

   - Clarify comment on access_override_creds()

   - Rework and simplify eventfd_signal() and eventfd_signal_mask()
     helpers

   - Process aio completions in batches to avoid needless wakeups

   - Completely decouple struct mnt_idmap from namespaces. We now only
     keep the actual idmapping around and don't stash references to
     namespaces

   - Reformat maintainer entries to indicate that a given subsystem
     belongs to fs/

   - Simplify fput() for files that were never opened

   - Get rid of various pointless file helpers

   - Rename various file helpers

   - Rename struct file members after SLAB_TYPESAFE_BY_RCU switch from
     last cycle

   - Make relatime_need_update() return bool

   - Use GFP_KERNEL instead of GFP_USER when allocating superblocks

   - Replace deprecated ida_simple_*() calls with their current ida_*()
     counterparts

  Fixes:

   - Fix comments on user namespace id mapping helpers. They aren't
     kernel doc comments so they shouldn't be using /**

   - s/Retuns/Returns/g in various places

   - Add missing parameter documentation on can_move_mount_beneath()

   - Rename i_mapping->private_data to i_mapping->i_private_data

   - Fix a false-positive lockdep warning in pipe_write() for watch
     queues

   - Improve __fget_files_rcu() code generation to improve performance

   - Only notify writer that pipe resizing has finished after setting
     pipe->max_usage otherwise writers are never notified that the pipe
     has been resized and hang

   - Fix some kernel docs in hfsplus

   - s/passs/pass/g in various places

   - Fix kernel docs in ntfs

   - Fix kcalloc() arguments order reported by gcc 14

   - Fix uninitialized value in reiserfs"

* tag 'vfs-6.8.misc' of git://git.kernel.org/pub/scm/linux/kernel/git/vfs/vfs: (36 commits)
  reiserfs: fix uninit-value in comp_keys
  watch_queue: fix kcalloc() arguments order
  ntfs: dir.c: fix kernel-doc function parameter warnings
  fs: fix doc comment typo fs tree wide
  selftests/overlayfs: verify device and inode numbers in /proc/pid/maps
  fs/proc: show correct device and inode numbers in /proc/pid/maps
  eventfd: Remove usage of the deprecated ida_simple_xx() API
  fs: super: use GFP_KERNEL instead of GFP_USER for super block allocation
  fs/hfsplus: wrapper.c: fix kernel-doc warnings
  fs: add Jan Kara as reviewer
  fs/inode: Make relatime_need_update return bool
  pipe: wakeup wr_wait after setting max_usage
  file: remove __receive_fd()
  file: stop exposing receive_fd_user()
  fs: replace f_rcuhead with f_task_work
  file: remove pointless wrapper
  file: s/close_fd_get_file()/file_close_fd()/g
  Improve __fget_files_rcu() code generation (and thus __fget_light())
  file: massage cleanup of files that failed to open
  fs/pipe: Fix lockdep false-positive in watchqueue pipe_write()
  ...
2024-01-08 10:26:08 -08:00
Joel Granados
9d5b947535 fs: Remove the now superfluous sentinel elements from ctl_table array
This commit comes at the tail end of a greater effort to remove the
empty elements at the end of the ctl_table arrays (sentinels) which
will reduce the overall build time size of the kernel and run time
memory bloat by ~64 bytes per sentinel (further information Link :
https://lore.kernel.org/all/ZO5Yx5JFogGi%2FcBo@bombadil.infradead.org/)

Remove sentinel elements ctl_table struct. Special attention was placed in
making sure that an empty directory for fs/verity was created when
CONFIG_FS_VERITY_BUILTIN_SIGNATURES is not defined. In this case we use the
register sysctl call that expects a size.

Signed-off-by: Joel Granados <j.granados@samsung.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>
Acked-by: Christian Brauner <brauner@kernel.org>
Signed-off-by: Luis Chamberlain <mcgrof@kernel.org>
2023-12-28 04:57:57 -08:00
Alexander Mikhalitsyn
376870aa23
fs: fix doc comment typo fs tree wide
Do the replacement:
s/simply passs @nop_mnt_idmap/simply pass @nop_mnt_idmap/
in the fs/ tree.

Found by chance while working on support for idmapped mounts in fuse.

Cc: Jan Kara <jack@suse.cz>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: <linux-fsdevel@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Signed-off-by: Alexander Mikhalitsyn <aleksandr.mikhalitsyn@canonical.com>
Link: https://lore.kernel.org/r/20231215130927.136917-1-aleksandr.mikhalitsyn@canonical.com
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-12-21 13:17:54 +01:00
Nhat Pham
0a97c01cd2 list_lru: allow explicit memcg and NUMA node selection
Patch series "workload-specific and memory pressure-driven zswap
writeback", v8.

There are currently several issues with zswap writeback:

1. There is only a single global LRU for zswap, making it impossible to
   perform worload-specific shrinking - an memcg under memory pressure
   cannot determine which pages in the pool it owns, and often ends up
   writing pages from other memcgs. This issue has been previously
   observed in practice and mitigated by simply disabling
   memcg-initiated shrinking:

   https://lore.kernel.org/all/20230530232435.3097106-1-nphamcs@gmail.com/T/#u

   But this solution leaves a lot to be desired, as we still do not
   have an avenue for an memcg to free up its own memory locked up in
   the zswap pool.

2. We only shrink the zswap pool when the user-defined limit is hit.
   This means that if we set the limit too high, cold data that are
   unlikely to be used again will reside in the pool, wasting precious
   memory. It is hard to predict how much zswap space will be needed
   ahead of time, as this depends on the workload (specifically, on
   factors such as memory access patterns and compressibility of the
   memory pages).

This patch series solves these issues by separating the global zswap LRU
into per-memcg and per-NUMA LRUs, and performs workload-specific (i.e
memcg- and NUMA-aware) zswap writeback under memory pressure.  The new
shrinker does not have any parameter that must be tuned by the user, and
can be opted in or out on a per-memcg basis.

As a proof of concept, we ran the following synthetic benchmark: build the
linux kernel in a memory-limited cgroup, and allocate some cold data in
tmpfs to see if the shrinker could write them out and improved the overall
performance.  Depending on the amount of cold data generated, we observe
from 14% to 35% reduction in kernel CPU time used in the kernel builds.


This patch (of 6):

The interface of list_lru is based on the assumption that the list node
and the data it represents belong to the same allocated on the correct
node/memcg.  While this assumption is valid for existing slab objects LRU
such as dentries and inodes, it is undocumented, and rather inflexible for
certain potential list_lru users (such as the upcoming zswap shrinker and
the THP shrinker).  It has caused us a lot of issues during our
development.

This patch changes list_lru interface so that the caller must explicitly
specify numa node and memcg when adding and removing objects.  The old
list_lru_add() and list_lru_del() are renamed to list_lru_add_obj() and
list_lru_del_obj(), respectively.

It also extends the list_lru API with a new function, list_lru_putback,
which undoes a previous list_lru_isolate call.  Unlike list_lru_add, it
does not increment the LRU node count (as list_lru_isolate does not
decrement the node count).  list_lru_putback also allows for explicit
memcg and NUMA node selection.

Link: https://lkml.kernel.org/r/20231130194023.4102148-1-nphamcs@gmail.com
Link: https://lkml.kernel.org/r/20231130194023.4102148-2-nphamcs@gmail.com
Signed-off-by: Nhat Pham <nphamcs@gmail.com>
Suggested-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Bagas Sanjaya <bagasdotme@gmail.com>
Cc: Chris Li <chrisl@kernel.org>
Cc: Dan Streetman <ddstreet@ieee.org>
Cc: Domenico Cerasuolo <cerasuolodomenico@gmail.com>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Seth Jennings <sjenning@redhat.com>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Cc: Vitaly Wool <vitaly.wool@konsulko.com>
Cc: Yosry Ahmed <yosryahmed@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2023-12-12 10:57:01 -08:00
Hao Ge
effa1870b2
fs/inode: Make relatime_need_update return bool
relatime_need_update should return bool to consistent with the function
__atime_needs_update that is caller

Signed-off-by: Hao Ge <gehao@kylinos.cn>
Link: https://lore.kernel.org/r/20231205064545.332322-1-gehao@kylinos.cn
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-12-12 14:24:54 +01:00
Al Viro
dbd4540df2 kill lock_two_inodes()
There's only one caller left (lock_two_nondirectories()), and it
needs less complexity.  Fold lock_two_inodes() in there and
simplify.

Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2023-11-25 02:53:20 -05:00
Matthew Wilcox (Oracle)
600f111ef5 fs: Rename mapping private members
It is hard to find where mapping->private_lock, mapping->private_list and
mapping->private_data are used, due to private_XXX being a relatively
common name for variables and structure members in the kernel.  To fit
with other members of struct address_space, rename them all to have an
i_ prefix.  Tested with an allmodconfig build.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Link: https://lore.kernel.org/r/20231117215823.2821906-1-willy@infradead.org
Acked-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Christian Brauner <brauner@kernel.org>
2023-11-21 11:57:10 +01:00