linux.git/fs/mbcache.c, branch v6.12.80

vfs: remove SLAB_MEM_SPREAD flag usage

2024-02-27T10:21:31+00:00

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 16a1d968358a ("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 
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

mbcache: Simplify the allocation of slab caches

2024-02-02T12:11:50+00:00

Use the new KMEM_CACHE() macro instead of direct kmem_cache_create
to simplify the creation of SLAB caches.

Signed-off-by: Kunwu Chan 
Link: https://lore.kernel.org/r/20240201093426.207932-1-chentao@kylinos.cn
Reviewed-by: Jan Kara 
Signed-off-by: Christian Brauner

mbcache: dynamically allocate the mbcache shrinker

2023-10-04T17:32:25+00:00

In preparation for implementing lockless slab shrink, use new APIs to
dynamically allocate the mbcache shrinker, so that it can be freed
asynchronously via RCU. Then it doesn't need to wait for RCU read-side
critical section when releasing the struct mb_cache.

Link: https://lkml.kernel.org/r/20230911094444.68966-30-zhengqi.arch@bytedance.com
Signed-off-by: Qi Zheng 
Reviewed-by: Muchun Song 
Cc: Alexander Viro 
Cc: Christian Brauner 
Cc: Abhinav Kumar 
Cc: Alasdair Kergon 
Cc: Alyssa Rosenzweig 
Cc: Andreas Dilger 
Cc: Andreas Gruenbacher 
Cc: Anna Schumaker 
Cc: Arnd Bergmann 
Cc: Bob Peterson 
Cc: Borislav Petkov 
Cc: Carlos Llamas 
Cc: Chandan Babu R 
Cc: Chao Yu 
Cc: Chris Mason 
Cc: Christian Koenig 
Cc: Chuck Lever 
Cc: Coly Li 
Cc: Dai Ngo 
Cc: Daniel Vetter 
Cc: Daniel Vetter 
Cc: "Darrick J. Wong" 
Cc: Dave Chinner 
Cc: Dave Hansen 
Cc: David Airlie 
Cc: David Hildenbrand 
Cc: David Sterba 
Cc: Dmitry Baryshkov 
Cc: Gao Xiang 
Cc: Greg Kroah-Hartman 
Cc: Huang Rui 
Cc: Ingo Molnar 
Cc: Jaegeuk Kim 
Cc: Jani Nikula 
Cc: Jan Kara 
Cc: Jason Wang 
Cc: Jeff Layton 
Cc: Jeffle Xu 
Cc: Joel Fernandes (Google) 
Cc: Joonas Lahtinen 
Cc: Josef Bacik 
Cc: Juergen Gross 
Cc: Kent Overstreet 
Cc: Kirill Tkhai 
Cc: Marijn Suijten 
Cc: "Michael S. Tsirkin" 
Cc: Mike Snitzer 
Cc: Minchan Kim 
Cc: Muchun Song 
Cc: Nadav Amit 
Cc: Neil Brown 
Cc: Oleksandr Tyshchenko 
Cc: Olga Kornievskaia 
Cc: Paul E. McKenney 
Cc: Richard Weinberger 
Cc: Rob Clark 
Cc: Rob Herring 
Cc: Rodrigo Vivi 
Cc: Roman Gushchin 
Cc: Sean Paul 
Cc: Sergey Senozhatsky 
Cc: Song Liu 
Cc: Stefano Stabellini 
Cc: Steven Price 
Cc: "Theodore Ts'o" 
Cc: Thomas Gleixner 
Cc: Tomeu Vizoso 
Cc: Tom Talpey 
Cc: Trond Myklebust 
Cc: Tvrtko Ursulin 
Cc: Vlastimil Babka 
Cc: Xuan Zhuo 
Cc: Yue Hu 
Signed-off-by: Andrew Morton

ext4: fix deadlock due to mbcache entry corruption

2022-12-09T02:49:25+00:00

When manipulating xattr blocks, we can deadlock infinitely looping
inside ext4_xattr_block_set() where we constantly keep finding xattr
block for reuse in mbcache but we are unable to reuse it because its
reference count is too big. This happens because cache entry for the
xattr block is marked as reusable (e_reusable set) although its
reference count is too big. When this inconsistency happens, this
inconsistent state is kept indefinitely and so ext4_xattr_block_set()
keeps retrying indefinitely.

The inconsistent state is caused by non-atomic update of e_reusable bit.
e_reusable is part of a bitfield and e_reusable update can race with
update of e_referenced bit in the same bitfield resulting in loss of one
of the updates. Fix the problem by using atomic bitops instead.

This bug has been around for many years, but it became *much* easier
to hit after commit 65f8b80053a1 ("ext4: fix race when reusing xattr
blocks").

Cc: stable@vger.kernel.org
Fixes: 6048c64b2609 ("mbcache: add reusable flag to cache entries")
Fixes: 65f8b80053a1 ("ext4: fix race when reusing xattr blocks")
Reported-and-tested-by: Jeremi Piotrowski 
Reported-by: Thilo Fromm 
Link: https://lore.kernel.org/r/c77bf00f-4618-7149-56f1-b8d1664b9d07@linux.microsoft.com/
Signed-off-by: Jan Kara 
Reviewed-by: Andreas Dilger 
Link: https://lore.kernel.org/r/20221123193950.16758-1-jack@suse.cz
Signed-off-by: Theodore Ts'o

mbcache: Avoid nesting of cache->c_list_lock under bit locks

2022-10-01T03:46:52+00:00

Commit 307af6c87937 ("mbcache: automatically delete entries from cache
on freeing") started nesting cache->c_list_lock under the bit locks
protecting hash buckets of the mbcache hash table in
mb_cache_entry_create(). This causes problems for real-time kernels
because there spinlocks are sleeping locks while bitlocks stay atomic.
Luckily the nesting is easy to avoid by holding entry reference until
the entry is added to the LRU list. This makes sure we cannot race with
entry deletion.

Cc: stable@kernel.org
Fixes: 307af6c87937 ("mbcache: automatically delete entries from cache on freeing")
Reported-by: Mike Galbraith 
Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/r/20220908091032.10513-1-jack@suse.cz
Signed-off-by: Theodore Ts'o

Merge tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm

2022-08-05T23:32:45+00:00

Pull MM updates from Andrew Morton:
 "Most of the MM queue. A few things are still pending.

  Liam's maple tree rework didn't make it. This has resulted in a few
  other minor patch series being held over for next time.

  Multi-gen LRU still isn't merged as we were waiting for mapletree to
  stabilize. The current plan is to merge MGLRU into -mm soon and to
  later reintroduce mapletree, with a view to hopefully getting both
  into 6.1-rc1.

  Summary:

   - The usual batches of cleanups from Baoquan He, Muchun Song, Miaohe
     Lin, Yang Shi, Anshuman Khandual and Mike Rapoport

   - Some kmemleak fixes from Patrick Wang and Waiman Long

   - DAMON updates from SeongJae Park

   - memcg debug/visibility work from Roman Gushchin

   - vmalloc speedup from Uladzislau Rezki

   - more folio conversion work from Matthew Wilcox

   - enhancements for coherent device memory mapping from Alex Sierra

   - addition of shared pages tracking and CoW support for fsdax, from
     Shiyang Ruan

   - hugetlb optimizations from Mike Kravetz

   - Mel Gorman has contributed some pagealloc changes to improve
     latency and realtime behaviour.

   - mprotect soft-dirty checking has been improved by Peter Xu

   - Many other singleton patches all over the place"

 [ XFS merge from hell as per Darrick Wong in

   https://lore.kernel.org/all/YshKnxb4VwXycPO8@magnolia/ ]

* tag 'mm-stable-2022-08-03' of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm: (282 commits)
  tools/testing/selftests/vm/hmm-tests.c: fix build
  mm: Kconfig: fix typo
  mm: memory-failure: convert to pr_fmt()
  mm: use is_zone_movable_page() helper
  hugetlbfs: fix inaccurate comment in hugetlbfs_statfs()
  hugetlbfs: cleanup some comments in inode.c
  hugetlbfs: remove unneeded header file
  hugetlbfs: remove unneeded hugetlbfs_ops forward declaration
  hugetlbfs: use helper macro SZ_1{K,M}
  mm: cleanup is_highmem()
  mm/hmm: add a test for cross device private faults
  selftests: add soft-dirty into run_vmtests.sh
  selftests: soft-dirty: add test for mprotect
  mm/mprotect: fix soft-dirty check in can_change_pte_writable()
  mm: memcontrol: fix potential oom_lock recursion deadlock
  mm/gup.c: fix formatting in check_and_migrate_movable_page()
  xfs: fail dax mount if reflink is enabled on a partition
  mm/memcontrol.c: remove the redundant updating of stats_flush_threshold
  userfaultfd: don't fail on unrecognized features
  hugetlb_cgroup: fix wrong hugetlb cgroup numa stat
  ...

mbcache: automatically delete entries from cache on freeing

2022-08-03T03:56:25+00:00

Use the fact that entries with elevated refcount are not removed from
the hash and just move removal of the entry from the hash to the entry
freeing time. When doing this we also change the generic code to hold
one reference to the cache entry, not two of them, which makes code
somewhat more obvious.

Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/r/20220712105436.32204-10-jack@suse.cz
Signed-off-by: Theodore Ts'o

mbcache: Remove mb_cache_entry_delete()

2022-08-03T03:56:25+00:00

Nobody uses mb_cache_entry_delete() anymore. Remove it.

Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/r/20220712105436.32204-9-jack@suse.cz
Signed-off-by: Theodore Ts'o

mbcache: add functions to delete entry if unused

2022-08-03T03:56:25+00:00

Add function mb_cache_entry_delete_or_get() to delete mbcache entry if
it is unused and also add a function to wait for entry to become unused
- mb_cache_entry_wait_unused(). We do not share code between the two
deleting function as one of them will go away soon.

CC: stable@vger.kernel.org
Fixes: 82939d7999df ("ext4: convert to mbcache2")
Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/r/20220712105436.32204-2-jack@suse.cz
Signed-off-by: Theodore Ts'o

mbcache: don't reclaim used entries

2022-08-03T03:56:25+00:00

Do not reclaim entries that are currently used by somebody from a
shrinker. Firstly, these entries are likely useful. Secondly, we will
need to keep such entries to protect pending increment of xattr block
refcount.

CC: stable@vger.kernel.org
Fixes: 82939d7999df ("ext4: convert to mbcache2")
Signed-off-by: Jan Kara 
Link: https://lore.kernel.org/r/20220712105436.32204-1-jack@suse.cz
Signed-off-by: Theodore Ts'o