diff options
| author | Minchan Kim <minchan@kernel.org> | 2022-03-22 14:39:34 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2022-03-22 15:57:01 -0700 |
| commit | c0226eb8bde854e016a594a16f5c0d98aca426fa (patch) | |
| tree | 47171e4a456ae9bf87f3c1036181527e85d68751 /fs/buffer.c | |
| parent | 854d8e36168d79ad09a831d60bd4d835ad33e188 (diff) | |
| download | lwn-c0226eb8bde854e016a594a16f5c0d98aca426fa.tar.gz lwn-c0226eb8bde854e016a594a16f5c0d98aca426fa.zip | |
mm: fs: fix lru_cache_disabled race in bh_lru
Check lru_cache_disabled under bh_lru_lock. Otherwise, it could introduce
race below and it fails to migrate pages containing buffer_head.
CPU 0 CPU 1
bh_lru_install
lru_cache_disable
lru_cache_disabled = false
atomic_inc(&lru_disable_count);
invalidate_bh_lrus_cpu of CPU 0
bh_lru_lock
__invalidate_bh_lrus
bh_lru_unlock
bh_lru_lock
install the bh
bh_lru_unlock
WHen this race happens a CMA allocation fails, which is critical for
the workload which depends on CMA.
Link: https://lkml.kernel.org/r/20220308180709.2017638-1-minchan@kernel.org
Fixes: 8cc621d2f45d ("mm: fs: invalidate BH LRU during page migration")
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: Chris Goldsworthy <cgoldswo@codeaurora.org>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: John Dias <joaodias@google.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/buffer.c')
| -rw-r--r-- | fs/buffer.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/fs/buffer.c b/fs/buffer.c index 8e112b6bd371..c76a8ef60a75 100644 --- a/fs/buffer.c +++ b/fs/buffer.c @@ -1235,16 +1235,18 @@ static void bh_lru_install(struct buffer_head *bh) int i; check_irqs_on(); + bh_lru_lock(); + /* * the refcount of buffer_head in bh_lru prevents dropping the * attached page(i.e., try_to_free_buffers) so it could cause * failing page migration. * Skip putting upcoming bh into bh_lru until migration is done. */ - if (lru_cache_disabled()) + if (lru_cache_disabled()) { + bh_lru_unlock(); return; - - bh_lru_lock(); + } b = this_cpu_ptr(&bh_lrus); for (i = 0; i < BH_LRU_SIZE; i++) { |