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authorMinchan Kim <minchan@kernel.org>2022-03-22 14:39:34 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2022-03-22 15:57:01 -0700
commitc0226eb8bde854e016a594a16f5c0d98aca426fa (patch)
tree47171e4a456ae9bf87f3c1036181527e85d68751 /fs
parent854d8e36168d79ad09a831d60bd4d835ad33e188 (diff)
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')
-rw-r--r--fs/buffer.c8
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++) {