diff options
| author | Vitaly Wool <[email protected]> | 2017-10-03 16:14:47 -0700 |
|---|---|---|
| committer | Linus Torvalds <[email protected]> | 2017-10-03 17:54:24 -0700 |
| commit | d5567c9df1ef001b2a7e6684b3b3498371ee4cae (patch) | |
| tree | b3ce7486314ee88b61cb34f010947c6b40f8548f | |
| parent | d9d73e81fe82fdf4ee65a48c26531edc04108349 (diff) | |
z3fold: fix potential race in z3fold_reclaim_page
It is possible that on a (partially) unsuccessful page reclaim,
kref_put() called in z3fold_reclaim_page() does not yield page release,
but the page is released shortly afterwards by another thread. Then
z3fold_reclaim_page() would try to list_add() that (released) page again
which is obviously a bug.
To avoid that, spin_lock() has to be taken earlier, before the
kref_put() call mentioned earlier.
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Vitaly Wool <[email protected]>
Cc: Dan Streetman <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
| -rw-r--r-- | mm/z3fold.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c index 486550df32be..b04fa3ba1bf2 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -875,16 +875,18 @@ static int z3fold_reclaim_page(struct z3fold_pool *pool, unsigned int retries) goto next; } next: + spin_lock(&pool->lock); if (test_bit(PAGE_HEADLESS, &page->private)) { if (ret == 0) { + spin_unlock(&pool->lock); free_z3fold_page(page); return 0; } } else if (kref_put(&zhdr->refcount, release_z3fold_page)) { atomic64_dec(&pool->pages_nr); + spin_unlock(&pool->lock); return 0; } - spin_lock(&pool->lock); /* * Add to the beginning of LRU. |