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.
Signed-off-by: Vitaly Wool <vitalyw...@gmail.com>
---
mm/z3fold.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
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.
--
2.11.0
