diff options
| author | Miaohe Lin <linmiaohe@huawei.com> | 2022-04-29 09:40:43 +0300 |
|---|---|---|
| committer | akpm <akpm@linux-foundation.org> | 2022-05-27 19:33:44 +0300 |
| commit | 4a1c3839108afcfec02f4d62d6862b2451b442ab (patch) | |
| tree | 269f48af652f59b12388a6b1a81e58b2694d5b72 | |
| parent | 6cf9a34967ed544ca4c0949e9928dc78fca57ef3 (diff) | |
| download | linux-4a1c3839108afcfec02f4d62d6862b2451b442ab.tar.xz | |
mm/z3fold: always clear PAGE_CLAIMED under z3fold page lock
Think about the below race window:
CPU1 CPU2
z3fold_reclaim_page z3fold_free
test_and_set_bit PAGE_CLAIMED
failed to reclaim page
z3fold_page_lock(zhdr);
add back to the lru list;
z3fold_page_unlock(zhdr);
get_z3fold_header
page_claimed=test_and_set_bit PAGE_CLAIMED
clear_bit(PAGE_CLAIMED, &page->private);
if (!page_claimed) /* it's false true */
free_handle is not called
free_handle won't be called in this case. So z3fold_buddy_slots will leak.
Fix it by always clear PAGE_CLAIMED under z3fold page lock.
Link: https://lkml.kernel.org/r/20220429064051.61552-8-linmiaohe@huawei.com
Signed-off-by: Miaohe Lin <linmiaohe@huawei.com>
Reviewed-by: Vitaly Wool <vitaly.wool@konsulko.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
| -rw-r--r-- | mm/z3fold.c | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/mm/z3fold.c b/mm/z3fold.c index a1c150fc8def..4a3cd2ff15b0 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -1221,8 +1221,8 @@ static void z3fold_free(struct z3fold_pool *pool, unsigned long handle) return; } if (test_and_set_bit(NEEDS_COMPACTING, &page->private)) { - put_z3fold_header(zhdr); clear_bit(PAGE_CLAIMED, &page->private); + put_z3fold_header(zhdr); return; } if (zhdr->cpu < 0 || !cpu_online(zhdr->cpu)) { @@ -1424,8 +1424,8 @@ next: spin_unlock(&pool->lock); if (list_empty(&zhdr->buddy)) add_to_unbuddied(pool, zhdr); - z3fold_page_unlock(zhdr); clear_bit(PAGE_CLAIMED, &page->private); + z3fold_page_unlock(zhdr); } /* We started off locked to we need to lock the pool back */ @@ -1577,8 +1577,8 @@ static int z3fold_page_migrate(struct address_space *mapping, struct page *newpa if (!z3fold_page_trylock(zhdr)) return -EAGAIN; if (zhdr->mapped_count != 0 || zhdr->foreign_handles != 0) { - z3fold_page_unlock(zhdr); clear_bit(PAGE_CLAIMED, &page->private); + z3fold_page_unlock(zhdr); return -EBUSY; } if (work_pending(&zhdr->work)) { |