In zs_page_migrate(), locks are acquired in the following order: 1. write_lock(&pool->lock) 2. spin_lock(&class->lock) 3. zspage_write_trylock(zspage) However, upon successful page migration, they were being released in forward acquisition (FIFO) order: 1. write_unlock(&pool->lock) 2. spin_unlock(&class->lock) 3. zspage_write_unlock(zspage) Fix the unlocking order to release locks in strict reverse (LIFO) order of acquisition: 3. zspage_write_unlock(zspage) 2. spin_unlock(&class->lock) 1. write_unlock(&pool->lock) Releasing locks in reverse order of acquisition adheres to standard kernel locking hygiene, prevents potential lock ordering and lockdep inconsistencies. Signed-off-by: Richard Chang --- mm/zsmalloc.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c index 83f5820c45f9..b09299115886 100644 --- a/mm/zsmalloc.c +++ b/mm/zsmalloc.c @@ -1772,9 +1772,9 @@ static int zs_page_migrate(struct page *newpage, struct page *page, * Since we complete the data copy and set up new zspage structure, * it's okay to release migration_lock. */ - write_unlock(&pool->lock); - spin_unlock(&class->lock); zspage_write_unlock(zspage); + spin_unlock(&class->lock); + write_unlock(&pool->lock); zpdesc_get(newzpdesc); if (zpdesc_zone(newzpdesc) != zpdesc_zone(zpdesc)) { -- 2.55.0.229.g6434b31f56-goog