The comment is confusing that Pool lock should be held as this function accesses first_num above the __encode_handle() because first_num is the element of z3fold_header which is protected by z3fold_header->page_lock. I found the same comment for encode_handle() in zbud.c by accident ,Pool lock should be held as this function accesses first|last_chunks, which is the element of zbud_header and it does not have any lock, so pool lock should be held. Z3fold is based on zbud, maybe the comment come from zbud, but it was wrong, so fix it. Signed-off-by: Zhongkun He <hezhongkun.hzk@xxxxxxxxxxxxx> --- mm/z3fold.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/z3fold.c b/mm/z3fold.c index 58946cacbfbb..446cd11e2cad 100644 --- a/mm/z3fold.c +++ b/mm/z3fold.c @@ -364,8 +364,9 @@ static inline int __idx(struct z3fold_header *zhdr, enum buddy bud) } /* - * Encodes the handle of a particular buddy within a z3fold page - * Pool lock should be held as this function accesses first_num + * Encodes the handle of a particular buddy within a z3fold page. + * Zhdr->page_lock should be held as this function accesses first_num + * if bud != HEADLESS. */ static unsigned long __encode_handle(struct z3fold_header *zhdr, struct z3fold_buddy_slots *slots, -- 2.25.1
