The patch titled
Subject: mm/z3fold: fix the comment for __encode_handle()
has been added to the -mm mm-unstable branch. Its filename is
mm-z3fold-fix-the-comment-for-__encode_handle.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-z3fold-fix-the-comment-for-__encode_handle.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Zhongkun He <hezhongkun.hzk@xxxxxxxxxxxxx>
Subject: mm/z3fold: fix the comment for __encode_handle()
Date: Mon, 19 Feb 2024 10:44:53 +0800
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.
Link: https://lkml.kernel.org/r/20240219024453.2240147-1-hezhongkun.hzk@xxxxxxxxxxxxx
Signed-off-by: Zhongkun He <hezhongkun.hzk@xxxxxxxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Vitaly Wool <vitaly.wool@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/z3fold.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)
--- a/mm/z3fold.c~mm-z3fold-fix-the-comment-for-__encode_handle
+++ a/mm/z3fold.c
@@ -364,8 +364,9 @@ static inline int __idx(struct z3fold_he
}
/*
- * 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,
_
Patches currently in -mm which might be from hezhongkun.hzk@xxxxxxxxxxxxx are
mm-z3fold-remove-unneeded-spinlock-in-z3fold_alloc.patch
mm-z3fold-remove-unneeded-spinlock.patch
mm-z3fold-fix-the-comment-for-__encode_handle.patch
