Re: [syzbot] [mm?] BUG: corrupted list in do_compact_page

[Hillf Danton]

On Wed, 02 Oct 2024 22:22:24 -0700
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    f23aa4c0761a Merge tag 'hid-for-linus-2024090201' of git:/..
> git tree:       upstream
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=174ab580580000

#syz test

--- x/mm/z3fold.c
+++ y/mm/z3fold.c
@@ -1351,8 +1351,11 @@ static void z3fold_page_putback(struct p
 	pool = zhdr_to_pool(zhdr);
 
 	z3fold_page_lock(zhdr);
-	if (!list_empty(&zhdr->buddy))
+	if (!list_empty(&zhdr->buddy)) {
+		spin_lock(&pool->lock);
 		list_del_init(&zhdr->buddy);
+		spin_unlock(&pool->lock);
+	}
 	INIT_LIST_HEAD(&page->lru);
 	if (put_z3fold_locked(zhdr))
 		return;
--