Re: [syzbot] [mm?] KASAN: slab-use-after-free Read in folio_evictable (3)

[Hillf Danton]

On Fri, Dec 13, 2024 at 9:18
> syzbot has found a reproducer for the following issue on:
>
> HEAD commit:    f932fb9b4074 Merge tag 'v6.13-rc2-ksmbd-server-fixes' of g..
> git tree:       upstream
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=14654730580000

#syz test

--- x/mm/filemap.c
+++ y/mm/filemap.c
@@ -871,6 +871,7 @@ noinline int __filemap_add_folio(struct
 	folio_ref_add(folio, nr);
 	folio->mapping = mapping;
 	folio->index = xas.xa_index;
+	BUG_ON(mapping_exiting(mapping));
 
 	for (;;) {
 		int order = -1, split_order = 0;
--