Re: [syzbot] [mm?] WARNING in __folio_rmap_sanity_checks (2)

[Hillf Danton]

On Fri, 27 Dec 2024 20:56:21 -0800
> syzbot has found a reproducer for the following issue on:
> 
> HEAD commit:    8155b4ef3466 Add linux-next specific files for 20241220
> git tree:       linux-next
> syz repro:      https://syzkaller.appspot.com/x/repro.syz?x=1652fadf980000

#syz test

--- x/mm/filemap.c
+++ y/mm/filemap.c
@@ -3636,6 +3636,7 @@ static vm_fault_t filemap_map_folio_rang
 		continue;
 skip:
 		if (count) {
+			VM_WARN_ON_FOLIO(page_folio(page) != folio, folio);
 			set_pte_range(vmf, folio, page, count, addr);
 			*rss += count;
 			folio_ref_add(folio, count);
--