Re: [syzbot] Re: [syzbot] [squashfs?] KMSAN: uninit-value in pick_link

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Subject: Re: [syzbot] [squashfs?] KMSAN: uninit-value in pick_link
Author: lizhi.xu@xxxxxxxxxxxxx

if alloc new folio for filemap, init mem to zero

#syz test: upstream 2f8c4f506285

diff --git a/mm/filemap.c b/mm/filemap.c
index 657bcd887fdb..1b22eab691e8 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -3753,6 +3753,11 @@ static struct folio *do_read_cache_folio(struct address_space *mapping,
 		folio = filemap_alloc_folio(gfp, 0);
 		if (!folio)
 			return ERR_PTR(-ENOMEM);
+
+		void *kaddr = kmap_local_folio(folio, 0);
+		memset(kaddr, 0, folio_size(folio));
+		kunmap_local(kaddr);
+
 		err = filemap_add_folio(mapping, folio, index, gfp);
 		if (unlikely(err)) {
 			folio_put(folio);