From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 11A1D20B38 for ; Wed, 20 Dec 2023 04:19:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="kvBk1zO1" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=RFQC95dSOgg5PvV853KUGsy4ImkW0LGUKynkOnk85XQ=; b=kvBk1zO1kRDMvoV1aHndE2MNaY 8jTbvEiGqTOs8FmAnv7M34l4/dpVAsqradgRAwhP69AzVproqwORmJw7O+0zfO2EUVo2NgbByqLp7 e5pLDfezQfOy8pAGcCSThqTGbIO+TM4uBv2KAIvRxDEFW2yJ+QruB8ax+ARP9Un68bRaYtVkPB1UM MFibTkWA36uAtIHtu3K95Jdmrjf8AVsBhTlfw+POThBKWNsVKEVbhtBx0g6rG9lErn7R4C01pTEW4 i89PzAdSUsHw02i+oHe0plUk51srhpGUS6WKA7h6UhsHwJ4fMS1f99F/HYZFsG7Zof8u9HU3I+DFn 0GTROXdw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1rFo3S-003g82-FO; Wed, 20 Dec 2023 04:19:34 +0000 Date: Wed, 20 Dec 2023 04:19:34 +0000 From: Matthew Wilcox To: syzbot Cc: akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [mm?] kernel BUG in add_to_swap Message-ID: References: <000000000000678f8b060cdc9313@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <000000000000678f8b060cdc9313@google.com> On Tue, Dec 19, 2023 at 05:09:25AM -0800, syzbot wrote: > raw: 05ffc00000480011 dead000000000100 dead000000000122 ffff0000d90d0aa1 > raw: 0000000000020ffd 0000000000000000 00000002ffffffff ffff00012a670000 > page dumped because: VM_BUG_ON_FOLIO(!folio_test_uptodate(folio)) The missing part of the dump: page:0000000058ec4ec0 refcount:2 mapcount:0 mapping:0000000000000000 index:0x20ffd pfn:0x16fc28 memcg:ffff00012a670000 anon flags: 0x5ffc00000480011(locked|dirty|swapbacked|hwpoison|node=0|zone=2|lastcpupid=0x7ff) page_type: 0xffffffff() raw: 05ffc00000480011 dead000000000100 dead000000000122 ffff0000d90d0aa1 raw: 0000000000020ffd 0000000000000000 00000002ffffffff ffff00012a670000 page dumped because: VM_BUG_ON_FOLIO(!folio_test_uptodate(folio)) I'm not sure how we get an anonymous dirty folio that's not uptodate. It's order-0, so that doesn't implicate any of the recent positive-order work.