From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 90DEEC74A5B for ; Wed, 29 Mar 2023 20:37:14 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id D9C006B0072; Wed, 29 Mar 2023 16:37:13 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id D4CEE6B0074; Wed, 29 Mar 2023 16:37:13 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C14C96B0075; Wed, 29 Mar 2023 16:37:13 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0017.hostedemail.com [216.40.44.17]) by kanga.kvack.org (Postfix) with ESMTP id AFE956B0072 for ; Wed, 29 Mar 2023 16:37:13 -0400 (EDT) Received: from smtpin09.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay09.hostedemail.com (Postfix) with ESMTP id 5B56580EB6 for ; Wed, 29 Mar 2023 20:37:13 +0000 (UTC) X-FDA: 80623095546.09.25F1CD3 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf26.hostedemail.com (Postfix) with ESMTP id 5D1B914000A for ; Wed, 29 Mar 2023 20:37:10 +0000 (UTC) Authentication-Results: imf26.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b="tuC4/n8E"; spf=pass (imf26.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1680122230; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=YxVLF2VcSmGaU3sU2pUZtyO6q4cvVmIwQJLtoeYYPQE=; b=iHK8QlMWlyqvYxeVB6B1puvbGOn1Dc49U1siEmGAcJfghsnqMMiBzJWQSPKHNfzLbvyzc3 8sx9dx0xkoB1SMuDWdtlpWs7LhRvTUzKVK+e9ZEcODoXMctZTwplG1V8Qrff52gVL0ZdXa jrXAGqY35iIdrhf+b0+7dCUxCzyKVd0= ARC-Authentication-Results: i=1; imf26.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b="tuC4/n8E"; spf=pass (imf26.hostedemail.com: domain of akpm@linux-foundation.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1680122230; a=rsa-sha256; cv=none; b=SXPwps/SaH/lM03741buMq6FAeQQEtnhG2tFlPgTrQAphxBbwlAtouBDK+yfH0Rl2U1wIZ j7KloTc13AytQXIonbWGyXYstQvB/HovzEloM/FwUWBpsN6S+QHBU+QJOj73OsoRemSsCW L1YPPEHdL9BPZp8z00RW/4kgopQlmSA= Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 5EC0B61E3F; Wed, 29 Mar 2023 20:37:09 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 75CD8C433D2; Wed, 29 Mar 2023 20:37:08 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1680122228; bh=2I0JCeUtFGxllsjUjz1+8sN/d7dbpHqfz5oKNQ3vfTY=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=tuC4/n8EzvpZ3/oHnj4RCNIEHbpjqOm2O7NDHEfSij+yazs7vKG3dO0+sNFPqQvn2 ZFZqMtZbZKqG3y0nzmgUlQ1bV27BNoS/irkhAPXDGl9zAo78A28DKnbyvaSY5Ir8dD DJ8lSYrMtRAvw1/ds6D3UROilqwNMntALQAkR+hc= Date: Wed, 29 Mar 2023 13:37:07 -0700 From: Andrew Morton To: Ivan Orlov Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, himadrispandya@gmail.com, skhan@linuxfoundation.org, linux-kernel-mentees@lists.linuxfoundation.org, syzbot+9578faa5475acb35fa50@syzkaller.appspotmail.com, Song Liu , Rik van Riel , Kirill A. Shutemov , Johannes Weiner Subject: Re: [PATCH] mm: khugepaged: Fix kernel BUG in hpage_collapse_scan_file Message-Id: <20230329133707.10b555eff630849a5293e4fd@linux-foundation.org> In-Reply-To: <20230329145330.23191-1-ivan.orlov0322@gmail.com> References: <20230329145330.23191-1-ivan.orlov0322@gmail.com> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Stat-Signature: kszg7jr6bzzm34hh4yd5pxhkybxirghk X-Rspam-User: X-Rspamd-Queue-Id: 5D1B914000A X-Rspamd-Server: rspam06 X-HE-Tag: 1680122230-832062 X-HE-Meta: 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 +Zp5zD/Z 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Wed, 29 Mar 2023 18:53:30 +0400 Ivan Orlov wrote: > Syzkaller reported the following issue: > > kernel BUG at mm/khugepaged.c:1823! > invalid opcode: 0000 [#1] PREEMPT SMP KASAN > CPU: 1 PID: 5097 Comm: syz-executor220 Not tainted 6.2.0-syzkaller-13154-g857f1268a591 #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/16/2023 > RIP: 0010:collapse_file mm/khugepaged.c:1823 [inline] > RIP: 0010:hpage_collapse_scan_file+0x67c8/0x7580 mm/khugepaged.c:2233 > Code: 00 00 89 de e8 c9 66 a3 ff 31 ff 89 de e8 c0 66 a3 ff 45 84 f6 0f 85 28 0d 00 00 e8 22 64 a3 ff e9 dc f7 ff ff e8 18 64 a3 ff <0f> 0b f3 0f 1e fa e8 0d 64 a3 ff e9 93 f6 ff ff f3 0f 1e fa 4c 89 > RSP: 0018:ffffc90003dff4e0 EFLAGS: 00010093 > RAX: ffffffff81e95988 RBX: 00000000000001c1 RCX: ffff8880205b3a80 > RDX: 0000000000000000 RSI: 00000000000001c0 RDI: 00000000000001c1 > RBP: ffffc90003dff830 R08: ffffffff81e90e67 R09: fffffbfff1a433c3 > R10: 0000000000000000 R11: dffffc0000000001 R12: 0000000000000000 > R13: ffffc90003dff6c0 R14: 00000000000001c0 R15: 0000000000000000 > FS: 00007fdbae5ee700(0000) GS:ffff8880b9900000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007fdbae6901e0 CR3: 000000007b2dd000 CR4: 00000000003506e0 > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > Call Trace: > > madvise_collapse+0x721/0xf50 mm/khugepaged.c:2693 > madvise_vma_behavior mm/madvise.c:1086 [inline] > madvise_walk_vmas mm/madvise.c:1260 [inline] > do_madvise+0x9e5/0x4680 mm/madvise.c:1439 > __do_sys_madvise mm/madvise.c:1452 [inline] > __se_sys_madvise mm/madvise.c:1450 [inline] > __x64_sys_madvise+0xa5/0xb0 mm/madvise.c:1450 > do_syscall_x64 arch/x86/entry/common.c:50 [inline] > do_syscall_64+0x41/0xc0 arch/x86/entry/common.c:80 > entry_SYSCALL_64_after_hwframe+0x63/0xcd > > The 'xas_store' call during page cache scanning can potentially > translate 'xas' into the error state (with the reproducer provided > by the syzkaller the error code is -ENOMEM). However, there are no > further checks after the 'xas_store', and the next call of 'xas_next' > at the start of the scanning cycle doesn't increase the xa_index, > and the issue occurs. > > This patch will add the xarray state error checking after the > 'xas_store' and the corresponding result error code. > Thanks. We'll want a Fixes: for this to go with a cc:stable. So when did we break this? I'm thinking 99cb0dbd47a15 ("mm,thp: add read-only THP support for (non-shmem) FS"), which did + if (!page) { + /* + * Stop if extent has been truncated or + * hole-punched, and is now completely + * empty. + */ + if (index == start) { + if (!xas_next_entry(&xas, end - 1)) { + result = SCAN_TRUNCATED; + goto xa_locked; + } + xas_set(&xas, index); + } + if (!shmem_charge(mapping->host, 1)) { + result = SCAN_FAIL; goto xa_locked; } - xas_set(&xas, index); + xas_store(&xas, new_page); + nr_none++; + continue; }