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 X-Spam-Level: X-Spam-Status: No, score=-11.7 required=3.0 tests=FORGED_MUA_MOZILLA, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 493D8C433DF for ; Tue, 2 Jun 2020 12:41:51 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 29BBB20679 for ; Tue, 2 Jun 2020 12:41:51 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728129AbgFBMlu (ORCPT ); Tue, 2 Jun 2020 08:41:50 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:21986 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725940AbgFBMlp (ORCPT ); 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Tue, 2 Jun 2020 12:41:31 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A973642041; Tue, 2 Jun 2020 12:41:31 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 256274203F; Tue, 2 Jun 2020 12:41:30 +0000 (GMT) Received: from localhost.localdomain (unknown [9.85.91.137]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Tue, 2 Jun 2020 12:41:29 +0000 (GMT) Subject: Re: linux-next test error: BUG: using smp_processor_id() in preemptible [ADDR] code: syz-fuzzer/6792 To: syzbot , adilger.kernel@dilger.ca, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, linux-next@vger.kernel.org, sfr@canb.auug.org.au, syzkaller-bugs@googlegroups.com, tytso@mit.edu References: <0000000000008ff8ea05a71818b5@google.com> From: Ritesh Harjani Date: Tue, 2 Jun 2020 18:11:29 +0530 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 MIME-Version: 1.0 In-Reply-To: <0000000000008ff8ea05a71818b5@google.com> Content-Type: multipart/mixed; boundary="------------8CCD057140658DF24F4D91CA" Content-Language: en-US Message-Id: <20200602124130.256274203F@d06av24.portsmouth.uk.ibm.com> X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.216,18.0.687 definitions=2020-06-02_13:2020-06-02,2020-06-02 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1011 priorityscore=1501 impostorscore=0 lowpriorityscore=0 bulkscore=0 adultscore=0 suspectscore=0 cotscore=-2147483648 phishscore=0 malwarescore=0 mlxscore=0 spamscore=0 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006020089 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------8CCD057140658DF24F4D91CA Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit #syz test: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git 0e21d4620dd047da7952f44a2e1ac777ded2d57e --------------8CCD057140658DF24F4D91CA Content-Type: text/x-patch; charset=UTF-8; name="0001-ext4-mballoc-Use-raw_cpu_ptr-in-case-if-preemption-i.patch" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename*0="0001-ext4-mballoc-Use-raw_cpu_ptr-in-case-if-preemption-i.pa"; filename*1="tch" >From cc1cf67d99d5fa61db0651c89c288df31bad6b8e Mon Sep 17 00:00:00 2001 From: Ritesh Harjani Date: Tue, 2 Jun 2020 17:54:12 +0530 Subject: [PATCH 1/1] ext4: mballoc: Use raw_cpu_ptr in case if preemption is enabled It doesn't matter really in ext4_mb_new_blocks() about whether the code is rescheduled on any other cpu due to preemption. Because we care about discard_pa_seq only when the block allocation fails and then too we add the seq counter of all the cpus against the initial sampled one to check if anyone has freed any blocks while we were doing allocation. So just use raw_cpu_ptr to not trigger this BUG. BUG: using smp_processor_id() in preemptible [00000000] code: syz-fuzzer/6927 caller is ext4_mb_new_blocks+0xa4d/0x3b70 fs/ext4/mballoc.c:4711 CPU: 1 PID: 6927 Comm: syz-fuzzer Not tainted 5.7.0-next-20200602-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x18f/0x20d lib/dump_stack.c:118 check_preemption_disabled+0x20d/0x220 lib/smp_processor_id.c:48 ext4_mb_new_blocks+0xa4d/0x3b70 fs/ext4/mballoc.c:4711 ext4_ext_map_blocks+0x201b/0x33e0 fs/ext4/extents.c:4244 ext4_map_blocks+0x4cb/0x1640 fs/ext4/inode.c:626 ext4_getblk+0xad/0x520 fs/ext4/inode.c:833 ext4_bread+0x7c/0x380 fs/ext4/inode.c:883 ext4_append+0x153/0x360 fs/ext4/namei.c:67 ext4_init_new_dir fs/ext4/namei.c:2757 [inline] ext4_mkdir+0x5e0/0xdf0 fs/ext4/namei.c:2802 vfs_mkdir+0x419/0x690 fs/namei.c:3632 do_mkdirat+0x21e/0x280 fs/namei.c:3655 do_syscall_64+0x60/0xe0 arch/x86/entry/common.c:359 entry_SYSCALL_64_after_hwframe+0x44/0xa9 Signed-off-by: Ritesh Harjani Reported-by: syzbot+82f324bb69744c5f6969@syzkaller.appspotmail.com --- fs/ext4/mballoc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index a9083113a8c0..b79b32dbe3ea 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4708,7 +4708,7 @@ ext4_fsblk_t ext4_mb_new_blocks(handle_t *handle, } ac->ac_op = EXT4_MB_HISTORY_PREALLOC; - seq = *this_cpu_ptr(&discard_pa_seq); + seq = *raw_cpu_ptr(&discard_pa_seq); if (!ext4_mb_use_preallocated(ac)) { ac->ac_op = EXT4_MB_HISTORY_ALLOC; ext4_mb_normalize_request(ac, ar); -- 2.21.3 --------------8CCD057140658DF24F4D91CA--