From patchwork Fri Sep 22 08:27:14 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chandan Rajendra X-Patchwork-Id: 9965489 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 011AA6057C for ; Fri, 22 Sep 2017 08:26:38 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id E0AC0289CA for ; Fri, 22 Sep 2017 08:26:37 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id D567A28E17; Fri, 22 Sep 2017 08:26:37 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 3AF3B28E80 for ; Fri, 22 Sep 2017 08:26:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751866AbdIVI0g (ORCPT ); Fri, 22 Sep 2017 04:26:36 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:36204 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751860AbdIVI0f (ORCPT ); Fri, 22 Sep 2017 04:26:35 -0400 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v8M8NuYG036288 for ; Fri, 22 Sep 2017 04:26:35 -0400 Received: from e16.ny.us.ibm.com (e16.ny.us.ibm.com [129.33.205.206]) by mx0a-001b2d01.pphosted.com with ESMTP id 2d4png9be0-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Fri, 22 Sep 2017 04:26:34 -0400 Received: from localhost by e16.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Fri, 22 Sep 2017 04:26:30 -0400 Received: from b01ledav002.gho.pok.ibm.com (b01ledav002.gho.pok.ibm.com [9.57.199.107]) by b01cxnp23034.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v8M8QU7j39911536; Fri, 22 Sep 2017 08:26:30 GMT Received: from b01ledav002.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id C755A124047; Fri, 22 Sep 2017 04:23:45 -0400 (EDT) Received: from localhost.in.ibm.com (unknown [9.124.35.186]) by b01ledav002.gho.pok.ibm.com (Postfix) with ESMTP id 404E7124035; Fri, 22 Sep 2017 04:23:44 -0400 (EDT) From: Chandan Rajendra To: linux-xfs@vger.kernel.org Cc: Chandan Rajendra , hch@infradead.org, eguan@redhat.com, linux-fsdevel@vger.kernel.org, david@fromorbit.com Subject: [PATCH V3] iomap_dio_rw: Allocate AIO completion queue before submitting dio Date: Fri, 22 Sep 2017 13:57:14 +0530 X-Mailer: git-send-email 2.9.5 In-Reply-To: <20170922070753.GF10955@dastard> References: <20170922070753.GF10955@dastard> X-TM-AS-GCONF: 00 x-cbid: 17092208-0024-0000-0000-000002D648B8 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007776; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000231; SDB=6.00920623; UDB=6.00462619; IPR=6.00700844; BA=6.00005601; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00017245; XFM=3.00000015; UTC=2017-09-22 08:26:32 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17092208-0025-0000-0000-0000458153B6 Message-Id: <20170922082714.14625-1-chandan@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-09-22_02:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=3 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1707230000 definitions=main-1709220117 Sender: linux-xfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-xfs@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Executing xfs/104 test in a loop on Linux-v4.13 kernel on a ppc64 machine can cause the following NULL pointer dereference, .queue_work_on+0x4c/0x80 .iomap_dio_bio_end_io+0xbc/0x1f0 .bio_endio+0x118/0x1f0 .blk_update_request+0xd0/0x470 .blk_mq_end_request+0x24/0xc0 .lo_complete_rq+0x40/0xe0 .__blk_mq_complete_request_remote+0x28/0x40 .flush_smp_call_function_queue+0xc4/0x1e0 .smp_ipi_demux_relaxed+0x8c/0x100 .icp_hv_ipi_action+0x54/0xa0 .__handle_irq_event_percpu+0x84/0x2c0 .handle_irq_event_percpu+0x28/0x80 .handle_percpu_irq+0x78/0xc0 .generic_handle_irq+0x40/0x70 .__do_irq+0x88/0x200 .call_do_irq+0x14/0x24 .do_IRQ+0x84/0x130 This occurs due to the following sequence of events, 1. Allocate dio for Direct I/O write. 2. Invoke iomap_apply() until iov_iter_count() bytes have been submitted. - Assume that we have submitted atleast one bio. Hence iomap_dio->ref value will be >= 2. - If during the second iteration, iomap_apply() ends up returning -ENOSPC, we would break out of the loop and since the 'ret' value is a negative number we end up not allocating memory for super_block->s_dio_done_wq. 3. Meanwhile, iomap_dio_bio_end_io() is invoked for bios that have been submitted and here the code ends up dereferencing the NULL pointer stored at super_block->s_dio_done_wq. This commit fixes the bug by allocating memory for super_block->s_dio_done_wq before iomap_apply() is invoked. Reported-by: Eryu Guan Reviewed-by: Christoph Hellwig Tested-by: Eryu Guan Signed-off-by: Chandan Rajendra --- Changelog: v1->v2: 1. Fix indentation for the continuation of the if conditional. v2->v3: 1. Remove architecture specific register dumps from the stack trace. fs/iomap.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/iomap.c b/fs/iomap.c index 269b24a..d4f526a 100644 --- a/fs/iomap.c +++ b/fs/iomap.c @@ -993,6 +993,13 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, WARN_ON_ONCE(ret); ret = 0; + if (iov_iter_rw(iter) == WRITE && !is_sync_kiocb(iocb) && + !inode->i_sb->s_dio_done_wq) { + ret = sb_init_dio_done_wq(inode->i_sb); + if (ret < 0) + goto out_free_dio; + } + inode_dio_begin(inode); blk_start_plug(&plug); @@ -1015,13 +1022,6 @@ iomap_dio_rw(struct kiocb *iocb, struct iov_iter *iter, if (ret < 0) iomap_dio_set_error(dio, ret); - if (ret >= 0 && iov_iter_rw(iter) == WRITE && !is_sync_kiocb(iocb) && - !inode->i_sb->s_dio_done_wq) { - ret = sb_init_dio_done_wq(inode->i_sb); - if (ret < 0) - iomap_dio_set_error(dio, ret); - } - if (!atomic_dec_and_test(&dio->ref)) { if (!is_sync_kiocb(iocb)) return -EIOCBQUEUED;