From patchwork Thu Sep 21 09:52:34 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Chandan Rajendra X-Patchwork-Id: 9963651 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 8E564600C5 for ; Thu, 21 Sep 2017 09:52:00 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 74DB3292FE for ; Thu, 21 Sep 2017 09:52:00 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6A53F2944C; Thu, 21 Sep 2017 09:52:00 +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=unavailable 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 01552292FE for ; Thu, 21 Sep 2017 09:52:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751678AbdIUJv5 (ORCPT ); Thu, 21 Sep 2017 05:51:57 -0400 Received: from mx0b-001b2d01.pphosted.com ([148.163.158.5]:44926 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751528AbdIUJv4 (ORCPT ); Thu, 21 Sep 2017 05:51:56 -0400 Received: from pps.filterd (m0098420.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id v8L9odoO033560 for ; Thu, 21 Sep 2017 05:51:56 -0400 Received: from e34.co.us.ibm.com (e34.co.us.ibm.com [32.97.110.152]) by mx0b-001b2d01.pphosted.com with ESMTP id 2d48cgrxpx-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 21 Sep 2017 05:51:55 -0400 Received: from localhost by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! 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Violators will be prosecuted; Thu, 21 Sep 2017 03:51:52 -0600 Received: from b03ledav002.gho.boulder.ibm.com (b03ledav002.gho.boulder.ibm.com [9.17.130.233]) by b03cxnp08026.gho.boulder.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id v8L9pqnT64553204; Thu, 21 Sep 2017 02:51:52 -0700 Received: from b03ledav002.gho.boulder.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id E65BB13603C; Thu, 21 Sep 2017 03:51:51 -0600 (MDT) Received: from localhost.localdomain.com (unknown [9.85.73.252]) by b03ledav002.gho.boulder.ibm.com (Postfix) with ESMTP id 0A206136044; Thu, 21 Sep 2017 03:51:49 -0600 (MDT) From: Chandan Rajendra To: linux-xfs@vger.kernel.org Cc: Chandan Rajendra , hch@infradead.org, eguan@redhat.com, linux-fsdevel@vger.kernel.org Subject: [PATCH] iomap_dio_rw: Allocate AIO completion queue before submitting dio Date: Thu, 21 Sep 2017 15:22:34 +0530 X-Mailer: git-send-email 2.9.5 X-TM-AS-GCONF: 00 x-cbid: 17092109-0016-0000-0000-0000078C6DE0 X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00007772; HX=3.00000241; KW=3.00000007; PH=3.00000004; SC=3.00000230; SDB=6.00920172; UDB=6.00462351; IPR=6.00700394; BA=6.00005599; NDR=6.00000001; ZLA=6.00000005; ZF=6.00000009; ZB=6.00000000; ZP=6.00000000; ZH=6.00000000; ZU=6.00000002; MB=3.00017234; XFM=3.00000015; UTC=2017-09-21 09:51:54 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 17092109-0017-0000-0000-00003B8EBA6C Message-Id: <20170921095234.12401-1-chandan@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:, , definitions=2017-09-21_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-1709210135 Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@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, Unable to handle kernel paging request for data at address 0x00000100 Faulting instruction address: 0xc0000000000fece8 Oops: Kernel access of bad area, sig: 11 [#1] SMP NR_CPUS=2048 DEBUG_PAGEALLOC NUMA pSeries Modules linked in: CPU: 2 PID: 0 Comm: swapper/2 Not tainted 4.13.0 #1 task: c00000063849c200 task.stack: c0000006384f0000 NIP: c0000000000fece8 LR: c0000000000ff2cc CTR: c000000000383380 REGS: c00000063ffdb400 TRAP: 0300 Not tainted (4.13.0) MSR: 8000000000009032 CR: 28002222 XER: 20000000 CFAR: c0000000000227a4 DAR: 0000000000000100 DSISR: 40000000 SOFTE: 0 GPR00: c0000000000ff2cc c00000063ffdb680 c000000001252e00 0000000000000800 GPR04: 0000000000000000 c0000006387b8730 c000000633d5db70 0000000fffffffe1 GPR08: c0000003aa89ed68 0000000000000000 0000000000000000 c000000633d5db70 GPR12: 0000000028002422 c00000000fd80a00 c0000006384f3f90 c00000063ffd8000 GPR16: 0000000000000000 c0000006387b8730 c0000000012475e0 c0000000012475e0 GPR20: 0000000000000002 0000000000000000 0000000000000001 0000000000000002 GPR24: 0000000000000010 c00000063e155800 0000000000000800 0000000000000800 GPR28: 0000000000000000 c000000633d5db00 0000000000000000 0000000000000000 NIP [c0000000000fece8] .__queue_work+0x68/0x600 LR [c0000000000ff2cc] .queue_work_on+0x4c/0x80 Call Trace: [c00000063ffdb680] [c00000063ffdb720] 0xc00000063ffdb720 (unreliable) [c00000063ffdb770] [c0000000000ff2cc] .queue_work_on+0x4c/0x80 [c00000063ffdb7f0] [c00000000038343c] .iomap_dio_bio_end_io+0xbc/0x1f0 [c00000063ffdb880] [c0000000006cdc18] .bio_endio+0x118/0x1f0 [c00000063ffdb910] [c0000000006d9e30] .blk_update_request+0xd0/0x470 [c00000063ffdb9b0] [c0000000006e8284] .blk_mq_end_request+0x24/0xc0 [c00000063ffdba30] [c00000000082ba50] .lo_complete_rq+0x40/0xe0 [c00000063ffdbab0] [c0000000006e5e48] .__blk_mq_complete_request_remote+0x28/0x40 [c00000063ffdbb20] [c00000000018e674] .flush_smp_call_function_queue+0xc4/0x1e0 [c00000063ffdbbb0] [c00000000003f94c] .smp_ipi_demux_relaxed+0x8c/0x100 [c00000063ffdbc40] [c000000000081054] .icp_hv_ipi_action+0x54/0xa0 [c00000063ffdbcc0] [c0000000001505a4] .__handle_irq_event_percpu+0x84/0x2c0 [c00000063ffdbd90] [c000000000150808] .handle_irq_event_percpu+0x28/0x80 [c00000063ffdbe20] [c000000000156858] .handle_percpu_irq+0x78/0xc0 [c00000063ffdbea0] [c00000000014ee70] .generic_handle_irq+0x40/0x70 [c00000063ffdbf10] [c000000000015a88] .__do_irq+0x88/0x200 [c00000063ffdbf90] [c000000000027a70] .call_do_irq+0x14/0x24 [c0000006384f3810] [c000000000015c84] .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 Signed-off-by: Chandan Rajendra Reviewed-by: Christoph Hellwig Tested-by: Eryu Guan --- fs/iomap.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) diff --git a/fs/iomap.c b/fs/iomap.c index 59cc98a..c91abc1 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;