From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:38580 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932273AbdJXMxt (ORCPT ); Tue, 24 Oct 2017 08:53:49 -0400 Subject: Patch "iomap_dio_rw: Allocate AIO completion queue before submitting dio" has been added to the 4.13-stable tree To: chandan@linux.vnet.ibm.com, darrick.wong@oracle.com, eguan@redhat.com, gregkh@linuxfoundation.org, hch@lst.de Cc: , From: Date: Tue, 24 Oct 2017 14:53:45 +0200 Message-ID: <1508849625203217@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled iomap_dio_rw: Allocate AIO completion queue before submitting dio to the 4.13-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: iomap_dio_rw-allocate-aio-completion-queue-before-submitting-dio.patch and it can be found in the queue-4.13 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 546e7be8244dc050effef0555df5b8d94d10dafc Mon Sep 17 00:00:00 2001 From: Chandan Rajendra Date: Fri, 22 Sep 2017 11:47:33 -0700 Subject: iomap_dio_rw: Allocate AIO completion queue before submitting dio From: Chandan Rajendra commit 546e7be8244dc050effef0555df5b8d94d10dafc upstream. 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 Reviewed-by: Darrick J. Wong Signed-off-by: Darrick J. Wong Signed-off-by: Greg Kroah-Hartman --- fs/iomap.c | 14 +++++++------- 1 file changed, 7 insertions(+), 7 deletions(-) --- a/fs/iomap.c +++ b/fs/iomap.c @@ -993,6 +993,13 @@ iomap_dio_rw(struct kiocb *iocb, struct 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 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; Patches currently in stable-queue which might be from chandan@linux.vnet.ibm.com are queue-4.13/iomap_dio_rw-allocate-aio-completion-queue-before-submitting-dio.patch