From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:54255 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1423252AbbEOCSI (ORCPT ); Thu, 14 May 2015 22:18:08 -0400 Subject: Patch "blk-mq: fix race between timeout and CPU hotplug" has been added to the 4.0-stable tree To: ming.lei@canonical.com, axboe@fb.com, dongsu.park@profitbricks.com, gregkh@linuxfoundation.org Cc: , From: Date: Thu, 14 May 2015 19:18:07 -0700 Message-ID: <14316562873596@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 blk-mq: fix race between timeout and CPU hotplug to the 4.0-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: blk-mq-fix-race-between-timeout-and-cpu-hotplug.patch and it can be found in the queue-4.0 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From f054b56c951bf1731ba7314a4c7f1cc0b2977cc9 Mon Sep 17 00:00:00 2001 From: Ming Lei Date: Tue, 21 Apr 2015 10:00:19 +0800 Subject: blk-mq: fix race between timeout and CPU hotplug From: Ming Lei commit f054b56c951bf1731ba7314a4c7f1cc0b2977cc9 upstream. Firstly during CPU hotplug, even queue is freezed, timeout handler still may come and access hctx->tags, which may cause use after free, so this patch deactivates timeout handler inside CPU hotplug notifier. Secondly, tags can be shared by more than one queues, so we have to check if the hctx has been unmapped, otherwise still use-after-free on tags can be triggered. Reported-by: Dongsu Park Tested-by: Dongsu Park Signed-off-by: Ming Lei Signed-off-by: Jens Axboe Signed-off-by: Greg Kroah-Hartman --- block/blk-mq.c | 16 +++++++++++++--- 1 file changed, 13 insertions(+), 3 deletions(-) --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -675,8 +675,11 @@ static void blk_mq_rq_timer(unsigned lon data.next = blk_rq_timeout(round_jiffies_up(data.next)); mod_timer(&q->timeout, data.next); } else { - queue_for_each_hw_ctx(q, hctx, i) - blk_mq_tag_idle(hctx); + queue_for_each_hw_ctx(q, hctx, i) { + /* the hctx may be unmapped, so check it here */ + if (blk_mq_hw_queue_mapped(hctx)) + blk_mq_tag_idle(hctx); + } } } @@ -2075,9 +2078,16 @@ static int blk_mq_queue_reinit_notify(st */ list_for_each_entry(q, &all_q_list, all_q_node) blk_mq_freeze_queue_start(q); - list_for_each_entry(q, &all_q_list, all_q_node) + list_for_each_entry(q, &all_q_list, all_q_node) { blk_mq_freeze_queue_wait(q); + /* + * timeout handler can't touch hw queue during the + * reinitialization + */ + del_timer_sync(&q->timeout); + } + list_for_each_entry(q, &all_q_list, all_q_node) blk_mq_queue_reinit(q); Patches currently in stable-queue which might be from ming.lei@canonical.com are queue-4.0/blk-mq-fix-race-between-timeout-and-cpu-hotplug.patch queue-4.0/blk-mq-fix-cpu-hotplug-handling.patch