From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:50231 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755579AbbFSTa4 (ORCPT ); Fri, 19 Jun 2015 15:30:56 -0400 Subject: Patch "md: Close race when setting 'action' to 'idle'." has been added to the 4.0-stable tree To: neilb@suse.de, gregkh@linuxfoundation.org Cc: , From: Date: Fri, 19 Jun 2015 12:30:56 -0700 Message-ID: <143474225625427@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 md: Close race when setting 'action' to 'idle'. 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: md-close-race-when-setting-action-to-idle.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 8e8e2518fceca407bb8fc2a6710d19d2e217892e Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Fri, 12 Jun 2015 19:51:27 +1000 Subject: md: Close race when setting 'action' to 'idle'. From: NeilBrown commit 8e8e2518fceca407bb8fc2a6710d19d2e217892e upstream. Checking ->sync_thread without holding the mddev_lock() isn't really safe, even after flushing the workqueue which ensures md_start_sync() has been run. While this code is waiting for the lock, md_check_recovery could reap the thread itself, and then start another thread (e.g. recovery might finish, then reshape starts). When this thread gets the lock md_start_sync() hasn't run so it doesn't get reaped, but MD_RECOVERY_RUNNING gets cleared. This allows two threads to start which leads to confusion. So don't both if MD_RECOVERY_RUNNING isn't set, but if it is do the flush and the test and the reap all under the mddev_lock to avoid any race with md_check_recovery. Signed-off-by: NeilBrown Fixes: 6791875e2e53 ("md: make reconfig_mutex optional for writes to md sysfs files.") Signed-off-by: Greg Kroah-Hartman --- drivers/md/md.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -4144,13 +4144,14 @@ action_store(struct mddev *mddev, const set_bit(MD_RECOVERY_FROZEN, &mddev->recovery); else clear_bit(MD_RECOVERY_FROZEN, &mddev->recovery); - flush_workqueue(md_misc_wq); - if (mddev->sync_thread) { - set_bit(MD_RECOVERY_INTR, &mddev->recovery); - if (mddev_lock(mddev) == 0) { + if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) && + mddev_lock(mddev) == 0) { + flush_workqueue(md_misc_wq); + if (mddev->sync_thread) { + set_bit(MD_RECOVERY_INTR, &mddev->recovery); md_reap_sync_thread(mddev); - mddev_unlock(mddev); } + mddev_unlock(mddev); } } else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) || test_bit(MD_RECOVERY_NEEDED, &mddev->recovery)) Patches currently in stable-queue which might be from neilb@suse.de are queue-4.0/md-close-race-when-setting-action-to-idle.patch queue-4.0/md-don-t-return-0-from-array_state_store.patch queue-4.0/block-fix-ext_dev_lock-lockdep-report.patch queue-4.0/block-discard-bdi_unregister-in-favour-of-bdi_destroy.patch queue-4.0/blk-mq-free-hctx-ctxs-in-queue-s-release-handler.patch -- To unsubscribe from this list: send the line "unsubscribe stable" in