From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752735AbdLMC7B (ORCPT ); Tue, 12 Dec 2017 21:59:01 -0500 Received: from omzsmtpe03.verizonbusiness.com ([199.249.25.208]:7684 "EHLO omzsmtpe03.verizonbusiness.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752582AbdLMB4N (ORCPT ); Tue, 12 Dec 2017 20:56:13 -0500 From: alexander.levin@verizon.com Cc: Guoqing Jiang , Shaohua Li , alexander.levin@verizon.com X-Host: pioneer.tdc.vzwcorp.com To: "linux-kernel@vger.kernel.org" , "stable@vger.kernel.org" Subject: [PATCH AUTOSEL for 4.14 26/60] md: always set THREAD_WAKEUP and wake up wqueue if thread existed Thread-Topic: [PATCH AUTOSEL for 4.14 26/60] md: always set THREAD_WAKEUP and wake up wqueue if thread existed Thread-Index: AQHTc7VsAUhWK+/jQEuU0LgjqSdhJA== Date: Wed, 13 Dec 2017 01:55:16 +0000 Message-ID: <20171213015455.6455-26-alexander.levin@verizon.com> References: <20171213015455.6455-1-alexander.levin@verizon.com> In-Reply-To: <20171213015455.6455-1-alexander.levin@verizon.com> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-messagesentrepresentingtype: 1 x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.144.60.250] Content-Type: text/plain; charset="iso-8859-1" MIME-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: 8bit X-MIME-Autoconverted: from quoted-printable to 8bit by nfs id vBD2x601025996 From: Guoqing Jiang [ Upstream commit d1d90147c9680aaec4a5757932c2103c42c9c23b ] Since commit 4ad23a976413 ("MD: use per-cpu counter for writes_pending"), the wait_queue is only got invoked if THREAD_WAKEUP is not set previously. With above change, I can see process_metadata_update could always hang on the wait queue, because mddev->thread could stay on 'D' status and the THREAD_WAKEUP flag is not cleared since there are lots of place to wake up mddev->thread. Then deadlock happened as follows: linux175:~ # ps aux|grep md|grep D root 20117 0.0 0.0 0 0 ? D 03:45 0:00 [md0_raid1] root 20125 0.0 0.0 0 0 ? D 03:45 0:00 [md0_cluster_rec] linux175:~ # cat /proc/20117/stack [] dlm_lock_sync+0x94/0xd0 [md_cluster] [] lock_token+0x34/0xd0 [md_cluster] [] metadata_update_start+0x64/0x110 [md_cluster] [] md_update_sb.part.58+0x9b/0x860 [md_mod] [] md_update_sb+0x15/0x30 [md_mod] [] md_check_recovery+0x266/0x490 [md_mod] [] raid1d+0x42/0x810 [raid1] [] md_thread+0x122/0x150 [md_mod] [] kthread+0x101/0x140 linux175:~ # cat /proc/20125/stack [] recv_daemon+0x3f9/0x5c0 [md_cluster] [] md_thread+0x122/0x150 [md_mod] [] kthread+0x101/0x140 So let's revert the part of code in the commit to resovle the problem since we can't get lots of benefits of previous change. Fixes: 4ad23a976413 ("MD: use per-cpu counter for writes_pending") Signed-off-by: Guoqing Jiang Signed-off-by: Shaohua Li Signed-off-by: Sasha Levin --- drivers/md/md.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/md/md.c b/drivers/md/md.c index 98ea86309ceb..6bf093cef958 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -7468,8 +7468,8 @@ void md_wakeup_thread(struct md_thread *thread) { if (thread) { pr_debug("md: waking up MD thread %s.\n", thread->tsk->comm); - if (!test_and_set_bit(THREAD_WAKEUP, &thread->flags)) - wake_up(&thread->wqueue); + set_bit(THREAD_WAKEUP, &thread->flags); + wake_up(&thread->wqueue); } } EXPORT_SYMBOL(md_wakeup_thread); -- 2.11.0