From patchwork Tue Sep 28 17:34:04 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Wen Yang X-Patchwork-Id: 12523375 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE60AC433EF for ; Tue, 28 Sep 2021 17:34:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 8AB2E60F21 for ; Tue, 28 Sep 2021 17:34:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242160AbhI1Rf6 (ORCPT ); Tue, 28 Sep 2021 13:35:58 -0400 Received: from out30-42.freemail.mail.aliyun.com ([115.124.30.42]:41359 "EHLO out30-42.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S242104AbhI1Rfx (ORCPT ); Tue, 28 Sep 2021 13:35:53 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R731e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04426;MF=wenyang@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0Upy3nXM_1632850446; Received: from localhost(mailfrom:wenyang@linux.alibaba.com fp:SMTPD_---0Upy3nXM_1632850446) by smtp.aliyun-inc.com(127.0.0.1); Wed, 29 Sep 2021 01:34:12 +0800 From: Wen Yang To: Alexander Viro Cc: Wen Yang , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] fs/fs-writeback.c: add a preemption point to move_expired_inodes Date: Wed, 29 Sep 2021 01:34:04 +0800 Message-Id: <20210928173404.10794-1-wenyang@linux.alibaba.com> X-Mailer: git-send-email 2.23.0 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org We encountered an unrecovered_softlockup issue on !PREEMPT kernel config with 4.9 based kernel. PID: 185895 TASK: ffff880455dac280 CPU: 8 COMMAND: "kworker/u449:39" #0 [ffff883f7e803c08] machine_kexec at ffffffff81061578 #1 [ffff883f7e803c68] __crash_kexec at ffffffff81127c19 #2 [ffff883f7e803d30] panic at ffffffff811b2255 #3 [ffff883f7e803db8] unrecovered_softlockup_detect at ffffffff811b2d57 #4 [ffff883f7e803ee0] watchdog_timer_fn at ffffffff8115827e #5 [ffff883f7e803f18] __hrtimer_run_queues at ffffffff811085e3 #6 [ffff883f7e803f70] hrtimer_interrupt at ffffffff81108d8a #7 [ffff883f7e803fc0] local_apic_timer_interrupt at ffffffff810580f8 #8 [ffff883f7e803fd8] smp_apic_timer_interrupt at ffffffff81745405 #9 [ffff883f7e803ff0] apic_timer_interrupt at ffffffff81743b90 --- --- #10 [ffffc90086a93b88] apic_timer_interrupt at ffffffff81743b90 [exception RIP: __list_del_entry+44] RIP: ffffffff813be22c RSP: ffffc90086a93c30 RFLAGS: 00000202 RAX: ffff88522b8f8418 RBX: ffff88522b8f8418 RCX: dead000000000200 RDX: ffff8816fab00e68 RSI: ffffc90086a93c60 RDI: ffff8816fab01af8 RBP: ffffc90086a93c30 R8: ffff8816fab01af8 R9: 0000000100400018 R10: ffff885ae5ed8280 R11: 0000000000000000 R12: ffff8816fab01af8 R13: ffffc90086a93c60 R14: ffffc90086a93d08 R15: ffff883f631d2000 ORIG_RAX: ffffffffffffff10 CS: 0010 SS: 0000 #11 [ffffc90086a93c38] move_expired_inodes at ffffffff8127c74c #12 [ffffc90086a93ca8] queue_io at ffffffff8127cde6 #13 [ffffc90086a93cd8] wb_writeback at ffffffff8128121f #14 [ffffc90086a93d80] wb_workfn at ffffffff812819f4 #15 [ffffc90086a93e18] process_one_work at ffffffff810a5dc9 #16 [ffffc90086a93e60] worker_thread at ffffffff810a60ae #17 [ffffc90086a93ec0] kthread at ffffffff810ac696 #18 [ffffc90086a93f50] ret_from_fork at ffffffff81741dd9 crash> set PID: 185895 COMMAND: "kworker/u449:39" TASK: ffff880455dac280 [THREAD_INFO: ffff880455dac280] CPU: 8 STATE: TASK_RUNNING (PANIC) It has been running continuously for 53.052, as follows: crash> ps -m | grep 185895 [ 0 00:00:53.052] [RU] PID: 185895 TASK: ffff880455dac280 CPU: 8 COMMAND: "kworker/u449:39" And the TIF_NEED_RESCHED flag has been set, as follows: crash> struct thread_info -x ffff880455dac280 struct thread_info { flags = 0x88, status = 0x0 } Let's just add cond_resched() within move_expired_inodes()'s list-moving loop in order to avoid the watchdog splats. Signed-off-by: Wen Yang Cc: Alexander Viro Cc: linux-fsdevel@vger.kernel.org Cc: linux-kernel@vger.kernel.org --- fs/fs-writeback.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/fs/fs-writeback.c b/fs/fs-writeback.c index 06d04a7..1546121 100644 --- a/fs/fs-writeback.c +++ b/fs/fs-writeback.c @@ -1404,6 +1404,7 @@ static int move_expired_inodes(struct list_head *delaying_queue, if (sb && sb != inode->i_sb) do_sb_sort = 1; sb = inode->i_sb; + cond_resched(); } /* just one sb in list, splice to dispatch_queue and we're done */ @@ -1420,6 +1421,7 @@ static int move_expired_inodes(struct list_head *delaying_queue, if (inode->i_sb == sb) list_move(&inode->i_io_list, dispatch_queue); } + cond_resched(); } out: return moved;