From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66507C52D4C for ; Thu, 27 Feb 2020 14:16:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3C4AE20801 for ; Thu, 27 Feb 2020 14:16:27 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582812987; bh=mcWs5hysCJ0vA6NTA/QZOnkdCPZ7v6LU7HoQobOuHYU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ZQXyXWhSlmCzhLbEitVfcIAmz0DVGlUngh85u16TpQ/3+hav9WGZ5o/Tzqlc9nGDN JX6iqTmD3l3i5ppvr1qdnI40pGmR8C0Clkabib3KBjJAvPczSJ1BbDFGtCPlPJDBex y/AcAALySsJtSe9eNACcS8GmCluQ77V5En76t9EE= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2389255AbgB0OQ0 (ORCPT ); Thu, 27 Feb 2020 09:16:26 -0500 Received: from mail.kernel.org ([198.145.29.99]:56512 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2389504AbgB0OQX (ORCPT ); Thu, 27 Feb 2020 09:16:23 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id C20DF20801; Thu, 27 Feb 2020 14:16:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1582812983; bh=mcWs5hysCJ0vA6NTA/QZOnkdCPZ7v6LU7HoQobOuHYU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Karne1HVuAi+FlPcRCJGfcfr1Qq4qXHm0XKVAv7UzsQJgATluqVUhU40hbW3qC0TG 9Ankk3s9VamtwrXMzhpy8cfv8MvDOOSFsW+ARKXPqAHVwF3ctsiQpQ98WF6Iqtl7gI yjsjBLDmmD07f8pKGNLiG2ZI1FgntpI8iZUY1tC0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Shijie Luo , Theodore Tso , Jan Kara , stable@kernel.org Subject: [PATCH 5.5 090/150] ext4: add cond_resched() to __ext4_find_entry() Date: Thu, 27 Feb 2020 14:37:07 +0100 Message-Id: <20200227132246.089058664@linuxfoundation.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200227132232.815448360@linuxfoundation.org> References: <20200227132232.815448360@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Shijie Luo commit 9424ef56e13a1f14c57ea161eed3ecfdc7b2770e upstream. We tested a soft lockup problem in linux 4.19 which could also be found in linux 5.x. When dir inode takes up a large number of blocks, and if the directory is growing when we are searching, it's possible the restart branch could be called many times, and the do while loop could hold cpu a long time. Here is the call trace in linux 4.19. [ 473.756186] Call trace: [ 473.756196] dump_backtrace+0x0/0x198 [ 473.756199] show_stack+0x24/0x30 [ 473.756205] dump_stack+0xa4/0xcc [ 473.756210] watchdog_timer_fn+0x300/0x3e8 [ 473.756215] __hrtimer_run_queues+0x114/0x358 [ 473.756217] hrtimer_interrupt+0x104/0x2d8 [ 473.756222] arch_timer_handler_virt+0x38/0x58 [ 473.756226] handle_percpu_devid_irq+0x90/0x248 [ 473.756231] generic_handle_irq+0x34/0x50 [ 473.756234] __handle_domain_irq+0x68/0xc0 [ 473.756236] gic_handle_irq+0x6c/0x150 [ 473.756238] el1_irq+0xb8/0x140 [ 473.756286] ext4_es_lookup_extent+0xdc/0x258 [ext4] [ 473.756310] ext4_map_blocks+0x64/0x5c0 [ext4] [ 473.756333] ext4_getblk+0x6c/0x1d0 [ext4] [ 473.756356] ext4_bread_batch+0x7c/0x1f8 [ext4] [ 473.756379] ext4_find_entry+0x124/0x3f8 [ext4] [ 473.756402] ext4_lookup+0x8c/0x258 [ext4] [ 473.756407] __lookup_hash+0x8c/0xe8 [ 473.756411] filename_create+0xa0/0x170 [ 473.756413] do_mkdirat+0x6c/0x140 [ 473.756415] __arm64_sys_mkdirat+0x28/0x38 [ 473.756419] el0_svc_common+0x78/0x130 [ 473.756421] el0_svc_handler+0x38/0x78 [ 473.756423] el0_svc+0x8/0xc [ 485.755156] watchdog: BUG: soft lockup - CPU#2 stuck for 22s! [tmp:5149] Add cond_resched() to avoid soft lockup and to provide a better system responding. Link: https://lore.kernel.org/r/20200215080206.13293-1-luoshijie1@huawei.com Signed-off-by: Shijie Luo Signed-off-by: Theodore Ts'o Reviewed-by: Jan Kara Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman --- fs/ext4/namei.c | 1 + 1 file changed, 1 insertion(+) --- a/fs/ext4/namei.c +++ b/fs/ext4/namei.c @@ -1507,6 +1507,7 @@ restart: /* * We deal with the read-ahead logic here. */ + cond_resched(); if (ra_ptr >= ra_max) { /* Refill the readahead buffer */ ra_ptr = 0;