From nobody Sat Oct 4 22:34:53 2025 Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 26999DDC3; Tue, 12 Aug 2025 06:45:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=45.249.212.56 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754981143; cv=none; b=sTJ1pEsl6WPl6M3KtJEp2imzi1o2wa1abr806Rl+/2u0U5kZ1EVes7/WE0V8wVgOrI+RSi20N3Fh/TVoUwHVRie44s/qCckMw6AZbQIQDyADO6JyOXGSKRO2D68RZ2b9LoWDnCXCFs8e8mAohMBx7uz1WhVrKWmf4PoMhWC7PhA= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754981143; c=relaxed/simple; bh=29ECu7mtTAeQD6TWYLdUNWx0I4czPhmreAg/gJJATfo=; h=From:To:Cc:Subject:Date:Message-Id:MIME-Version; b=B1pglXNI/oWrXodwPmgj3MF5QVHEEYIm+Fd43erWYk9LbfeYQnPMIcR1ACDJx8z4useOpH2BKZcuGlpvD2omie5IIcvf6NeDzM3KW7XwjHLLWcVkiXSoADT17vm8v0/rIMTNknfJuy5oLBVMhMRCJU7tDW68R5k2Ap9VwyBOkyA= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com; spf=pass smtp.mailfrom=huaweicloud.com; arc=none smtp.client-ip=45.249.212.56 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=huaweicloud.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=huaweicloud.com Received: from mail.maildlp.com (unknown [172.19.163.235]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTPS id 4c1MTG227fzKHN1m; Tue, 12 Aug 2025 14:45:38 +0800 (CST) Received: from mail02.huawei.com (unknown [10.116.40.128]) by mail.maildlp.com (Postfix) with ESMTP id 7DF1F1A0C29; Tue, 12 Aug 2025 14:45:37 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.104.67]) by APP4 (Coremail) with SMTP id gCh0CgAHgxMP45po3vuiDQ--.42402S4; Tue, 12 Aug 2025 14:45:37 +0800 (CST) From: libaokun@huaweicloud.com To: linux-ext4@vger.kernel.org Cc: tytso@mit.edu, jack@suse.cz, linux-kernel@vger.kernel.org, yi.zhang@huawei.com, yangerkun@huawei.com, libaokun1@huawei.com, libaokun@huaweicloud.com Subject: [PATCH] jbd2: prevent softlockup in jbd2_log_do_checkpoint() Date: Tue, 12 Aug 2025 14:37:52 +0800 Message-Id: <20250812063752.912130-1-libaokun@huaweicloud.com> X-Mailer: git-send-email 2.39.2 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-CM-TRANSID: gCh0CgAHgxMP45po3vuiDQ--.42402S4 X-Coremail-Antispam: 1UD129KBjvJXoWxZryUWw4xuryxuFy5KFyfJFb_yoW5GFy5pF 93u3yjqrWku34UZrsIvaykAr929a1kury7JrnY9F17Zw48JrsrKFW3t34jqryUArZ5A3yS yFWj9wnagrnFy3JanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvv14x267AKxVW8JVW5JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26w1j6s0DM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4U JVWxJr1l84ACjcxK6I8E87Iv67AKxVW0oVCq3wA2z4x0Y4vEx4A2jsIEc7CjxVAFwI0_Gc CE3s1le2I262IYc4CY6c8Ij28IcVAaY2xG8wAqx4xG64xvF2IEw4CE5I8CrVC2j2WlYx0E 2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r1j6r4UMcvjeVCFs4IE7xkEbVWUJV W8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAqYI8I648v4I1lw4CEc2x0rVAKj4xx MxkF7I0En4kS14v26r126r1DMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r1j6r 4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CEb7AF 67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0xvE2I x0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_Jr0_JF4lIxAIcVC2 z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267AKxVWUJVW8JbIYCTnIWIevJa73Uj IFyTuYvjfU5R6zUUUUU X-CM-SenderInfo: 5olet0hnxqqx5xdzvxpfor3voofrz/1tbiAQASBWiZm3JUBAAAse Content-Type: text/plain; charset="utf-8" From: Baokun Li Both jbd2_log_do_checkpoint() and jbd2_journal_shrink_checkpoint_list() periodically release j_list_lock after processing a batch of buffers to avoid long hold times on the j_list_lock. However, since both functions contend for j_list_lock, the combined time spent waiting and processing can be significant. jbd2_journal_shrink_checkpoint_list() explicitly calls cond_resched() when need_resched() is true to avoid softlockups during prolonged operations. But jbd2_log_do_checkpoint() only exits its loop when need_resched() is true, relying on potentially sleeping functions like __flush_batch() or wait_on_buffer() to trigger rescheduling. If those functions do not sleep, the kernel may hit a softlockup. watchdog: BUG: soft lockup - CPU#3 stuck for 156s! [kworker/u129:2:373] CPU: 3 PID: 373 Comm: kworker/u129:2 Kdump: loaded Not tainted 6.6.0+ #10 Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.27 06/13/2017 Workqueue: writeback wb_workfn (flush-7:2) pstate: 20000005 (nzCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=3D--) pc : native_queued_spin_lock_slowpath+0x358/0x418 lr : jbd2_log_do_checkpoint+0x31c/0x438 [jbd2] Call trace: native_queued_spin_lock_slowpath+0x358/0x418 jbd2_log_do_checkpoint+0x31c/0x438 [jbd2] __jbd2_log_wait_for_space+0xfc/0x2f8 [jbd2] add_transaction_credits+0x3bc/0x418 [jbd2] start_this_handle+0xf8/0x560 [jbd2] jbd2__journal_start+0x118/0x228 [jbd2] __ext4_journal_start_sb+0x110/0x188 [ext4] ext4_do_writepages+0x3dc/0x740 [ext4] ext4_writepages+0xa4/0x190 [ext4] do_writepages+0x94/0x228 __writeback_single_inode+0x48/0x318 writeback_sb_inodes+0x204/0x590 __writeback_inodes_wb+0x54/0xf8 wb_writeback+0x2cc/0x3d8 wb_do_writeback+0x2e0/0x2f8 wb_workfn+0x80/0x2a8 process_one_work+0x178/0x3e8 worker_thread+0x234/0x3b8 kthread+0xf0/0x108 ret_from_fork+0x10/0x20 So explicitly call cond_resched() in jbd2_log_do_checkpoint() to avoid softlockup. Signed-off-by: Baokun Li --- fs/jbd2/checkpoint.c | 1 + 1 file changed, 1 insertion(+) diff --git a/fs/jbd2/checkpoint.c b/fs/jbd2/checkpoint.c index b3971e91e8eb..38861ca04899 100644 --- a/fs/jbd2/checkpoint.c +++ b/fs/jbd2/checkpoint.c @@ -285,6 +285,7 @@ int jbd2_log_do_checkpoint(journal_t *journal) retry: if (batch_count) __flush_batch(journal, &batch_count); + cond_resched(); spin_lock(&journal->j_list_lock); goto restart; } --=20 2.39.2