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=-12.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, 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 05C33C388F9 for ; Tue, 27 Oct 2020 17:00:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 97E4F21707 for ; Tue, 27 Oct 2020 17:00:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603818021; bh=i892Am8JcUqWpZVV4ZyYZjchzORclpVQquaP8i3w2To=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=s0nvf/w34zmvigNZB/wWHNzHvhxJpuJRD7YCtOcyKQ74EUbbpOUX7OS8hI34o8ONy hL16bNVQEypWqoTYibKhwlVV1LFgbeYftRvmaGnd4wLgMXXKr1ogw37uI7HUYBD1bI 4vj69y+kPjAHuldT99NkTt3tB9z8cJrHpRBou3XA= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1814900AbgJ0RAU (ORCPT ); Tue, 27 Oct 2020 13:00:20 -0400 Received: from mail.kernel.org ([198.145.29.99]:44276 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755361AbgJ0PIz (ORCPT ); Tue, 27 Oct 2020 11:08:55 -0400 Received: from localhost (83-86-74-64.cable.dynamic.v4.ziggo.nl [83.86.74.64]) (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 25FE621D24; Tue, 27 Oct 2020 15:08:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603811333; bh=i892Am8JcUqWpZVV4ZyYZjchzORclpVQquaP8i3w2To=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OFdUvTqIrWpyAnk61PZZCY/5ZB6JLG7OV3UsoqmGhqjVUOWgm47T+Hdew+OvTvUey cRK9tglmw9yxP21kCH5zXSdc1NVqwZx2U+rzDBNngPmCikS/CQhVRjollKg19EU07c wEq7LMLlQnX4VjL44K5lVvSL8YQtXyJC53g+VVUg= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ye Bin , Jan Kara , Ritesh Harjani , Theodore Tso , Sasha Levin Subject: [PATCH 5.8 457/633] ext4: fix dead loop in ext4_mb_new_blocks Date: Tue, 27 Oct 2020 14:53:20 +0100 Message-Id: <20201027135544.152034382@linuxfoundation.org> X-Mailer: git-send-email 2.29.1 In-Reply-To: <20201027135522.655719020@linuxfoundation.org> References: <20201027135522.655719020@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ye Bin [ Upstream commit 70022da804f0f3f152115688885608c39182082e ] As we test disk offline/online with running fsstress, we find fsstress process is keeping running state. kworker/u32:3-262 [004] ...1 140.787471: ext4_mb_discard_preallocations: dev 8,32 needed 114 .... kworker/u32:3-262 [004] ...1 140.787471: ext4_mb_discard_preallocations: dev 8,32 needed 114 ext4_mb_new_blocks repeat: ext4_mb_discard_preallocations_should_retry(sb, ac, &seq) freed = ext4_mb_discard_preallocations ext4_mb_discard_group_preallocations this_cpu_inc(discard_pa_seq); ---> freed == 0 seq_retry = ext4_get_discard_pa_seq_sum for_each_possible_cpu(__cpu) __seq += per_cpu(discard_pa_seq, __cpu); if (seq_retry != *seq) { *seq = seq_retry; ret = true; } As we see seq_retry is sum of discard_pa_seq every cpu, if ext4_mb_discard_group_preallocations return zero discard_pa_seq in this cpu maybe increase one, so condition "seq_retry != *seq" have always been met. Ritesh Harjani suggest to in ext4_mb_discard_group_preallocations function we only increase discard_pa_seq when there is some PA to free. Fixes: 07b5b8e1ac40 ("ext4: mballoc: introduce pcpu seqcnt for freeing PA to improve ENOSPC handling") Signed-off-by: Ye Bin Reviewed-by: Jan Kara Reviewed-by: Ritesh Harjani Link: https://lore.kernel.org/r/20200916113859.1556397-3-yebin10@huawei.com Signed-off-by: Theodore Ts'o Signed-off-by: Sasha Levin --- fs/ext4/mballoc.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c index e88eff999bd15..787a894f5d1da 100644 --- a/fs/ext4/mballoc.c +++ b/fs/ext4/mballoc.c @@ -4066,7 +4066,6 @@ ext4_mb_discard_group_preallocations(struct super_block *sb, INIT_LIST_HEAD(&list); repeat: ext4_lock_group(sb, group); - this_cpu_inc(discard_pa_seq); list_for_each_entry_safe(pa, tmp, &grp->bb_prealloc_list, pa_group_list) { spin_lock(&pa->pa_lock); @@ -4083,6 +4082,9 @@ ext4_mb_discard_group_preallocations(struct super_block *sb, /* seems this one can be freed ... */ ext4_mb_mark_pa_deleted(sb, pa); + if (!free) + this_cpu_inc(discard_pa_seq); + /* we can trust pa_free ... */ free += pa->pa_free; -- 2.25.1