From patchwork Sat Oct 22 07:27:01 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 7837 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a5d:4242:0:0:0:0:0 with SMTP id s2csp1153118wrr; Sat, 22 Oct 2022 04:04:48 -0700 (PDT) X-Google-Smtp-Source: AMsMyM6sv3n4y+4W86LzVqteeEqHE2j7mGaRrVPIA8g1ZFBsH8VoNtJ2K/hRYX/0sSETN8JBq6jk X-Received: by 2002:a17:907:a43:b0:77b:ba98:d2f with SMTP id be3-20020a1709070a4300b0077bba980d2fmr19918196ejc.270.1666436688704; Sat, 22 Oct 2022 04:04:48 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1666436688; cv=none; d=google.com; s=arc-20160816; b=Bpv3ZrLIwrKSYW9vzsgIPMhHJgJ5RwtGy0k1ThtSwJCByhpqjFE2y0TfJO3ylHiF7X W72ypiFca4gp42XLOk04y8MTb0zw+W6RTbXz2UwP6lqk2dUPGKMFPsot6bjeHYkQxDLo aEqyHYWDraIxjE0Pcv68lIQHm+u8FI4AD76xIzekIaenT2bTPjt6jsc6TZ8J0ted8JlW yZ8Pvt07weY1NxMu4Fof22v7HYbNif6yPzJJHEZInGPJJziN3pOxyAj76euJsuHBcpx/ Yf/rE/Zgwf/cIyH5ffxhbXK3OK0pUtQWA0K68K8mqtRMxivMbcD/YsZuixaucMwSrGVm xwEQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :user-agent:references:in-reply-to:message-id:date:subject:cc:to :from:dkim-signature; bh=ZcDcx/IUi6ez1wMrW547lc5GlhnjRxbT4bVG/UeRZFY=; b=ZHzYZeV5E07wHGu2XaOWFPhADjaDDF6+yZgIY35726+/XYECPeemfAVM9dsUQhMqK/ FEGAErTz/UE7bKb1jkk4rgJA4EFi5oDG7FSq63OZ9SfLi/L7Dm4wfQLS6dvHTNGAmKdq 226JmYd61MCheDKlN8NrwEUW5abJp0eq4haMqRzxgLRicaNV4Nsg71PY+WKLwXF4xQA4 ijs6sCT1YAbia/64dt6tIeC/GbWlEdg4MaPjLFuMG5a72ROmJGmGGF1kd7gqRe8j3rlG 71hyoDOPvgNnENU+mabyuriODwoRfZ/+W3wC9/7OfDPiKWAlOkn0rRmYL/sTp2iWZl4R mAiw== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=qxMIuck9; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id b21-20020a056402139500b00448d387c327si19454686edv.181.2022.10.22.04.04.15; Sat, 22 Oct 2022 04:04:48 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; dkim=pass header.i=@linuxfoundation.org header.s=korg header.b=qxMIuck9; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linuxfoundation.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230507AbiJVK6o (ORCPT + 99 others); Sat, 22 Oct 2022 06:58:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39286 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230447AbiJVK6P (ORCPT ); Sat, 22 Oct 2022 06:58:15 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 9CF2540BCA; Sat, 22 Oct 2022 03:17:04 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id B95D3B82DEF; Sat, 22 Oct 2022 07:59:25 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id ED9B7C433C1; Sat, 22 Oct 2022 07:59:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1666425564; bh=jWnmZB96YzuwtBqDfWonjmLe0fepcA22GyA5+Yn5wxE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=qxMIuck9RQOhAZPkOqLk/0DMLiMqJZbHO81r59tN1SW1pN8829v6m0x2tGTdiPlgq dPmb3BSkBdRHHWkLKbxfzKGNpr5HAPvv8faOnlE+pR9pEK+R2Xr73YRH2VcsJ5sEYi 2oGQN/odXYyX7kEwU6sn1o7UCHWXsmc/f7yj+bVE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, "Uladzislau Rezki (Sony)" , "Paul E. McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Josh Triplett , Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , Michal Hocko , Sasha Levin Subject: [PATCH 5.19 542/717] rcu: Back off upon fill_page_cache_func() allocation failure Date: Sat, 22 Oct 2022 09:27:01 +0200 Message-Id: <20221022072522.317578067@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221022072415.034382448@linuxfoundation.org> References: <20221022072415.034382448@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 X-Spam-Status: No, score=-7.4 required=5.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,RCVD_IN_DNSWL_HI, SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: =?utf-8?q?INBOX?= X-GMAIL-THRID: =?utf-8?q?1747385517424160476?= X-GMAIL-MSGID: =?utf-8?q?1747385517424160476?= From: Michal Hocko [ Upstream commit 093590c16b447f53e66771c8579ae66c96f6ef61 ] The fill_page_cache_func() function allocates couple of pages to store kvfree_rcu_bulk_data structures. This is a lightweight (GFP_NORETRY) allocation which can fail under memory pressure. The function will, however keep retrying even when the previous attempt has failed. This retrying is in theory correct, but in practice the allocation is invoked from workqueue context, which means that if the memory reclaim gets stuck, these retries can hog the worker for quite some time. Although the workqueues subsystem automatically adjusts concurrency, such adjustment is not guaranteed to happen until the worker context sleeps. And the fill_page_cache_func() function's retry loop is not guaranteed to sleep (see the should_reclaim_retry() function). And we have seen this function cause workqueue lockups: kernel: BUG: workqueue lockup - pool cpus=93 node=1 flags=0x1 nice=0 stuck for 32s! [...] kernel: pool 74: cpus=37 node=0 flags=0x1 nice=0 hung=32s workers=2 manager: 2146 kernel: pwq 498: cpus=249 node=1 flags=0x1 nice=0 active=4/256 refcnt=5 kernel: in-flight: 1917:fill_page_cache_func kernel: pending: dbs_work_handler, free_work, kfree_rcu_monitor Originally, we thought that the root cause of this lockup was several retries with direct reclaim, but this is not yet confirmed. Furthermore, we have seen similar lockups without any heavy memory pressure. This suggests that there are other factors contributing to these lockups. However, it is not really clear that endless retries are desireable. So let's make the fill_page_cache_func() function back off after allocation failure. Cc: Uladzislau Rezki (Sony) Cc: "Paul E. McKenney" Cc: Frederic Weisbecker Cc: Neeraj Upadhyay Cc: Josh Triplett Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Lai Jiangshan Cc: Joel Fernandes Signed-off-by: Michal Hocko Reviewed-by: Uladzislau Rezki (Sony) Signed-off-by: Paul E. McKenney Signed-off-by: Sasha Levin --- kernel/rcu/tree.c | 17 +++++++++-------- 1 file changed, 9 insertions(+), 8 deletions(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index c25ba442044a..54a3a19c4c0b 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -3508,15 +3508,16 @@ static void fill_page_cache_func(struct work_struct *work) bnode = (struct kvfree_rcu_bulk_data *) __get_free_page(GFP_KERNEL | __GFP_NORETRY | __GFP_NOMEMALLOC | __GFP_NOWARN); - if (bnode) { - raw_spin_lock_irqsave(&krcp->lock, flags); - pushed = put_cached_bnode(krcp, bnode); - raw_spin_unlock_irqrestore(&krcp->lock, flags); + if (!bnode) + break; - if (!pushed) { - free_page((unsigned long) bnode); - break; - } + raw_spin_lock_irqsave(&krcp->lock, flags); + pushed = put_cached_bnode(krcp, bnode); + raw_spin_unlock_irqrestore(&krcp->lock, flags); + + if (!pushed) { + free_page((unsigned long) bnode); + break; } }