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=-5.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 205C7C4727F for ; Fri, 25 Sep 2020 10:55:43 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BDB2E20838 for ; Fri, 25 Sep 2020 10:55:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601031342; bh=1CGfR6nV/0roujv2jCFmWNNypuMeXMaY0JOYlD8nOqw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=uCKkxf67sLIbgQAHAnMNGmZYixNWh68b24ilCkL5ttEfIGzVQwBrRk8RkIt/TL3B2 YEyj5MlUUQpEAu57CAG3hzaziVZM8dvuyUkxueVl3XRVJzTvyAnA8AqXitoyrxRAkd vFTle3jtXDfCa3Al3qruAfGKGloEasLPwCSqSkCI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727901AbgIYKzl (ORCPT ); Fri, 25 Sep 2020 06:55:41 -0400 Received: from mail.kernel.org ([198.145.29.99]:59034 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726255AbgIYKzl (ORCPT ); Fri, 25 Sep 2020 06:55:41 -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 9414020809; Fri, 25 Sep 2020 10:55:39 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1601031340; bh=1CGfR6nV/0roujv2jCFmWNNypuMeXMaY0JOYlD8nOqw=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=o/Mjf8rloCokxg1rcOAx6WCaezFdt+QJGHbz5lBgfhDEad7fgc7D0QeuusD/T5pFr lGQ84YY0Ah6PqppljUBdP3liHqW041nRnQKV/e9+GPoJ4Y7kNSo0NDSjrJnIfMvcAB +LKm26Ts+R5E7Zzn7UWLcQzgpovT60J7hmevbzpI= Date: Fri, 25 Sep 2020 12:55:55 +0200 From: Greg KH To: Julius Hemanth Pitti Cc: akpm@linux-foundation.org, xlpang@linux.alibaba.com, mhocko@suse.com, vdavydov.dev@gmail.com, ktkhai@virtuozzo.com, hannes@cmpxchg.org, stable@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, xe-linux-external@cisco.com, Linus Torvalds Subject: Re: [PATCH stable v5.4] mm: memcg: fix memcg reclaim soft lockup Message-ID: <20200925105555.GA2525199@kroah.com> References: <20200921180508.61905-1-jpitti@cisco.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200921180508.61905-1-jpitti@cisco.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 21, 2020 at 11:05:08AM -0700, Julius Hemanth Pitti wrote: > From: Xunlei Pang > > commit e3336cab2579012b1e72b5265adf98e2d6e244ad upstream > > We've met softlockup with "CONFIG_PREEMPT_NONE=y", when the target memcg > doesn't have any reclaimable memory. > > It can be easily reproduced as below: > > watchdog: BUG: soft lockup - CPU#0 stuck for 111s![memcg_test:2204] > CPU: 0 PID: 2204 Comm: memcg_test Not tainted 5.9.0-rc2+ #12 > Call Trace: > shrink_lruvec+0x49f/0x640 > shrink_node+0x2a6/0x6f0 > do_try_to_free_pages+0xe9/0x3e0 > try_to_free_mem_cgroup_pages+0xef/0x1f0 > try_charge+0x2c1/0x750 > mem_cgroup_charge+0xd7/0x240 > __add_to_page_cache_locked+0x2fd/0x370 > add_to_page_cache_lru+0x4a/0xc0 > pagecache_get_page+0x10b/0x2f0 > filemap_fault+0x661/0xad0 > ext4_filemap_fault+0x2c/0x40 > __do_fault+0x4d/0xf9 > handle_mm_fault+0x1080/0x1790 > > It only happens on our 1-vcpu instances, because there's no chance for > oom reaper to run to reclaim the to-be-killed process. > > Add a cond_resched() at the upper shrink_node_memcgs() to solve this > issue, this will mean that we will get a scheduling point for each memcg > in the reclaimed hierarchy without any dependency on the reclaimable > memory in that memcg thus making it more predictable. > > [jpitti@cisco.com: > - backported to v5.4.y > - Upstream patch applies fix in shrink_node_memcgs(), which > is not present to v5.4.y. Appled to shrink_node()] Thanks for this, now queued up here and for 4.19 greg k-h