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=-12.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 DE339C433E2 for ; Tue, 8 Sep 2020 18:51:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 567CA2067C for ; Tue, 8 Sep 2020 18:51:46 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=cisco.com header.i=@cisco.com header.b="STkp2Xx/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 567CA2067C Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=cisco.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9D8506B0003; Tue, 8 Sep 2020 14:51:45 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 987C16B0037; Tue, 8 Sep 2020 14:51:45 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 876B56B0055; Tue, 8 Sep 2020 14:51:45 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0025.hostedemail.com [216.40.44.25]) by kanga.kvack.org (Postfix) with ESMTP id 6F3536B0003 for ; Tue, 8 Sep 2020 14:51:45 -0400 (EDT) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 2E6BD8248D51 for ; Tue, 8 Sep 2020 18:51:45 +0000 (UTC) X-FDA: 77240788170.28.chair56_250e49c270d7 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin28.hostedemail.com (Postfix) with ESMTP id 0329C6C04 for ; Tue, 8 Sep 2020 18:51:44 +0000 (UTC) X-HE-Tag: chair56_250e49c270d7 X-Filterd-Recvd-Size: 3295 Received: from rcdn-iport-9.cisco.com (rcdn-iport-9.cisco.com [173.37.86.80]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Tue, 8 Sep 2020 18:51:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=1391; q=dns/txt; s=iport; t=1599591104; x=1600800704; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=m2WVpZpXrtQFXh3Ql4JrliPwX+fM66/2SHqLhNxgwkY=; b=STkp2Xx/mNfqxZKgPWJ0TvHMfTU7B/fmOllDGw6XBWC9r/GPQOHU1rdx QIPOSvPgpnts2YRin7I+k9/XWj3KPz5zWBOwAdB1k7L89hBTf58Nx/uaO G0sWg9kNBo4x/XcJHUyCQfs6FSRrbkcyx8lM7OLCeLhjJCO4p6+Wu10z3 4=; X-IronPort-AV: E=Sophos;i="5.76,406,1592870400"; d="scan'208";a="732158731" Received: from rcdn-core-1.cisco.com ([173.37.93.152]) by rcdn-iport-9.cisco.com with ESMTP/TLS/DHE-RSA-SEED-SHA; 08 Sep 2020 18:51:43 +0000 Received: from sjc-ads-9087.cisco.com (sjc-ads-9087.cisco.com [10.30.208.97]) by rcdn-core-1.cisco.com (8.15.2/8.15.2) with ESMTP id 088IphYE005304; Tue, 8 Sep 2020 18:51:43 GMT Received: by sjc-ads-9087.cisco.com (Postfix, from userid 396877) id D89BFBFD; Tue, 8 Sep 2020 11:51:42 -0700 (PDT) From: Julius Hemanth Pitti To: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, akpm@linux-foundation.org Cc: cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, xe-linux-external@cisco.com, Julius Hemanth Pitti Subject: [PATCH] mm: memcg: yield cpu when we fail to charge pages Date: Tue, 8 Sep 2020 11:50:51 -0700 Message-Id: <20200908185051.62420-1-jpitti@cisco.com> X-Mailer: git-send-email 2.19.1 MIME-Version: 1.0 X-Auto-Response-Suppress: DR, OOF, AutoReply X-Outbound-SMTP-Client: 10.30.208.97, sjc-ads-9087.cisco.com X-Outbound-Node: rcdn-core-1.cisco.com X-Rspamd-Queue-Id: 0329C6C04 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: For non root CG, in try_charge(), we keep trying to charge until we succeed. On non-preemptive kernel, when we are OOM, this results in holding CPU forever. On SMP systems, this doesn't create a big problem because oom_reaper get a change to kill victim and make some free pages. However on a single-core CPU (or cases where oom_reaper pinned to same CPU where try_charge is executing), oom_reaper shall never get scheduled and we stay in try_charge forever. Steps to repo this on non-smp: 1. mount -t tmpfs none /sys/fs/cgroup 2. mkdir /sys/fs/cgroup/memory 3. mount -t cgroup none /sys/fs/cgroup/memory -o memory 4. mkdir /sys/fs/cgroup/memory/0 5. echo 40M > /sys/fs/cgroup/memory/0/memory.limit_in_bytes 6. echo $$ > /sys/fs/cgroup/memory/0/tasks 7. stress -m 5 --vm-bytes 10M --vm-hang 0 Signed-off-by: Julius Hemanth Pitti --- mm/memcontrol.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 0d6f3ea86738..4620d70267cb 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2652,6 +2652,8 @@ static int try_charge(struct mem_cgroup *memcg, gfp= _t gfp_mask, if (fatal_signal_pending(current)) goto force; =20 + cond_resched(); + /* * keep retrying as long as the memcg oom killer is able to make * a forward progress or bypass the charge if the oom killer --=20 2.17.1