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 8996CC433E2 for ; Tue, 8 Sep 2020 20:14:33 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1FCCA208FE for ; Tue, 8 Sep 2020 20:14:32 +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="U61sLZhU" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1FCCA208FE 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 8B0E96B0073; Tue, 8 Sep 2020 16:14:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8621B6B0074; Tue, 8 Sep 2020 16:14:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7784A6B0075; Tue, 8 Sep 2020 16:14:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0075.hostedemail.com [216.40.44.75]) by kanga.kvack.org (Postfix) with ESMTP id 61B8A6B0073 for ; Tue, 8 Sep 2020 16:14:32 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id 1908E3624 for ; Tue, 8 Sep 2020 20:14:32 +0000 (UTC) X-FDA: 77240996784.14.jelly80_1209677270d7 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id E10B018229835 for ; Tue, 8 Sep 2020 20:14:31 +0000 (UTC) X-HE-Tag: jelly80_1209677270d7 X-Filterd-Recvd-Size: 3705 Received: from rcdn-iport-9.cisco.com (rcdn-iport-9.cisco.com [173.37.86.80]) by imf18.hostedemail.com (Postfix) with ESMTP for ; Tue, 8 Sep 2020 20:14:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=cisco.com; i=@cisco.com; l=1785; q=dns/txt; s=iport; t=1599596071; x=1600805671; h=from:to:cc:subject:date:message-id:mime-version: content-transfer-encoding; bh=T8mkCE6PfAz3UDsDi/PeT6rnbi3jy36h40OMXp16Ecg=; b=U61sLZhUNNtzSgy/ZvhN0PCvlzZ1rjldAVJmTkljxua+9DT3h2Eaemo5 4zVlJvjrAElwCzqWI1wQqo+p8tlH1PR60dXyaHZZKmjTR5X/bSZO1fi/6 CtOyOmCD31HSTAHudGiCd/ghVoXeFMxTPqYzUUmGFTo9kosleg+ShVMC+ I=; X-IronPort-AV: E=Sophos;i="5.76,406,1592870400"; d="scan'208";a="732193483" Received: from rcdn-core-4.cisco.com ([173.37.93.155]) by rcdn-iport-9.cisco.com with ESMTP/TLS/DHE-RSA-SEED-SHA; 08 Sep 2020 20:14:30 +0000 Received: from sjc-ads-9087.cisco.com (sjc-ads-9087.cisco.com [10.30.208.97]) by rcdn-core-4.cisco.com (8.15.2/8.15.2) with ESMTP id 088KETHu020960; Tue, 8 Sep 2020 20:14:30 GMT Received: by sjc-ads-9087.cisco.com (Postfix, from userid 396877) id BDD7AA40; Tue, 8 Sep 2020 13:14:29 -0700 (PDT) From: Julius Hemanth Pitti To: hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com, akpm@linux-foundation.org, guro@fb.com Cc: cgroups@vger.kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, xe-linux-external@cisco.com, Julius Hemanth Pitti Subject: [PATCH v2] mm: memcg: yield cpu when we fail to charge pages Date: Tue, 8 Sep 2020 13:14:26 -0700 Message-Id: <20200908201426.14837-1-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-4.cisco.com X-Rspamd-Queue-Id: E10B018229835 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam05 Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000001, 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 Acked-by: Roman Gushchin --- Changes in v2: - Added comments. - Added "Acked-by: Roman Gushchin ". --- mm/memcontrol.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index cfa6cbad21d5..4f293bf8c7ed 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -2745,6 +2745,15 @@ static int try_charge(struct mem_cgroup *memcg, gf= p_t gfp_mask, if (fatal_signal_pending(current)) goto force; =20 + /* + * We failed to charge even after retries, give oom_reaper or + * other process a change to make some free pages. + * + * On non-preemptive, Non-SMP system, this is critical, else + * we keep retrying with no success, forever. + */ + 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