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=-15.0 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 C705EC433DF for ; Thu, 30 Jul 2020 12:00:46 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9700920829 for ; Thu, 30 Jul 2020 12:00:46 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 9700920829 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 258A76B0002; Thu, 30 Jul 2020 08:00:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2092F6B0005; Thu, 30 Jul 2020 08:00:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 11F276B0006; Thu, 30 Jul 2020 08:00:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0215.hostedemail.com [216.40.44.215]) by kanga.kvack.org (Postfix) with ESMTP id F172D6B0002 for ; Thu, 30 Jul 2020 08:00:45 -0400 (EDT) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 95C5B3620 for ; Thu, 30 Jul 2020 12:00:45 +0000 (UTC) X-FDA: 77094600450.07.berry36_510bdaf26f7b Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id 785E21803F9B5 for ; Thu, 30 Jul 2020 12:00:45 +0000 (UTC) X-HE-Tag: berry36_510bdaf26f7b X-Filterd-Recvd-Size: 5193 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf20.hostedemail.com (Postfix) with ESMTP for ; Thu, 30 Jul 2020 12:00:44 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 114D2AE70; Thu, 30 Jul 2020 12:00:56 +0000 (UTC) Date: Thu, 30 Jul 2020 14:00:43 +0200 From: Michal Hocko To: Johannes Weiner Cc: Andrew Morton , Roman Gushchin , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH] mm: memcontrol: don't count limit-setting reclaim as memory pressure Message-ID: <20200730120043.GI18727@dhcp22.suse.cz> References: <20200728135210.379885-2-hannes@cmpxchg.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200728135210.379885-2-hannes@cmpxchg.org> X-Rspamd-Queue-Id: 785E21803F9B5 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam02 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: On Tue 28-07-20 09:52:10, Johannes Weiner wrote: > When an outside process lowers one of the memory limits of a cgroup > (or uses the force_empty knob in cgroup1), direct reclaim is performed > in the context of the write(), in order to directly enforce the new > limit and have it being met by the time the write() returns. > > Currently, this reclaim activity is accounted as memory pressure in > the cgroup that the writer(!) belongs to. This is unexpected. It > specifically causes problems for senpai > (https://github.com/facebookincubator/senpai), which is an agent that > routinely adjusts the memory limits and performs associated reclaim > work in tens or even hundreds of cgroups running on the host. The > cgroup that senpai is running in itself will report elevated levels of > memory pressure, even though it itself is under no memory shortage or > any sort of distress. > > Move the psi annotation from the central cgroup reclaim function to > callsites in the allocation context, and thereby no longer count any > limit-setting reclaim as memory pressure. If the newly set limit > causes the workload inside the cgroup into direct reclaim, that of > course will continue to count as memory pressure. > > Signed-off-by: Johannes Weiner Acked-by: Michal Hocko > --- > mm/memcontrol.c | 12 +++++++++++- > mm/vmscan.c | 6 ------ > 2 files changed, 11 insertions(+), 7 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 805a44bf948c..8377640ad494 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -2233,11 +2233,18 @@ static void reclaim_high(struct mem_cgroup *memcg, > gfp_t gfp_mask) > { > do { > + unsigned long pflags; > + > if (page_counter_read(&memcg->memory) <= > READ_ONCE(memcg->memory.high)) > continue; > + > memcg_memory_event(memcg, MEMCG_HIGH); > + > + psi_memstall_enter(&pflags); > try_to_free_mem_cgroup_pages(memcg, nr_pages, gfp_mask, true); > + psi_memstall_leave(&pflags); > + > } while ((memcg = parent_mem_cgroup(memcg)) && > !mem_cgroup_is_root(memcg)); > } > @@ -2451,10 +2458,11 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, > int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; > struct mem_cgroup *mem_over_limit; > struct page_counter *counter; > + enum oom_status oom_status; > unsigned long nr_reclaimed; > bool may_swap = true; > bool drained = false; > - enum oom_status oom_status; > + unsigned long pflags; > > if (mem_cgroup_is_root(memcg)) > return 0; > @@ -2514,8 +2522,10 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, > > memcg_memory_event(mem_over_limit, MEMCG_MAX); > > + psi_memstall_enter(&pflags); > nr_reclaimed = try_to_free_mem_cgroup_pages(mem_over_limit, nr_pages, > gfp_mask, may_swap); > + psi_memstall_leave(&pflags); > > if (mem_cgroup_margin(mem_over_limit) >= nr_pages) > goto retry; > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 749d239c62b2..742538543c79 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -3318,7 +3318,6 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, > bool may_swap) > { > unsigned long nr_reclaimed; > - unsigned long pflags; > unsigned int noreclaim_flag; > struct scan_control sc = { > .nr_to_reclaim = max(nr_pages, SWAP_CLUSTER_MAX), > @@ -3339,17 +3338,12 @@ unsigned long try_to_free_mem_cgroup_pages(struct mem_cgroup *memcg, > struct zonelist *zonelist = node_zonelist(numa_node_id(), sc.gfp_mask); > > set_task_reclaim_state(current, &sc.reclaim_state); > - > trace_mm_vmscan_memcg_reclaim_begin(0, sc.gfp_mask); > - > - psi_memstall_enter(&pflags); > noreclaim_flag = memalloc_noreclaim_save(); > > nr_reclaimed = do_try_to_free_pages(zonelist, &sc); > > memalloc_noreclaim_restore(noreclaim_flag); > - psi_memstall_leave(&pflags); > - > trace_mm_vmscan_memcg_reclaim_end(nr_reclaimed); > set_task_reclaim_state(current, NULL); > > -- > 2.27.0 > -- Michal Hocko SUSE Labs