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=-12.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,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 ED1A0C433E0 for ; Fri, 7 Aug 2020 06:22:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id BFF71221E5 for ; Fri, 7 Aug 2020 06:22:17 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781337; bh=57YwXGxS5eIpgfsMtX1iESNczBzRJgaBM2J+QLcJ8mw=; h=Date:From:To:Subject:In-Reply-To:Reply-To:List-ID:From; b=ft0/JRC0454T2a8KdYN7cu0/9a3ktn2SWyOwtUbXlP4wLQ7YH2WSdJjJXiymNLRNH oHEZILfBGrokJ1gMkWdjiAHEFqzYgyMd0DQ/Tk+Jq6w0QXobN++mIIQHEOwFplEAVm +gm+hU0QF0g/FS8XTFcwzHOizZBzG5VfvQaiw0yc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726249AbgHGGWR (ORCPT ); Fri, 7 Aug 2020 02:22:17 -0400 Received: from mail.kernel.org ([198.145.29.99]:58698 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725379AbgHGGWR (ORCPT ); Fri, 7 Aug 2020 02:22:17 -0400 Received: from localhost.localdomain (c-73-231-172-41.hsd1.ca.comcast.net [73.231.172.41]) (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 E17A92177B; Fri, 7 Aug 2020 06:22:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1596781336; bh=57YwXGxS5eIpgfsMtX1iESNczBzRJgaBM2J+QLcJ8mw=; h=Date:From:To:Subject:In-Reply-To:From; b=EzfEXjag1a8vgc3bbaGHAP7muVKYiyHDUTboSj7tOeNxWLuyaU4f3zToafL1nKJ+r kZgne3bvIH/RpmHDg2GLEhFx0AAwtbI1WgZo8JmX21oKghMIUABiho8H1PIPsg/PBx xBSuZgjciN3mPdvxf+jb1wfxAPlqcBX/A/Szhqa4= Date: Thu, 06 Aug 2020 23:22:15 -0700 From: Andrew Morton To: akpm@linux-foundation.org, chris@chrisdown.name, guro@fb.com, hannes@cmpxchg.org, linux-mm@kvack.org, mhocko@suse.com, mm-commits@vger.kernel.org, shakeelb@google.com, torvalds@linux-foundation.org Subject: [patch 092/163] mm: memcontrol: don't count limit-setting reclaim as memory pressure Message-ID: <20200807062215.hpQOJtMdn%akpm@linux-foundation.org> In-Reply-To: <20200806231643.a2711a608dd0f18bff2caf2b@linux-foundation.org> User-Agent: s-nail v14.8.16 Sender: mm-commits-owner@vger.kernel.org Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Johannes Weiner Subject: mm: memcontrol: don't count limit-setting reclaim as memory pressure 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. Link: http://lkml.kernel.org/r/20200728135210.379885-2-hannes@cmpxchg.org Signed-off-by: Johannes Weiner Reviewed-by: Shakeel Butt Reviewed-by: Roman Gushchin Acked-by: Chris Down Acked-by: Michal Hocko Signed-off-by: Andrew Morton --- mm/memcontrol.c | 11 ++++++++++- mm/vmscan.c | 6 ------ 2 files changed, 10 insertions(+), 7 deletions(-) --- a/mm/memcontrol.c~mm-memcontrol-dont-count-limit-setting-reclaim-as-memory-pressure +++ a/mm/memcontrol.c @@ -2374,12 +2374,18 @@ static unsigned long reclaim_high(struct unsigned long nr_reclaimed = 0; 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); nr_reclaimed += 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)); @@ -2621,10 +2627,11 @@ static int try_charge(struct mem_cgroup int nr_retries = MAX_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; @@ -2684,8 +2691,10 @@ retry: 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; --- a/mm/vmscan.c~mm-memcontrol-dont-count-limit-setting-reclaim-as-memory-pressure +++ a/mm/vmscan.c @@ -3310,7 +3310,6 @@ unsigned long try_to_free_mem_cgroup_pag 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), @@ -3331,17 +3330,12 @@ unsigned long try_to_free_mem_cgroup_pag 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); _