From patchwork Tue May 5 08:41:26 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yafang Shao X-Patchwork-Id: 11528425 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 00072912 for ; Tue, 5 May 2020 08:42:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id B419C2068E for ; Tue, 5 May 2020 08:42:18 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="D97jDPF7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org B419C2068E Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id C3D258E00A1; Tue, 5 May 2020 04:42:17 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id BED048E0058; Tue, 5 May 2020 04:42:17 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id ADB4B8E00A1; Tue, 5 May 2020 04:42:17 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0132.hostedemail.com [216.40.44.132]) by kanga.kvack.org (Postfix) with ESMTP id 928CD8E0058 for ; Tue, 5 May 2020 04:42:17 -0400 (EDT) Received: from smtpin11.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 4DF8D824934B for ; Tue, 5 May 2020 08:42:17 +0000 (UTC) X-FDA: 76782023514.11.yard08_13edf0620605c X-Spam-Summary: 2,0,0,36616b20b9e68ece,d41d8cd98f00b204,laoar.shao@gmail.com,,RULES_HIT:2:41:355:379:541:800:960:973:988:989:1260:1345:1359:1437:1535:1605:1730:1747:1777:1792:2393:2553:2559:2562:2897:3138:3139:3140:3141:3142:3865:3866:3867:3868:3870:3871:3872:3874:4049:4120:4250:4321:4470:4605:5007:6261:6653:7514:7875:7903:7904:9413:10004:11026:11473:11658:11914:12043:12219:12291:12295:12296:12297:12438:12517:12519:12555:12664:12679:12683:12895:13149:13161:13229:13230:13255:14096:14394:14687:21080:21433:21444:21451:21627:21666:21740:21939:21966:21990:30054:30056:30064:30074:30090,0,RBL:209.85.216.67:@gmail.com:.lbl8.mailshell.net-62.50.0.100 66.100.201.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:23,LUA_SUMMARY:none X-HE-Tag: yard08_13edf0620605c X-Filterd-Recvd-Size: 9634 Received: from mail-pj1-f67.google.com (mail-pj1-f67.google.com [209.85.216.67]) by imf42.hostedemail.com (Postfix) with ESMTP for ; Tue, 5 May 2020 08:42:16 +0000 (UTC) Received: by mail-pj1-f67.google.com with SMTP id t40so714124pjb.3 for ; Tue, 05 May 2020 01:42:16 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=uNXSdEUBpc3xWP7djY2ze56IO2uIUgfCKO2NyW30Dck=; b=D97jDPF7pJRvvGaVoCW6UlzjpMr7H5DOZlC/aGmGyv/FNHecOYKhA3muG5v4zgdTVT Fehu8BpMixpRo7d6C31z2/Qwp/NH5uZr6nB5S70I9Gzf9VlFfydxdf4A/a8x+olV/Caq rcFRCjUqU/Y0wfAGf5si8tR6BNje9J9ZHiMqizH4wjXJ6Rx3JZ2N6Kkm5iDV5M8rX23u wP+c6naS2GRNThO0ONgdc0rkfCdFU+gVJY0Hyry0BuluwqYUaoPA3nnWgmqA1TUXq4dK 3rOjbQNvP+NRgdfz6J5LXZA4TMN2WRIxNdmeTKmay3secfl5lVnthmCJcUmo7d8mFlp3 +Cdg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=uNXSdEUBpc3xWP7djY2ze56IO2uIUgfCKO2NyW30Dck=; b=EVyMwamhIpOtRHOOW+Qphk5/v/eZPsy3OtQyDnvzlvOgDAo6zJd3GsZI3K5McW3vKs 6SE1NFOu5ydLNVa66ZZzqEz13k6QI++4QmZ5nyA3d8TrttMhWz3XeS9D9H/lB9B6ZVOb 2Bil5I2swWBRSQ9zdPRmnGD6qIvZnMNsqJO646zLasIZrNeRvcdSvr44wEAcSl50wPy/ xmBxqGWM0cDey/5tcvEneCmxj9eEfeEEVSMs2maj3hcdgU+RwqP9GWjW8OicHmD+5E9q Wh28p/YSwDRn37xdYiMySXaK/tARh1J10+2vmATTaoOMqOMiZha1sblsTJxJJLt4Abfs C4hQ== X-Gm-Message-State: AGi0PuY+5aNeqfKfxgHgse5tF96eIW1hUd69ULGNN4atfxepRYePChwA 8JTPPrbmJepMzf2B2XCcblE= X-Google-Smtp-Source: APiQypKkl2yBbJWZ+3+d391ViVXNqxbwJdeakoqTLvcOVr7z8+Tmv4ZWBy7VlPgL2n0NiX/wCcsUgA== X-Received: by 2002:a17:902:b708:: with SMTP id d8mr2006175pls.69.1588668136028; Tue, 05 May 2020 01:42:16 -0700 (PDT) Received: from localhost.localdomain ([203.100.54.194]) by smtp.gmail.com with ESMTPSA id p190sm1443802pfp.207.2020.05.05.01.42.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2020 01:42:15 -0700 (PDT) From: Yafang Shao To: akpm@linux-foundation.org Cc: mhocko@kernel.org, hannes@cmpxchg.org, chris@chrisdown.name, guro@fb.com, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Yafang Shao Subject: [PATCH v3 1/2] mm, memcg: Avoid stale protection values when cgroup is above protection Date: Tue, 5 May 2020 04:41:26 -0400 Message-Id: <20200505084127.12923-2-laoar.shao@gmail.com> X-Mailer: git-send-email 2.18.1 In-Reply-To: <20200505084127.12923-1-laoar.shao@gmail.com> References: <20200505084127.12923-1-laoar.shao@gmail.com> 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: A cgroup can have both memory protection and a memory limit to isolate it from its siblings in both directions - for example, to prevent it from being shrunk below 2G under high pressure from outside, but also from growing beyond 4G under low pressure. Commit 9783aa9917f8 ("mm, memcg: proportional memory.{low,min} reclaim") implemented proportional scan pressure so that multiple siblings in excess of their protection settings don't get reclaimed equally but instead in accordance to their unprotected portion. During limit reclaim, this proportionality shouldn't apply of course: there is no competition, all pressure is from within the cgroup and should be applied as such. Reclaim should operate at full efficiency. However, mem_cgroup_protected() never expected anybody to look at the effective protection values when it indicated that the cgroup is above its protection. As a result, a query during limit reclaim may return stale protection values that were calculated by a previous reclaim cycle in which the cgroup did have siblings. When this happens, reclaim is unnecessarily hesitant and potentially slow to meet the desired limit. In theory this could lead to premature OOM kills, although it's not obvious this has occurred in practice. Workaround the problem by special casing reclaim roots in mem_cgroup_protection. These memcgs are never participating in the reclaim protection because the reclaim is internal. We have to ignore effective protection values for reclaim roots because mem_cgroup_protected might be called from racing reclaim contexts with different roots. Calculation is relying on root -> leaf tree traversal therefore top-down reclaim protection invariants should hold. The only exception is the reclaim root which should have effective protection set to 0 but that would be problematic for the following setup: Let's have global and A's reclaim in parallel: | A (low=2G, usage = 3G, max = 3G, children_low_usage = 1.5G) |\ | C (low = 1G, usage = 2.5G) B (low = 1G, usage = 0.5G) for A reclaim we have B.elow = B.low C.elow = C.low For the global reclaim A.elow = A.low B.elow = min(B.usage, B.low) because children_low_usage <= A.elow C.elow = min(C.usage, C.low) With the effective values resetting we have A reclaim A.elow = 0 B.elow = B.low C.elow = C.low and global reclaim could see the above and then B.elow = C.elow = 0 because children_low_usage > A.elow Which means that protected memcgs would get reclaimed. In future we would like to make mem_cgroup_protected more robust against racing reclaim contexts but that is likely more complex solution than this simple workaround. [hannes@cmpxchg.org - large part of the changelog] [mhocko@suse.com - workaround explanation] [chris@chrisdown.name - retitle] Fixes: 9783aa9917f8 ("mm, memcg: proportional memory.{low,min} reclaim") Signed-off-by: Yafang Shao Acked-by: Michal Hocko Acked-by: Johannes Weiner Acked-by: Chris Down Acked-by: Roman Gushchin --- include/linux/memcontrol.h | 42 ++++++++++++++++++++++++++++++++++++-- mm/memcontrol.c | 8 ++++++++ mm/vmscan.c | 3 ++- 3 files changed, 50 insertions(+), 3 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index d275c72c4f8e..c07548ce26cb 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -344,12 +344,49 @@ static inline bool mem_cgroup_disabled(void) return !cgroup_subsys_enabled(memory_cgrp_subsys); } -static inline unsigned long mem_cgroup_protection(struct mem_cgroup *memcg, +static inline unsigned long mem_cgroup_protection(struct mem_cgroup *root, + struct mem_cgroup *memcg, bool in_low_reclaim) { if (mem_cgroup_disabled()) return 0; + /* + * There is no reclaim protection applied to a targeted reclaim. + * We are special casing this specific case here because + * mem_cgroup_protected calculation is not robust enough to keep + * the protection invariant for calculated effective values for + * parallel reclaimers with different reclaim target. This is + * especially a problem for tail memcgs (as they have pages on LRU) + * which would want to have effective values 0 for targeted reclaim + * but a different value for external reclaim. + * + * Example + * Let's have global and A's reclaim in parallel: + * | + * A (low=2G, usage = 3G, max = 3G, children_low_usage = 1.5G) + * |\ + * | C (low = 1G, usage = 2.5G) + * B (low = 1G, usage = 0.5G) + * + * For the global reclaim + * A.elow = A.low + * B.elow = min(B.usage, B.low) because children_low_usage <= A.elow + * C.elow = min(C.usage, C.low) + * + * With the effective values resetting we have A reclaim + * A.elow = 0 + * B.elow = B.low + * C.elow = C.low + * + * If the global reclaim races with A's reclaim then + * B.elow = C.elow = 0 because children_low_usage > A.elow) + * is possible and reclaiming B would be violating the protection. + * + */ + if (root == memcg) + return 0; + if (in_low_reclaim) return READ_ONCE(memcg->memory.emin); @@ -835,7 +872,8 @@ static inline void memcg_memory_event_mm(struct mm_struct *mm, { } -static inline unsigned long mem_cgroup_protection(struct mem_cgroup *memcg, +static inline unsigned long mem_cgroup_protection(struct mem_cgroup *root, + struct mem_cgroup *memcg, bool in_low_reclaim) { return 0; diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 5beea03dd58a..1206682edc1a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6388,6 +6388,14 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root, if (!root) root = root_mem_cgroup; + + /* + * Effective values of the reclaim targets are ignored so they + * can be stale. Have a look at mem_cgroup_protection for more + * details. + * TODO: calculation should be more robust so that we do not need + * that special casing. + */ if (memcg == root) return MEMCG_PROT_NONE; diff --git a/mm/vmscan.c b/mm/vmscan.c index b06868fc4926..4d3027ac131c 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2346,7 +2346,8 @@ static void get_scan_count(struct lruvec *lruvec, struct scan_control *sc, unsigned long protection; lruvec_size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx); - protection = mem_cgroup_protection(memcg, + protection = mem_cgroup_protection(sc->target_mem_cgroup, + memcg, sc->memcg_low_reclaim); if (protection) { From patchwork Tue May 5 08:41:27 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yafang Shao X-Patchwork-Id: 11528427 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 7582F15AB for ; Tue, 5 May 2020 08:42:23 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 31622206B8 for ; Tue, 5 May 2020 08:42:23 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ZE2IcKT/" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 31622206B8 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 44DCA8E00A2; Tue, 5 May 2020 04:42:22 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 3D6D48E0058; Tue, 5 May 2020 04:42:22 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2A1058E00A2; Tue, 5 May 2020 04:42:22 -0400 (EDT) X-Original-To: linux-mm@kvack.org X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0111.hostedemail.com [216.40.44.111]) by kanga.kvack.org (Postfix) with ESMTP id 10BB18E0058 for ; Tue, 5 May 2020 04:42:22 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id BFA832816 for ; Tue, 5 May 2020 08:42:21 +0000 (UTC) X-FDA: 76782023682.18.pie41_1495dbb7dbb2a X-Spam-Summary: 2,0,0,ccb89162ce8254ba,d41d8cd98f00b204,laoar.shao@gmail.com,,RULES_HIT:2:41:69:355:379:541:800:960:973:988:989:1260:1345:1359:1437:1535:1605:1730:1747:1777:1792:2198:2199:2393:2553:2559:2562:2731:2897:2898:3138:3139:3140:3141:3142:3865:3866:3867:3868:3870:3871:3872:3874:4049:4120:4321:4605:5007:6261:6653:7514:7576:7903:9040:9413:9592:10004:11026:11232:11473:11658:11914:12043:12291:12295:12296:12297:12438:12517:12519:12555:12679:12683:12895:12986:13255:14096:14394:14687:21063:21080:21444:21451:21627:21666:21795:21966:21990:30041:30045:30051:30054:30064:30070:30090,0,RBL:209.85.216.68:@gmail.com:.lbl8.mailshell.net-66.100.201.100 62.18.0.100,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:none,Custom_rules:0:0:0,LFtime:24,LUA_SUMMARY:none X-HE-Tag: pie41_1495dbb7dbb2a X-Filterd-Recvd-Size: 9488 Received: from mail-pj1-f68.google.com (mail-pj1-f68.google.com [209.85.216.68]) by imf14.hostedemail.com (Postfix) with ESMTP for ; Tue, 5 May 2020 08:42:21 +0000 (UTC) Received: by mail-pj1-f68.google.com with SMTP id a7so719596pju.2 for ; Tue, 05 May 2020 01:42:21 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=cFskabmmHvp4C/dLmH3xd8j3vuwmgpDBL417EZ/Ewyw=; b=ZE2IcKT/v16LxgSX7/LGBmaV8h9lSA3IAukZ28Yx3M0eVAZgzcocSZ0N+LHp1V40s/ 6h6OLhHJA6bW3SOc/Dt6jxIAL/bMJ2HrPGg+Ke3WpjWa1vfh9MnBBaqxDxq67avZXdDj bOPli6joNV1r3S042vpilqGizaljOVRYRp0Q2dCmrMM9oS0GSeyOii4C7GdHLsH/FvFK wK3Ntb/KCfmiceYN2owoId25A7cE6SMt8Nnpeb2NLQv5hPFmpR/j1aqgBsaibPw8nQb9 KXW5IL0W6pAkFmfB18b1kx9pyFA/ifrXLUMTt3r5q0Eznw5yM7kYH25VToF04s6ezP84 UkIg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=cFskabmmHvp4C/dLmH3xd8j3vuwmgpDBL417EZ/Ewyw=; b=nhkZQGQz7Gh7XcUZ7IY1H5ylPOOcZ9Bnaff2UkB/4etd61Bd7Yo+ZpjJwNzgTEr7Tg iOxbqSpnhGgejdENqZtMl1mCcbex5kchvJt7r7PTuE93f63XRxkDuc/csyXs9pexY1oV YrOrGlE7Lb8ewdMFLq7RUA7GVxGbA4Qei66dKTab6Qc39Fjq2+oKi6Z0mqpSVAzwhJRr 6Wo4wRaN3i7Ylyo1wm+ugs4nDfWBxupyqIpkAOO3ExG+gjdceBmcI8EtjSYWNgKRRmDG aSwFYk70uLUcujWVg4tOQWTCCq5PSuuy9X/FnrVh4Ct1yo2KQeWmmIcCdk8FcrdRm/Th 4eiA== X-Gm-Message-State: AGi0PuacV0FhIvDE2z6d8NutH0IXF5X/EqWqo4ESa0OqnovXdNhMMWla UrVCUUSCgIV8ZHt5u0FV77o= X-Google-Smtp-Source: APiQypLkIBAw7b/wIXu/OuUUdCasl8aw/yoD+hgWC91mTpRhXmosnl4Jl/TBALIdaVOQ2vde7kbg9Q== X-Received: by 2002:a17:90a:734b:: with SMTP id j11mr1661343pjs.108.1588668140507; Tue, 05 May 2020 01:42:20 -0700 (PDT) Received: from localhost.localdomain ([203.100.54.194]) by smtp.gmail.com with ESMTPSA id p190sm1443802pfp.207.2020.05.05.01.42.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 05 May 2020 01:42:19 -0700 (PDT) From: Yafang Shao To: akpm@linux-foundation.org Cc: mhocko@kernel.org, hannes@cmpxchg.org, chris@chrisdown.name, guro@fb.com, linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, Yafang Shao Subject: [PATCH v3 2/2] mm, memcg: Decouple e{low,min} state mutations from protection checks Date: Tue, 5 May 2020 04:41:27 -0400 Message-Id: <20200505084127.12923-3-laoar.shao@gmail.com> X-Mailer: git-send-email 2.18.1 In-Reply-To: <20200505084127.12923-1-laoar.shao@gmail.com> References: <20200505084127.12923-1-laoar.shao@gmail.com> 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: From: Chris Down mem_cgroup_protected currently is both used to set effective low and min and return a mem_cgroup_protection based on the result. As a user, this can be a little unexpected: it appears to be a simple predicate function, if not for the big warning in the comment above about the order in which it must be executed. This change makes it so that we separate the state mutations from the actual protection checks, which makes it more obvious where we need to be careful mutating internal state, and where we are simply checking and don't need to worry about that. Signed-off-by: Chris Down Suggested-by: Johannes Weiner Acked-by: Johannes Weiner Acked-by: Michal Hocko Cc: Roman Gushchin Signed-off-by: Yafang Shao --- include/linux/memcontrol.h | 43 ++++++++++++++++++++++++++++---------- mm/memcontrol.c | 28 +++++++------------------ mm/vmscan.c | 17 ++++----------- 3 files changed, 43 insertions(+), 45 deletions(-) diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h index c07548ce26cb..7a2c56fc220c 100644 --- a/include/linux/memcontrol.h +++ b/include/linux/memcontrol.h @@ -50,12 +50,6 @@ enum memcg_memory_event { MEMCG_NR_MEMORY_EVENTS, }; -enum mem_cgroup_protection { - MEMCG_PROT_NONE, - MEMCG_PROT_LOW, - MEMCG_PROT_MIN, -}; - struct mem_cgroup_reclaim_cookie { pg_data_t *pgdat; unsigned int generation; @@ -394,8 +388,26 @@ static inline unsigned long mem_cgroup_protection(struct mem_cgroup *root, READ_ONCE(memcg->memory.elow)); } -enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root, - struct mem_cgroup *memcg); +void mem_cgroup_calculate_protection(struct mem_cgroup *root, + struct mem_cgroup *memcg); + +static inline bool mem_cgroup_below_low(struct mem_cgroup *memcg) +{ + if (mem_cgroup_disabled()) + return false; + + return READ_ONCE(memcg->memory.elow) >= + page_counter_read(&memcg->memory); +} + +static inline bool mem_cgroup_below_min(struct mem_cgroup *memcg) +{ + if (mem_cgroup_disabled()) + return false; + + return READ_ONCE(memcg->memory.emin) >= + page_counter_read(&memcg->memory); +} int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm, gfp_t gfp_mask, struct mem_cgroup **memcgp, @@ -879,10 +891,19 @@ static inline unsigned long mem_cgroup_protection(struct mem_cgroup *root, return 0; } -static inline enum mem_cgroup_protection mem_cgroup_protected( - struct mem_cgroup *root, struct mem_cgroup *memcg) +static inline void mem_cgroup_calculate_protection(struct mem_cgroup *root, + struct mem_cgroup *memcg) +{ +} + +static inline bool mem_cgroup_below_low(struct mem_cgroup *memcg) { - return MEMCG_PROT_NONE; + return false; +} + +static inline bool mem_cgroup_below_min(struct mem_cgroup *memcg) +{ + return false; } static inline int mem_cgroup_try_charge(struct page *page, struct mm_struct *mm, diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1206682edc1a..474815acaf93 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6370,21 +6370,15 @@ static unsigned long effective_protection(unsigned long usage, * * WARNING: This function is not stateless! It can only be used as part * of a top-down tree iteration, not for isolated queries. - * - * Returns one of the following: - * MEMCG_PROT_NONE: cgroup memory is not protected - * MEMCG_PROT_LOW: cgroup memory is protected as long there is - * an unprotected supply of reclaimable memory from other cgroups. - * MEMCG_PROT_MIN: cgroup memory is protected */ -enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root, - struct mem_cgroup *memcg) +void mem_cgroup_calculate_protection(struct mem_cgroup *root, + struct mem_cgroup *memcg) { unsigned long usage, parent_usage; struct mem_cgroup *parent; if (mem_cgroup_disabled()) - return MEMCG_PROT_NONE; + return; if (!root) root = root_mem_cgroup; @@ -6397,21 +6391,21 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root, * that special casing. */ if (memcg == root) - return MEMCG_PROT_NONE; + return; usage = page_counter_read(&memcg->memory); if (!usage) - return MEMCG_PROT_NONE; + return; parent = parent_mem_cgroup(memcg); /* No parent means a non-hierarchical mode on v1 memcg */ if (!parent) - return MEMCG_PROT_NONE; + return; if (parent == root) { memcg->memory.emin = READ_ONCE(memcg->memory.min); memcg->memory.elow = memcg->memory.low; - goto out; + return; } parent_usage = page_counter_read(&parent->memory); @@ -6424,14 +6418,6 @@ enum mem_cgroup_protection mem_cgroup_protected(struct mem_cgroup *root, WRITE_ONCE(memcg->memory.elow, effective_protection(usage, parent_usage, memcg->memory.low, READ_ONCE(parent->memory.elow), atomic_long_read(&parent->memory.children_low_usage))); - -out: - if (usage <= memcg->memory.emin) - return MEMCG_PROT_MIN; - else if (usage <= memcg->memory.elow) - return MEMCG_PROT_LOW; - else - return MEMCG_PROT_NONE; } /** diff --git a/mm/vmscan.c b/mm/vmscan.c index 4d3027ac131c..c71660e2c304 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -2635,14 +2635,15 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) unsigned long reclaimed; unsigned long scanned; - switch (mem_cgroup_protected(target_memcg, memcg)) { - case MEMCG_PROT_MIN: + mem_cgroup_calculate_protection(target_memcg, memcg); + + if (mem_cgroup_below_min(memcg)) { /* * Hard protection. * If there is no reclaimable memory, OOM. */ continue; - case MEMCG_PROT_LOW: + } else if (mem_cgroup_below_low(memcg)) { /* * Soft protection. * Respect the protection only as long as @@ -2654,16 +2655,6 @@ static void shrink_node_memcgs(pg_data_t *pgdat, struct scan_control *sc) continue; } memcg_memory_event(memcg, MEMCG_LOW); - break; - case MEMCG_PROT_NONE: - /* - * All protection thresholds breached. We may - * still choose to vary the scan pressure - * applied based on by how much the cgroup in - * question has exceeded its protection - * thresholds (see get_scan_count). - */ - break; } reclaimed = sc->nr_reclaimed;