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=-7.0 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,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 C3DB8C433E0 for ; Wed, 20 May 2020 16:59:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 827F8206B6 for ; Wed, 20 May 2020 16:59:35 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 827F8206B6 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 1AC0480007; Wed, 20 May 2020 12:59:35 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 15D4D900002; Wed, 20 May 2020 12:59:35 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 09A8480007; Wed, 20 May 2020 12:59:35 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0247.hostedemail.com [216.40.44.247]) by kanga.kvack.org (Postfix) with ESMTP id E7AD7900002 for ; Wed, 20 May 2020 12:59:34 -0400 (EDT) Received: from smtpin05.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 95BCA40EE for ; Wed, 20 May 2020 16:59:34 +0000 (UTC) X-FDA: 76837708668.05.title78_8dc341528622b X-HE-Tag: title78_8dc341528622b X-Filterd-Recvd-Size: 6322 Received: from mail-ej1-f67.google.com (mail-ej1-f67.google.com [209.85.218.67]) by imf23.hostedemail.com (Postfix) with ESMTP for ; Wed, 20 May 2020 16:59:34 +0000 (UTC) Received: by mail-ej1-f67.google.com with SMTP id s3so4822228eji.6 for ; Wed, 20 May 2020 09:59:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=ulK8UjBcVR88erWI+DBVtEzBcjfexz2ALmk1KaikEeE=; b=tYynvbL/T4qRhU1f8CloO6yclW24+5ZcbvsLViVeWgL8yCU++EAczsBLnRXCN1G+Am qNo3kiOWVj2X+Cpo8FIrivHa7yQvrjD2Ja7eLns3TcslYfRgNrVUNd8gPDUJTgwenjS+ 6XRq/qqCmON5cQ0eOYv5Gl/4zWFS5aMcU9IZAvAJ2SAQuW4IdyVT9emF8WB549JNRzfF /k85QjeRG2YLmw1TXRdqRD08nCenj75n3JRxebcp83B5BbM6wSXfO5Lwg8zgNmAf0G6S BQPI4RtKAkRWpvB0jv3Oeal8vCxUAZ+fj7qqPDTNmw0aXeY+iSNamzTZmcsjWy8CowIp jp/g== X-Gm-Message-State: AOAM531YydDil2qpvCGKYovy5rOuXBakWSNUMkUlt1yB2EeHbwgnS281 JmCMOTaoyRoorOdXuNcAm7rZ1PA4 X-Google-Smtp-Source: ABdhPJxKJgx5XBPyBkWBT1fGe9dfNWGjBmU9XzwJaHwySJbBASqYFUxO125YFnq5b+LbkAd0l7I75g== X-Received: by 2002:a17:906:3912:: with SMTP id f18mr4709801eje.539.1589993973055; Wed, 20 May 2020 09:59:33 -0700 (PDT) Received: from localhost (ip-37-188-251-131.eurotel.cz. [37.188.251.131]) by smtp.gmail.com with ESMTPSA id z14sm2355795ejd.37.2020.05.20.09.59.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 20 May 2020 09:59:32 -0700 (PDT) Date: Wed, 20 May 2020 18:59:30 +0200 From: Michal Hocko To: Chris Down Cc: Andrew Morton , Johannes Weiner , linux-mm@kvack.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com Subject: Re: [PATCH] mm, memcg: unify reclaim retry limits with page allocator Message-ID: <20200520165930.GF6462@dhcp22.suse.cz> References: <20200520163142.GA808793@chrisdown.name> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200520163142.GA808793@chrisdown.name> 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 Wed 20-05-20 17:31:42, Chris Down wrote: > Reclaim retries have been set to 5 since the beginning of time in > 66e1707bc346 ("Memory controller: add per cgroup LRU and reclaim"). > However, we now have a generally agreed-upon standard for page reclaim: > MAX_RECLAIM_RETRIES (currently 16), added many years later in > 0a0337e0d1d1 ("mm, oom: rework oom detection"). > > In the absence of a compelling reason to declare an OOM earlier in memcg > context than page allocator context, it seems reasonable to supplant > MEM_CGROUP_RECLAIM_RETRIES with MAX_RECLAIM_RETRIES, making the page > allocator and memcg internals more similar in semantics when reclaim > fails to produce results, avoiding premature OOMs or throttling. > > Signed-off-by: Chris Down > Cc: Andrew Morton > Cc: Johannes Weiner > Cc: Michal Hocko I have already expressed my dislike to some of the MEM_CGROUP_RECLAIM_RETRIES usage but using MAX_RECLAIM_RETRIES is a reasonable thing to do. There is simply no reason to have two retry limits. Acked-by: Michal Hocko > --- > mm/memcontrol.c | 15 ++++++--------- > 1 file changed, 6 insertions(+), 9 deletions(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index b040951ccd6b..d3b23c57bed4 100644 > --- a/mm/memcontrol.c > +++ b/mm/memcontrol.c > @@ -73,9 +73,6 @@ EXPORT_SYMBOL(memory_cgrp_subsys); > > struct mem_cgroup *root_mem_cgroup __read_mostly; > > -/* The number of times we should retry reclaim failures before giving up. */ > -#define MEM_CGROUP_RECLAIM_RETRIES 5 > - > /* Socket memory accounting disabled? */ > static bool cgroup_memory_nosocket; > > @@ -2386,7 +2383,7 @@ void mem_cgroup_handle_over_high(void) > unsigned long pflags; > unsigned long nr_reclaimed; > unsigned int nr_pages = current->memcg_nr_pages_over_high; > - int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; > + int nr_retries = MAX_RECLAIM_RETRIES; > struct mem_cgroup *memcg; > > if (likely(!nr_pages)) > @@ -2438,7 +2435,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, > unsigned int nr_pages) > { > unsigned int batch = max(MEMCG_CHARGE_BATCH, nr_pages); > - int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; > + int nr_retries = MAX_RECLAIM_RETRIES; > struct mem_cgroup *mem_over_limit; > struct page_counter *counter; > unsigned long nr_reclaimed; > @@ -2557,7 +2554,7 @@ static int try_charge(struct mem_cgroup *memcg, gfp_t gfp_mask, > get_order(nr_pages * PAGE_SIZE)); > switch (oom_status) { > case OOM_SUCCESS: > - nr_retries = MEM_CGROUP_RECLAIM_RETRIES; > + nr_retries = MAX_RECLAIM_RETRIES; > goto retry; > case OOM_FAILED: > goto force; > @@ -3168,7 +3165,7 @@ static inline bool memcg_has_children(struct mem_cgroup *memcg) > */ > static int mem_cgroup_force_empty(struct mem_cgroup *memcg) > { > - int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; > + int nr_retries = MAX_RECLAIM_RETRIES; > > /* we call try-to-free pages for make this cgroup empty */ > lru_add_drain_all(); > @@ -6001,7 +5998,7 @@ static ssize_t memory_high_write(struct kernfs_open_file *of, > char *buf, size_t nbytes, loff_t off) > { > struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); > - unsigned int nr_retries = MEM_CGROUP_RECLAIM_RETRIES; > + unsigned int nr_retries = MAX_RECLAIM_RETRIES; > bool drained = false; > unsigned long high; > int err; > @@ -6049,7 +6046,7 @@ static ssize_t memory_max_write(struct kernfs_open_file *of, > char *buf, size_t nbytes, loff_t off) > { > struct mem_cgroup *memcg = mem_cgroup_from_css(of_css(of)); > - unsigned int nr_reclaims = MEM_CGROUP_RECLAIM_RETRIES; > + unsigned int nr_reclaims = MAX_RECLAIM_RETRIES; > bool drained = false; > unsigned long max; > int err; > -- > 2.26.2 -- Michal Hocko SUSE Labs