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=-6.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, 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 73149C43613 for ; Fri, 21 Jun 2019 12:09:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 2CAE82084E for ; Fri, 21 Jun 2019 12:09:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 2CAE82084E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id A5E158E0002; Fri, 21 Jun 2019 08:09:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A100F8E0001; Fri, 21 Jun 2019 08:09:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8D77B8E0002; Fri, 21 Jun 2019 08:09:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from mail-ed1-f72.google.com (mail-ed1-f72.google.com [209.85.208.72]) by kanga.kvack.org (Postfix) with ESMTP id 3C3AD8E0001 for ; Fri, 21 Jun 2019 08:09:33 -0400 (EDT) Received: by mail-ed1-f72.google.com with SMTP id l26so8963893eda.2 for ; Fri, 21 Jun 2019 05:09:33 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-original-authentication-results:x-gm-message-state:subject:to:cc :references:from:openpgp:autocrypt:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=cb+bWGD+HBxNB97rApn/jGEHo8WyU4g8aZHvN3ZHHKo=; b=WuID5Nw5JJDfH1eo2N5BK1/MCM+STqBihlvRTIV4xx69aqqYqWfQSfSNQ94bSzSm20 0hZq10n29dYs/DYJRw0rfLAGrVhjgqNltAyyHQZHhn+bwZQ/Xgqk9ME8XTtap4cOoGoh Xwn6XitcjKd3fpv4LW9ot3CZkPE9fylL1BAgH/jFNw2jWgdsMZmr4CpXSDkw13ixWnO7 eF8K65fiEl8jgtcdJlSnUrMtnU3G+fkFUcD+0NIOApzCI83m9rUI+81AVMplq0USp481 AngHUyNkMmwIKg3uoCv5SLIzrGfwtcmbZKqLsb5rjAyticTdJb39oNtOGaA9+arn1vDZ OS6Q== X-Original-Authentication-Results: mx.google.com; spf=pass (google.com: domain of vbabka@suse.cz designates 195.135.220.15 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Gm-Message-State: APjAAAX8PYT+crkq3hXRLdcXPsrPpl+yAQQYhVuLN5Okwiz2u1gKzrWf OXdaD4qbMEYmvZ+yQ3Auibz9MGLv2ER6oFhRJqRp71za5fR6RBmlNywQ3bcaR1+BhwgCh7BD9XZ drlqNO+0Hc19f2DlREVxE13nPfAjtnSvQjk2NlzMEcozNOJdGbSyjy1HJIVv3QSh67A== X-Received: by 2002:a50:84e2:: with SMTP id 89mr72503265edq.218.1561118972794; Fri, 21 Jun 2019 05:09:32 -0700 (PDT) X-Google-Smtp-Source: APXvYqydSLYM4daJzVEfD/PkYALcy+uGLCLQu1RBkk/9y+mPoDF2fBZArTYBiZQY9iR85dT+eB75 X-Received: by 2002:a50:84e2:: with SMTP id 89mr72503181edq.218.1561118971953; Fri, 21 Jun 2019 05:09:31 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1561118971; cv=none; d=google.com; s=arc-20160816; b=D5vF4deKv63vToJQAkt0bpGpV0kxeeZ9yUzQeWBQVeTuX81RqMX7029jBkLWx+NaY0 MJWmGkr4M4/IM/M2x0dQP1o6ZJR/mqnG//7+EjP+Yb2nLbMTNgZfDqavJu1AvOccdxvT +ToyJ4orZWHvQ6lZ0+PW4IBif29SFaKcRslRJKzuVqIDanlPgDpOEoDFQAbwVJP79knw EP6atvd9sY33nIr2Rljbgioa8Sdv28Wi+EQl6B47bcA9gVqUqeVNsY8+SmyXUvSJRRIe PRz39ZCmb6Sueqs/xT+Gx0wVEjLiHm+sa1euW7LEuwBTVT1qxUi7t7HsqMEpDjjihwsY hn3Q== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:content-language:in-reply-to:mime-version :user-agent:date:message-id:autocrypt:openpgp:from:references:cc:to :subject; bh=cb+bWGD+HBxNB97rApn/jGEHo8WyU4g8aZHvN3ZHHKo=; b=Ehq/JObJtqNaOffEQ7FIfEzlnGZ7kJabbDnfGCG5CHLEppo19M8ZyphJ7GKfpfOFV2 yry/jdw9DGKyeAF0XMlWUk+MoI31qFmedlKTzVI20MwlJhBCHIirUOqbIOoIQeluPEON ebMeHvR7N11ZtYU758Rb3GrQvYeha8eBUKW+1BLtQCX1YkwSzV0gjhFQDalDN+l+upGv 5p810RfDeeJK5bse952odDuB4dBC0amthtWAzoZ2efW1vGQ6vdq4XbvEDbno1vNyEbM1 76NATyNpWAycKK+/EcvPNnOXVmGMmIPRy4vXXAjVkBQ4lvGYd74Rw2dgst/+wOdL9TQF ZhhQ== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of vbabka@suse.cz designates 195.135.220.15 as permitted sender) smtp.mailfrom=vbabka@suse.cz Received: from mx1.suse.de (mx2.suse.de. [195.135.220.15]) by mx.google.com with ESMTPS id o7si1618570ejd.303.2019.06.21.05.09.31 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 21 Jun 2019 05:09:31 -0700 (PDT) Received-SPF: pass (google.com: domain of vbabka@suse.cz designates 195.135.220.15 as permitted sender) client-ip=195.135.220.15; Authentication-Results: mx.google.com; spf=pass (google.com: domain of vbabka@suse.cz designates 195.135.220.15 as permitted sender) smtp.mailfrom=vbabka@suse.cz X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 554C9AF1E; Fri, 21 Jun 2019 12:09:31 +0000 (UTC) Subject: Re: [PATCH] mm: fix setting the high and low watermarks To: Alan Jenkins , Mel Gorman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20190621114325.711-1-alan.christopher.jenkins@gmail.com> From: Vlastimil Babka Openpgp: preference=signencrypt Autocrypt: addr=vbabka@suse.cz; prefer-encrypt=mutual; keydata= mQINBFZdmxYBEADsw/SiUSjB0dM+vSh95UkgcHjzEVBlby/Fg+g42O7LAEkCYXi/vvq31JTB KxRWDHX0R2tgpFDXHnzZcQywawu8eSq0LxzxFNYMvtB7sV1pxYwej2qx9B75qW2plBs+7+YB 87tMFA+u+L4Z5xAzIimfLD5EKC56kJ1CsXlM8S/LHcmdD9Ctkn3trYDNnat0eoAcfPIP2OZ+ 9oe9IF/R28zmh0ifLXyJQQz5ofdj4bPf8ecEW0rhcqHfTD8k4yK0xxt3xW+6Exqp9n9bydiy tcSAw/TahjW6yrA+6JhSBv1v2tIm+itQc073zjSX8OFL51qQVzRFr7H2UQG33lw2QrvHRXqD Ot7ViKam7v0Ho9wEWiQOOZlHItOOXFphWb2yq3nzrKe45oWoSgkxKb97MVsQ+q2SYjJRBBH4 8qKhphADYxkIP6yut/eaj9ImvRUZZRi0DTc8xfnvHGTjKbJzC2xpFcY0DQbZzuwsIZ8OPJCc LM4S7mT25NE5kUTG/TKQCk922vRdGVMoLA7dIQrgXnRXtyT61sg8PG4wcfOnuWf8577aXP1x 6mzw3/jh3F+oSBHb/GcLC7mvWreJifUL2gEdssGfXhGWBo6zLS3qhgtwjay0Jl+kza1lo+Cv BB2T79D4WGdDuVa4eOrQ02TxqGN7G0Biz5ZLRSFzQSQwLn8fbwARAQABtCBWbGFzdGltaWwg QmFia2EgPHZiYWJrYUBzdXNlLmN6PokCVAQTAQoAPgIbAwULCQgHAwUVCgkICwUWAgMBAAIe AQIXgBYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJcbbyGBQkH8VTqAAoJECJPp+fMgqZkpGoP /1jhVihakxw1d67kFhPgjWrbzaeAYOJu7Oi79D8BL8Vr5dmNPygbpGpJaCHACWp+10KXj9yz fWABs01KMHnZsAIUytVsQv35DMMDzgwVmnoEIRBhisMYOQlH2bBn/dqBjtnhs7zTL4xtqEcF 1hoUFEByMOey7gm79utTk09hQE/Zo2x0Ikk98sSIKBETDCl4mkRVRlxPFl4O/w8dSaE4eczH LrKezaFiZOv6S1MUKVKzHInonrCqCNbXAHIeZa3JcXCYj1wWAjOt9R3NqcWsBGjFbkgoKMGD usiGabetmQjXNlVzyOYdAdrbpVRNVnaL91sB2j8LRD74snKsV0Wzwt90YHxDQ5z3M75YoIdl byTKu3BUuqZxkQ/emEuxZ7aRJ1Zw7cKo/IVqjWaQ1SSBDbZ8FAUPpHJxLdGxPRN8Pfw8blKY 8mvLJKoF6i9T6+EmlyzxqzOFhcc4X5ig5uQoOjTIq6zhLO+nqVZvUDd2Kz9LMOCYb516cwS/ Enpi0TcZ5ZobtLqEaL4rupjcJG418HFQ1qxC95u5FfNki+YTmu6ZLXy+1/9BDsPuZBOKYpUm 3HWSnCS8J5Ny4SSwfYPH/JrtberWTcCP/8BHmoSpS/3oL3RxrZRRVnPHFzQC6L1oKvIuyXYF rkybPXYbmNHN+jTD3X8nRqo+4Qhmu6SHi3VquQENBFsZNQwBCACuowprHNSHhPBKxaBX7qOv KAGCmAVhK0eleElKy0sCkFghTenu1sA9AV4okL84qZ9gzaEoVkgbIbDgRbKY2MGvgKxXm+kY n8tmCejKoeyVcn9Xs0K5aUZiDz4Ll9VPTiXdf8YcjDgeP6/l4kHb4uSW4Aa9ds0xgt0gP1Xb AMwBlK19YvTDZV5u3YVoGkZhspfQqLLtBKSt3FuxTCU7hxCInQd3FHGJT/IIrvm07oDO2Y8J DXWHGJ9cK49bBGmK9B4ajsbe5GxtSKFccu8BciNluF+BqbrIiM0upJq5Xqj4y+Xjrpwqm4/M ScBsV0Po7qdeqv0pEFIXKj7IgO/d4W2bABEBAAGJA3IEGAEKACYWIQSpQNQ0mSwujpkQPVAi T6fnzIKmZAUCWxk1DAIbAgUJA8JnAAFACRAiT6fnzIKmZMB0IAQZAQoAHRYhBKZ2GgCcqNxn k0Sx9r6Fd25170XjBQJbGTUMAAoJEL6Fd25170XjDBUH/2jQ7a8g+FC2qBYxU/aCAVAVY0NE YuABL4LJ5+iWwmqUh0V9+lU88Cv4/G8fWwU+hBykSXhZXNQ5QJxyR7KWGy7LiPi7Cvovu+1c 9Z9HIDNd4u7bxGKMpn19U12ATUBHAlvphzluVvXsJ23ES/F1c59d7IrgOnxqIcXxr9dcaJ2K k9VP3TfrjP3g98OKtSsyH0xMu0MCeyewf1piXyukFRRMKIErfThhmNnLiDbaVy6biCLx408L Mo4cCvEvqGKgRwyckVyo3JuhqreFeIKBOE1iHvf3x4LU8cIHdjhDP9Wf6ws1XNqIvve7oV+w B56YWoalm1rq00yUbs2RoGcXmtX1JQ//aR/paSuLGLIb3ecPB88rvEXPsizrhYUzbe1TTkKc 4a4XwW4wdc6pRPVFMdd5idQOKdeBk7NdCZXNzoieFntyPpAq+DveK01xcBoXQ2UktIFIsXey uSNdLd5m5lf7/3f0BtaY//f9grm363NUb9KBsTSnv6Vx7Co0DWaxgC3MFSUhxzBzkJNty+2d 10jvtwOWzUN+74uXGRYSq5WefQWqqQNnx+IDb4h81NmpIY/X0PqZrapNockj3WHvpbeVFAJ0 9MRzYP3x8e5OuEuJfkNnAbwRGkDy98nXW6fKeemREjr8DWfXLKFWroJzkbAVmeIL0pjXATxr +tj5JC0uvMrrXefUhXTo0SNoTsuO/OsAKOcVsV/RHHTwCDR2e3W8mOlA3QbYXsscgjghbuLh J3oTRrOQa8tUXWqcd5A0+QPo5aaMHIK0UAthZsry5EmCY3BrbXUJlt+23E93hXQvfcsmfi0N rNh81eknLLWRYvMOsrbIqEHdZBT4FHHiGjnck6EYx/8F5BAZSodRVEAgXyC8IQJ+UVa02QM5 D2VL8zRXZ6+wARKjgSrW+duohn535rG/ypd0ctLoXS6dDrFokwTQ2xrJiLbHp9G+noNTHSan ExaRzyLbvmblh3AAznb68cWmM3WVkceWACUalsoTLKF1sGrrIBj5updkKkzbKOq5gcC5AQ0E Wxk1NQEIAJ9B+lKxYlnKL5IehF1XJfknqsjuiRzj5vnvVrtFcPlSFL12VVFVUC2tT0A1Iuo9 NAoZXEeuoPf1dLDyHErrWnDyn3SmDgb83eK5YS/K363RLEMOQKWcawPJGGVTIRZgUSgGusKL NuZqE5TCqQls0x/OPljufs4gk7E1GQEgE6M90Xbp0w/r0HB49BqjUzwByut7H2wAdiNAbJWZ F5GNUS2/2IbgOhOychHdqYpWTqyLgRpf+atqkmpIJwFRVhQUfwztuybgJLGJ6vmh/LyNMRr8 J++SqkpOFMwJA81kpjuGR7moSrUIGTbDGFfjxmskQV/W/c25Xc6KaCwXah3OJ40AEQEAAYkC PAQYAQoAJhYhBKlA1DSZLC6OmRA9UCJPp+fMgqZkBQJbGTU1AhsMBQkDwmcAAAoJECJPp+fM gqZkPN4P/Ra4NbETHRj5/fM1fjtngt4dKeX/6McUPDIRuc58B6FuCQxtk7sX3ELs+1+w3eSV rHI5cOFRSdgw/iKwwBix8D4Qq0cnympZ622KJL2wpTPRLlNaFLoe5PkoORAjVxLGplvQIlhg miljQ3R63ty3+MZfkSVsYITlVkYlHaSwP2t8g7yTVa+q8ZAx0NT9uGWc/1Sg8j/uoPGrctml hFNGBTYyPq6mGW9jqaQ8en3ZmmJyw3CHwxZ5FZQ5qc55xgshKiy8jEtxh+dgB9d8zE/S/UGI E99N/q+kEKSgSMQMJ/CYPHQJVTi4YHh1yq/qTkHRX+ortrF5VEeDJDv+SljNStIxUdroPD29 2ijoaMFTAU+uBtE14UP5F+LWdmRdEGS1Ah1NwooL27uAFllTDQxDhg/+LJ/TqB8ZuidOIy1B xVKRSg3I2m+DUTVqBy7Lixo73hnW69kSjtqCeamY/NSu6LNP+b0wAOKhwz9hBEwEHLp05+mj 5ZFJyfGsOiNUcMoO/17FO4EBxSDP3FDLllpuzlFD7SXkfJaMWYmXIlO0jLzdfwfcnDzBbPwO hBM8hvtsyq8lq8vJOxv6XD6xcTtj5Az8t2JjdUX6SF9hxJpwhBU0wrCoGDkWp4Bbv6jnF7zP Nzftr4l8RuJoywDIiJpdaNpSlXKpj/K6KrnyAI/joYc7 Message-ID: <3d15b808-b7cd-7379-a6a9-d3cf04b7dcec@suse.cz> Date: Fri, 21 Jun 2019 14:09:31 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: <20190621114325.711-1-alan.christopher.jenkins@gmail.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit 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 6/21/19 1:43 PM, Alan Jenkins wrote: > When setting the low and high watermarks we use min_wmark_pages(zone). > I guess this is to reduce the line length. But we forgot that this macro > includes zone->watermark_boost. We need to reset zone->watermark_boost > first. Otherwise the watermarks will be set inconsistently. > > E.g. this could cause inconsistent values if the watermarks have been > boosted, and then you change a sysctl which triggers > __setup_per_zone_wmarks(). > > I strongly suspect this explains why I have seen slightly high watermarks. > Suspicious-looking zoneinfo below - notice high-low != low-min. > > Node 0, zone Normal > pages free 74597 > min 9582 > low 34505 > high 36900 > > https://unix.stackexchange.com/questions/525674/my-low-and-high-watermarks-seem-higher-than-predicted-by-documentation-sysctl-vm/525687 > > Signed-off-by: Alan Jenkins > Fixes: 1c30844d2dfe ("mm: reclaim small amounts of memory when an external > fragmentation event occurs") > Cc: stable@vger.kernel.org Nice catch, thanks! Acked-by: Vlastimil Babka Personally I would implement it a bit differently, see below. If you agree, it's fine if you keep the authorship of the whole patch. > --- > > Tested by compiler :-). > > Ideally the commit message would be clear about what happens the > *first* time __setup_per_zone_watermarks() is called. I guess that > zone->watermark_boost is *usually* zero, or we would have noticed > some wild problems :-). However I am not familiar with how the zone > structures are allocated & initialized. Maybe there is a case where > zone->watermark_boost could contain an arbitrary unitialized value > at this point. Can we rule that out? Dunno if there's some arch override, but generic_alloc_nodedata() uses kzalloc() so it's zeroed. -----8<----- diff --git a/mm/page_alloc.c b/mm/page_alloc.c index d66bc8abe0af..3b2f0cedf78e 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -7624,6 +7624,7 @@ static void __setup_per_zone_wmarks(void) for_each_zone(zone) { u64 tmp; + unsigned long wmark_min; spin_lock_irqsave(&zone->lock, flags); tmp = (u64)pages_min * zone_managed_pages(zone); @@ -7642,13 +7643,13 @@ static void __setup_per_zone_wmarks(void) min_pages = zone_managed_pages(zone) / 1024; min_pages = clamp(min_pages, SWAP_CLUSTER_MAX, 128UL); - zone->_watermark[WMARK_MIN] = min_pages; + wmark_min = min_pages; } else { /* * If it's a lowmem zone, reserve a number of pages * proportionate to the zone's size. */ - zone->_watermark[WMARK_MIN] = tmp; + wmark_min = tmp; } /* @@ -7660,8 +7661,9 @@ static void __setup_per_zone_wmarks(void) mult_frac(zone_managed_pages(zone), watermark_scale_factor, 10000)); - zone->_watermark[WMARK_LOW] = min_wmark_pages(zone) + tmp; - zone->_watermark[WMARK_HIGH] = min_wmark_pages(zone) + tmp * 2; + zone->_watermark[WMARK_MIN] = wmark_min; + zone->_watermark[WMARK_LOW] = wmark_min + tmp; + zone->_watermark[WMARK_HIGH] = wmark_min + tmp * 2; zone->watermark_boost = 0; spin_unlock_irqrestore(&zone->lock, flags);