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=-3.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no 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 56C9DC433C1 for ; Thu, 25 Mar 2021 12:16:09 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id CEFDA61A10 for ; Thu, 25 Mar 2021 12:16:08 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org CEFDA61A10 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 5B01F6B008A; Thu, 25 Mar 2021 08:16:08 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 538C46B008C; Thu, 25 Mar 2021 08:16:08 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 3D9CA6B0092; Thu, 25 Mar 2021 08:16:08 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0233.hostedemail.com [216.40.44.233]) by kanga.kvack.org (Postfix) with ESMTP id 1E30D6B008A for ; Thu, 25 Mar 2021 08:16:08 -0400 (EDT) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay05.hostedemail.com (Postfix) with ESMTP id D3E5718495710 for ; Thu, 25 Mar 2021 12:16:07 +0000 (UTC) X-FDA: 77958293574.30.1A4A6B2 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf27.hostedemail.com (Postfix) with ESMTP id 82B9980192D8 for ; Thu, 25 Mar 2021 12:16:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=WHCc14VHAl0E1rtR7XCz+SysoOI7DyQ6FX+b+kCG0A4=; b=WX3isQ84S9El/isa7ddU7bux/K 0g1qr4leAT3T3g+/U2/EIojJLVifkLuv8ZJUKt7zAYkAK7mlzuuFTk/lprNEvmef4B9OSfJ//NaiR IKlbOkCZDm5yeeYuShQW9BJnJmYYwmXQ5pS3xtJNxEezEhEyHt2+mXYFVCvCOdzIyYG+kZjbWG0mX YrCxxafw2sWKP2dqRhTE1wc9FJMcSvDt95L2gArFbIavef2PHRIodcCFNhEXuujcxb420RnyJrAFp Cv1DTpQ6Niz4eDLMj4TGJJo1tKKIgDFMkapxdycn9vgDdUlsKeF2PUVsCvkwWWgS0VWiNtgOfncf5 y8ML6fOg==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lPOqX-00CsAu-Ma; Thu, 25 Mar 2021 12:12:50 +0000 Date: Thu, 25 Mar 2021 12:12:17 +0000 From: Matthew Wilcox To: Mel Gorman Cc: Andrew Morton , Chuck Lever , Jesper Dangaard Brouer , Christoph Hellwig , Alexander Duyck , Vlastimil Babka , Ilias Apalodimas , LKML , Linux-Net , Linux-MM , Linux-NFS Subject: Re: [PATCH 4/9] mm/page_alloc: optimize code layout for __alloc_pages_bulk Message-ID: <20210325121217.GV1719932@casper.infradead.org> References: <20210325114228.27719-1-mgorman@techsingularity.net> <20210325114228.27719-5-mgorman@techsingularity.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210325114228.27719-5-mgorman@techsingularity.net> X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 82B9980192D8 X-Stat-Signature: fqqxc5g13h7cfcpxj93e7ikgk5wbz51c Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf27; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1616674564-300304 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 Thu, Mar 25, 2021 at 11:42:23AM +0000, Mel Gorman wrote: > > - if (WARN_ON_ONCE(nr_pages <= 0)) > + if (unlikely(nr_pages <= 0)) > return 0; If we made nr_pages unsigned, we wouldn't need this check at all (ok, we'd still need to figure out what to do with 0). But then, if a user inadvertently passes in -ENOMEM, we'll try to allocate 4 billion pages. So maybe we should check it. Gah, API design is hard.