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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 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 996BEC48BDF for ; Fri, 18 Jun 2021 10:14:47 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 15B02613CB for ; Fri, 18 Jun 2021 10:14:47 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 15B02613CB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=techsingularity.net Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 420EE6B0070; Fri, 18 Jun 2021 06:14:46 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 3D16D6B0071; Fri, 18 Jun 2021 06:14:46 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 29B396B0072; Fri, 18 Jun 2021 06:14:46 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0201.hostedemail.com [216.40.44.201]) by kanga.kvack.org (Postfix) with ESMTP id EE5846B0070 for ; Fri, 18 Jun 2021 06:14:45 -0400 (EDT) Received: from smtpin08.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 7A1DD180AD806 for ; Fri, 18 Jun 2021 10:14:45 +0000 (UTC) X-FDA: 78266435730.08.18AD59F Received: from outbound-smtp63.blacknight.com (outbound-smtp63.blacknight.com [46.22.136.252]) by imf11.hostedemail.com (Postfix) with ESMTP id DF5CD2001102 for ; Fri, 18 Jun 2021 10:14:44 +0000 (UTC) Received: from mail.blacknight.com (pemlinmail02.blacknight.ie [81.17.254.11]) by outbound-smtp63.blacknight.com (Postfix) with ESMTPS id 06D5DFB245 for ; Fri, 18 Jun 2021 11:14:43 +0100 (IST) Received: (qmail 5412 invoked from network); 18 Jun 2021 10:14:42 -0000 Received: from unknown (HELO techsingularity.net) (mgorman@techsingularity.net@[84.203.17.255]) by 81.17.254.9 with ESMTPSA (AES256-SHA encrypted, authenticated); 18 Jun 2021 10:14:42 -0000 Date: Fri, 18 Jun 2021 11:14:41 +0100 From: Mel Gorman To: Dan Carpenter Cc: linux-mm@kvack.org Subject: Re: [bug report] mm/page_alloc: add an array-based interface to the bulk page allocator Message-ID: <20210618101441.GS30378@techsingularity.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-15 Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Authentication-Results: imf11.hostedemail.com; dkim=none; dmarc=none; spf=pass (imf11.hostedemail.com: domain of mgorman@techsingularity.net designates 46.22.136.252 as permitted sender) smtp.mailfrom=mgorman@techsingularity.net X-Rspamd-Server: rspam02 X-Stat-Signature: 9boo61o4697gdew3g4n91cy8dp83sksm X-Rspamd-Queue-Id: DF5CD2001102 X-HE-Tag: 1624011284-319700 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 Fri, Jun 18, 2021 at 12:03:45PM +0300, Dan Carpenter wrote: > Hello Mel Gorman, > > The patch 0f87d9d30f21: "mm/page_alloc: add an array-based interface > to the bulk page allocator" from Apr 29, 2021, leads to the following > static checker warning: > > mm/page_alloc.c:5338 __alloc_pages_bulk() > warn: potentially one past the end of array 'page_array[nr_populated]' > Thanks Dan. Does this work for you? --8<--- mm/page_alloc: do bulk array bounds check after checking populated elements Dan Carpenter reported the following The patch 0f87d9d30f21: "mm/page_alloc: add an array-based interface to the bulk page allocator" from Apr 29, 2021, leads to the following static checker warning: mm/page_alloc.c:5338 __alloc_pages_bulk() warn: potentially one past the end of array 'page_array[nr_populated]' The problem can occur if an array is passed in that is fully populated. That potentially ends up allocating a single page and storing it past the end of the array. This patch returns 0 if the array is fully populated. Fixes: 0f87d9d30f21 ("mm/page_alloc: add an array-based interface to the bulk page allocator") Reported-by: Dan Carpenter Signed-off-by: Mel Gorman --- mm/page_alloc.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 8836e54721ae..602deee90eb3 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -5243,6 +5243,10 @@ unsigned long __alloc_pages_bulk(gfp_t gfp, int preferred_nid, while (page_array && nr_populated < nr_pages && page_array[nr_populated]) nr_populated++; + /* Already populated array? */ + if (unlikely(page_array && nr_pages - nr_populated == 0)) + return 0; + /* Use the single page allocator for one page. */ if (nr_pages - nr_populated == 1) goto failed;