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=-11.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A, SIGNED_OFF_BY,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 1E66BC43467 for ; Tue, 20 Oct 2020 10:19:35 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 72D9B2222D for ; Tue, 20 Oct 2020 10:19:34 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 72D9B2222D 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 968396B005C; Tue, 20 Oct 2020 06:19:33 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 93D646B0062; Tue, 20 Oct 2020 06:19:33 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 82DDA6B0068; Tue, 20 Oct 2020 06:19:33 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0058.hostedemail.com [216.40.44.58]) by kanga.kvack.org (Postfix) with ESMTP id 53CB86B005C for ; Tue, 20 Oct 2020 06:19:33 -0400 (EDT) Received: from smtpin14.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with ESMTP id DB8EA34A3 for ; Tue, 20 Oct 2020 10:19:32 +0000 (UTC) X-FDA: 77391906984.14.ducks57_41119732723e Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin14.hostedemail.com (Postfix) with ESMTP id B8F5E18229835 for ; Tue, 20 Oct 2020 10:19:32 +0000 (UTC) X-HE-Tag: ducks57_41119732723e X-Filterd-Recvd-Size: 2143 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf06.hostedemail.com (Postfix) with ESMTP for ; Tue, 20 Oct 2020 10:19:32 +0000 (UTC) X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id DE8ECADE2; Tue, 20 Oct 2020 10:19:30 +0000 (UTC) To: Nikita Ermakov , linux-mm@kvack.org Cc: Andrew Morton References: <20201012160911.6282-1-sh1r4s3@mail.si-head.nl> From: Vlastimil Babka Subject: Re: [PATCH] mm/msync: exit early when the flags is an MS_ASYNC and start < vm_start Message-ID: Date: Tue, 20 Oct 2020 12:19:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.3.2 MIME-Version: 1.0 In-Reply-To: <20201012160911.6282-1-sh1r4s3@mail.si-head.nl> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: quoted-printable 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 10/12/20 6:09 PM, Nikita Ermakov wrote: > Exit from the loop over the VMA in the case when the flags > contain only an MS_ASYNC and start < vm_start. In this case msync() > would return with -ENOMEM anyway so make it return early. >=20 > Signed-off-by: Nikita Ermakov AFAICS it can still return -EBUSY if there's MS_INVALIDATE and a mlocked = vma.=20 This is all subtle and I don't think we should risk breaking something fo= r this=20 optimization. > --- > mm/msync.c | 2 ++ > 1 file changed, 2 insertions(+) >=20 > diff --git a/mm/msync.c b/mm/msync.c > index 69c6d2029531..ed20c3621d4c 100644 > --- a/mm/msync.c > +++ b/mm/msync.c > @@ -69,6 +69,8 @@ SYSCALL_DEFINE3(msync, unsigned long, start, size_t, = len, int, flags) > goto out_unlock; > /* Here start < vma->vm_end. */ > if (start < vma->vm_start) { > + if (flags =3D=3D MS_ASYNC) > + goto out_unlock; > start =3D vma->vm_start; > if (start >=3D end) > goto out_unlock; >=20 > base-commit: 6824a8a9b4861d7df7ee132a952bdf6f84a99cb8 >=20