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 DD474C43461 for ; Sun, 13 Sep 2020 14:55:48 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D98A32151B for ; Sun, 13 Sep 2020 14:55:47 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="mjl/pwv2" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D98A32151B 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 E9CF56B0002; Sun, 13 Sep 2020 10:55:36 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id E4E306B0037; Sun, 13 Sep 2020 10:55:36 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id D64226B0055; Sun, 13 Sep 2020 10:55:36 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0054.hostedemail.com [216.40.44.54]) by kanga.kvack.org (Postfix) with ESMTP id BE8E46B0002 for ; Sun, 13 Sep 2020 10:55:36 -0400 (EDT) Received: from smtpin27.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 80C47180AD801 for ; Sun, 13 Sep 2020 14:55:26 +0000 (UTC) X-FDA: 77258336652.27.boot84_0a149cc27100 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin27.hostedemail.com (Postfix) with ESMTP id 582823D669 for ; Sun, 13 Sep 2020 14:55:26 +0000 (UTC) X-HE-Tag: boot84_0a149cc27100 X-Filterd-Recvd-Size: 2095 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf19.hostedemail.com (Postfix) with ESMTP for ; Sun, 13 Sep 2020 14:55:24 +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=FxMUBqjhqzQag30kB1vCRLwvMGWcO/P6G1bHhegnt8w=; b=mjl/pwv2uwM5/ynAJUW91t8l6j pV/J5hlT8/SQl4Ui86urJ3P/Ys/HfeGVJn6k2ncrCbQR7GNPlx3HHsGJAyDNBng4eFVgHJmkOgmL7 sQo+J/SkHxB2s3FqKov3wSjy+zH5ZTQIjJ08ibr5MqZgkEsdTRtO9nkgxbEHMDlzaHxDcOf3j2Ddj 4iwCGlibMe/nnXZTEhfvRjbjDAstIGr/nZAYfR/Y5ZPga0G1DZ6P7ShGYxikYwxQkzajdPW1q9UmK yNV/CxIcfdSYpJfNY6gi/0jJZrWP5uaUyzRsE3lEwu6Lfec+8j6u3YJy2aynbWSwQtkpljlNbjECa DY75PHYA==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kHTPU-0005tx-Q6; Sun, 13 Sep 2020 14:55:20 +0000 Date: Sun, 13 Sep 2020 15:55:20 +0100 From: Matthew Wilcox To: Souptick Joarder Cc: akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, John Hubbard Subject: Re: [PATCH] mm/gup.c: Handling ERR within unpin_user_pages() Message-ID: <20200913145520.GH6583@casper.infradead.org> References: <1600007555-11650-1-git-send-email-jrdr.linux@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1600007555-11650-1-git-send-email-jrdr.linux@gmail.com> X-Rspamd-Queue-Id: 582823D669 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam01 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 Sun, Sep 13, 2020 at 08:02:35PM +0530, Souptick Joarder wrote: > It is possible that a buggy caller of unpin_user_pages() > (specially in error handling path) may end up calling it with > npages < 0 which is unnecessary. > @@ -328,6 +328,9 @@ void unpin_user_pages(struct page **pages, unsigned long npages) > { > unsigned long index; > > + if (WARN_ON_ONCE(npages < 0)) > + return; But npages is unsigned long. So it can't be less than zero.