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=-8.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,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 51843CA9EAF for ; Mon, 21 Oct 2019 17:28:02 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1261E2077C for ; Mon, 21 Oct 2019 17:28:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="VZDu0XB5" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1261E2077C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9B89E6B0003; Mon, 21 Oct 2019 13:28:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 942CA6B0005; Mon, 21 Oct 2019 13:28:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 809FC6B0006; Mon, 21 Oct 2019 13:28:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0122.hostedemail.com [216.40.44.122]) by kanga.kvack.org (Postfix) with ESMTP id 569716B0003 for ; Mon, 21 Oct 2019 13:28:01 -0400 (EDT) Received: from smtpin18.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with SMTP id F0DAB8249980 for ; Mon, 21 Oct 2019 17:28:00 +0000 (UTC) X-FDA: 76068474720.18.trail94_7fd4bab2cdd10 X-HE-Tag: trail94_7fd4bab2cdd10 X-Filterd-Recvd-Size: 4513 Received: from hqemgate15.nvidia.com (hqemgate15.nvidia.com [216.228.121.64]) by imf43.hostedemail.com (Postfix) with ESMTP for ; Mon, 21 Oct 2019 17:27:58 +0000 (UTC) Received: from hqpgpgate101.nvidia.com (Not Verified[216.228.121.13]) by hqemgate15.nvidia.com (using TLS: TLSv1.2, DES-CBC3-SHA) id ; Mon, 21 Oct 2019 10:28:07 -0700 Received: from hqmail.nvidia.com ([172.20.161.6]) by hqpgpgate101.nvidia.com (PGP Universal service); Mon, 21 Oct 2019 10:27:56 -0700 X-PGP-Universal: processed; by hqpgpgate101.nvidia.com on Mon, 21 Oct 2019 10:27:56 -0700 Received: from DRHQMAIL107.nvidia.com (10.27.9.16) by HQMAIL111.nvidia.com (172.20.187.18) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 21 Oct 2019 17:27:56 +0000 Received: from [10.110.48.28] (10.124.1.5) by DRHQMAIL107.nvidia.com (10.27.9.16) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Mon, 21 Oct 2019 17:27:56 +0000 Subject: Re: [PATCH] mm/gup: allow CMA migration to propagate errors back to caller To: zhong jiang , CC: , References: <1571671030-58029-1-git-send-email-zhongjiang@huawei.com> X-Nvconfidentiality: public From: John Hubbard Message-ID: Date: Mon, 21 Oct 2019 10:27:55 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.8.0 MIME-Version: 1.0 In-Reply-To: <1571671030-58029-1-git-send-email-zhongjiang@huawei.com> X-Originating-IP: [10.124.1.5] X-ClientProxiedBy: HQMAIL111.nvidia.com (172.20.187.18) To DRHQMAIL107.nvidia.com (10.27.9.16) Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1; t=1571678887; bh=AWOdIZlimY4ZpYd6zZSHtl4bLKfSnJdYnNRVwu2cxPg=; h=X-PGP-Universal:Subject:To:CC:References:X-Nvconfidentiality:From: Message-ID:Date:User-Agent:MIME-Version:In-Reply-To: X-Originating-IP:X-ClientProxiedBy:Content-Type:Content-Language: Content-Transfer-Encoding; b=VZDu0XB5Ve7GGRE0HYpaDyTG+N3W8ZBpr+Vkmf3fs0hRgVPTpsP6TkOttJqo3na/5 UqQlRBXh7AQfRzcZhBTE0rsRn3jjJPJFEEL6hpZIxIVNZ3LtOcxpbyT3EUIXDxrCta Zp1bQYh95lvttVIr5zvFvoP8F+ZlptqiKBw1rCWM9jvUURjh8AEU8wv0gZPVC4S/GL oCY73IHjX2uleQW45kM8be9SaWiQiXV9xFsgSqe0wFfXZxaXaO4Dozk0XkefwlK/c5 S+HHomnHXJu8kkqsfGLQ7BPDcQ/2rDhS7vlIYMQZGi8heWD3o+TMk+Pj2vDShjkpvG 5+IGBiJiP2zXg== 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 10/21/19 8:17 AM, zhong jiang wrote: > check_and_migrate_cma_pages() was recording the result of > __get_user_pages_locked() in an unsigned "nr_pages" variable. Because > __get_user_pages_locked() returns a signed value that can include > negative errno values, this had the effect of hiding errors. > > Change check_and_migrate_cma_pages() implementation so that it > uses a signed variable instead, and propagates the results back > to the caller just as other gup internal functions do. > > This was discovered with the help of unsigned_lesser_than_zero.cocci. > > Suggested-by: John Hubbard > Signed-off-by: zhong jiang > --- Reviewed-by: John Hubbard thanks, John Hubbard NVIDIA > mm/gup.c | 8 +++++--- > 1 file changed, 5 insertions(+), 3 deletions(-) > > diff --git a/mm/gup.c b/mm/gup.c > index 8f236a3..c2b3e11 100644 > --- a/mm/gup.c > +++ b/mm/gup.c > @@ -1443,6 +1443,7 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk, > bool drain_allow = true; > bool migrate_allow = true; > LIST_HEAD(cma_page_list); > + long ret = nr_pages; > > check_again: > for (i = 0; i < nr_pages;) { > @@ -1504,17 +1505,18 @@ static long check_and_migrate_cma_pages(struct task_struct *tsk, > * again migrating any new CMA pages which we failed to isolate > * earlier. > */ > - nr_pages = __get_user_pages_locked(tsk, mm, start, nr_pages, > + ret = __get_user_pages_locked(tsk, mm, start, nr_pages, > pages, vmas, NULL, > gup_flags); > > - if ((nr_pages > 0) && migrate_allow) { > + if ((ret > 0) && migrate_allow) { > + nr_pages = ret; > drain_allow = true; > goto check_again; > } > } > > - return nr_pages; > + return ret; > } > #else > static long check_and_migrate_cma_pages(struct task_struct *tsk, >