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=-10.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable 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 B502FC4338F for ; Sat, 7 Aug 2021 18:45:49 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 324EC61078 for ; Sat, 7 Aug 2021 18:45:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 324EC61078 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 89C018D0001; Sat, 7 Aug 2021 14:45:48 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 825736B0071; Sat, 7 Aug 2021 14:45:48 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 6EC888D0001; Sat, 7 Aug 2021 14:45:48 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0220.hostedemail.com [216.40.44.220]) by kanga.kvack.org (Postfix) with ESMTP id 526E26B006C for ; Sat, 7 Aug 2021 14:45:48 -0400 (EDT) Received: from smtpin38.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id E6BA68249980 for ; Sat, 7 Aug 2021 18:45:47 +0000 (UTC) X-FDA: 78449163534.38.3C12B09 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf24.hostedemail.com (Postfix) with ESMTP id 94002B00962D for ; Sat, 7 Aug 2021 18:45:47 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 82D0E6105A; Sat, 7 Aug 2021 18:45:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1628361946; bh=63Jc6H88mizk3nUpvFQNU59wRQKIju43S/xVoUsb28w=; h=Date:From:To:Subject:In-Reply-To:References:From; b=ZWbhHPbYrBKKHHFzhGRwXYCeGqFdPaIIKIrm9PmOPVIqDUA/RVrG8O/yz83O6F3KD QRrxUlQBmg/CXG6xr3202Tv/cNOVgHOIIfdCOCvD+4dXrEXHGhp+8Pk1jO0kra1SVh I2gTaRiKRkukwEy0BUnEDBYVxjkmEj8f3oplpCvU= Date: Sat, 7 Aug 2021 11:45:45 -0700 From: Andrew Morton To: Miaohe Lin , , , , , , Subject: Re: [PATCH 4/5] mm: gup: fix potential pgmap refcnt leak in __gup_device_huge() Message-Id: <20210807114545.eaee318909a9215c4e056aa3@linux-foundation.org> In-Reply-To: <20210807114112.6e45b31c65dd62169fee8718@linux-foundation.org> References: <20210807093620.21347-1-linmiaohe@huawei.com> <20210807093620.21347-5-linmiaohe@huawei.com> <20210807114112.6e45b31c65dd62169fee8718@linux-foundation.org> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.32; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Authentication-Results: imf24.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=ZWbhHPbY; dmarc=none; spf=pass (imf24.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org X-Stat-Signature: weiyo11fzfuxzj9r17b91anmx3bmhf33 X-Rspamd-Queue-Id: 94002B00962D X-Rspamd-Server: rspam01 X-HE-Tag: 1628361947-970948 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 Sat, 7 Aug 2021 11:41:12 -0700 Andrew Morton wrote: > We can simplify further, and remove the troublesome multiple return points? > oops. --- a/mm/gup.c~mm-gup-fix-potential-pgmap-refcnt-leak-in-__gup_device_huge-fix-fix +++ a/mm/gup.c @@ -2240,6 +2240,7 @@ static int __gup_device_huge(unsigned lo { int nr_start = *nr; struct dev_pagemap *pgmap = NULL; + int ret = 1; do { struct page *page = pfn_to_page(pfn); @@ -2247,12 +2248,14 @@ static int __gup_device_huge(unsigned lo pgmap = get_dev_pagemap(pfn, pgmap); if (unlikely(!pgmap)) { undo_dev_pagemap(nr, nr_start, flags, pages); + ret = 0; break; } SetPageReferenced(page); pages[*nr] = page; if (unlikely(!try_grab_page(page, flags))) { undo_dev_pagemap(nr, nr_start, flags, pages); + ret = 0; break; } (*nr)++; @@ -2260,7 +2263,7 @@ static int __gup_device_huge(unsigned lo } while (addr += PAGE_SIZE, addr != end); put_dev_pagemap(pgmap); - return 1; + return ret; } static int __gup_device_huge_pmd(pmd_t orig, pmd_t *pmdp, unsigned long addr, Not sure if it's worth bothering, really...