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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 564D7C433EF for ; Sun, 14 Nov 2021 15:28:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 9EC4661105 for ; Sun, 14 Nov 2021 15:28:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 9EC4661105 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 0A9E26B007B; Sun, 14 Nov 2021 10:28:27 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 05A736B007D; Sun, 14 Nov 2021 10:28:27 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E8B296B007E; Sun, 14 Nov 2021 10:28:26 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0173.hostedemail.com [216.40.44.173]) by kanga.kvack.org (Postfix) with ESMTP id D62FF6B007B for ; Sun, 14 Nov 2021 10:28:26 -0500 (EST) Received: from smtpin28.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id 7DB002483 for ; Sun, 14 Nov 2021 15:28:26 +0000 (UTC) X-FDA: 78807917412.28.7DF318D Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf15.hostedemail.com (Postfix) with ESMTP id AF8FDD0000A1 for ; Sun, 14 Nov 2021 15:28:10 +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=E/Bl7CXqwUF/cWYj/ZAt0H/eac5hQHkzocJWz7wDRFI=; b=h1vn6lOwqFNP6Ym+XERGzxu1iW MEgr6t75Yxw0zHIvuHkAJgrU0sJeZtadqRiMPR36JvWELDHqWfqN74IpXK2cs9YxetTV5dvfx61mc kiJUooezW9RdT1O1MWWxb7fl47oiRI2cIQejqD+nJUyLtyPngFmnVuPdlG91FanGtXn4EMPmu+LTh kN6sHhBGuxRYZ5ERcToJK9FTb9QynqzYcC+8Lf4ZLO5Yy9e4JXd6EVVG/HakqQG1wDSc96LzQJ0gY QVNMK1UZb+jLJSroVeqyT7kbgSigohCXWT9sJ1kJnlS/09B+hgMNhpaw15iUpoS3FfCcukE6v7F9g dQHuq5gw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1mmHQO-0052q9-7F; Sun, 14 Nov 2021 15:28:08 +0000 Date: Sun, 14 Nov 2021 15:28:08 +0000 From: Matthew Wilcox To: Yang Shi Cc: torvalds@linux-foundation.org, arnd@arndb.de, hughd@google.com, kirill.shutemov@linux.intel.com, naoya.horiguchi@nec.com, osalvador@suse.de, peterx@redhat.com, ajaygargnsit@gmail.com, songmuchun@bytedance.com, akpm@linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [UPDATE PATCH] mm: shmem: don't truncate page if memory failure happens Message-ID: References: <20211114053221.315753-1-shy828301@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20211114053221.315753-1-shy828301@gmail.com> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: AF8FDD0000A1 X-Stat-Signature: 3pj66so1oqtygg734e7uai5e8zarx98t Authentication-Results: imf15.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=h1vn6lOw; spf=none (imf15.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org; dmarc=none X-HE-Tag: 1636903690-58043 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, Nov 13, 2021 at 09:32:21PM -0800, Yang Shi wrote: > @@ -2466,7 +2467,18 @@ shmem_write_begin(struct file *file, struct address_space *mapping, > return -EPERM; > } > > - return shmem_getpage(inode, index, pagep, SGP_WRITE); > + ret = shmem_getpage(inode, index, pagep, SGP_WRITE); > + > + if (ret) > + return ret; > + > + if (*pagep && PageHWPoison(*pagep)) { > + unlock_page(*pagep); > + put_page(*pagep); > + ret = -EIO; You definitely need to add: *pagep = NULL; I'm not entirely convinced that you need the conditional on '*pagep'. If we returned 0, there had better be a page at pagep! I also think this would be clearer if written as: if (PageHWPoison(*pagep)) { unlock_page(*pagep); put_page(*pagep); *pagep = NULL; return -EIO; } return 0; instead of re-using ret. Sometimes that can make the code flow clearer, but here, I don't think it does. > @@ -4168,9 +4201,12 @@ struct page *shmem_read_mapping_page_gfp(struct address_space *mapping, > error = shmem_getpage_gfp(inode, index, &page, SGP_CACHE, > gfp, NULL, NULL, NULL); > if (error) > - page = ERR_PTR(error); > - else > - unlock_page(page); > + return ERR_PTR(error); > + > + unlock_page(page); > + if (PageHWPoison(page)) > + return ERR_PTR(-EIO); Do we need to put_page() the page in this error case?