From patchwork Mon Oct 28 09:59:34 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Konstantin Khlebnikov X-Patchwork-Id: 11215063 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 537CF1515 for ; Mon, 28 Oct 2019 09:59:42 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1F9F420B7C for ; Mon, 28 Oct 2019 09:59:42 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=yandex-team.ru header.i=@yandex-team.ru header.b="jUI0uMDZ" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1F9F420B7C Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=yandex-team.ru Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 37BE16B0003; Mon, 28 Oct 2019 05:59:41 -0400 (EDT) Delivered-To: linux-mm-outgoing@kvack.org Received: by kanga.kvack.org (Postfix, from userid 40) id 32D2B6B0006; Mon, 28 Oct 2019 05:59:41 -0400 (EDT) X-Original-To: int-list-linux-mm@kvack.org X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 242846B0007; Mon, 28 Oct 2019 05:59:41 -0400 (EDT) X-Original-To: linux-mm@kvack.org 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 029316B0003 for ; Mon, 28 Oct 2019 05:59:40 -0400 (EDT) Received: from smtpin26.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay02.hostedemail.com (Postfix) with SMTP id 899A5C5B1 for ; Mon, 28 Oct 2019 09:59:40 +0000 (UTC) X-FDA: 76092746520.26.value59_7174e47ca044f X-Spam-Summary: 2,0,0,f3f7eaddaafdf058,d41d8cd98f00b204,khlebnikov@yandex-team.ru,::akpm@linux-foundation.org:linux-kernel@vger.kernel.org:linux-fsdevel@vger.kernel.org:torvalds@linux-foundation.org:viro@zeniv.linux.org.uk:hannes@cmpxchg.org,RULES_HIT:41:152:355:379:800:960:988:989:1260:1277:1311:1313:1314:1345:1437:1515:1516:1518:1534:1541:1593:1594:1711:1730:1747:1777:1792:2194:2199:2393:2559:2562:3138:3139:3140:3141:3142:3352:3865:3866:3867:3868:3870:3871:3872:3874:4321:5007:6261:6653:8603:9207:10004:10400:11026:11658:11914:12043:12297:12438:12517:12519:12555:12760:13069:13184:13229:13311:13357:14096:14097:14181:14394:14687:14721:14922:21080:21324:21451:21627:30054:30070,0,RBL:5.45.199.163:@yandex-team.ru:.lbl8.mailshell.net-62.2.3.100 64.100.201.201,CacheIP:none,Bayesian:0.5,0.5,0.5,Netcheck:none,DomainCache:0,MSF:not bulk,SPF:fp,MSBL:0,DNSBL:neutral,Custom_rules:0:0:0,LFtime:23,LUA_SUMMARY:none X-HE-Tag: value59_7174e47ca044f X-Filterd-Recvd-Size: 3388 Received: from forwardcorp1j.mail.yandex.net (forwardcorp1j.mail.yandex.net [5.45.199.163]) by imf06.hostedemail.com (Postfix) with ESMTP for ; Mon, 28 Oct 2019 09:59:39 +0000 (UTC) Received: from mxbackcorp1o.mail.yandex.net (mxbackcorp1o.mail.yandex.net [IPv6:2a02:6b8:0:1a2d::301]) by forwardcorp1j.mail.yandex.net (Yandex) with ESMTP id 2EB892E14B4; Mon, 28 Oct 2019 12:59:36 +0300 (MSK) Received: from sas2-62907d92d1d8.qloud-c.yandex.net (sas2-62907d92d1d8.qloud-c.yandex.net [2a02:6b8:c08:b895:0:640:6290:7d92]) by mxbackcorp1o.mail.yandex.net (nwsmtp/Yandex) with ESMTP id 1MMz6MIGFv-xZl450v5; Mon, 28 Oct 2019 12:59:36 +0300 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=yandex-team.ru; s=default; t=1572256776; bh=qKbZKUhxXAikWcE9+erLx+dDD7QZSmSl+7ceSjN66mg=; h=Message-ID:Date:To:From:Subject:Cc; b=jUI0uMDZxH7owFu2UKMQ7KRNEqVM5Fbnu6SXj3wPdJctmvDEmSPHmXmo6rltQ5bhe 694+7ixWanoElRRUS6lOxjlbB4kBGFgbbUylTyyYmSJ2L0Qk/29Wqo1A4QYeNHpyPk Zu7c2Lxu3D39+XN8kJyMx7YY88JeIlPMHJ3VhZak= Authentication-Results: mxbackcorp1o.mail.yandex.net; dkim=pass header.i=@yandex-team.ru Received: from dynamic-red.dhcp.yndx.net (dynamic-red.dhcp.yndx.net [2a02:6b8:0:40c:148a:8f3:5b61:9f4]) by sas2-62907d92d1d8.qloud-c.yandex.net (nwsmtp/Yandex) with ESMTPSA id brINrBKnHB-xZV0tdEe; Mon, 28 Oct 2019 12:59:35 +0300 (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client certificate not present) Subject: [PATCH] mm/filemap: do not allocate cache pages beyond end of file at read From: Konstantin Khlebnikov To: linux-mm@kvack.org, Andrew Morton , linux-kernel@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, Linus Torvalds , Alexander Viro , Johannes Weiner Date: Mon, 28 Oct 2019 12:59:34 +0300 Message-ID: <157225677483.3442.4227193290486305330.stgit@buzz> User-Agent: StGit/0.17.1-dirty MIME-Version: 1.0 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: Page cache could contain pages beyond end of file during write or if read races with truncate. But generic_file_buffered_read() always allocates unneeded pages beyond eof if somebody reads here and one extra page at the end if file size is page-aligned. Function generic_file_buffered_read() calls page_cache_sync_readahead() if page not found in cache and then do another lookup. Readahead checks file size in __do_page_cache_readahead() before allocating pages. After that generic_file_buffered_read() falls back to slow path and allocates page for ->readpage() without checking file size. This patch checks file size before allocating page for ->readpage(). Signed-off-by: Konstantin Khlebnikov --- mm/filemap.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/filemap.c b/mm/filemap.c index 85b7d087eb45..92abf5f348a9 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -2225,6 +2225,10 @@ static ssize_t generic_file_buffered_read(struct kiocb *iocb, goto out; no_cached_page: + /* Do not allocate cache pages beyond end of file. */ + if (((loff_t)index << PAGE_SHIFT) >= i_size_read(inode)) + goto out; + /* * Ok, it wasn't cached, so we need to create a new * page..