From patchwork Wed Apr 26 18:05:31 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Ross Zwisler X-Patchwork-Id: 9701783 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id D97A3603F6 for ; Wed, 26 Apr 2017 18:05:45 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id D05661FFD6 for ; Wed, 26 Apr 2017 18:05:45 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id C4F8E28634; Wed, 26 Apr 2017 18:05:45 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.9 required=2.0 tests=BAYES_00,RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4DD6E1FFD6 for ; Wed, 26 Apr 2017 18:05:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753785AbdDZSFo (ORCPT ); Wed, 26 Apr 2017 14:05:44 -0400 Received: from mga14.intel.com ([192.55.52.115]:20566 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753774AbdDZSFl (ORCPT ); Wed, 26 Apr 2017 14:05:41 -0400 Received: from fmsmga003.fm.intel.com ([10.253.24.29]) by fmsmga103.fm.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 26 Apr 2017 11:05:40 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.37,255,1488873600"; d="scan'208";a="850119470" Received: from theros.lm.intel.com ([10.232.112.77]) by FMSMGA003.fm.intel.com with ESMTP; 26 Apr 2017 11:05:39 -0700 From: Ross Zwisler To: fstests@vger.kernel.org, Xiong Zhou , jmoyer@redhat.com, eguan@redhat.com Cc: Ross Zwisler , Christoph Hellwig , Dan Williams , "Darrick J. Wong" , Jan Kara , linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, linux-nvdimm@lists.01.org, Andrew Morton Subject: [PATCH v3 2/2] dax: add regression test for stale mmap reads Date: Wed, 26 Apr 2017 12:05:31 -0600 Message-Id: <20170426180531.26291-2-ross.zwisler@linux.intel.com> X-Mailer: git-send-email 2.9.3 In-Reply-To: <20170426180531.26291-1-ross.zwisler@linux.intel.com> References: <20170426180531.26291-1-ross.zwisler@linux.intel.com> Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP This adds a regression test for the following kernel patch: dax: fix data corruption due to stale mmap reads The above patch fixes an issue where users of DAX can suffer data corruption from stale mmap reads via the following sequence: - open an mmap over a 2MiB hole - read from a 2MiB hole, faulting in a 2MiB zero page - write to the hole with write(3p). The write succeeds but we incorrectly leave the 2MiB zero page mapping intact. - via the mmap, read the data that was just written. Since the zero page mapping is still intact we read back zeroes instead of the new data. Signed-off-by: Ross Zwisler --- .gitignore | 1 + src/Makefile | 2 +- src/t_mmap_stale_pmd.c | 73 ++++++++++++++++++++++++++++++++++++++++++++++++++ tests/generic/427 | 59 ++++++++++++++++++++++++++++++++++++++++ tests/generic/427.out | 2 ++ tests/generic/group | 1 + 6 files changed, 137 insertions(+), 1 deletion(-) create mode 100644 src/t_mmap_stale_pmd.c create mode 100755 tests/generic/427 create mode 100644 tests/generic/427.out diff --git a/.gitignore b/.gitignore index ded4a61..4d64414 100644 --- a/.gitignore +++ b/.gitignore @@ -134,6 +134,7 @@ /src/renameat2 /src/t_rename_overwrite /src/t_mmap_dio +/src/t_mmap_stale_pmd # dmapi/ binaries /dmapi/src/common/cmd/read_invis diff --git a/src/Makefile b/src/Makefile index abfd873..f1338ca 100644 --- a/src/Makefile +++ b/src/Makefile @@ -12,7 +12,7 @@ TARGETS = dirstress fill fill2 getpagesize holes lstat64 \ godown resvtest writemod makeextents itrash rename \ multi_open_unlink dmiperf unwritten_sync genhashnames t_holes \ t_mmap_writev t_truncate_cmtime dirhash_collide t_rename_overwrite \ - holetest t_truncate_self t_mmap_dio af_unix + holetest t_truncate_self t_mmap_dio af_unix t_mmap_stale_pmd LINUX_TARGETS = xfsctl bstat t_mtab getdevicesize preallo_rw_pattern_reader \ preallo_rw_pattern_writer ftrunc trunc fs_perms testx looptest \ diff --git a/src/t_mmap_stale_pmd.c b/src/t_mmap_stale_pmd.c new file mode 100644 index 0000000..b447222 --- /dev/null +++ b/src/t_mmap_stale_pmd.c @@ -0,0 +1,73 @@ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define MiB(a) ((a)*1024*1024) + +void err_exit(char *op) +{ + fprintf(stderr, "%s: %s\n", op, strerror(errno)); + exit(1); +} + +int main(int argc, char *argv[]) +{ + volatile int a __attribute__((__unused__)); + char *buffer = "HELLO WORLD!"; + char *data; + int fd, err, ret = 0; + + if (argc < 2) { + printf("Usage: %s \n", basename(argv[0])); + exit(0); + } + + fd = open(argv[1], O_RDWR|O_CREAT, S_IRUSR|S_IWUSR); + if (fd < 0) + err_exit("fd"); + + /* + * This allows us to map a huge zero page, and we do it at a non-zero + * offset for a little additional testing. + */ + ftruncate(fd, 0); + ftruncate(fd, MiB(4)); + + data = mmap(NULL, MiB(2), PROT_READ, MAP_SHARED, fd, MiB(2)); + + /* + * This faults in a 2MiB zero page to satisfy the read. + * 'a' is volatile so this read doesn't get optimized out. + */ + a = data[0]; + + pwrite(fd, buffer, strlen(buffer), MiB(2)); + + /* + * Try and use the mmap to read back the data we just wrote with + * pwrite(). If the kernel bug is present the mapping from the 2MiB + * zero page will still be intact, and we'll read back zeros instead. + */ + if (strncmp(buffer, data, strlen(buffer))) { + fprintf(stderr, "strncmp mismatch: '%s' vs '%s'\n", buffer, + data); + ret = 1; + } + + err = munmap(data, MiB(2)); + if (err < 0) + err_exit("munmap"); + + err = close(fd); + if (err < 0) + err_exit("close"); + + return ret; +} diff --git a/tests/generic/427 b/tests/generic/427 new file mode 100755 index 0000000..3677fce --- /dev/null +++ b/tests/generic/427 @@ -0,0 +1,59 @@ +#! /bin/bash +# FS QA Test 427 +# +# This is a regression test for kernel patch: +# dax: fix data corruption due to stale mmap reads +# created by Ross Zwisler +# +#----------------------------------------------------------------------- +# Copyright (c) 2017 Intel Corporation. All Rights Reserved. +# +# This program is free software; you can redistribute it and/or +# modify it under the terms of the GNU General Public License as +# published by the Free Software Foundation. +# +# This program is distributed in the hope that it would be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program; if not, write the Free Software Foundation, +# Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA +#----------------------------------------------------------------------- +# + +seq=`basename $0` +seqres=$RESULT_DIR/$seq +echo "QA output created by $seq" + +here=`pwd` +tmp=/tmp/$$ +status=1 # failure is the default! +trap "_cleanup; exit \$status" 0 1 2 3 15 + +_cleanup() +{ + cd / + rm -f $tmp.* +} + +# get standard environment, filters and checks +. ./common/rc +. ./common/filter + +# remove previous $seqres.full before test +rm -f $seqres.full + +# Modify as appropriate. +_supported_fs generic +_supported_os Linux +_require_test_program "t_mmap_stale_pmd" + +# real QA test starts here +src/t_mmap_stale_pmd $TEST_DIR/testfile + +# success, all done +echo "Silence is golden" +status=0 +exit diff --git a/tests/generic/427.out b/tests/generic/427.out new file mode 100644 index 0000000..61295e5 --- /dev/null +++ b/tests/generic/427.out @@ -0,0 +1,2 @@ +QA output created by 427 +Silence is golden diff --git a/tests/generic/group b/tests/generic/group index f29009c..06f6e9d 100644 --- a/tests/generic/group +++ b/tests/generic/group @@ -429,3 +429,4 @@ 424 auto quick 425 auto quick attr 426 auto quick exportfs +427 auto quick