| Message ID | 20170424174932.15613-2-ross.zwisler@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Mon, Apr 24, 2017 at 11:49:32AM -0600, Ross Zwisler wrote: > This adds a regression test for the following kernel patch: > > dax: fix data corruption due to stale mmap reads > Seems that this patch hasn't been merged into linus tree, thus 4.11-rc8 kernel should fail this test, but it passed for me, tested with 4.11-rc8 kernel on both ext4 and xfs, with both brd devices and pmem devices created from "memmap=10G!5G memmap=15G!15G" kernel boot command line. Did I miss anything? # ./check -s ext4_pmem_4k generic/427 SECTION -- ext4_pmem_4k RECREATING -- ext4 on /dev/pmem0 FSTYP -- ext4 PLATFORM -- Linux/x86_64 hp-dl360g9-15 4.11.0-rc8.kasan MKFS_OPTIONS -- -b 4096 /dev/pmem1 MOUNT_OPTIONS -- -o acl,user_xattr -o context=system_u:object_r:root_t:s0 /dev/pmem1 /scratch generic/427 1s ... 1s Ran: generic/427 Passed all 1 tests Some comments inline. > 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 <ross.zwisler@linux.intel.com> > --- > .gitignore | 1 + > src/Makefile | 2 +- > src/t_dax_stale_pmd.c | 56 ++++++++++++++++++++++++++++++++++++++++++ > tests/generic/427 | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++ > tests/generic/427.out | 2 ++ > tests/generic/group | 1 + > 6 files changed, 129 insertions(+), 1 deletion(-) > create mode 100644 src/t_dax_stale_pmd.c > create mode 100755 tests/generic/427 > create mode 100644 tests/generic/427.out > > diff --git a/.gitignore b/.gitignore > index ded4a61..9664dc9 100644 > --- a/.gitignore > +++ b/.gitignore > @@ -134,6 +134,7 @@ > /src/renameat2 > /src/t_rename_overwrite > /src/t_mmap_dio > +/src/t_dax_stale_pmd > > # dmapi/ binaries > /dmapi/src/common/cmd/read_invis > diff --git a/src/Makefile b/src/Makefile > index abfd873..7e22b50 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_dax_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_dax_stale_pmd.c b/src/t_dax_stale_pmd.c > new file mode 100644 > index 0000000..d0016eb > --- /dev/null > +++ b/src/t_dax_stale_pmd.c > @@ -0,0 +1,56 @@ > +#include <errno.h> > +#include <fcntl.h> > +#include <libgen.h> > +#include <stdio.h> > +#include <stdlib.h> > +#include <string.h> > +#include <sys/mman.h> > +#include <sys/stat.h> > +#include <sys/types.h> > +#include <unistd.h> > + > +#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; > + > + if (argc < 2) { > + printf("Usage: %s <pmem file>\n", basename(argv[0])); > + exit(0); > + } > + > + fd = open(argv[1], O_RDWR); > + if (fd < 0) > + err_exit("fd"); ^^^^ Nitpick, the "op" should be "open"? > + > + 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))) > + err_exit("strncmp mismatch!"); strncmp doesn't set errno, this err_exit message might be confusing: "strncmp mismatch!: Success" > + > + close(fd); > + return 0; > +} > diff --git a/tests/generic/427 b/tests/generic/427 > new file mode 100755 > index 0000000..baf1099 > --- /dev/null > +++ b/tests/generic/427 > @@ -0,0 +1,68 @@ > +#! /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 <ross.zwisler@linux.intel.com> > +# > +#----------------------------------------------------------------------- > +# 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_scratch_dax I don't think dax is a requirement here, this test could run on normal block device without "-o dax" option too. It won't hurt to run with more test configurations. And test on nvdimm device with dax mount option could be one of the test configs, e.g. TEST_DEV=/dev/pmem0 SCRATCH_DEV=/dev/pmem1 MOUNT_OPTIONS="-o dax" ... > +_require_test_program "t_dax_stale_pmd" > +_require_user _require_xfs_io_command "falloc" So test _notrun on ext2/3. > + > +# real QA test starts here > +_scratch_mkfs >>$seqres.full 2>&1 > +_scratch_mount "-o dax" Same here, dax is not required. > + > +$XFS_IO_PROG -f -c "falloc 0 4M" $SCRATCH_MNT/testfile >> $seqres.full 2>&1 > +chmod 0644 $SCRATCH_MNT/testfile > +chown $qa_user $SCRATCH_MNT/testfile Any specific reason to use $qa_user to run this test? Comments would be great. Thanks, Eryu > + > +_user_do "src/t_dax_stale_pmd $SCRATCH_MNT/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 > -- > 2.9.3 >
On Tue, Apr 25, 2017 at 07:27:39PM +0800, Eryu Guan wrote: > On Mon, Apr 24, 2017 at 11:49:32AM -0600, Ross Zwisler wrote: > > This adds a regression test for the following kernel patch: > > > > dax: fix data corruption due to stale mmap reads > > > > Seems that this patch hasn't been merged into linus tree, thus 4.11-rc8 > kernel should fail this test, but it passed for me, tested with 4.11-rc8 > kernel on both ext4 and xfs, with both brd devices and pmem devices > created from "memmap=10G!5G memmap=15G!15G" kernel boot command line. > Did I miss anything? > > # ./check -s ext4_pmem_4k generic/427 > SECTION -- ext4_pmem_4k Ooh, I didn't add this 'ext4_pmem_4k' section goodness, and it's not present in the xfstests/master that I was using. Do you have patches to add that? > RECREATING -- ext4 on /dev/pmem0 > FSTYP -- ext4 > PLATFORM -- Linux/x86_64 hp-dl360g9-15 4.11.0-rc8.kasan > MKFS_OPTIONS -- -b 4096 /dev/pmem1 > MOUNT_OPTIONS -- -o acl,user_xattr -o context=system_u:object_r:root_t:s0 /dev/pmem1 /scratch > > generic/427 1s ... 1s > Ran: generic/427 > Passed all 1 tests Your memmap params look fine. I tested with BRD and PMEM, and with EXT4 and XFS, and all combinations failed for me as expected with v4.11-rc8. One issue could have been that the test file already existed when the test was run. I wasn't removing it between runs earlier, but I've fixed that for v2. Another issue I guess could have been that the hole that we got back from the filesystem was smaller than 2MiB? Can you try running v2 (which I'll post in a second) against a TEST_DEV made with one of the following: ext4: mkfs.ext4 -b 4096 -E stride=512 -F $TEST_DEV xfs: mkfs.xfs -f -d su=2m,sw=1 $TEST_DEV This helps us get 2MiB sized and aligned allocations so we can fault in PMDs, but I'm not sure whether or not it would matter for holes. > Some comments inline. > > > 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 <ross.zwisler@linux.intel.com> > > --- > > .gitignore | 1 + > > src/Makefile | 2 +- > > src/t_dax_stale_pmd.c | 56 ++++++++++++++++++++++++++++++++++++++++++ > > tests/generic/427 | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++ > > tests/generic/427.out | 2 ++ > > tests/generic/group | 1 + > > 6 files changed, 129 insertions(+), 1 deletion(-) > > create mode 100644 src/t_dax_stale_pmd.c > > create mode 100755 tests/generic/427 > > create mode 100644 tests/generic/427.out > > > > diff --git a/.gitignore b/.gitignore > > index ded4a61..9664dc9 100644 > > --- a/.gitignore > > +++ b/.gitignore > > @@ -134,6 +134,7 @@ > > /src/renameat2 > > /src/t_rename_overwrite > > /src/t_mmap_dio > > +/src/t_dax_stale_pmd > > > > # dmapi/ binaries > > /dmapi/src/common/cmd/read_invis > > diff --git a/src/Makefile b/src/Makefile > > index abfd873..7e22b50 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_dax_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_dax_stale_pmd.c b/src/t_dax_stale_pmd.c > > new file mode 100644 > > index 0000000..d0016eb > > --- /dev/null > > +++ b/src/t_dax_stale_pmd.c > > @@ -0,0 +1,56 @@ > > +#include <errno.h> > > +#include <fcntl.h> > > +#include <libgen.h> > > +#include <stdio.h> > > +#include <stdlib.h> > > +#include <string.h> > > +#include <sys/mman.h> > > +#include <sys/stat.h> > > +#include <sys/types.h> > > +#include <unistd.h> > > + > > +#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; > > + > > + if (argc < 2) { > > + printf("Usage: %s <pmem file>\n", basename(argv[0])); > > + exit(0); > > + } > > + > > + fd = open(argv[1], O_RDWR); > > + if (fd < 0) > > + err_exit("fd"); > ^^^^ Nitpick, the "op" should be "open"? > > + > > + 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))) > > + err_exit("strncmp mismatch!"); > > strncmp doesn't set errno, this err_exit message might be confusing: > "strncmp mismatch!: Success" Ah, thanks, fixed in v2. > > + > > + close(fd); > > + return 0; > > +} > > diff --git a/tests/generic/427 b/tests/generic/427 > > new file mode 100755 > > index 0000000..baf1099 > > --- /dev/null > > +++ b/tests/generic/427 > > @@ -0,0 +1,68 @@ > > +#! /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 <ross.zwisler@linux.intel.com> > > +# > > +#----------------------------------------------------------------------- > > +# 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 $seqres.full > > + > > +# Modify as appropriate. > > +_supported_fs generic > > +_supported_os Linux > > +_require_scratch_dax > > I don't think dax is a requirement here, this test could run on normal > block device without "-o dax" option too. It won't hurt to run with more > test configurations. And test on nvdimm device with dax mount option > could be one of the test configs, e.g. > > TEST_DEV=/dev/pmem0 > SCRATCH_DEV=/dev/pmem1 > MOUNT_OPTIONS="-o dax" > ... Yep, agreed, fixed in v2. > > +_require_test_program "t_dax_stale_pmd" > > +_require_user > > _require_xfs_io_command "falloc" > > So test _notrun on ext2/3. Fixed in v2. > > + > > +# real QA test starts here > > +_scratch_mkfs >>$seqres.full 2>&1 > > +_scratch_mount "-o dax" > > Same here, dax is not required. Fixed in v2. > > > + > > +$XFS_IO_PROG -f -c "falloc 0 4M" $SCRATCH_MNT/testfile >> $seqres.full 2>&1 > > +chmod 0644 $SCRATCH_MNT/testfile > > +chown $qa_user $SCRATCH_MNT/testfile > > Any specific reason to use $qa_user to run this test? Comments would be > great. Nope, just cargo-culting my way through my first xfstest. :) I've removed this for v2. > Thanks, > Eryu Thanks for the review! > > + > > +_user_do "src/t_dax_stale_pmd $SCRATCH_MNT/testfile" > > + > > +# success, all done > > +echo "Silence is golden" > > +status=0 > > +exit > > diff --git a/tests/generic/427.out b/tests/generic/427.out
On Tue, Apr 25, 2017 at 02:39:11PM -0600, Ross Zwisler wrote: > On Tue, Apr 25, 2017 at 07:27:39PM +0800, Eryu Guan wrote: > > On Mon, Apr 24, 2017 at 11:49:32AM -0600, Ross Zwisler wrote: > > > This adds a regression test for the following kernel patch: > > > > > > dax: fix data corruption due to stale mmap reads > > > > > > > Seems that this patch hasn't been merged into linus tree, thus 4.11-rc8 > > kernel should fail this test, but it passed for me, tested with 4.11-rc8 > > kernel on both ext4 and xfs, with both brd devices and pmem devices > > created from "memmap=10G!5G memmap=15G!15G" kernel boot command line. > > Did I miss anything? > > > > # ./check -s ext4_pmem_4k generic/427 > > SECTION -- ext4_pmem_4k > > Ooh, I didn't add this 'ext4_pmem_4k' section goodness, and it's not present > in the xfstests/master that I was using. Do you have patches to add that? That's one of my config sections, it's all user-defined, not committed to fstests repo :) You can take a look at README.config-sections for more details. Here is my local.config file for your reference [default] TEST_DEV=/dev/pmem0 SCRATCH_DEV=/dev/pmem1 TEST_DIR=/mnt SCRATCH_MNT=/scratch RECREATE_TEST_DEV=true [xfs_pmem_4k] FSTYP=xfs MKFS_OPTIONS="-f -m crc=1 -b size=4k" [ext4_pmem_4k] FSTYP=ext4 MKFS_OPTIONS="-b 4096" > > > RECREATING -- ext4 on /dev/pmem0 > > FSTYP -- ext4 > > PLATFORM -- Linux/x86_64 hp-dl360g9-15 4.11.0-rc8.kasan > > MKFS_OPTIONS -- -b 4096 /dev/pmem1 > > MOUNT_OPTIONS -- -o acl,user_xattr -o context=system_u:object_r:root_t:s0 /dev/pmem1 /scratch > > > > generic/427 1s ... 1s > > Ran: generic/427 > > Passed all 1 tests > > Your memmap params look fine. I tested with BRD and PMEM, and with EXT4 and > XFS, and all combinations failed for me as expected with v4.11-rc8. > > One issue could have been that the test file already existed when the test was > run. I wasn't removing it between runs earlier, but I've fixed that for v2. > > Another issue I guess could have been that the hole that we got back from the > filesystem was smaller than 2MiB? Can you try running v2 (which I'll post in > a second) against a TEST_DEV made with one of the following: > > ext4: mkfs.ext4 -b 4096 -E stride=512 -F $TEST_DEV > xfs: mkfs.xfs -f -d su=2m,sw=1 $TEST_DEV > > This helps us get 2MiB sized and aligned allocations so we can fault in PMDs, > but I'm not sure whether or not it would matter for holes. I guess that's the point to reproduce the failure, I'll confirm with v2 patches. If these non-default & not widely tested mkfs options are required to reproduce it, I think we can specify them in the test, as extra mkfs options to _scratch_mkfs, as what generic/413 does. > > > Some comments inline. > > > > > 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 <ross.zwisler@linux.intel.com> > > > --- > > > .gitignore | 1 + > > > src/Makefile | 2 +- > > > src/t_dax_stale_pmd.c | 56 ++++++++++++++++++++++++++++++++++++++++++ > > > tests/generic/427 | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++ > > > tests/generic/427.out | 2 ++ > > > tests/generic/group | 1 + > > > 6 files changed, 129 insertions(+), 1 deletion(-) > > > create mode 100644 src/t_dax_stale_pmd.c > > > create mode 100755 tests/generic/427 > > > create mode 100644 tests/generic/427.out > > > > > > diff --git a/.gitignore b/.gitignore > > > index ded4a61..9664dc9 100644 > > > --- a/.gitignore > > > +++ b/.gitignore > > > @@ -134,6 +134,7 @@ > > > /src/renameat2 > > > /src/t_rename_overwrite > > > /src/t_mmap_dio > > > +/src/t_dax_stale_pmd > > > > > > # dmapi/ binaries > > > /dmapi/src/common/cmd/read_invis > > > diff --git a/src/Makefile b/src/Makefile > > > index abfd873..7e22b50 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_dax_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_dax_stale_pmd.c b/src/t_dax_stale_pmd.c > > > new file mode 100644 > > > index 0000000..d0016eb > > > --- /dev/null > > > +++ b/src/t_dax_stale_pmd.c > > > @@ -0,0 +1,56 @@ > > > +#include <errno.h> > > > +#include <fcntl.h> > > > +#include <libgen.h> > > > +#include <stdio.h> > > > +#include <stdlib.h> > > > +#include <string.h> > > > +#include <sys/mman.h> > > > +#include <sys/stat.h> > > > +#include <sys/types.h> > > > +#include <unistd.h> > > > + > > > +#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; > > > + > > > + if (argc < 2) { > > > + printf("Usage: %s <pmem file>\n", basename(argv[0])); > > > + exit(0); > > > + } > > > + > > > + fd = open(argv[1], O_RDWR); > > > + if (fd < 0) > > > + err_exit("fd"); > > ^^^^ Nitpick, the "op" should be "open"? > > > + > > > + 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))) > > > + err_exit("strncmp mismatch!"); > > > > strncmp doesn't set errno, this err_exit message might be confusing: > > "strncmp mismatch!: Success" > > Ah, thanks, fixed in v2. > > > > + > > > + close(fd); > > > + return 0; > > > +} > > > diff --git a/tests/generic/427 b/tests/generic/427 > > > new file mode 100755 > > > index 0000000..baf1099 > > > --- /dev/null > > > +++ b/tests/generic/427 > > > @@ -0,0 +1,68 @@ > > > +#! /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 <ross.zwisler@linux.intel.com> > > > +# > > > +#----------------------------------------------------------------------- > > > +# 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_scratch_dax > > > > I don't think dax is a requirement here, this test could run on normal > > block device without "-o dax" option too. It won't hurt to run with more > > test configurations. And test on nvdimm device with dax mount option > > could be one of the test configs, e.g. > > > > TEST_DEV=/dev/pmem0 > > SCRATCH_DEV=/dev/pmem1 > > MOUNT_OPTIONS="-o dax" > > ... > > Yep, agreed, fixed in v2. Then perhaps the test program should be renamed? As no dax is required. How about t_mmap_stale_pmd? > > > > +_require_test_program "t_dax_stale_pmd" > > > +_require_user > > > > _require_xfs_io_command "falloc" > > > > So test _notrun on ext2/3. > > Fixed in v2. > > > > + > > > +# real QA test starts here > > > +_scratch_mkfs >>$seqres.full 2>&1 > > > +_scratch_mount "-o dax" > > > > Same here, dax is not required. > > Fixed in v2. > > > > > > + > > > +$XFS_IO_PROG -f -c "falloc 0 4M" $SCRATCH_MNT/testfile >> $seqres.full 2>&1 > > > +chmod 0644 $SCRATCH_MNT/testfile > > > +chown $qa_user $SCRATCH_MNT/testfile > > > > Any specific reason to use $qa_user to run this test? Comments would be > > great. > > Nope, just cargo-culting my way through my first xfstest. :) I've removed > this for v2. I think it's in a pretty good shape for "first fstests test" :) > > > Thanks, > > Eryu > > Thanks for the review! Thanks for adding new test! Eryu > > > > + > > > +_user_do "src/t_dax_stale_pmd $SCRATCH_MNT/testfile" > > > + > > > +# success, all done > > > +echo "Silence is golden" > > > +status=0 > > > +exit > > > diff --git a/tests/generic/427.out b/tests/generic/427.out > -- > To unsubscribe from this list: send the line "unsubscribe fstests" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/.gitignore b/.gitignore index ded4a61..9664dc9 100644 --- a/.gitignore +++ b/.gitignore @@ -134,6 +134,7 @@ /src/renameat2 /src/t_rename_overwrite /src/t_mmap_dio +/src/t_dax_stale_pmd # dmapi/ binaries /dmapi/src/common/cmd/read_invis diff --git a/src/Makefile b/src/Makefile index abfd873..7e22b50 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_dax_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_dax_stale_pmd.c b/src/t_dax_stale_pmd.c new file mode 100644 index 0000000..d0016eb --- /dev/null +++ b/src/t_dax_stale_pmd.c @@ -0,0 +1,56 @@ +#include <errno.h> +#include <fcntl.h> +#include <libgen.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> +#include <sys/mman.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <unistd.h> + +#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; + + if (argc < 2) { + printf("Usage: %s <pmem file>\n", basename(argv[0])); + exit(0); + } + + fd = open(argv[1], O_RDWR); + if (fd < 0) + err_exit("fd"); + + 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))) + err_exit("strncmp mismatch!"); + + close(fd); + return 0; +} diff --git a/tests/generic/427 b/tests/generic/427 new file mode 100755 index 0000000..baf1099 --- /dev/null +++ b/tests/generic/427 @@ -0,0 +1,68 @@ +#! /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 <ross.zwisler@linux.intel.com> +# +#----------------------------------------------------------------------- +# 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 $seqres.full + +# Modify as appropriate. +_supported_fs generic +_supported_os Linux +_require_scratch_dax +_require_test_program "t_dax_stale_pmd" +_require_user + +# real QA test starts here +_scratch_mkfs >>$seqres.full 2>&1 +_scratch_mount "-o dax" + +$XFS_IO_PROG -f -c "falloc 0 4M" $SCRATCH_MNT/testfile >> $seqres.full 2>&1 +chmod 0644 $SCRATCH_MNT/testfile +chown $qa_user $SCRATCH_MNT/testfile + +_user_do "src/t_dax_stale_pmd $SCRATCH_MNT/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
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 <ross.zwisler@linux.intel.com> --- .gitignore | 1 + src/Makefile | 2 +- src/t_dax_stale_pmd.c | 56 ++++++++++++++++++++++++++++++++++++++++++ tests/generic/427 | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++ tests/generic/427.out | 2 ++ tests/generic/group | 1 + 6 files changed, 129 insertions(+), 1 deletion(-) create mode 100644 src/t_dax_stale_pmd.c create mode 100755 tests/generic/427 create mode 100644 tests/generic/427.out