| Message ID | 20170425205106.20576-2-ross.zwisler@linux.intel.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Tue, Apr 25, 2017 at 02:51:06PM -0600, Ross Zwisler wrote: > 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> I reproduced it now with 4.10 kernel, I think it was because I enalbed KASAN on my 4.11-rc8 kernel. And the special mkfs options for ext4/xfs are not needed either. > --- > .gitignore | 1 + > src/Makefile | 2 +- > src/t_dax_stale_pmd.c | 59 +++++++++++++++++++++++++++++++++++++++++++++ > tests/generic/427 | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++ > tests/generic/427.out | 2 ++ > tests/generic/group | 1 + > 6 files changed, 131 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..59fbbe1 > --- /dev/null > +++ b/src/t_dax_stale_pmd.c > @@ -0,0 +1,59 @@ > +#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))) { > + fprintf(stderr, "strncmp mismatch: '%s' vs '%s'\n", buffer, > + data); > + exit(1); > + } > + > + close(fd); > + return 0; > +} > diff --git a/tests/generic/427 b/tests/generic/427 > new file mode 100755 > index 0000000..6e265a1 > --- /dev/null > +++ b/tests/generic/427 > @@ -0,0 +1,67 @@ > +#! /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_test_program "t_dax_stale_pmd" > +_require_xfs_io_command "falloc" I'm wondering if falloc is really needed? If not, this test could be run with ext2/3 too. See below. > +_require_user This is not needed anymore. > + > +# real QA test starts here > + > +# ensure we have no pre-existing block allocations, so we get a hole > +rm -f $TEST_DIR/testfile > +$XFS_IO_PROG -f -c "falloc 0 4M" $TEST_DIR/testfile >> $seqres.full 2>&1 I found that 'xfs_io -fc "truncate 4M" $TEST_DIR/testfile' works too, from the comments in test and kernel patch, if I understand correctly, we only need to mmap un-allocated blocks, right? If truncate(2) works too, I think we can move truncate operation to the t_dax_stale_pmd program too, because the whole truncate && mmap && read sequence are logically together, this also avoids the confusion on why testfile is in 4M size. Thanks, Eryu > +chmod 0644 $TEST_DIR/testfile > + > +src/t_dax_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 > -- > 2.9.3 > -- 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
On Tue, Apr 25, 2017 at 02:51:06PM -0600, Ross Zwisler wrote: > 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 | 59 +++++++++++++++++++++++++++++++++++++++++++++ > tests/generic/427 | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++ > tests/generic/427.out | 2 ++ > tests/generic/group | 1 + > 6 files changed, 131 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..59fbbe1 > --- /dev/null > +++ b/src/t_dax_stale_pmd.c > @@ -0,0 +1,59 @@ > +#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))) { > + fprintf(stderr, "strncmp mismatch: '%s' vs '%s'\n", buffer, > + data); munmap close(fd); > + exit(1); > + } > + munmap Thanks, :) -- Xiong > + close(fd); > + return 0; > +} > diff --git a/tests/generic/427 b/tests/generic/427 > new file mode 100755 > index 0000000..6e265a1 > --- /dev/null > +++ b/tests/generic/427 > @@ -0,0 +1,67 @@ > +#! /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_test_program "t_dax_stale_pmd" > +_require_xfs_io_command "falloc" > +_require_user > + > +# real QA test starts here > + > +# ensure we have no pre-existing block allocations, so we get a hole > +rm -f $TEST_DIR/testfile > +$XFS_IO_PROG -f -c "falloc 0 4M" $TEST_DIR/testfile >> $seqres.full 2>&1 > +chmod 0644 $TEST_DIR/testfile > + > +src/t_dax_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 > -- > 2.9.3 > -- 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
On Wed, Apr 26, 2017 at 03:47:27PM +0800, Eryu Guan wrote: > On Tue, Apr 25, 2017 at 02:51:06PM -0600, Ross Zwisler wrote: <> > > diff --git a/tests/generic/427 b/tests/generic/427 > > new file mode 100755 > > index 0000000..6e265a1 > > --- /dev/null > > +++ b/tests/generic/427 > > @@ -0,0 +1,67 @@ > > +#! /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_test_program "t_dax_stale_pmd" > > +_require_xfs_io_command "falloc" > > I'm wondering if falloc is really needed? If not, this test could be run > with ext2/3 too. See below. > > > +_require_user > > This is not needed anymore. Fixed in v3. > > + > > +# real QA test starts here > > + > > +# ensure we have no pre-existing block allocations, so we get a hole > > +rm -f $TEST_DIR/testfile > > +$XFS_IO_PROG -f -c "falloc 0 4M" $TEST_DIR/testfile >> $seqres.full 2>&1 > > I found that 'xfs_io -fc "truncate 4M" $TEST_DIR/testfile' works too, > from the comments in test and kernel patch, if I understand correctly, > we only need to mmap un-allocated blocks, right? > > If truncate(2) works too, I think we can move truncate operation to the > t_dax_stale_pmd program too, because the whole truncate && mmap && read > sequence are logically together, this also avoids the confusion on why > testfile is in 4M size. Yep, that works. In v3 I've moved to using only ftruncate so we can enable ext2/3, and I've moved those calls into the C file with comments explaining why we're doing things. -- 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
On Wed, Apr 26, 2017 at 05:09:07PM +0800, Xiong Zhou wrote: > On Tue, Apr 25, 2017 at 02:51:06PM -0600, Ross Zwisler wrote: <> > > + /* > > + * 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); > munmap > close(fd); > > + exit(1); > > + } > > + > munmap Yep, thanks, fixed in v3. -- 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..59fbbe1 --- /dev/null +++ b/src/t_dax_stale_pmd.c @@ -0,0 +1,59 @@ +#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))) { + fprintf(stderr, "strncmp mismatch: '%s' vs '%s'\n", buffer, + data); + exit(1); + } + + close(fd); + return 0; +} diff --git a/tests/generic/427 b/tests/generic/427 new file mode 100755 index 0000000..6e265a1 --- /dev/null +++ b/tests/generic/427 @@ -0,0 +1,67 @@ +#! /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_test_program "t_dax_stale_pmd" +_require_xfs_io_command "falloc" +_require_user + +# real QA test starts here + +# ensure we have no pre-existing block allocations, so we get a hole +rm -f $TEST_DIR/testfile +$XFS_IO_PROG -f -c "falloc 0 4M" $TEST_DIR/testfile >> $seqres.full 2>&1 +chmod 0644 $TEST_DIR/testfile + +src/t_dax_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
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 | 59 +++++++++++++++++++++++++++++++++++++++++++++ tests/generic/427 | 67 +++++++++++++++++++++++++++++++++++++++++++++++++++ tests/generic/427.out | 2 ++ tests/generic/group | 1 + 6 files changed, 131 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