On Wed, Jun 21, 2017 at 04:23:26PM +0800, Zorro Lang wrote:
> We met a kernel assertion failure recently as below:
>
> XFS: Assertion failed: tp->t_blk_res_used <= tp->t_blk_res, file: fs/xfs/xfs_trans.c, line: 309
>
> The problem comes when the several IO vectors are copied in, and
> it runs into page faults.
Can you please provide more information in commit log? It's not so clear
where the problem lies in right now.
And there's a typo in subject line :)
generic: test writev with pega fault when it processes iov
^^^^ page
>
> Signed-off-by: Zorro Lang <zlang@xxxxxxxxxx>
> ---
>
> Hi,
>
> Although I'm trying to add writev/readv test to fsstress, and it has tiny
> chance to cover this bug (very hard to reproduce). But I still think using
> a special case to cover this part is better.
>
> Thanks,
> Zorro
>
> .gitignore | 1 +
> src/Makefile | 2 +-
> src/writev_on_pagefault.c | 74 +++++++++++++++++++++++++++++++++++++++++++++++
> tests/generic/443 | 61 ++++++++++++++++++++++++++++++++++++++
> tests/generic/443.out | 2 ++
> tests/generic/group | 1 +
> 6 files changed, 140 insertions(+), 1 deletion(-)
> create mode 100644 src/writev_on_pagefault.c
> create mode 100755 tests/generic/443
> create mode 100644 tests/generic/443.out
>
> diff --git a/.gitignore b/.gitignore
> index 39664b0..043e87f 100644
> --- a/.gitignore
> +++ b/.gitignore
> @@ -130,6 +130,7 @@
> /src/unwritten_sync
> /src/usemem
> /src/writemod
> +/src/writev_on_pagefault
> /src/xfsctl
> /src/aio-dio-regress/aio-dio-extend-stat
> /src/aio-dio-regress/aio-dio-fcntl-race
> diff --git a/src/Makefile b/src/Makefile
> index 6b0e4b0..9d54fe7 100644
> --- a/src/Makefile
> +++ b/src/Makefile
> @@ -9,7 +9,7 @@ TARGETS = dirstress fill fill2 getpagesize holes lstat64 \
> nametest permname randholes runas truncfile usemem \
> mmapcat append_reader append_writer dirperf metaperf \
> devzero feature alloc fault fstest t_access_root \
> - godown resvtest writemod makeextents itrash rename \
> + godown resvtest writemod writev_on_pagefault 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 t_mmap_stale_pmd \
> diff --git a/src/writev_on_pagefault.c b/src/writev_on_pagefault.c
> new file mode 100644
> index 0000000..54845c3
> --- /dev/null
> +++ b/src/writev_on_pagefault.c
> @@ -0,0 +1,74 @@
> +/*
> + * Takes page fault while writev is iterating over the vectors in the IOV
> + *
> + * Copyright (C) 2017 Red Hat, Inc. 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; either version 2 of the License, or
> + * (at your option) any later version.
> + *
> + * This program is distributed in the hope that it will 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 to the Free Software
> + * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
> + */
> +#include <stdio.h>
> +#include <stdlib.h>
> +#include <sys/types.h>
> +#include <sys/stat.h>
> +#include <fcntl.h>
> +#include <string.h>
> +#include <unistd.h>
> +#include <sys/uio.h>
> +
> +#define IOV_CNT 3
Make it a default value and can be specified via command line as well?
> +
> +void
> +usage(char *progname)
> +{
> + fprintf(stderr, "usage: %s filename\n", progname);
> + exit(1);
> +}
> +
> +int main(int argc, char *argv[])
> +{
> + int fd, i;
> + size_t ret;
> + struct iovec *iov;
> + int pagesz = 4096;
> + char *data = NULL;
> +
> + if (argc != 2)
> + usage(argv[0]);
> +
> + pagesz = getpagesize();
> + data = malloc(pagesz * IOV_CNT);
Check return value of malloc.
> +
> + /* no pre-writing on the buffer before writev */
> +
> + iov = calloc(IOV_CNT, sizeof(struct iovec));
Check return value of iov.
And from this line on, you're mixing tab and spaces for indention.
Please use tab consistently.
Thanks,
Eryu
> + for (i = 0; i < IOV_CNT; i++) {
> + (iov + i)->iov_base = (data + pagesz * i);
> + (iov + i)->iov_len = 1;
> + }
> +
> + if ((fd = open(argv[1], O_TRUNC|O_CREAT|O_RDWR, 0644)) < 0) {
> + perror("open failed");
> + return 1;
> + }
> +
> +
> + ret = writev(fd, iov, IOV_CNT);
> + if (ret < 0)
> + perror("writev failed");
> + else
> + printf("wrote %d bytes\n", (int)ret);
> +
> + close(fd);
> + return 0;
> +}
> diff --git a/tests/generic/443 b/tests/generic/443
> new file mode 100755
> index 0000000..89e12b0
> --- /dev/null
> +++ b/tests/generic/443
> @@ -0,0 +1,61 @@
> +#! /bin/bash
> +# FS QA Test 443
> +#
> +# Takes page fault while writev is iterating over the vectors in the IOV
> +#
> +#-----------------------------------------------------------------------
> +# Copyright (c) 2017 Red Hat, Inc. 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 $seqres.full
> +
> +# real QA test starts here
> +_supported_fs generic
> +_supported_os Linux
> +_require_test
> +_require_test_program "writev_on_pagefault"
> +
> +# This program use several vectors for writev(), the kernel goes over them
> +# one at a time, copying them from userspace, getting the user data ready
> +# for IO. If it takes a page fault while iterating over the vectors in the
> +# IOV, it stops, and sends what it got so far. We try to find a bug at this
> +# moment.
> +$here/src/writev_on_pagefault $TEST_DIR/testfile.$seq
> +
> +# success, all done
> +status=0
> +exit
> diff --git a/tests/generic/443.out b/tests/generic/443.out
> new file mode 100644
> index 0000000..2d5acf9
> --- /dev/null
> +++ b/tests/generic/443.out
> @@ -0,0 +1,2 @@
> +QA output created by 443
> +wrote 3 bytes
> diff --git a/tests/generic/group b/tests/generic/group
> index ab1e9d3..5046c97 100644
> --- a/tests/generic/group
> +++ b/tests/generic/group
> @@ -443,3 +443,4 @@
> 440 auto quick encrypt
> 441 auto quick
> 442 blockdev
> +443 auto quick rw
> --
> 2.7.5
>
> --
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