On 9/28/22 20:45, Dave Chinner wrote:
On Tue, Sep 27, 2022 at 09:54:27PM -0700, Darrick J. Wong wrote:
Btw, can you share the reproducer?
Not sure. The current reproducer I have is 2500 lines of complex C
code that was originally based on a reproducer the original reporter
provided. It does lots of stuff that isn't directly related to
reproducing the issue, and will be impossible to review and maintain
as it stands in fstests.
Too true. Fortunately, now that I understand the necessary conditions
and IO patterns, I managed to prune it all down to ~75 lines of bash
calling xfs_io. See below.
Frank
--
Frank Sorenson
sorenson@xxxxxxxxxx
Principal Software Maintenance Engineer
Global Support Services - filesystems
Red Hat
###########################################
#!/bin/bash
# Frank Sorenson <sorenson@xxxxxxxxxx>, 2022
num_files=8
num_writers=3
KiB=1024
MiB=$(( $KiB * $KiB ))
GiB=$(( $KiB * $KiB * $KiB ))
file_size=$(( 500 * $MiB ))
#file_size=$(( 1 * $GiB ))
write_size=$(( 1 * $MiB ))
start_offset=512
num_loops=$(( ($file_size - $start_offset + (($num_writers * $write_size) - 1)) / ($num_writers * $write_size) ))
total_size=$(( ($num_loops * $num_writers * $write_size) + $start_offset ))
cgroup_path=/sys/fs/cgroup/test_write_bug
mkdir -p $cgroup_path || { echo "unable to create cgroup" ; exit ; }
max_mem=$(( 40 * $MiB ))
high_mem=$(( ($max_mem * 9) / 10 ))
echo $high_mem >$cgroup_path/memory.high
echo $max_mem >$cgroup_path/memory.max
mkdir -p testfiles
rm -f testfiles/expected
xfs_io -f -c "pwrite -b $((1 * $MiB)) -S 0x40 0 $total_size" testfiles/expected >/dev/null 2>&1
expected_sum=$(md5sum testfiles/expected | awk '{print $1}')
echo $$ > $cgroup_path/cgroup.procs || exit # put ourselves in the cgroup
do_one_testfile() {
filenum=$1
cpids=""
offset=$start_offset
rm -f testfiles/test$filenum
xfs_io -f -c "pwrite -b $start_offset -S 0x40 0 $start_offset" testfiles/test$filenum >/dev/null 2>&1
while [[ $offset -lt $file_size ]] ; do
cpids=""
for i in $(seq 1 $num_writers) ; do
xfs_io -f -c "pwrite -b $write_size -S 0x40 $(( ($offset + (($num_writers - $i) * $write_size) ) )) $write_size" testfiles/test$filenum >/dev/null 2>&1 &
cpids="$cpids $!"
done
wait $cpids
offset=$(( $offset + ($num_writers * $write_size) ))
done
}
round=1
while [[ 42 ]] ; do
echo "test round: $round"
cpids=""
for i in $(seq 1 $num_files) ; do
do_one_testfile $i &
cpids="$cpids $!"
done
wait $cpids
replicated="" # now check the files
for i in $(seq 1 $num_files) ; do
sum=$(md5sum testfiles/test$i | awk '{print $1}')
[[ $sum == $expected_sum ]] || replicated="$replicated testfiles/test$i"
done
[[ -n $replicated ]] && break
round=$(($round + 1))
done
echo "replicated bug with: $replicated"
echo $$ > /sys/fs/cgroup/cgroup.procs
rmdir $cgroup_path
