mdadm regression tests, slight progress

I'm still trying to figure out why some of the mdadm regression tests fail. I started looking at tests/00raid1:

# ./test --tests=00raid1

It is nice that ./test is a bash script so it is easy to do some debugging.

The test script looks like:

# create a simple mirror
# test version0, version1, and no super
# test resync and recovery.

mdadm -CR $md0 -l 1 -n2 $dev0 $dev1
check resync
check raid1
testdev $md0 1 $mdsize1a 64
mdadm -S $md0

# now with version-0.90 superblock, spare
mdadm -CR $md0 -e0.90 --level=raid1 -n3 -x2 $dev0 missing missing $dev1 $dev2
check recovery
check raid1
testdev $md0 1 $mdsize0 64
mdadm -S $md0

# now with no superblock
mdadm -B $md0 -l mirror  -n2 $dev0 $dev1
check resync
check raid1
testdev $md0 1 $size 1
#### Point 1
mdadm -S $md0

# again, but with no resync
mdadm -B $md0 -l 1 --assume-clean -n2 $dev0 $dev1
check raid1
check nosync
testdev $md0 1 $size 1
mdadm -S $md0
exit 0

What I did was add a couple of 'cat /proc/mdstat' commands where the script was failing. At Point 1 above, I got:

++ cat /proc/mdstat
Personalities : [raid1] [raid10] [raid6] [raid5] [raid4] [multipath] md127 : inactive md0[0](S)

      19904 blocks

md0 : active raid1 loop1[1] loop0[0]

      20000 blocks super non-persistent [2/2] [UU]
      [==>..................]  resync = 12.5% (2688/20000)

finish=0.1min speed=2688K/sec

The line with resync looked suspicious so at that point I added a 'sleep 10' command. The test now passes.

The full log is at
http://anduin.linuxfromscratch.org/~bdubbs/files/mdadm-test1.log

Does anyone know what is going on to need this sleep in order for this test to pass?

Quoted 17 lines

What I did was add a couple of 'cat /proc/mdstat' commands where the script was failing. At Point 1 above, I got:

++ cat /proc/mdstat
Personalities : [raid1] [raid10] [raid6] [raid5] [raid4] [multipath] md127 : inactive md0[0](S)

       19904 blocks

md0 : active raid1 loop1[1] loop0[0]

       20000 blocks super non-persistent [2/2] [UU]
       [==>..................]  resync = 12.5% (2688/20000)

finish=0.1min speed=2688K/sec

The line with resync looked suspicious so at that point I added a 'sleep 10' command. The test now passes.

Quoted 5 lines

The full log is at
http://anduin.linuxfromscratch.org/~bdubbs/files/mdadm-test1.log

Does anyone know what is going on to need this sleep in order for this test to pass?

It sounds to like the thing hangs if you try to stop the array before the resync completes. That could be a race in the kernel code.