Comment # 5 on bug 1200259 from Gr���ner

# Check which Devices are trimmed
> fstrim -anv
/raid/local: 0 B (dry run) trimmed on /dev/md0
/windows/D: 0 B (dry run) trimmed on /dev/sdb1

# What is behind md0
> cat /proc/mdstat 
Personalities : [raid10] 
md0 : active raid10 sdb3[4] sdc3[3]
      536867680 blocks super 1.0 2 near-copies [2/2] [UU]
      bitmap: 0/4 pages [0KB], 65536KB chunk

unused devices: <none>

# Show Schedulers
> for i in md0 sdb sdc; do echo -n "$i:" ; cat /sys/block/$i/queue/scheduler; done
md0:none
sdb:mq-deadline kyber [bfq] none
sdc:mq-deadline kyber [bfq] none

# What Filesystem is behind
> mount
/dev/sdb1 on /windows/D type fuseblk
(rw,nosuid,nodev,noexec,relatime,user_id=0,group_id=0,default_permissions,allow_other,blksize=4096)
/dev/md0 on /raid/local type ext4 (rw,relatime,stripe=8)


# Test sdb1 with bfq scheduler 100 times
for i in {0..100}; do fstrim -v /windows/D; done
=> No crash

# update Scheduler for raid devices
> echo "none" >> /sys/block/sdb/queue/scheduler
> echo "none" >> /sys/block/sdc/queue/scheduler
> cat /sys/block/sdb/queue/scheduler
[none] mq-deadline kyber bfq 
> cat /sys/block/sdc/queue/scheduler
[none] mq-deadline kyber bfq 

# run fstrim
fstrim -v /raid/local
=> Fine

> echo "bfq" >> /sys/block/sdb/queue/scheduler
> echo "bfq" >> /sys/block/sdc/queue/scheduler
> cat /sys/block/sdb/queue/scheduler
mq-deadline kyber [bfq] none
> cat /sys/block/sdc/queue/scheduler
mq-deadline kyber [bfq] none
> cat /sys/block/md0/queue/scheduler
none
fstrim -v /raid/local
=> Kernel Panic

Based on this picture, the differences are Raid and different Filesystem.