On 3/30/21 3:43 PM, Zhao Heming wrote:
commit d3374825ce57 ("md: make devices disappear when they are no longer
needed.") introduced protection between mddev creating & removing. The
md_open shouldn't create mddev when all_mddevs list doesn't contain
mddev. With currently code logic, there will be very easy to trigger
soft lockup in non-preempt env.
*** env ***
kvm-qemu VM 2C1G with 2 iscsi luns
kernel should be non-preempt
*** script ***
about trigger 1 time with 10 tests
```
1 node1="15sp3-mdcluster1"
2 node2="15sp3-mdcluster2"
3
4 mdadm -Ss
5 ssh ${node2} "mdadm -Ss"
6 wipefs -a /dev/sda /dev/sdb
7 mdadm -CR /dev/md0 -b clustered -e 1.2 -n 2 -l mirror /dev/sda \
/dev/sdb --assume-clean
8
9 for i in {1..100}; do
10 echo ==== $i ====;
11
12 echo "test ...."
13 ssh ${node2} "mdadm -A /dev/md0 /dev/sda /dev/sdb"
14 sleep 1
15
16 echo "clean ....."
17 ssh ${node2} "mdadm -Ss"
18 done
```
the non-clustered test script. (again: run on non-preempt kernel)
```
#!/bin/bash
mdadm -Ss
wipefs -a /dev/sda /dev/sdb
mdadm -CR /dev/md0 -b internal -e 1.2 -n 2 -l mirror /dev/sda /dev/sdb --assume-clean
sleep 5
mdadm -Ss
for i in {1..200}; do
echo ==== $i ====;
echo "test ...."
mdadm -A /dev/md0 /dev/sda /dev/sdb
sleep 1
echo "clean ....."
mdadm -Ss
done
```
the value N on "/sys/module/md_mod/parameters/create_on_open" is useless.
Thanks,
heming
