[dm-devel] [PATCH] dm mirror: fix crash caused by NULL-pointer dereference

[Johannes Thumshirn]

On Mon, Jun 26, 2017 at 05:08:48PM +0800, Eric Ren wrote:
> When the primary mirror device fails, activating a mirrored
> LV will crash the kernel. It can be reproduced 100% with the
> scripts below:
> 
> """
> dd if=/dev/zero of=file.raw bs=1G count=1
> loopdev=$(losetup -f)
> losetup $loopdev file.raw
> dmsetup create pv1 --table "0 102399 linear $loopdev 0"
> dmsetup create pv2 --table "0 102399 linear $loopdev 102400"
> vgcreate vgtest /dev/mapper/pv1 /dev/mapper/pv2
> lvcreate -l1 --type mirror -m1 -n mirror12 --mirrorlog core \
>                  vgtest /dev/mapper/pv1 /dev/mapper/pv2
> vgchange -an vgtest
> echo 0 10000000 error | dmsetup load /dev/mapper/pv1
> dmsetup resume /dev/mapper/pv1
> vgchange -ay vgtest
> """

So as you have a reproducer, can you eventually write an blktest [1]
regression test for it?


Thanks,
	Johannes

[1] https://github.com/osandov/blktests

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Johannes Thumshirn                                          Storage
jthumshirn at suse.de                                +49 911 74053 689
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