Bug#993738: udev: symlink creation race condition can cause log delays

[Michael Biebl]

Am 05.09.21 um 19:24 schrieb Lukas Schwaighofer:
> Package: udev
> Version: 247.3-6
> Severity: important
> 
> 
> Dear systemd/udev Maintainers,
> 
> I've noticed a race condition with udev symlink creation, that can
> cause long delays when activating logical volumes in LVM. Steps to
> reproduce the problem (needs root):
> 
>      # prepare
>      truncate -s 1G test.img
>      loop="$(losetup --show -f test.img)"
>      echo "Loop device used: $loop"
>      pvcreate "$loop"
>      vgcreate vgtest "$loop"
>      # create 50 LVs with an ext4 fs, all with same label
>      # (increase the number to make the problem more sever)
>      for i in `seq 0 49` ; do
>        lvcreate -L 4M -n dummy-${i} vgtest
>        mkfs.ext4 -L dummy /dev/vgtest/dummy-${i}

So you create a lot of partitions which all have the same label?

Isn't this asking for trouble anyway as you can't be certain, which 
device the /dev/disk/by-label/dummy will point to?


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