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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