Status changed to 'Confirmed' because the bug affects multiple users.
** Changed in: linux (Ubuntu)
Status: New => Confirmed
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https://bugs.launchpad.net/bugs/2015400
Title:
losetup with mknod fails on jammy with kernel 5.15.0-69-generic
Status in linux package in Ubuntu:
Confirmed
Status in linux-hwe-5.15 package in Ubuntu:
New
Bug description:
losetup fails with devices created manually by mknod on kernel
5.15.0-69-generic
# fallocate -l 1G test
# mknod -m 660 /dev/loop8 b 7 8
# chown root:disk /dev/loop8
# losetup /dev/loop8 ./test
losetup: ./test: failed to set up loop device: Device or resource busy
Possibly as a result of this patch:
https://lore.kernel.org/lkml/[email protected]/T/
which was introduced in 5.15.0-68:
http://launchpadlibrarian.net/653145495/linux_5.15.0-67.74_5.15.0-68.75.diff.gz
On a machine prior to this change (no issue with losetup):
# cat /sys/module/loop/parameters/max_loop
0
# uname -r
5.15.0-58-generic
On a machine after the change (has losetup issue as described above):
# cat /sys/module/loop/parameters/max_loop
8
# uname -r
5.15.0-69-generic
So it looks like the default changed and the max amount of loop
devices that can be created with mknod (not loop-control) is 8. If we
set max_loop=0 on the kernel command line, it works as before. Cannot
unload and reload module on a running system to change the parameter
because it is built into the kernel.
Another workaround is to use `losetup --find` but that means you
cannot create with named devices created with mknod.
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