Public bug reported: 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/20221208200605.756287-1-isaacmanjar...@google.com/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. ** Affects: linux (Ubuntu) Importance: Undecided Status: Confirmed ** Affects: linux-hwe-5.15 (Ubuntu) Importance: Undecided Status: New ** Tags: jammy ** Package changed: nvidia-graphics-drivers-525 (Ubuntu) => ubuntu ** Package changed: ubuntu => linux (Ubuntu) ** Package changed: linux (Ubuntu) => linux ** Project changed: linux => linux (Ubuntu) -- You received this bug notification because you are a member of Kernel Packages, which is subscribed to nvidia-graphics-drivers-525 in Ubuntu. 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/20221208200605.756287-1-isaacmanjar...@google.com/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. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2015400/+subscriptions -- Mailing list: https://launchpad.net/~kernel-packages Post to : kernel-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~kernel-packages More help : https://help.launchpad.net/ListHelp
