Commits
Alexey Dobriyan authored and Pavel Emelianov committed 5ef5503c0fb
[PATCH] loopback: oops on loopback mount/umount (mainstream) After LOOP_SET_FD/LOOP_CLR_FD combo loop device's queue gets request handler which is persistent. After, say mount -t iso9660 /dev/loop0 /mnt # sic this request handler is called directly with a) ->lo_state being Lo_unbound b) ->lo_pending being zero Error path in loop_make_request() completes ->lo_bh_done completion which is persistent as well. Now, let's start worker thread as usual. It'll set ->lo_pending to 1, don't wait for completion because it was already completed (brokenly), and will not get out of infinite loop because of ->lo_pending. Loop device doesn't have bios at this point and triggers BUG_ON. So, don't complete ->lo_bh_done when loop device isn't setup fully. In mainstream it was accidentaly fixed when converting to kthreads. Bug #79521