kernel BUG at drivers/block/loop.c:621

[Rob Landley <rob@landley.net>]

I can reproduce the following in 2.6.16-rc5, User Mode Linux:

kernel BUG at drivers/block/loop.c:621!
Kernel panic - not syncing: BUG!

EIP: 0073:[<ffffe410>] CPU: 0 Not tainted ESP: 007b:b7de1f9c EFLAGS: 00200246
    Not tainted
EAX: 00000000 EBX: 000018be ECX: 00000013 EDX: 000018be
ESI: 000018bb EDI: 00000011 EBP: b7de1fb8 DS: 007b ES: 007b
09b87bb4:  [<0806c762>] show_regs+0x102/0x110
09b87bd0:  [<0805b6fc>] panic_exit+0x2c/0x50
09b87be0:  [<0807ff7d>] notifier_call_chain+0x2d/0x50
09b87c00:  [<08071095>] panic+0x75/0x120
09b87c20:  [<0812e181>] loop_thread+0x151/0x160
09b87c4c:  [<08065297>] run_kernel_thread+0x37/0x60
09b87cfc:  [<0805bbd1>] new_thread_handler+0x91/0xc0
09b87d20:  [<ffffe420>] disks+0xf7e7ec84/0x4

The reproduction sequence is a bit involved (my mount regression test and the 
current svn snapshot of busybox are involved), and running the following 
sequence of commands:

mount; mount -a; mount; mount /dev/loop1 /images/vfat.dir ; 
losetup /dev/loop1; ls; vi /etc/fstab; cat /etc/fstab; losetup /dev/loop0; 
mount /images/vfat.img /images/vfat.dir -o ro

The current busybox mount is still broken in a couple of known places (hence 
the testing; I'm fixing it).  But it probably shouldn't panic the kernel...

Rob
-- 
Never bet against the cheap plastic solution.
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