Re: [uml-devel] kernel BUG at drivers/block/loop.c:621

[Blaisorblade <blaisorblade@yahoo.it>]

On Saturday 18 March 2006 01:55, Rob Landley wrote:
> On Friday 17 March 2006 7:24 pm, Blaisorblade wrote:
> > On Saturday 18 March 2006 01:12, Rob Landley wrote:
> > > 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+0x9 1/0xc0
> >
> > The below is strange - GCC is putting disks in the .text section or
> > kallsyms has some bug.
> >
> > > 09b87d20:  [<ffffe420>] disks+0xf7e7ec84/0x4
>
> Isn't ffffe??? the FASTCALL page?

Sorry, didn't mention that according to ctags, disks is defined only as a 
struct member or as a static variable... clearly neither is valid on a call 
stack.

The call trace decoder filters out hex values outside _stext - _etext, but 
maybe it also considers valid the FASTCALL page... leading to this 
interesting bogus output :-)

> Haven't tried.  I value my laptop. :)

> My host is running unbuntu 2.6.12, and my mount test requires a clean
> environment with nothing else mounted when it first runs.  (It basically
> needs to run as PID 1.  Among other things, it synthesizes variants of its
> own fstab...)

> I don't think it's a uml bug, but I cc'd the UML list because that's where
> I can easily reproduce it.

Ok - didn't notice the LKML cc, sorry (it's really late).

> Rob

-- 
Inform me of my mistakes, so I can keep imitating Homer Simpson's "Doh!".
Paolo Giarrusso, aka Blaisorblade (Skype ID "PaoloGiarrusso", ICQ 215621894)
http://www.user-mode-linux.org/~blaisorblade

		
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