lkml.org 
[lkml]   [2013]   [Mar]   [15]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: Kernel oops on mmap ?
On Thu, Mar 14, 2013 at 09:38:02AM +0800, Hillf Danton wrote:
> [cc Russell]
> On Wed, Mar 13, 2013 at 11:04 PM, Mark Jackson <mpfj-list@mimc.co.uk> wrote:
> > Can any help diagnose what my userspace task is doing to get the followings oops ?
> >
> > [ 42.587772] Unable to handle kernel paging request at virtual address bfac6004
> > [ 42.595431] pgd = cf748000
> > [ 42.598291] [bfac6004] *pgd=00000000
>
> None pgd, why is pgd_none_or_clear_bad() not triggered?

I think you're misunderstanding what's happened here.

> > [ 42.602079] Internal error: Oops: 5 [#1] ARM
> > [ 42.606592] CPU: 0 Not tainted (3.8.0-next-20130225-00001-g2d0ce24-dirty #38)
> > [ 42.614509] PC is at unmap_single_vma+0x2d8/0x5bc
> > [ 42.619476] LR is at unmap_single_vma+0x29c/0x5bc
> > [ 42.624447] pc : [<c00aed0c>] lr : [<c00aecd0>] psr: 60000013
> > [ 42.624447] sp : cf685d88 ip : 8f9523cd fp : cf680004
> > [ 42.636567] r10: 00000000 r9 : bfac6000 r8 : 00200000
> > [ 42.642079] r7 : cf685e00 r6 : cf5e93a8 r5 : cf5e93ac r4 : 000ea000
> > [ 42.648969] r3 : 00000001 r2 : 00000000 r1 : 00000040 r0 : 00000000
...
> > [ 42.935472] Code: 0affffa4 e59d000c e3500000 1a0000a2 (e5993004)

That disassembles to this:
0: 0affffa4 beq 0xfffffe98
4: e59d000c ldr r0, [sp, #12]
8: e3500000 cmp r0, #0
c: 1a0000a2 bne 0x29c
10: e5993004 ldr r3, [r9, #4]

and r9 = 0xbfac6000, which is _not_ the address of a page table.

Unfortunately, the above doesn't tie up with the output from my
compiler, so I've no idea what that corresponds with in
unmap_single_vma().

The other surprising thing about this oops dump is the lack of
backtrace...

I think I need to see the disassembly of this function before
there can be any further diagnosis of what's going on here.


\
 
 \ /
  Last update: 2013-03-15 19:01    [W:0.059 / U:0.044 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site