Re: btrfs panic in 3.5.0

[Marc MERLIN <marc@merlins.org>]

On Tue, Aug 07, 2012 at 11:47:36AM -0700, Marc MERLIN wrote:
> On Tue, Aug 07, 2012 at 08:14:23PM +0200, Arne Jansen wrote:
> > On 08/07/2012 07:40 PM, Marc MERLIN wrote:
> > > Unfortunately I only have a screenshot.
> > > 
> > > Apparently the panic was in 
> > > btrfs_set_lock_blocking_rw
> > > with a RIP in btrfs_cow_block
> > 
> > Can you please resolve btrfs_cow_block+0x3b to a line number?
> > 
> > gdb btrfs.ko
> > (gdb) info line *btrfs_cow_block+0x3b
> 
> So, I'm not very good at this, sorry if I'm doing it wrong:
> gandalfthegreat:~# gdb /lib/modules/3.5.0-amd64-preempt-noide-20120410/kernel/fs/btrfs/btrfs.ko
> Reading symbols from /lib/modules/3.5.0-amd64-preempt-noide-20120410/kernel/fs/btrfs/btrfs.ko...(no debugging symbols found)...done.
> (gdb) info line *btrfs_cow_block+0x3b
> No line number information available for address 0x9a6e
> 
> Mmmh, it seems that I'm missing a kernel option that adds symbols in modules?
> 
> I can add it for my next kernel compile. Do you have the config option name
> off hand?
> 
> I put my module here if that helps:
> http://marc.merlins.org/tmp/btrfs.ko

I felt bad for having a kernel without debug symbols it seems, so I looked
at my kernel config and I do have:
CONFIG_DEBUG_BUGVERBOSE=y
CONFIG_DEBUG_INFO=y
# CONFIG_DEBUG_INFO_REDUCED is not set

Any idea what else I'm missing to provide better debug info if I have a
problem again?

And is it reasonably easy to take the .ko apparently without line numbers,
like the one I gave you, and infer the line of code for a function offset?

Thanks,
Marc
-- 
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Microsoft is to operating systems ....
                                      .... what McDonalds is to gourmet cooking
Home page: http://marc.merlins.org/