Re: Still seeing hangs in xlog_grant_log_space

Dave Chinner
2012-06-11T23:53:42Z

On Mon, Jun 11, 2012 at 01:42:31PM -0700, Chris J Arges wrote:
> Mark Tinguely-3 wrote:
> >
> > The perl script to recreate this problem is very similar to xfstest 273.
> > I use that because it avoids all the filesystem mount/unmount that
> > happen between the test 273 loops. You can build the log size that you
> > want to test, create the directories and let it run until it hangs.
> >
>
> I tested xfstest 273, and it looks like it exhibits a different issue than
> the OP in this thread.
> For example, if I run this test in a while [1] loop, I get the following
> backtrace:
>
> [16413.073946] XFS (sda5): Invalid block length (0xfffff48b) for buffer

That looks bad. How big is the log on this filesystem?

> [16413.073963] BUG: unable to handle kernel NULL pointer dereference at
> 0000000000000130
> [16413.074274] IP: [<ffffffffa02bb870>] uuid_is_nil+0x10/0x50 [xfs]

I can't really see how this function can get a null pointer
dereference. It checks the pointer passed in for being null before
doing anything, and otherwise it just increments and dereferences
the char pointer 16 times. I can't see how that results in a NULL
being dereferenced - I might just be blind though.

Cheers,

Dave.
--
Dave Chinner
david@fromorbit.com