> On Sun, Jun 01, 2008 at 07:11:02PM +0200, Simon Holm Thøgersen wrote:
> > søn, 01 06 2008 kl. 11:01 +0200, skrev j.mell@t-online.de:
> > [...]
> > >
> > > 3. If I revert the patch
> > >
> > >
http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=acc207616a...
> > >
> > > in 2.6.20, Einstein does not crash anymore (program was run for more than
> > > 30 hours while system was in normal use with programming, multi-media
> > > etc.). Unfortunately git refuses to revert this patch in 2.6.26-rc4.
> > [...]
> >
> > I don't think the bisected commit is responsible for anything, but
> > triggering a bug elsewhere with your workload. I've been chasing the
> > same problem I think, but with other symptoms.
>
> Simon, There seems to be multiple issues here. fpu corruption seems
> to be a different problem compared to the issue you have encountered.
>
> >
> > I'm triggering the following by running an lguest guest, but I guess the
> > workload just need to have the right scheduler intensity to trigger the
> > bug.
> >
> > BUG: sleeping function called from invalid context at mm/slab.c:3052
> > in_atomic():1, irqs_disabled():0
> > Pid: 4771, comm: lguest Not tainted
> > 2.6.26-rc4-debug-only-preemptible-00103-g1beee8d #3
> > [<c01146ee>] __might_sleep+0xe4/0xeb
> > [<c01605d9>] kmem_cache_alloc+0x22/0xb4
> > [<c0108479>] init_fpu+0xb0/0x14d
> > [<c0104768>] math_state_restore+0x26/0x5d
> > [<c01045ab>] device_not_available+0x43/0x48
> > [<c011007b>] ? handle_vm86_fault+0x213/0x6b8
> > [<c01029ad>] ? __switch_to+0x23/0x113
> > [<c02d6c9f>] schedule+0x221/0x2a4
>
> Simon, Can you please try the appended patch and see if it fixes this
> issue? Thanks.
> ---
>
> [patch] x86: fix blocking call (math_state_restore()) condition in __switch_to
>
> Add tsk_used_math() checks to prevent calling math_state_restore()
> which can sleep in the case of !tsk_used_math(). This prevents
> making a blocking call in __switch_to().
>
> Apparently "fpu_counter > 5" check is not enough, as in some signal handling
> and fork/exec scenarios, fpu_counter > 5 and !tsk_used_math() is possible.
>
> Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
> ---
