* Oleg Nesterov <o...@redhat.com> wrote: > On 03/06, Ingo Molnar wrote: > > > > * Oleg Nesterov <o...@redhat.com> wrote: > > > > > [...] The patch above looks "obviously safe", but perhaps I am > > > paranoid too much... > > > > IMHO your hack above isn't really acceptable, even for a backport. > > So lets test the patch below (assuming it's the right thing to do) > > and move forward? > > OK, but please note that this patch is not beckportable. If you think > that -stable doesn't need this fix, then I agree. > > If the caller is do_device_not_available(), then we can not enable > irqs before __thread_fpu_begin() + restore_fpu_checking(). > > 1. Preemption in between can destroy ->fpu.state initialized by > fpu_finit(), __switch_to() will save the live (wrong) FPU state > again. > > 2. kernel_fpu_begin() from irq right after __thread_fpu_begin() is > not nice too. It will do __save_init_fpu() and this overwrites > ->fpu.state too. > > Starting from v4.0 it does kernel_fpu_disable(), but the older kernels > do not. > > Ingo, this code is really horrible and fragile. We need to cleanup it > step-by-step, imho.
How about the patch from David Vrabel? That seems to solve the irq-disable problem too, right? Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/