| Date | Wed, 14 Jan 2015 19:43:43 +0100 | From | Oleg Nesterov <> | Subject | Re: [RFC PATCH 08/11] x86,fpu: restore user FPU state lazily after __kernel_fpu_end |
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On 01/11, riel@redhat.com wrote: > > --- a/arch/x86/kernel/i387.c > +++ b/arch/x86/kernel/i387.c > @@ -89,13 +89,11 @@ void __kernel_fpu_end(void) > if (use_eager_fpu()) { > /* > * For eager fpu, most the time, tsk_used_math() is true. > - * Restore the user math as we are done with the kernel usage. > - * At few instances during thread exit, signal handling etc, > - * tsk_used_math() is false. Those few places will take proper > - * actions, so we don't need to restore the math here. > + * Make sure the user math state is restored on return to > + * userspace. > */ > if (likely(tsk_used_math(current))) > - math_state_restore(); > + set_thread_flag(TIF_LOAD_FPU);
Hmm. And this looks obviously wrong if interrupted_user_mode().
Oleg.
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