On 03/13, Borislav Petkov wrote: > > On Wed, Mar 11, 2015 at 06:34:09PM +0100, Oleg Nesterov wrote: > > @@ -464,7 +464,9 @@ static inline int restore_xstate_sig(void __user *buf, > > int ia32_frame) > > * Need to be preemption-safe. > > * > > * NOTE! user_fpu_begin() must be used only immediately before restoring > > - * it. This function does not do any save/restore on their own. > > + * it. This function does not do any save/restore on its own. In a lazy > > + * fpu mode this is just optimization to avoid a dna fault, the task can > > + * lose FPU right after preempt_enable(). > > */ > > I cleaned it up a bit more, if you don't mind: ...
> /* > - * Need to be preemption-safe. > + * Needs to be preemption-safe. > * > * NOTE! user_fpu_begin() must be used only immediately before restoring > - * it. This function does not do any save/restore on their own. > + * the save state. It does not do any saving/restoring on its own. In > + * lazy FPU mode, it is just an optimization to avoid a #NM exception, > + * the task can lose the FPU right after preempt_enable(). > */ Thank! Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
