Messages in this thread | | | Date | Wed, 14 Aug 2019 15:07:08 +0200 | From | Sebastian Andrzej Siewior <> | Subject | Re: [PATCH 8/9] x86/fpu: correctly check for kthreads |
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On 2019-08-14 11:41:30 [+0100], Mark Rutland wrote: > Per commit: > > 0cecca9d03c964ab ("x86/fpu: Eager switch PKRU state") > > ... switch_fpu_state() is trying to distinguish user threads from > kthreads, such that kthreads consistently use init_pkru_value. It does > do by looking at current->mm. > > In general, a non-NULL current->mm doesn't imply that current is a > kthread, as kthreads can install an mm via use_mm(), and so it's > preferable to use is_kthread() to determine whether a thread is a > kthread.
I think this was missed in commit. 8d3289f2fa1e0 ("x86/fpu: Don't use current->mm to check for a kthread")
A kthread with use_mm() would load here non-existing FPU state.
Acked-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Sebastian
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