| Date | Mon, 9 Mar 2015 18:10:41 +0100 | From | Oleg Nesterov <> | Subject | [PATCH] x86/fpu: drop_fpu() should not assume that tsk == current |
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drop_fpu() does clear_used_math() and usually this is correct because tsk == current. However switch_fpu_finish()->restore_fpu_checking() is called before it updates the "current_task" variable. If it fails, we will wrongly clear the PF_USED_MATH flag of the previous task.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: <stable@vger.kernel.org> --- arch/x86/include/asm/fpu-internal.h | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/arch/x86/include/asm/fpu-internal.h b/arch/x86/include/asm/fpu-internal.h index 99a2067..81c86fa 100644 --- a/arch/x86/include/asm/fpu-internal.h +++ b/arch/x86/include/asm/fpu-internal.h @@ -336,7 +336,7 @@ static inline void drop_fpu(struct task_struct *tsk) preempt_disable(); tsk->thread.fpu_counter = 0; __drop_fpu(tsk); - clear_used_math(); + clear_stopped_child_used_math(tsk); preempt_enable(); } -- 1.5.5.1
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