1 files changed, 5 insertions, 1 deletions

diff --git a/arch/x86/kernel/process_64.c b/arch/x86/kernel/process_64.c
index e2319f39988b..c6eb5c91e5f6 100644
--- a/arch/x86/kernel/process_64.c
+++ b/arch/x86/kernel/process_64.c
@@ -294,6 +294,7 @@ void flush_thread(void)
         /*
          * Forget coprocessor state..
          */
+        tsk->fpu_counter = 0;
         clear_fpu(tsk);
         clear_used_math();
 }
@@ -658,8 +659,11 @@ __switch_to(struct task_struct *prev_p, struct task_struct *next_p)
         /* If the task has used fpu the last 5 timeslices, just do a full
          * restore of the math state immediately to avoid the trap; the
          * chances of needing FPU soon are obviously high now
+         *
+         * tsk_used_math() checks prevent calling math_state_restore(),
+         * which can sleep in the case of !tsk_used_math()
          */
-        if (next_p->fpu_counter>5)
+        if (tsk_used_math(next_p) && next_p->fpu_counter > 5)
                 math_state_restore();
         return prev_p;
 }