Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-tip:
  x86, fpu: fix CONFIG_PREEMPT=y corruption of application's FPU stack
  suspend-vs-iommu: prevent suspend if we could not resume
  x86: section mismatch fix
  x86: fix Xorg crash with xf86MapVidMem error
  x86: fix pointer type warning in arch/x86/mm/init_64.c:early_memtest
  x86: fix bad pmd ffff810000207xxx(9090909090909090)
  x86: ioremap fix failing nesting check
  x86: fix broken math-emu with lazy allocation of fpu area
  x86: enable preemption in delay
  x86: disable preemption in native_smp_prepare_cpus
  x86: fix APIC warning on 32bit v2

1 files changed, 4 insertions, 1 deletions

diff --git a/arch/x86/kernel/process_32.c b/arch/x86/kernel/process_32.c
index f8476dfbb60d..6d5483356e74 100644
--- a/arch/x86/kernel/process_32.c
+++ b/arch/x86/kernel/process_32.c
@@ -649,8 +649,11 @@ struct task_struct * __switch_to(struct task_struct *prev_p, struct task_struct
         /* 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();
 
         /*