diff options
Diffstat (limited to 'kernel/kthread.c')
| -rw-r--r-- | kernel/kthread.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/kernel/kthread.c b/kernel/kthread.c index 1f1b60f1a746..470708c205e8 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -1415,6 +1415,11 @@ void kthread_use_mm(struct mm_struct *mm) WARN_ON_ONCE(!(tsk->flags & PF_KTHREAD)); WARN_ON_ONCE(tsk->mm); + /* + * It is possible for mm to be the same as tsk->active_mm, but + * we must still mmgrab(mm) and mmdrop_lazy_tlb(active_mm), + * because these references are not equivalent. + */ mmgrab(mm); task_lock(tsk); @@ -1438,9 +1443,9 @@ void kthread_use_mm(struct mm_struct *mm) * memory barrier after storing to tsk->mm, before accessing * user-space memory. A full memory barrier for membarrier * {PRIVATE,GLOBAL}_EXPEDITED is implicitly provided by - * mmdrop(). + * mmdrop_lazy_tlb(). */ - mmdrop(active_mm); + mmdrop_lazy_tlb(active_mm); } EXPORT_SYMBOL_GPL(kthread_use_mm); @@ -1468,10 +1473,13 @@ void kthread_unuse_mm(struct mm_struct *mm) local_irq_disable(); tsk->mm = NULL; membarrier_update_current_mm(NULL); + mmgrab_lazy_tlb(mm); /* active_mm is still 'mm' */ enter_lazy_tlb(mm, tsk); local_irq_enable(); task_unlock(tsk); + + mmdrop(mm); } EXPORT_SYMBOL_GPL(kthread_unuse_mm); |