mm: make sure that kthreads will not refault oom reaped memory

[karo-tx-linux.git] / mm / oom_kill.c

diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 3b990544db6d2989cd2a79c9f26bf66f1c9ee5ba..5a3ba96c8338495eb78ccd688fc87fd933d5f437 100644 (file)
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -495,6 +495,14 @@ static bool __oom_reap_task_mm(struct task_struct *tsk, struct mm_struct *mm)
                goto unlock_oom;
        }
 
+       /*
+        * Tell all users of get_user/copy_from_user etc... that the content
+        * is no longer stable. No barriers really needed because unmapping
+        * should imply barriers already and the reader would hit a page fault
+        * if it stumbled over a reaped memory.
+        */
+       set_bit(MMF_UNSTABLE, &mm->flags);
+
        tlb_gather_mmu(&tlb, mm, 0, -1);
        for (vma = mm->mmap ; vma; vma = vma->vm_next) {
                if (is_vm_hugetlb_page(vma))