mm: don't use radix tree writeback tags for pages in swap cache

[cascardo/linux.git] / mm / memory.c

diff --git a/mm/memory.c b/mm/memory.c
index f1a6804..4bfc3a9 100644 (file)
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -3658,6 +3658,19 @@ int handle_mm_fault(struct vm_area_struct *vma, unsigned long address,
                         mem_cgroup_oom_synchronize(false);
        }
 
+       /*
+        * This mm has been already reaped by the oom reaper and so the
+        * refault cannot be trusted in general. Anonymous refaults would
+        * lose data and give a zero page instead e.g. This is especially
+        * problem for use_mm() because regular tasks will just die and
+        * the corrupted data will not be visible anywhere while kthread
+        * will outlive the oom victim and potentially propagate the date
+        * further.
+        */
+       if (unlikely((current->flags & PF_KTHREAD) && !(ret & VM_FAULT_ERROR)
+                               && test_bit(MMF_UNSTABLE, &vma->vm_mm->flags)))
+               ret = VM_FAULT_SIGBUS;
+
        return ret;
 }
 EXPORT_SYMBOL_GPL(handle_mm_fault);