HWPOISON: Add poison check to page fault handling

Bail out early when hardware poisoned pages are found in page fault handling.
Since they are poisoned they should not be mapped freshly into processes,
because that would cause another (potentially deadly) machine check

This is generally handled in the same way as OOM, just a different
error code is returned to the architecture code.

v2: Do a page unlock if needed (Fengguang Wu)

Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/mm/memory.c b/mm/memory.c
index 02bae2d540d4..44ea41196c13 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2711,6 +2711,12 @@ static int __do_fault(struct mm_struct *mm, struct vm_area_struct *vma,
         if (unlikely(ret & (VM_FAULT_ERROR | VM_FAULT_NOPAGE)))
                 return ret;
 
+        if (unlikely(PageHWPoison(vmf.page))) {
+                if (ret & VM_FAULT_LOCKED)
+                        unlock_page(vmf.page);
+                return VM_FAULT_HWPOISON;
+        }
+
         /*
          * For consistency in subsequent calls, make the faulted page always
          * locked.