HWPOISON: Handle hardware poisoned pages in try_to_unmap

When a page has the poison bit set replace the PTE with a poison entry.
This causes the right error handling to be done later when a process runs
into it.

v2: add a new flag to not do that (needed for the memory-failure handler
later) (Fengguang)
v3: remove unnecessary is_migration_entry() test (Fengguang, Minchan)

Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

2 files changed, 9 insertions, 1 deletions

diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index 4c4a2d4d289e..ce989f1fc2ed 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -93,6 +93,7 @@ enum ttu_flags {
 
         TTU_IGNORE_MLOCK = (1 << 8),    /* ignore mlock */
         TTU_IGNORE_ACCESS = (1 << 9),   /* don't age */
+        TTU_IGNORE_HWPOISON = (1 << 10),/* corrupted page is recoverable */
 };
 #define TTU_ACTION(x) ((x) & TTU_ACTION_MASK)
 
diff --git a/mm/rmap.c b/mm/rmap.c
index 08c112a776a7..7e72ca19d68b 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -820,7 +820,14 @@ static int try_to_unmap_one(struct page *page, struct vm_area_struct *vma,
         /* Update high watermark before we lower rss */
         update_hiwater_rss(mm);
 
-        if (PageAnon(page)) {
+        if (PageHWPoison(page) && !(flags & TTU_IGNORE_HWPOISON)) {
+                if (PageAnon(page))
+                        dec_mm_counter(mm, anon_rss);
+                else
+                        dec_mm_counter(mm, file_rss);
+                set_pte_at(mm, address, pte,
+                                swp_entry_to_pte(make_hwpoison_entry(page)));
+        } else if (PageAnon(page)) {
                 swp_entry_t entry = { .val = page_private(page) };
 
                 if (PageSwapCache(page)) {