3 files changed, 68 insertions, 8 deletions

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 7c15334f3ff2..f077e454c659 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -34,16 +34,38 @@ static inline int current_is_kswapd(void)
  * the type/offset into the pte as 5/27 as well.
  */
 #define MAX_SWAPFILES_SHIFT     5
-#ifndef CONFIG_MIGRATION
-#define MAX_SWAPFILES           (1 << MAX_SWAPFILES_SHIFT)
+
+/*
+ * Use some of the swap files numbers for other purposes. This
+ * is a convenient way to hook into the VM to trigger special
+ * actions on faults.
+ */
+
+/*
+ * NUMA node memory migration support
+ */
+#ifdef CONFIG_MIGRATION
+#define SWP_MIGRATION_NUM 2
+#define SWP_MIGRATION_READ      (MAX_SWAPFILES + SWP_HWPOISON_NUM)
+#define SWP_MIGRATION_WRITE     (MAX_SWAPFILES + SWP_HWPOISON_NUM + 1)
 #else
-/* Use last two entries for page migration swap entries */
-#define MAX_SWAPFILES           ((1 << MAX_SWAPFILES_SHIFT)-2)
-#define SWP_MIGRATION_READ      MAX_SWAPFILES
-#define SWP_MIGRATION_WRITE     (MAX_SWAPFILES + 1)
+#define SWP_MIGRATION_NUM 0
 #endif
 
 /*
+ * Handling of hardware poisoned pages with memory corruption.
+ */
+#ifdef CONFIG_MEMORY_FAILURE
+#define SWP_HWPOISON_NUM 1
+#define SWP_HWPOISON            MAX_SWAPFILES
+#else
+#define SWP_HWPOISON_NUM 0
+#endif
+
+#define MAX_SWAPFILES \
+        ((1 << MAX_SWAPFILES_SHIFT) - SWP_MIGRATION_NUM - SWP_HWPOISON_NUM)
+
+/*
  * Magic header for a swap area. The first part of the union is
  * what the swap magic looks like for the old (limited to 128MB)
  * swap area format, the second part of the union adds - in the
diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 6ec39ab27b4b..cd42e30b7c6e 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -131,3 +131,41 @@ static inline int is_write_migration_entry(swp_entry_t entry)
 
 #endif
 
+#ifdef CONFIG_MEMORY_FAILURE
+/*
+ * Support for hardware poisoned pages
+ */
+static inline swp_entry_t make_hwpoison_entry(struct page *page)
+{
+        BUG_ON(!PageLocked(page));
+        return swp_entry(SWP_HWPOISON, page_to_pfn(page));
+}
+
+static inline int is_hwpoison_entry(swp_entry_t entry)
+{
+        return swp_type(entry) == SWP_HWPOISON;
+}
+#else
+
+static inline swp_entry_t make_hwpoison_entry(struct page *page)
+{
+        return swp_entry(0, 0);
+}
+
+static inline int is_hwpoison_entry(swp_entry_t swp)
+{
+        return 0;
+}
+#endif
+
+#if defined(CONFIG_MEMORY_FAILURE) || defined(CONFIG_MIGRATION)
+static inline int non_swap_entry(swp_entry_t entry)
+{
+        return swp_type(entry) >= MAX_SWAPFILES;
+}
+#else
+static inline int non_swap_entry(swp_entry_t entry)
+{
+        return 0;
+}
+#endif
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 74f1102e8749..ce5dda6d604b 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -699,7 +699,7 @@ int free_swap_and_cache(swp_entry_t entry)
         struct swap_info_struct *p;
         struct page *page = NULL;
 
-        if (is_migration_entry(entry))
+        if (non_swap_entry(entry))
                 return 1;
 
         p = swap_info_get(entry);
@@ -2085,7 +2085,7 @@ static int __swap_duplicate(swp_entry_t entry, bool cache)
         int count;
         bool has_cache;
 
-        if (is_migration_entry(entry))
+        if (non_swap_entry(entry))
                 return -EINVAL;
 
         type = swp_type(entry);