HWPOISON: Add support for poison swap entries v2

Memory migration uses special swap entry types to trigger special actions on
page faults. Extend this mechanism to also support poisoned swap entries, to
trigger poison handling on page faults. This allows follow-on patches to
prevent processes from faulting in poisoned pages again.

v2: Fix overflow in MAX_SWAPFILES (Fengguang Wu)
v3: Better overflow fix (Hidehiro Kawai)

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

1 files changed, 2 insertions, 2 deletions

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);