HWPOISON: introduce delete_from_lru_cache()

Introduce delete_from_lru_cache() to
- clear PG_active, PG_unevictable to avoid complains at unpoison time
- move the isolate_lru_page() call back to the handlers instead of the
  entrance of __memory_failure(), this is more hwpoison filter friendly

Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>

1 files changed, 37 insertions, 8 deletions

diff --git a/mm/memory-failure.c b/mm/memory-failure.c
index dc47415a5511..9a285f8cdbe1 100644
--- a/mm/memory-failure.c
+++ b/mm/memory-failure.c
@@ -350,6 +350,30 @@ static const char *action_name[] = {
 };
 
 /*
+ * XXX: It is possible that a page is isolated from LRU cache,
+ * and then kept in swap cache or failed to remove from page cache.
+ * The page count will stop it from being freed by unpoison.
+ * Stress tests should be aware of this memory leak problem.
+ */
+static int delete_from_lru_cache(struct page *p)
+{
+        if (!isolate_lru_page(p)) {
+                /*
+                 * Clear sensible page flags, so that the buddy system won't
+                 * complain when the page is unpoison-and-freed.
+                 */
+                ClearPageActive(p);
+                ClearPageUnevictable(p);
+                /*
+                 * drop the page count elevated by isolate_lru_page()
+                 */
+                page_cache_release(p);
+                return 0;
+        }
+        return -EIO;
+}
+
+/*
  * Error hit kernel page.
  * Do nothing, try to be lucky and not touch this instead. For a few cases we
  * could be more sophisticated.
@@ -393,6 +417,8 @@ static int me_pagecache_clean(struct page *p, unsigned long pfn)
         int ret = FAILED;
         struct address_space *mapping;
 
+        delete_from_lru_cache(p);
+
         /*
          * For anonymous pages we're done the only reference left
          * should be the one m_f() holds.
@@ -522,14 +548,20 @@ static int me_swapcache_dirty(struct page *p, unsigned long pfn)
         /* Trigger EIO in shmem: */
         ClearPageUptodate(p);
 
-        return DELAYED;
+        if (!delete_from_lru_cache(p))
+                return DELAYED;
+        else
+                return FAILED;
 }
 
 static int me_swapcache_clean(struct page *p, unsigned long pfn)
 {
         delete_from_swap_cache(p);
 
-        return RECOVERED;
+        if (!delete_from_lru_cache(p))
+                return RECOVERED;
+        else
+                return FAILED;
 }
 
 /*
@@ -746,7 +778,6 @@ static int hwpoison_user_mappings(struct page *p, unsigned long pfn,
 
 int __memory_failure(unsigned long pfn, int trapno, int flags)
 {
-        unsigned long lru_flag;
         struct page_state *ps;
         struct page *p;
         int res;
@@ -796,13 +827,11 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
          */
         if (!PageLRU(p))
                 lru_add_drain_all();
-        lru_flag = p->flags & lru;
-        if (isolate_lru_page(p)) {
+        if (!PageLRU(p)) {
                 action_result(pfn, "non LRU", IGNORED);
                 put_page(p);
                 return -EBUSY;
         }
-        page_cache_release(p);
 
         /*
          * Lock the page and wait for writeback to finish.
@@ -825,7 +854,7 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
         /*
          * Torn down by someone else?
          */
-        if ((lru_flag & lru) && !PageSwapCache(p) && p->mapping == NULL) {
+        if (PageLRU(p) && !PageSwapCache(p) && p->mapping == NULL) {
                 action_result(pfn, "already truncated LRU", IGNORED);
                 res = 0;
                 goto out;
@@ -833,7 +862,7 @@ int __memory_failure(unsigned long pfn, int trapno, int flags)
 
         res = -EBUSY;
         for (ps = error_states;; ps++) {
-                if (((p->flags | lru_flag)& ps->mask) == ps->res) {
+                if ((p->flags & ps->mask) == ps->res) {
                         res = page_action(ps, p, pfn);
                         break;
                 }