7 files changed, 65 insertions, 9 deletions

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 11a9a05cf554..fb45d88a2446 100644
--- a/drivers/base/node.c
+++ b/drivers/base/node.c
@@ -71,7 +71,8 @@ static ssize_t node_read_meminfo(struct sys_device * dev,
                        "Node %d Active(file):   %8lu kB\n"
                        "Node %d Inactive(file): %8lu kB\n"
 #ifdef CONFIG_UNEVICTABLE_LRU
-                       "Node %d Noreclaim:      %8lu kB\n"
+                       "Node %d Unevictable:    %8lu kB\n"
+                       "Node %d Mlocked:        %8lu kB\n"
 #endif
 #ifdef CONFIG_HIGHMEM
                        "Node %d HighTotal:      %8lu kB\n"
@@ -104,6 +105,7 @@ static ssize_t node_read_meminfo(struct sys_device * dev,
                        nid, K(node_page_state(nid, NR_INACTIVE_FILE)),
 #ifdef CONFIG_UNEVICTABLE_LRU
                        nid, K(node_page_state(nid, NR_UNEVICTABLE)),
+                       nid, K(node_page_state(nid, NR_MLOCK)),
 #endif
 #ifdef CONFIG_HIGHMEM
                        nid, K(i.totalhigh),
diff --git a/fs/proc/proc_misc.c b/fs/proc/proc_misc.c
index 6dd60eaea997..61b25f4eabe6 100644
--- a/fs/proc/proc_misc.c
+++ b/fs/proc/proc_misc.c
@@ -176,6 +176,7 @@ static int meminfo_read_proc(char *page, char **start, off_t off,
                 "Inactive(file): %8lu kB\n"
 #ifdef CONFIG_UNEVICTABLE_LRU
                 "Unevictable:    %8lu kB\n"
+                "Mlocked:        %8lu kB\n"
 #endif
 #ifdef CONFIG_HIGHMEM
                 "HighTotal:      %8lu kB\n"
@@ -217,6 +218,7 @@ static int meminfo_read_proc(char *page, char **start, off_t off,
                 K(pages[LRU_INACTIVE_FILE]),
 #ifdef CONFIG_UNEVICTABLE_LRU
                 K(pages[LRU_UNEVICTABLE]),
+                K(global_page_state(NR_MLOCK)),
 #endif
 #ifdef CONFIG_HIGHMEM
                 K(i.totalhigh),
diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d1f60d5fe2ea..da2d053a95f1 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -88,8 +88,10 @@ enum zone_stat_item {
         NR_ACTIVE_FILE,         /*  "     "     "   "       "         */
 #ifdef CONFIG_UNEVICTABLE_LRU
         NR_UNEVICTABLE,         /*  "     "     "   "       "         */
+        NR_MLOCK,               /* mlock()ed pages found and moved off LRU */
 #else
         NR_UNEVICTABLE = NR_ACTIVE_FILE, /* avoid compiler errors in dead code */
+        NR_MLOCK = NR_ACTIVE_FILE,
 #endif
         NR_ANON_PAGES,  /* Mapped anonymous pages */
         NR_FILE_MAPPED, /* pagecache pages mapped into pagetables.
diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 135840cd7feb..05b805020be2 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -45,6 +45,10 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
                 UNEVICTABLE_PGCULLED,   /* culled to noreclaim list */
                 UNEVICTABLE_PGSCANNED,  /* scanned for reclaimability */
                 UNEVICTABLE_PGRESCUED,  /* rescued from noreclaim list */
+                UNEVICTABLE_PGMLOCKED,
+                UNEVICTABLE_PGMUNLOCKED,
+                UNEVICTABLE_PGCLEARED,  /* on COW, page truncate */
+                UNEVICTABLE_PGSTRANDED, /* unable to isolate on unlock */
 #endif
                 NR_VM_EVENT_ITEMS
 };
diff --git a/mm/internal.h b/mm/internal.h
index 48e32f790571..1cfbf2e2bc9e 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -101,7 +101,10 @@ static inline int is_mlocked_vma(struct vm_area_struct *vma, struct page *page)
         if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
                 return 0;
 
-        SetPageMlocked(page);
+        if (!TestSetPageMlocked(page)) {
+                inc_zone_page_state(page, NR_MLOCK);
+                count_vm_event(UNEVICTABLE_PGMLOCKED);
+        }
         return 1;
 }
 
@@ -128,12 +131,19 @@ static inline void clear_page_mlock(struct page *page)
 
 /*
  * mlock_migrate_page - called only from migrate_page_copy() to
- * migrate the Mlocked page flag
+ * migrate the Mlocked page flag; update statistics.
  */
 static inline void mlock_migrate_page(struct page *newpage, struct page *page)
 {
-        if (TestClearPageMlocked(page))
+        if (TestClearPageMlocked(page)) {
+                unsigned long flags;
+
+                local_irq_save(flags);
+                __dec_zone_page_state(page, NR_MLOCK);
                 SetPageMlocked(newpage);
+                __inc_zone_page_state(newpage, NR_MLOCK);
+                local_irq_restore(flags);
+        }
 }
 
 
diff --git a/mm/mlock.c b/mm/mlock.c
index 8b478350a2a1..bce1b22c36c2 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -60,6 +60,8 @@ void __clear_page_mlock(struct page *page)
                 return;
         }
 
+        dec_zone_page_state(page, NR_MLOCK);
+        count_vm_event(UNEVICTABLE_PGCLEARED);
         if (!isolate_lru_page(page)) {
                 putback_lru_page(page);
         } else {
@@ -69,6 +71,9 @@ void __clear_page_mlock(struct page *page)
                 lru_add_drain_all();
                 if (!isolate_lru_page(page))
                         putback_lru_page(page);
+                else if (PageUnevictable(page))
+                        count_vm_event(UNEVICTABLE_PGSTRANDED);
+
         }
 }
 
@@ -80,8 +85,12 @@ void mlock_vma_page(struct page *page)
 {
         BUG_ON(!PageLocked(page));
 
-        if (!TestSetPageMlocked(page) && !isolate_lru_page(page))
-                putback_lru_page(page);
+        if (!TestSetPageMlocked(page)) {
+                inc_zone_page_state(page, NR_MLOCK);
+                count_vm_event(UNEVICTABLE_PGMLOCKED);
+                if (!isolate_lru_page(page))
+                        putback_lru_page(page);
+        }
 }
 
 /*
@@ -106,9 +115,31 @@ static void munlock_vma_page(struct page *page)
 {
         BUG_ON(!PageLocked(page));
 
-        if (TestClearPageMlocked(page) && !isolate_lru_page(page)) {
-                try_to_munlock(page);
-                putback_lru_page(page);
+        if (TestClearPageMlocked(page)) {
+                dec_zone_page_state(page, NR_MLOCK);
+                if (!isolate_lru_page(page)) {
+                        int ret = try_to_munlock(page);
+                        /*
+                         * did try_to_unlock() succeed or punt?
+                         */
+                        if (ret == SWAP_SUCCESS || ret == SWAP_AGAIN)
+                                count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+
+                        putback_lru_page(page);
+                } else {
+                        /*
+                         * We lost the race.  let try_to_unmap() deal
+                         * with it.  At least we get the page state and
+                         * mlock stats right.  However, page is still on
+                         * the noreclaim list.  We'll fix that up when
+                         * the page is eventually freed or we scan the
+                         * noreclaim list.
+                         */
+                        if (PageUnevictable(page))
+                                count_vm_event(UNEVICTABLE_PGSTRANDED);
+                        else
+                                count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+                }
         }
 }
 
diff --git a/mm/vmstat.c b/mm/vmstat.c
index 6db2f6319313..9e28abc0a0b9 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -625,6 +625,7 @@ static const char * const vmstat_text[] = {
         "nr_active_file",
 #ifdef CONFIG_UNEVICTABLE_LRU
         "nr_unevictable",
+        "nr_mlock",
 #endif
         "nr_anon_pages",
         "nr_mapped",
@@ -684,6 +685,10 @@ static const char * const vmstat_text[] = {
         "unevictable_pgs_culled",
         "unevictable_pgs_scanned",
         "unevictable_pgs_rescued",
+        "unevictable_pgs_mlocked",
+        "unevictable_pgs_munlocked",
+        "unevictable_pgs_cleared",
+        "unevictable_pgs_stranded",
 #endif
 #endif
 };