vmstat: mlocked pages statistics

Add NR_MLOCK zone page state, which provides a (conservative) count of
mlocked pages (actually, the number of mlocked pages moved off the LRU).

Reworked by lts to fit in with the modified mlock page support in the
Reclaim Scalability series.

[kosaki.motohiro@jp.fujitsu.com: fix incorrect Mlocked field of /proc/meminfo]
[lee.schermerhorn@hp.com: mlocked-pages: add event counting with statistics]
Signed-off-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/drivers/base/node.c b/drivers/base/node.c
index 11a9a05cf5540f11105db223f6a318bdc1e0ca2d..fb45d88a24464f8e3b2340e0b675a75785b20fc4 100644 (file)
--- 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 6dd60eaea9976527675134fabe95d0f3a59feb53..61b25f4eabe6635bdf013e4879dd8e725f10f01d 100644 (file)
--- 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 d1f60d5fe2eab1e06ed09386f7ae4e8104e97013..da2d053a95f10612a1ce252584acfed9d604f3ce 100644 (file)
--- 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 135840cd7feb0e8df67edb7c01ca754adb83fa3f..05b805020be2b63e801861e3f7ad476d6f8b79f7 100644 (file)
--- 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 48e32f790571f8868e69771e2c91c8c2fd3a34ae..1cfbf2e2bc9e57e85776f19f1578edf8a70044b1 100644 (file)
--- 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 8b478350a2a1528487ea60113db54b5e6976a4cb..bce1b22c36c246a8db5f5493acc2c85de21630e9 100644 (file)
--- 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 6db2f6319313d4ab59a771b0e5b663eaf22e30a6..9e28abc0a0b905c7926325df01722a6d1c2ae4fa 100644 (file)
--- 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
 };