mm, thp: fix mlock statistics
David Rientjes [Mon, 8 Oct 2012 23:34:06 +0000 (16:34 -0700)]
NR_MLOCK is only accounted in single page units: there's no logic to
handle transparent hugepages.  This patch checks the appropriate number of
pages to adjust the statistics by so that the correct amount of memory is
reflected.

Currently:

$ grep Mlocked /proc/meminfo
Mlocked:           19636 kB

#define MAP_SIZE (4 << 30) /* 4GB */

void *ptr = mmap(NULL, MAP_SIZE, PROT_READ | PROT_WRITE,
 MAP_PRIVATE | MAP_ANONYMOUS, 0, 0);
mlock(ptr, MAP_SIZE);

$ grep Mlocked /proc/meminfo
Mlocked:           29844 kB

munlock(ptr, MAP_SIZE);

$ grep Mlocked /proc/meminfo
Mlocked:           19636 kB

And with this patch:

$ grep Mlock /proc/meminfo
Mlocked:           19636 kB

mlock(ptr, MAP_SIZE);

$ grep Mlock /proc/meminfo
Mlocked:         4213664 kB

munlock(ptr, MAP_SIZE);

$ grep Mlock /proc/meminfo
Mlocked:           19636 kB

Signed-off-by: David Rientjes <rientjes@google.com>
Reported-by: Hugh Dickens <hughd@google.com>
Acked-by: Hugh Dickins <hughd@google.com>
Reviewed-by: Andrea Arcangeli <aarcange@redhat.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Michel Lespinasse <walken@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/internal.h
mm/mlock.c

index f5f295f..a4fa284 100644 (file)
@@ -180,7 +180,8 @@ static inline int mlocked_vma_newpage(struct vm_area_struct *vma,
                return 0;
 
        if (!TestSetPageMlocked(page)) {
-               inc_zone_page_state(page, NR_MLOCK);
+               mod_zone_page_state(page_zone(page), NR_MLOCK,
+                                   hpage_nr_pages(page));
                count_vm_event(UNEVICTABLE_PGMLOCKED);
        }
        return 1;
index de73215..f0b9ce5 100644 (file)
@@ -56,7 +56,8 @@ void clear_page_mlock(struct page *page)
        if (!TestClearPageMlocked(page))
                return;
 
-       dec_zone_page_state(page, NR_MLOCK);
+       mod_zone_page_state(page_zone(page), NR_MLOCK,
+                           -hpage_nr_pages(page));
        count_vm_event(UNEVICTABLE_PGCLEARED);
        if (!isolate_lru_page(page)) {
                putback_lru_page(page);
@@ -78,7 +79,8 @@ void mlock_vma_page(struct page *page)
        BUG_ON(!PageLocked(page));
 
        if (!TestSetPageMlocked(page)) {
-               inc_zone_page_state(page, NR_MLOCK);
+               mod_zone_page_state(page_zone(page), NR_MLOCK,
+                                   hpage_nr_pages(page));
                count_vm_event(UNEVICTABLE_PGMLOCKED);
                if (!isolate_lru_page(page))
                        putback_lru_page(page);
@@ -105,7 +107,8 @@ void munlock_vma_page(struct page *page)
        BUG_ON(!PageLocked(page));
 
        if (TestClearPageMlocked(page)) {
-               dec_zone_page_state(page, NR_MLOCK);
+               mod_zone_page_state(page_zone(page), NR_MLOCK,
+                                   -hpage_nr_pages(page));
                if (!isolate_lru_page(page)) {
                        int ret = SWAP_AGAIN;