mlock: fix unevictable_pgs event counts on THP

5.8 commit 5d91f31faf8e ("mm: swap: fix vmstats for huge page") has
established that vm_events should count every subpage of a THP, including
unevictable_pgs_culled and unevictable_pgs_rescued; but
lru_cache_add_inactive_or_unevictable() was not doing so for
unevictable_pgs_mlocked, and mm/mlock.c was not doing so for
unevictable_pgs mlocked, munlocked, cleared and stranded.

Fix them; but THPs don't go the pagevec way in mlock.c, so no fixes needed
on that path.

Fixes: 5d91f31faf8e ("mm: swap: fix vmstats for huge page")
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Yang Shi <shy828301@gmail.com>
Cc: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Qian Cai <cai@lca.pw>
Link: http://lkml.kernel.org/r/alpine.LSU.2.11.2008301408230.5954@eggly.anvils
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/mm/mlock.c b/mm/mlock.c
index 93ca2bf..884b121 100644 (file)
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -58,11 +58,14 @@ EXPORT_SYMBOL(can_do_mlock);
  */
 void clear_page_mlock(struct page *page)
 {
+       int nr_pages;
+
        if (!TestClearPageMlocked(page))
                return;
 
-       mod_zone_page_state(page_zone(page), NR_MLOCK, -thp_nr_pages(page));
-       count_vm_event(UNEVICTABLE_PGCLEARED);
+       nr_pages = thp_nr_pages(page);
+       mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
+       count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages);
        /*
         * The previous TestClearPageMlocked() corresponds to the smp_mb()
         * in __pagevec_lru_add_fn().
@@ -76,7 +79,7 @@ void clear_page_mlock(struct page *page)
                 * We lost the race. the page already moved to evictable list.
                 */
                if (PageUnevictable(page))
-                       count_vm_event(UNEVICTABLE_PGSTRANDED);
+                       count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages);
        }
 }
 
@@ -93,9 +96,10 @@ void mlock_vma_page(struct page *page)
        VM_BUG_ON_PAGE(PageCompound(page) && PageDoubleMap(page), page);
 
        if (!TestSetPageMlocked(page)) {
-               mod_zone_page_state(page_zone(page), NR_MLOCK,
-                                   thp_nr_pages(page));
-               count_vm_event(UNEVICTABLE_PGMLOCKED);
+               int nr_pages = thp_nr_pages(page);
+
+               mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);
+               count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
                if (!isolate_lru_page(page))
                        putback_lru_page(page);
        }
@@ -138,7 +142,7 @@ static void __munlock_isolated_page(struct page *page)
 
        /* Did try_to_unlock() succeed or punt? */
        if (!PageMlocked(page))
-               count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+               count_vm_events(UNEVICTABLE_PGMUNLOCKED, thp_nr_pages(page));
 
        putback_lru_page(page);
 }
@@ -154,10 +158,12 @@ static void __munlock_isolated_page(struct page *page)
  */
 static void __munlock_isolation_failed(struct page *page)
 {
+       int nr_pages = thp_nr_pages(page);
+
        if (PageUnevictable(page))
-               __count_vm_event(UNEVICTABLE_PGSTRANDED);
+               __count_vm_events(UNEVICTABLE_PGSTRANDED, nr_pages);
        else
-               __count_vm_event(UNEVICTABLE_PGMUNLOCKED);
+               __count_vm_events(UNEVICTABLE_PGMUNLOCKED, nr_pages);
 }
 
 /**

diff --git a/mm/swap.c b/mm/swap.c
index d16d65d..e7bdf09 100644 (file)
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -494,14 +494,14 @@ void lru_cache_add_inactive_or_unevictable(struct page *page,
 
        unevictable = (vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED;
        if (unlikely(unevictable) && !TestSetPageMlocked(page)) {
+               int nr_pages = thp_nr_pages(page);
                /*
                 * We use the irq-unsafe __mod_zone_page_stat because this
                 * counter is not modified from interrupt context, and the pte
                 * lock is held(spinlock), which implies preemption disabled.
                 */
-               __mod_zone_page_state(page_zone(page), NR_MLOCK,
-                                   thp_nr_pages(page));
-               count_vm_event(UNEVICTABLE_PGMLOCKED);
+               __mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);
+               count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
        }
        lru_cache_add(page);
 }