mm: remove free_page_mlock

We should not be seeing non-0 unevictable_pgs_mlockfreed any longer.  So
remove free_page_mlock() from the page freeing paths: __PG_MLOCKED is
already in PAGE_FLAGS_CHECK_AT_FREE, so free_pages_check() will now be
checking it, reporting "BUG: Bad page state" if it's ever found set.
Comment UNEVICTABLE_MLOCKFREED and unevictable_pgs_mlockfreed always 0.

Signed-off-by: Hugh Dickins <hughd@google.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Cc: Rik van Riel <riel@redhat.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michel Lespinasse <walken@google.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/include/linux/vm_event_item.h b/include/linux/vm_event_item.h
index 57f7b10..ede4ddd 100644 (file)
--- a/include/linux/vm_event_item.h
+++ b/include/linux/vm_event_item.h
@@ -52,7 +52,7 @@ enum vm_event_item { PGPGIN, PGPGOUT, PSWPIN, PSWPOUT,
                UNEVICTABLE_PGMUNLOCKED,
                UNEVICTABLE_PGCLEARED,  /* on COW, page truncate */
                UNEVICTABLE_PGSTRANDED, /* unable to isolate on unlock */
-               UNEVICTABLE_MLOCKFREED,
+               UNEVICTABLE_MLOCKFREED, /* no longer useful: always zero */
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
                THP_FAULT_ALLOC,
                THP_FAULT_FALLBACK,

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 00750bc..dbb5386 100644 (file)
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -598,17 +598,6 @@ out:
        zone->free_area[order].nr_free++;
 }
 
-/*
- * free_page_mlock() -- clean up attempts to free and mlocked() page.
- * Page should not be on lru, so no need to fix that up.
- * free_pages_check() will verify...
- */
-static inline void free_page_mlock(struct page *page)
-{
-       __dec_zone_page_state(page, NR_MLOCK);
-       __count_vm_event(UNEVICTABLE_MLOCKFREED);
-}
-
 static inline int free_pages_check(struct page *page)
 {
        if (unlikely(page_mapcount(page) |
@@ -728,15 +717,12 @@ static bool free_pages_prepare(struct page *page, unsigned int order)
 static void __free_pages_ok(struct page *page, unsigned int order)
 {
        unsigned long flags;
-       int wasMlocked = __TestClearPageMlocked(page);
        int migratetype;
 
        if (!free_pages_prepare(page, order))
                return;
 
        local_irq_save(flags);
-       if (unlikely(wasMlocked))
-               free_page_mlock(page);
        __count_vm_events(PGFREE, 1 << order);
        migratetype = get_pageblock_migratetype(page);
        set_freepage_migratetype(page, migratetype);
@@ -1310,7 +1296,6 @@ void free_hot_cold_page(struct page *page, int cold)
        struct per_cpu_pages *pcp;
        unsigned long flags;
        int migratetype;
-       int wasMlocked = __TestClearPageMlocked(page);
 
        if (!free_pages_prepare(page, 0))
                return;
@@ -1318,8 +1303,6 @@ void free_hot_cold_page(struct page *page, int cold)
        migratetype = get_pageblock_migratetype(page);
        set_freepage_migratetype(page, migratetype);
        local_irq_save(flags);
-       if (unlikely(wasMlocked))
-               free_page_mlock(page);
        __count_vm_event(PGFREE);
 
        /*

diff --git a/mm/vmstat.c b/mm/vmstat.c
index acbd85c..05e3a99 100644 (file)
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -782,7 +782,7 @@ const char * const vmstat_text[] = {
        "unevictable_pgs_munlocked",
        "unevictable_pgs_cleared",
        "unevictable_pgs_stranded",
-       "unevictable_pgs_mlockfreed",
+       "unevictable_pgs_mlockfreed",   /* no longer useful: always zero */
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
        "thp_fault_alloc",