mlock: count attempts to free mlocked page

985737cf · Lee Schermerhorn <[email protected]> · 2008-10-18 20:26:53 -07:00

Allow free of mlock()ed pages.  This shouldn't happen, but during
developement, it occasionally did.

This patch allows us to survive that condition, while keeping the
statistics and events correct for debug.

Signed-off-by: Lee Schermerhorn <[email protected]>
Signed-off-by: Rik van Riel <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Commit: 985737cf2ea096ea946aed82c7484d40defc71a8
Parents: af936a16

Changes

4 files changed · +20 −0

File	Status	Add	Del	Content
include/linux/vmstat.h	modified	+1	−0	View file
mm/internal.h	modified	+17	−0	View file
mm/page_alloc.c	modified	+1	−0	View file
mm/vmstat.c	modified	+1	−0	View file

include/linux/vmstat.h

View file

diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h
index 05b8050..9cd3ab0 100644
--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -49,6 +49,7 @@ 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,
 #endif
 		NR_VM_EVENT_ITEMS
 };

mm/internal.h

View file

diff --git a/mm/internal.h b/mm/internal.h
index 1cfbf2e..e4e728b 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -146,6 +146,22 @@ static inline void mlock_migrate_page(struct page *newpage, struct page *page)
 	}
 }
 
+/*
+ * 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)
+{
+	if (unlikely(TestClearPageMlocked(page))) {
+		unsigned long flags;
+
+		local_irq_save(flags);
+		__dec_zone_page_state(page, NR_MLOCK);
+		__count_vm_event(UNEVICTABLE_MLOCKFREED);
+		local_irq_restore(flags);
+	}
+}
 
 #else /* CONFIG_UNEVICTABLE_LRU */
 static inline int is_mlocked_vma(struct vm_area_struct *v, struct page *p)
@@ -155,6 +171,7 @@ static inline int is_mlocked_vma(struct vm_area_struct *v, struct page *p)
 static inline void clear_page_mlock(struct page *page) { }
 static inline void mlock_vma_page(struct page *page) { }
 static inline void mlock_migrate_page(struct page *new, struct page *old) { }
+static inline void free_page_mlock(struct page *page) { }
 
 #endif /* CONFIG_UNEVICTABLE_LRU */
 

mm/page_alloc.c

View file

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 5886586..cfbadad 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -454,6 +454,7 @@ static inline void __free_one_page(struct page *page,
 
 static inline int free_pages_check(struct page *page)
 {
+	free_page_mlock(page);
 	if (unlikely(page_mapcount(page) |
 		(page->mapping != NULL)  |
 		(page_get_page_cgroup(page) != NULL) |

mm/vmstat.c

View file

diff --git a/mm/vmstat.c b/mm/vmstat.c
index 9e28abc..9343227 100644
--- a/mm/vmstat.c
+++ b/mm/vmstat.c
@@ -689,6 +689,7 @@ static const char * const vmstat_text[] = {
 	"unevictable_pgs_munlocked",
 	"unevictable_pgs_cleared",
 	"unevictable_pgs_stranded",
+	"unevictable_pgs_mlockfreed",
 #endif
 #endif
 };