Commit 451ea25d authored by Johannes Weiner's avatar Johannes Weiner Committed by Linus Torvalds

mm: perform non-atomic test-clear of PG_mlocked on free

By the time PG_mlocked is cleared in the page freeing path, nobody else is
looking at our page->flags anymore.

It is thus safe to make the test-and-clear non-atomic and thereby removing
an unnecessary and expensive operation from a hotpath.
Signed-off-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Reviewed-by: default avatarChristoph Lameter <cl@linux-foundation.org>
Reviewed-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bf88c8c8
......@@ -158,6 +158,9 @@ static inline int TestSetPage##uname(struct page *page) \
static inline int TestClearPage##uname(struct page *page) \
{ return test_and_clear_bit(PG_##lname, &page->flags); }
#define __TESTCLEARFLAG(uname, lname) \
static inline int __TestClearPage##uname(struct page *page) \
{ return __test_and_clear_bit(PG_##lname, &page->flags); }
#define PAGEFLAG(uname, lname) TESTPAGEFLAG(uname, lname) \
SETPAGEFLAG(uname, lname) CLEARPAGEFLAG(uname, lname)
......@@ -184,6 +187,9 @@ static inline void __ClearPage##uname(struct page *page) { }
#define TESTCLEARFLAG_FALSE(uname) \
static inline int TestClearPage##uname(struct page *page) { return 0; }
#define __TESTCLEARFLAG_FALSE(uname) \
static inline int __TestClearPage##uname(struct page *page) { return 0; }
struct page; /* forward declaration */
TESTPAGEFLAG(Locked, locked) TESTSETFLAG(Locked, locked)
......@@ -250,11 +256,11 @@ PAGEFLAG(Unevictable, unevictable) __CLEARPAGEFLAG(Unevictable, unevictable)
#ifdef CONFIG_HAVE_MLOCKED_PAGE_BIT
#define MLOCK_PAGES 1
PAGEFLAG(Mlocked, mlocked) __CLEARPAGEFLAG(Mlocked, mlocked)
TESTSCFLAG(Mlocked, mlocked)
TESTSCFLAG(Mlocked, mlocked) __TESTCLEARFLAG(Mlocked, mlocked)
#else
#define MLOCK_PAGES 0
PAGEFLAG_FALSE(Mlocked)
SETPAGEFLAG_NOOP(Mlocked) TESTCLEARFLAG_FALSE(Mlocked)
PAGEFLAG_FALSE(Mlocked) SETPAGEFLAG_NOOP(Mlocked)
TESTCLEARFLAG_FALSE(Mlocked) __TESTCLEARFLAG_FALSE(Mlocked)
#endif
#ifdef CONFIG_ARCH_USES_PG_UNCACHED
......
......@@ -557,7 +557,7 @@ static void __free_pages_ok(struct page *page, unsigned int order)
unsigned long flags;
int i;
int bad = 0;
int wasMlocked = TestClearPageMlocked(page);
int wasMlocked = __TestClearPageMlocked(page);
kmemcheck_free_shadow(page, order);
......@@ -1026,7 +1026,7 @@ static void free_hot_cold_page(struct page *page, int cold)
struct zone *zone = page_zone(page);
struct per_cpu_pages *pcp;
unsigned long flags;
int wasMlocked = TestClearPageMlocked(page);
int wasMlocked = __TestClearPageMlocked(page);
kmemcheck_free_shadow(page, 0);
......
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