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Commit 8a38082d authored by Andy Whitcroft's avatar Andy Whitcroft Committed by Linus Torvalds
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slub: record page flag overlays explicitly 



SLUB reuses two page bits for internal purposes, it overlays PG_active and
PG_error.  This is hidden away in slub.c.  Document these overlays
explicitly in the main page-flags enum along with all the others.

Signed-off-by: default avatarAndy Whitcroft <apw@shadowen.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Tested-by: default avatarKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 0cad47cf

include/linux/page-flags.h

+7 −0
Original line number Diff line number Diff line
@@ -104,6 +104,10 @@ enum pageflags { 
	/* XEN */

	PG_pinned = PG_owner_priv_1,

	PG_savepinned = PG_dirty,



	/* SLUB */

	PG_slub_frozen = PG_active,

	PG_slub_debug = PG_error,

};



#ifndef __GENERATING_BOUNDS_H
@@ -169,6 +173,9 @@ PAGEFLAG(Reserved, reserved) __CLEARPAGEFLAG(Reserved, reserved) 
PAGEFLAG(Private, private) __CLEARPAGEFLAG(Private, private)

	__SETPAGEFLAG(Private, private)



__PAGEFLAG(SlubFrozen, slub_frozen)

__PAGEFLAG(SlubDebug, slub_debug)



/*

 * Only test-and-set exist for PG_writeback.  The unconditional operators are

 * risky: they bypass page accounting.

mm/slub.c

+17 −48
Original line number Diff line number Diff line
@@ -102,44 +102,12 @@ 
 * 			the fast path and disables lockless freelists.

 */



#define FROZEN (1 << PG_active)



#ifdef CONFIG_SLUB_DEBUG

#define SLABDEBUG (1 << PG_error)

#define SLABDEBUG 1

#else

#define SLABDEBUG 0

#endif



static inline int SlabFrozen(struct page *page)

{

	return page->flags & FROZEN;

}



static inline void SetSlabFrozen(struct page *page)

{

	page->flags |= FROZEN;

}



static inline void ClearSlabFrozen(struct page *page)

{

	page->flags &= ~FROZEN;

}



static inline int SlabDebug(struct page *page)

{

	return page->flags & SLABDEBUG;

}



static inline void SetSlabDebug(struct page *page)

{

	page->flags |= SLABDEBUG;

}



static inline void ClearSlabDebug(struct page *page)

{

	page->flags &= ~SLABDEBUG;

}



/*

 * Issues still to be resolved:

 *
@@ -971,7 +939,7 @@ static int free_debug_processing(struct kmem_cache *s, struct page *page, 
	}



	/* Special debug activities for freeing objects */

	if (!SlabFrozen(page) && !page->freelist)

	if (!PageSlubFrozen(page) && !page->freelist)

		remove_full(s, page);

	if (s->flags & SLAB_STORE_USER)

		set_track(s, object, TRACK_FREE, addr);
@@ -1157,7 +1125,7 @@ static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node) 
	page->flags |= 1 << PG_slab;

	if (s->flags & (SLAB_DEBUG_FREE | SLAB_RED_ZONE | SLAB_POISON |

			SLAB_STORE_USER | SLAB_TRACE))

		SetSlabDebug(page);

		__SetPageSlubDebug(page);



	start = page_address(page);
@@ -1184,14 +1152,14 @@ static void __free_slab(struct kmem_cache *s, struct page *page) 
	int order = compound_order(page);

	int pages = 1 << order;



	if (unlikely(SlabDebug(page))) {

	if (unlikely(SLABDEBUG && PageSlubDebug(page))) {

		void *p;



		slab_pad_check(s, page);

		for_each_object(p, s, page_address(page),

						page->objects)

			check_object(s, page, p, 0);

		ClearSlabDebug(page);

		__ClearPageSlubDebug(page);

	}



	mod_zone_page_state(page_zone(page),
@@ -1288,7 +1256,7 @@ static inline int lock_and_freeze_slab(struct kmem_cache_node *n, 
	if (slab_trylock(page)) {

		list_del(&page->lru);

		n->nr_partial--;

		SetSlabFrozen(page);

		__SetPageSlubFrozen(page);

		return 1;

	}

	return 0;
@@ -1398,7 +1366,7 @@ static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail) 
	struct kmem_cache_node *n = get_node(s, page_to_nid(page));

	struct kmem_cache_cpu *c = get_cpu_slab(s, smp_processor_id());



	ClearSlabFrozen(page);

	__ClearPageSlubFrozen(page);

	if (page->inuse) {



		if (page->freelist) {
@@ -1406,7 +1374,8 @@ static void unfreeze_slab(struct kmem_cache *s, struct page *page, int tail) 
			stat(c, tail ? DEACTIVATE_TO_TAIL : DEACTIVATE_TO_HEAD);

		} else {

			stat(c, DEACTIVATE_FULL);

			if (SlabDebug(page) && (s->flags & SLAB_STORE_USER))

			if (SLABDEBUG && PageSlubDebug(page) &&

						(s->flags & SLAB_STORE_USER))

				add_full(n, page);

		}

		slab_unlock(page);
@@ -1551,7 +1520,7 @@ static void *__slab_alloc(struct kmem_cache *s, 
	object = c->page->freelist;

	if (unlikely(!object))

		goto another_slab;

	if (unlikely(SlabDebug(c->page)))

	if (unlikely(SLABDEBUG && PageSlubDebug(c->page)))

		goto debug;



	c->freelist = object[c->offset];
@@ -1588,7 +1557,7 @@ static void *__slab_alloc(struct kmem_cache *s, 
		if (c->page)

			flush_slab(s, c);

		slab_lock(new);

		SetSlabFrozen(new);

		__SetPageSlubFrozen(new);

		c->page = new;

		goto load_freelist;

	}
@@ -1674,7 +1643,7 @@ static void __slab_free(struct kmem_cache *s, struct page *page, 
	stat(c, FREE_SLOWPATH);

	slab_lock(page);



	if (unlikely(SlabDebug(page)))

	if (unlikely(SLABDEBUG && PageSlubDebug(page)))

		goto debug;



checks_ok:
@@ -1682,7 +1651,7 @@ static void __slab_free(struct kmem_cache *s, struct page *page, 
	page->freelist = object;

	page->inuse--;



	if (unlikely(SlabFrozen(page))) {

	if (unlikely(PageSlubFrozen(page))) {

		stat(c, FREE_FROZEN);

		goto out_unlock;

	}
@@ -3317,12 +3286,12 @@ static void validate_slab_slab(struct kmem_cache *s, struct page *page, 
			s->name, page);



	if (s->flags & DEBUG_DEFAULT_FLAGS) {

		if (!SlabDebug(page))

			printk(KERN_ERR "SLUB %s: SlabDebug not set "

		if (!PageSlubDebug(page))

			printk(KERN_ERR "SLUB %s: SlubDebug not set "

				"on slab 0x%p\n", s->name, page);

	} else {

		if (SlabDebug(page))

			printk(KERN_ERR "SLUB %s: SlabDebug set on "

		if (PageSlubDebug(page))

			printk(KERN_ERR "SLUB %s: SlubDebug set on "

				"slab 0x%p\n", s->name, page);

	}

}