[RFC] Common code 00/12] Sl[auo]b: Common functionality V2

[RFC] Common code 00/12] Sl[auo]b: Common functionality V2

[Christoph Lameter]

V1->V2:
- Incorporate glommers feedback.
- Add 2 more patches dealing with common code in kmem_cache_destroy

This is a series of patches that extracts common functionality from
slab allocators into a common code base. The intend is to standardize
as much as possible of the allocator behavior while keeping the
distinctive features of each allocator which are mostly due to their
storage format and serialization approaches.

This patchset makes a beginning by extracting common functionality in
kmem_cache_create() and kmem_cache_destroy(). However, there are
numerous other areas where such work could be beneficial:

1. Extract the sysfs support from SLUB and make it common. That way
   all allocators have a common sysfs API and are handleable in the same
   way regardless of the allocator chose.

2. Extract the error reporting and checking from SLUB and make
   it available for all allocators. This means that all allocators
   will gain the resiliency and error handling capabilties.

3. Extract the memory hotplug and cpu hotplug handling. It seems that
   SLAB may be more sophisticated here. Having common code here will
   make it easier to maintain the special code.

4. Extract the aliasing capability of SLUB. This will enable fast
   slab creation without creating too many additional slab caches.
   The arrays of caches of varying sizes in numerous subsystems
   do not cause the creation of numerous slab caches. Storage
   density is increased and the cache footprint is reduced.

Ultimately it is to be hoped that the special code for each allocator
shrinks to a mininum. This will also make it easier to make modification
to allocators.

In the far future one could envision that the current allocators will
just become storage algorithms that can be chosen based on the need of
the subsystem. F.e.

Cpu cache dependend performance		= Bonwick allocator (SLAB)
Minimal cycle count and cache footprint	= SLUB
Maximum storage density			= K&R allocator (SLOB)

But that could be controversial and inefficient if indirect calls are needed.

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[RFC] Common code 01/12] [slob] define page struct fields used in mm_types.h

[Christoph Lameter]

[-- Attachment #1: slob_use_page_struct --]
[-- Type: text/plain, Size: 8759 bytes --]

Define the fields used by slob in mm_types.h and use struct page instead
of struct slob_page in slob. This cleans up numerous of typecasts in slob.c and
makes readers aware of slob's use of page struct fields.

[Also cleans up some bitrot in slob.c. The page struct field layout
in slob.c is an old layout and does not match the one in mm_types.h]

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 include/linux/mm_types.h |    6 +-
 mm/slob.c                |   95 ++++++++++++++++++-----------------------------
 2 files changed, 41 insertions(+), 60 deletions(-)

Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2012-05-16 04:38:50.139864464 -0500
+++ linux-2.6/mm/slob.c	2012-05-17 03:28:03.630162187 -0500
@@ -92,33 +92,12 @@ struct slob_block {
 typedef struct slob_block slob_t;
 
 /*
- * We use struct page fields to manage some slob allocation aspects,
- * however to avoid the horrible mess in include/linux/mm_types.h, we'll
- * just define our own struct page type variant here.
- */
-struct slob_page {
-	union {
-		struct {
-			unsigned long flags;	/* mandatory */
-			atomic_t _count;	/* mandatory */
-			slobidx_t units;	/* free units left in page */
-			unsigned long pad[2];
-			slob_t *free;		/* first free slob_t in page */
-			struct list_head list;	/* linked list of free pages */
-		};
-		struct page page;
-	};
-};
-static inline void struct_slob_page_wrong_size(void)
-{ BUILD_BUG_ON(sizeof(struct slob_page) != sizeof(struct page)); }
-
-/*
  * free_slob_page: call before a slob_page is returned to the page allocator.
  */
-static inline void free_slob_page(struct slob_page *sp)
+static inline void free_slob_page(struct page *sp)
 {
-	reset_page_mapcount(&sp->page);
-	sp->page.mapping = NULL;
+	reset_page_mapcount(sp);
+	sp->mapping = NULL;
 }
 
 /*
@@ -133,44 +112,44 @@ static LIST_HEAD(free_slob_large);
 /*
  * is_slob_page: True for all slob pages (false for bigblock pages)
  */
-static inline int is_slob_page(struct slob_page *sp)
+static inline int is_slob_page(struct page *sp)
 {
-	return PageSlab((struct page *)sp);
+	return PageSlab(sp);
 }
 
-static inline void set_slob_page(struct slob_page *sp)
+static inline void set_slob_page(struct page *sp)
 {
-	__SetPageSlab((struct page *)sp);
+	__SetPageSlab(sp);
 }
 
-static inline void clear_slob_page(struct slob_page *sp)
+static inline void clear_slob_page(struct page *sp)
 {
-	__ClearPageSlab((struct page *)sp);
+	__ClearPageSlab(sp);
 }
 
-static inline struct slob_page *slob_page(const void *addr)
+static inline struct page *slob_page(const void *addr)
 {
-	return (struct slob_page *)virt_to_page(addr);
+	return virt_to_page(addr);
 }
 
 /*
  * slob_page_free: true for pages on free_slob_pages list.
  */
-static inline int slob_page_free(struct slob_page *sp)
+static inline int slob_page_free(struct page *sp)
 {
-	return PageSlobFree((struct page *)sp);
+	return PageSlobFree(sp);
 }
 
-static void set_slob_page_free(struct slob_page *sp, struct list_head *list)
+static void set_slob_page_free(struct page *sp, struct list_head *list)
 {
 	list_add(&sp->list, list);
-	__SetPageSlobFree((struct page *)sp);
+	__SetPageSlobFree(sp);
 }
 
-static inline void clear_slob_page_free(struct slob_page *sp)
+static inline void clear_slob_page_free(struct page *sp)
 {
 	list_del(&sp->list);
-	__ClearPageSlobFree((struct page *)sp);
+	__ClearPageSlobFree(sp);
 }
 
 #define SLOB_UNIT sizeof(slob_t)
@@ -267,12 +246,12 @@ static void slob_free_pages(void *b, int
 /*
  * Allocate a slob block within a given slob_page sp.
  */
-static void *slob_page_alloc(struct slob_page *sp, size_t size, int align)
+static void *slob_page_alloc(struct page *sp, size_t size, int align)
 {
 	slob_t *prev, *cur, *aligned = NULL;
 	int delta = 0, units = SLOB_UNITS(size);
 
-	for (prev = NULL, cur = sp->free; ; prev = cur, cur = slob_next(cur)) {
+	for (prev = NULL, cur = sp->freelist; ; prev = cur, cur = slob_next(cur)) {
 		slobidx_t avail = slob_units(cur);
 
 		if (align) {
@@ -296,12 +275,12 @@ static void *slob_page_alloc(struct slob
 				if (prev)
 					set_slob(prev, slob_units(prev), next);
 				else
-					sp->free = next;
+					sp->freelist = next;
 			} else { /* fragment */
 				if (prev)
 					set_slob(prev, slob_units(prev), cur + units);
 				else
-					sp->free = cur + units;
+					sp->freelist = cur + units;
 				set_slob(cur + units, avail - units, next);
 			}
 
@@ -320,7 +299,7 @@ static void *slob_page_alloc(struct slob
  */
 static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
 {
-	struct slob_page *sp;
+	struct page *sp;
 	struct list_head *prev;
 	struct list_head *slob_list;
 	slob_t *b = NULL;
@@ -341,7 +320,7 @@ static void *slob_alloc(size_t size, gfp
 		 * If there's a node specification, search for a partial
 		 * page with a matching node id in the freelist.
 		 */
-		if (node != -1 && page_to_nid(&sp->page) != node)
+		if (node != -1 && page_to_nid(sp) != node)
 			continue;
 #endif
 		/* Enough room on this page? */
@@ -374,7 +353,7 @@ static void *slob_alloc(size_t size, gfp
 
 		spin_lock_irqsave(&slob_lock, flags);
 		sp->units = SLOB_UNITS(PAGE_SIZE);
-		sp->free = b;
+		sp->freelist = b;
 		INIT_LIST_HEAD(&sp->list);
 		set_slob(b, SLOB_UNITS(PAGE_SIZE), b + SLOB_UNITS(PAGE_SIZE));
 		set_slob_page_free(sp, slob_list);
@@ -392,7 +371,7 @@ static void *slob_alloc(size_t size, gfp
  */
 static void slob_free(void *block, int size)
 {
-	struct slob_page *sp;
+	struct page *sp;
 	slob_t *prev, *next, *b = (slob_t *)block;
 	slobidx_t units;
 	unsigned long flags;
@@ -421,7 +400,7 @@ static void slob_free(void *block, int s
 	if (!slob_page_free(sp)) {
 		/* This slob page is about to become partially free. Easy! */
 		sp->units = units;
-		sp->free = b;
+		sp->freelist = b;
 		set_slob(b, units,
 			(void *)((unsigned long)(b +
 					SLOB_UNITS(PAGE_SIZE)) & PAGE_MASK));
@@ -441,15 +420,15 @@ static void slob_free(void *block, int s
 	 */
 	sp->units += units;
 
-	if (b < sp->free) {
-		if (b + units == sp->free) {
-			units += slob_units(sp->free);
-			sp->free = slob_next(sp->free);
+	if (b < (slob_t *)sp->freelist) {
+		if (b + units == sp->freelist) {
+			units += slob_units(sp->freelist);
+			sp->freelist = slob_next(sp->freelist);
 		}
-		set_slob(b, units, sp->free);
-		sp->free = b;
+		set_slob(b, units, sp->freelist);
+		sp->freelist = b;
 	} else {
-		prev = sp->free;
+		prev = sp->freelist;
 		next = slob_next(prev);
 		while (b > next) {
 			prev = next;
@@ -522,7 +501,7 @@ EXPORT_SYMBOL(__kmalloc_node);
 
 void kfree(const void *block)
 {
-	struct slob_page *sp;
+	struct page *sp;
 
 	trace_kfree(_RET_IP_, block);
 
@@ -536,14 +515,14 @@ void kfree(const void *block)
 		unsigned int *m = (unsigned int *)(block - align);
 		slob_free(m, *m + align);
 	} else
-		put_page(&sp->page);
+		put_page(sp);
 }
 EXPORT_SYMBOL(kfree);
 
 /* can't use ksize for kmem_cache_alloc memory, only kmalloc */
 size_t ksize(const void *block)
 {
-	struct slob_page *sp;
+	struct page *sp;
 
 	BUG_ON(!block);
 	if (unlikely(block == ZERO_SIZE_PTR))
@@ -555,7 +534,7 @@ size_t ksize(const void *block)
 		unsigned int *m = (unsigned int *)(block - align);
 		return SLOB_UNITS(*m) * SLOB_UNIT;
 	} else
-		return sp->page.private;
+		return sp->private;
 }
 EXPORT_SYMBOL(ksize);
 
Index: linux-2.6/include/linux/mm_types.h
===================================================================
--- linux-2.6.orig/include/linux/mm_types.h	2012-05-16 04:38:50.131864458 -0500
+++ linux-2.6/include/linux/mm_types.h	2012-05-17 03:28:03.630162187 -0500
@@ -52,7 +52,7 @@ struct page {
 	struct {
 		union {
 			pgoff_t index;		/* Our offset within mapping. */
-			void *freelist;		/* slub first free object */
+			void *freelist;		/* slub/slob first free object */
 		};
 
 		union {
@@ -80,11 +80,12 @@ struct page {
 					 */
 					atomic_t _mapcount;
 
-					struct {
+					struct { /* SLUB */
 						unsigned inuse:16;
 						unsigned objects:15;
 						unsigned frozen:1;
 					};
+					int units;	/* SLOB */
 				};
 				atomic_t _count;		/* Usage count, see below. */
 			};
@@ -96,6 +97,7 @@ struct page {
 		struct list_head lru;	/* Pageout list, eg. active_list
 					 * protected by zone->lru_lock !
 					 */
+		struct list_head list;	/* slobs list of pages */
 		struct {		/* slub per cpu partial pages */
 			struct page *next;	/* Next partial slab */
 #ifdef CONFIG_64BIT

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Re: [RFC] Common code 01/12] [slob] define page struct fields used in mm_types.h

[Glauber Costa]

On 05/18/2012 08:19 PM, Christoph Lameter wrote:
> Define the fields used by slob in mm_types.h and use struct page instead
> of struct slob_page in slob. This cleans up numerous of typecasts in slob.c and
> makes readers aware of slob's use of page struct fields.
>
> [Also cleans up some bitrot in slob.c. The page struct field layout
> in slob.c is an old layout and does not match the one in mm_types.h]
>
> Signed-off-by: Christoph Lameter<cl@linux.com>

Reviewed by: Glauber Costa <glommer@parallels.com>

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Re: [RFC] Common code 01/12] [slob] define page struct fields used in mm_types.h

[JoonSoo Kim]

2012/5/19 Christoph Lameter <cl@linux.com>:

> -/*
>  * free_slob_page: call before a slob_page is returned to the page allocator.
>  */
> -static inline void free_slob_page(struct slob_page *sp)
> +static inline void free_slob_page(struct page *sp)
>  {
> -       reset_page_mapcount(&sp->page);
> -       sp->page.mapping = NULL;
> +       reset_page_mapcount(sp);
> +       sp->mapping = NULL;
>  }

Currently, sp->mapping = NULL is useless, because Slob doesn't touch
this field anymore.

>  /*
> @@ -133,44 +112,44 @@ static LIST_HEAD(free_slob_large);
>  /*
>  * is_slob_page: True for all slob pages (false for bigblock pages)
>  */
> -static inline int is_slob_page(struct slob_page *sp)
> +static inline int is_slob_page(struct page *sp)
>  {
> -       return PageSlab((struct page *)sp);
> +       return PageSlab(sp);
>  }
>
> -static inline void set_slob_page(struct slob_page *sp)
> +static inline void set_slob_page(struct page *sp)
>  {
> -       __SetPageSlab((struct page *)sp);
> +       __SetPageSlab(sp);
>  }
>
> -static inline void clear_slob_page(struct slob_page *sp)
> +static inline void clear_slob_page(struct page *sp)
>  {
> -       __ClearPageSlab((struct page *)sp);
> +       __ClearPageSlab(sp);
>  }

Now, type casting is useless, so using __SetPageSlab() is possible.
If we use __SetPageSlab() directly, we lose some readability.
Which one is preferable?

> -static inline struct slob_page *slob_page(const void *addr)
> +static inline struct page *slob_page(const void *addr)
>  {
> -       return (struct slob_page *)virt_to_page(addr);
> +       return virt_to_page(addr);
>  }

It is redundant, just using virt_to_page(addr) directly is more preferable

>  /*
>  * slob_page_free: true for pages on free_slob_pages list.
>  */
> -static inline int slob_page_free(struct slob_page *sp)
> +static inline int slob_page_free(struct page *sp)
>  {
> -       return PageSlobFree((struct page *)sp);
> +       return PageSlobFree(sp);
>  }
>
> -static void set_slob_page_free(struct slob_page *sp, struct list_head *list)
> +static void set_slob_page_free(struct page *sp, struct list_head *list)
>  {
>        list_add(&sp->list, list);
> -       __SetPageSlobFree((struct page *)sp);
> +       __SetPageSlobFree(sp);
>  }
>
> -static inline void clear_slob_page_free(struct slob_page *sp)
> +static inline void clear_slob_page_free(struct page *sp)
>  {
>        list_del(&sp->list);
> -       __ClearPageSlobFree((struct page *)sp);
> +       __ClearPageSlobFree(sp);
>  }

I think we shouldn't use __ClearPageSlobFree anymore.
Before this patch, list_del affect page->private,
so when we manipulate slob list,
using PageSlobFree overloaded with PagePrivate is reasonable.
But, after this patch is applied, list_del doesn't touch page->private,
so manipulate PageSlobFree is not reasonable.
We would use another method for checking slob_page_free without
PageSlobFree flag.

> Index: linux-2.6/include/linux/mm_types.h
> ===================================================================
> --- linux-2.6.orig/include/linux/mm_types.h     2012-05-16 04:38:50.131864458 -0500
> +++ linux-2.6/include/linux/mm_types.h  2012-05-17 03:28:03.630162187 -0500
> @@ -52,7 +52,7 @@ struct page {
>        struct {
>                union {
>                        pgoff_t index;          /* Our offset within mapping. */
> -                       void *freelist;         /* slub first free object */
> +                       void *freelist;         /* slub/slob first free object */
>                };
>
>                union {
> @@ -80,11 +80,12 @@ struct page {
>                                         */
>                                        atomic_t _mapcount;
>
> -                                       struct {
> +                                       struct { /* SLUB */
>                                                unsigned inuse:16;
>                                                unsigned objects:15;
>                                                unsigned frozen:1;
>                                        };
> +                                       int units;      /* SLOB */
>                                };
>                                atomic_t _count;                /* Usage count, see below. */
>                        };
> @@ -96,6 +97,7 @@ struct page {
>                struct list_head lru;   /* Pageout list, eg. active_list
>                                         * protected by zone->lru_lock !
>                                         */
> +               struct list_head list;  /* slobs list of pages */
>                struct {                /* slub per cpu partial pages */
>                        struct page *next;      /* Next partial slab */
>  #ifdef CONFIG_64BIT
>

When we define field in mm_types.h for slauob,
sorted order between these is good for readability.
For example, in case of lru, list for slob is first,
but in case of _mapcount, field for slub is first.
Consistent ordering is more preferable I think.

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Re: [RFC] Common code 01/12] [slob] define page struct fields used in mm_types.h

[Christoph Lameter]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1748 bytes --]

On Tue, 22 May 2012, JoonSoo Kim wrote:

> 2012/5/19 Christoph Lameter <cl@linux.com>:
>
> > -/*
> >  * free_slob_page: call before a slob_page is returned to the page allocator.
> >  */
> > -static inline void free_slob_page(struct slob_page *sp)
> > +static inline void free_slob_page(struct page *sp)
> >  {
> > -       reset_page_mapcount(&sp->page);
> > -       sp->page.mapping = NULL;
> > +       reset_page_mapcount(sp);
> > +       sp->mapping = NULL;
> >  }
>
> Currently, sp->mapping = NULL is useless, because Slob doesn't touch
> this field anymore.

Ok. Adding another patch that does this.

> It is redundant, just using virt_to_page(addr) directly is more preferable

Ok adding another patch that avoids the accessors.

> > +static inline void clear_slob_page_free(struct page *sp)
> >  {
> >        list_del(&sp->list);
> > -       __ClearPageSlobFree((struct page *)sp);
> > +       __ClearPageSlobFree(sp);
> >  }
>
> I think we shouldn't use __ClearPageSlobFree anymore.
> Before this patch, list_del affect page->private,
> so when we manipulate slob list,
> using PageSlobFree overloaded with PagePrivate is reasonable.
> But, after this patch is applied, list_del doesn't touch page->private,
> so manipulate PageSlobFree is not reasonable.
> We would use another method for checking slob_page_free without
> PageSlobFree flag.

What method should we be using?

> When we define field in mm_types.h for slauob,
> sorted order between these is good for readability.
> For example, in case of lru, list for slob is first,
> but in case of _mapcount, field for slub is first.
> Consistent ordering is more preferable I think.

Ok. Reordered for next patchset (probably Friday).

Re: [RFC] Common code 01/12] [slob] define page struct fields used in mm_types.h

[JoonSoo Kim]

>> > +static inline void clear_slob_page_free(struct page *sp)
>> >  {
>> >        list_del(&sp->list);
>> > -       __ClearPageSlobFree((struct page *)sp);
>> > +       __ClearPageSlobFree(sp);
>> >  }
>>
>> I think we shouldn't use __ClearPageSlobFree anymore.
>> Before this patch, list_del affect page->private,
>> so when we manipulate slob list,
>> using PageSlobFree overloaded with PagePrivate is reasonable.
>> But, after this patch is applied, list_del doesn't touch page->private,
>> so manipulate PageSlobFree is not reasonable.
>> We would use another method for checking slob_page_free without
>> PageSlobFree flag.
>
> What method should we be using?

Actually, I have no good idea.
How about below implementation?

static inline int slob_page_free(struct page *sp)
{
        return !list_empty(&sp->list);
}

static void set_slob_page_free(struct page *sp, struct list_head *list)
{
        list_add(&sp->list, list);
}

static inline void clear_slob_page_free(struct page *sp)
{
        list_del_init(&sp->list);
}

Above functions' name should be changed something like "add_freelist,
remove_freelist, in_freelist" for readability

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[RFC] Common code 02/12] [slab]: Use page struct fields instead of casting

[Christoph Lameter]

[-- Attachment #1: slab_page_struct_fields --]
[-- Type: text/plain, Size: 2192 bytes --]

Add fields to the page struct so that it is properly documented that
slab overlays the lru fields.

This cleans up some casts in slab.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>

---
 include/linux/mm_types.h |    4 ++++
 mm/slab.c                |    8 ++++----
 2 files changed, 8 insertions(+), 4 deletions(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-05-15 09:59:03.385256611 -0500
+++ linux-2.6/mm/slab.c	2012-05-16 04:39:08.435864090 -0500
@@ -496,25 +496,25 @@ static bool slab_max_order_set __initdat
  */
 static inline void page_set_cache(struct page *page, struct kmem_cache *cache)
 {
-	page->lru.next = (struct list_head *)cache;
+	page->slab_cache = cache;
 }
 
 static inline struct kmem_cache *page_get_cache(struct page *page)
 {
 	page = compound_head(page);
 	BUG_ON(!PageSlab(page));
-	return (struct kmem_cache *)page->lru.next;
+	return page->slab_cache;
 }
 
 static inline void page_set_slab(struct page *page, struct slab *slab)
 {
-	page->lru.prev = (struct list_head *)slab;
+	page->slab_page = slab;
 }
 
 static inline struct slab *page_get_slab(struct page *page)
 {
 	BUG_ON(!PageSlab(page));
-	return (struct slab *)page->lru.prev;
+	return page->slab_page;
 }
 
 static inline struct kmem_cache *virt_to_cache(const void *obj)
Index: linux-2.6/include/linux/mm_types.h
===================================================================
--- linux-2.6.orig/include/linux/mm_types.h	2012-05-16 04:39:04.671864156 -0500
+++ linux-2.6/include/linux/mm_types.h	2012-05-16 04:39:08.435864090 -0500
@@ -108,6 +108,10 @@ struct page {
 			short int pobjects;
 #endif
 		};
+		struct {		/* SLAB */
+			struct kmem_cache *slab_cache;
+			struct slab *slab_page;
+		};
 	};
 
 	/* Remainder is not double word aligned */

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Re: [RFC] Common code 02/12] [slab]: Use page struct fields instead of casting

[JoonSoo Kim]

2012/5/19 Christoph Lameter <cl@linux.com>:
> Add fields to the page struct so that it is properly documented that
> slab overlays the lru fields.
>
> This cleans up some casts in slab.
>
> Reviewed-by: Glauber Costa <glommer@parallels.com>
> Signed-off-by: Christoph Lameter <cl@linux.com>

Reviewed-by: Joonsoo Kim <js1304@gmail.com>

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[RFC] Common code 03/12] Extract common fields from struct kmem_cache

[Christoph Lameter]

[-- Attachment #1: common_fields --]
[-- Type: text/plain, Size: 9749 bytes --]

Define "COMMON" to include definitions for fields used in all
slab allocators. After that it will be possible to share code that
only operates on those fields of kmem_cache.

The patch basically takes the slob definition of kmem cache and
uses the field namees for the other allocators.

The slob definition of kmem_cache is moved from slob.c to slob_def.h
so that the location of the kmem_cache definition is the same for
all allocators.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 include/linux/slab.h     |   11 +++++++++++
 include/linux/slab_def.h |    8 ++------
 include/linux/slob_def.h |    4 ++++
 include/linux/slub_def.h |   11 ++++-------
 mm/slab.c                |   30 +++++++++++++++---------------
 mm/slob.c                |    7 -------
 6 files changed, 36 insertions(+), 35 deletions(-)

Index: linux-2.6/include/linux/slab.h
===================================================================
--- linux-2.6.orig/include/linux/slab.h	2012-05-15 04:24:47.781672177 -0500
+++ linux-2.6/include/linux/slab.h	2012-05-16 04:40:24.143862602 -0500
@@ -93,6 +93,17 @@
 				(unsigned long)ZERO_SIZE_PTR)
 
 /*
+ * Common fields provided in kmem_cache by all slab allocators
+ */
+#define SLAB_COMMON \
+	unsigned int size, align;					\
+	unsigned long flags;						\
+	const char *name;						\
+	int refcount;							\
+	void (*ctor)(void *);						\
+	struct list_head list;
+
+/*
  * struct kmem_cache related prototypes
  */
 void __init kmem_cache_init(void);
Index: linux-2.6/include/linux/slab_def.h
===================================================================
--- linux-2.6.orig/include/linux/slab_def.h	2012-05-15 04:24:47.757672180 -0500
+++ linux-2.6/include/linux/slab_def.h	2012-05-16 04:40:24.143862602 -0500
@@ -31,7 +31,6 @@ struct kmem_cache {
 	u32 reciprocal_buffer_size;
 /* 2) touched by every alloc & free from the backend */
 
-	unsigned int flags;		/* constant flags */
 	unsigned int num;		/* # of objs per slab */
 
 /* 3) cache_grow/shrink */
@@ -47,12 +46,9 @@ struct kmem_cache {
 	unsigned int slab_size;
 	unsigned int dflags;		/* dynamic flags */
 
-	/* constructor func */
-	void (*ctor)(void *obj);
-
 /* 4) cache creation/removal */
-	const char *name;
-	struct list_head next;
+
+	SLAB_COMMON
 
 /* 5) statistics */
 #ifdef CONFIG_DEBUG_SLAB
Index: linux-2.6/include/linux/slub_def.h
===================================================================
--- linux-2.6.orig/include/linux/slub_def.h	2012-05-16 04:32:33.243872269 -0500
+++ linux-2.6/include/linux/slub_def.h	2012-05-16 04:40:24.143862602 -0500
@@ -80,9 +80,7 @@ struct kmem_cache_order_objects {
 struct kmem_cache {
 	struct kmem_cache_cpu __percpu *cpu_slab;
 	/* Used for retriving partial slabs etc */
-	unsigned long flags;
 	unsigned long min_partial;
-	int size;		/* The size of an object including meta data */
 	int objsize;		/* The size of an object without meta data */
 	int offset;		/* Free pointer offset. */
 	int cpu_partial;	/* Number of per cpu partial objects to keep around */
@@ -92,13 +90,12 @@ struct kmem_cache {
 	struct kmem_cache_order_objects max;
 	struct kmem_cache_order_objects min;
 	gfp_t allocflags;	/* gfp flags to use on each alloc */
-	int refcount;		/* Refcount for slab cache destroy */
-	void (*ctor)(void *);
+
+	SLAB_COMMON
+
 	int inuse;		/* Offset to metadata */
-	int align;		/* Alignment */
 	int reserved;		/* Reserved bytes at the end of slabs */
-	const char *name;	/* Name (only for display!) */
-	struct list_head list;	/* List of slab caches */
+
 #ifdef CONFIG_SYSFS
 	struct kobject kobj;	/* For sysfs */
 #endif
Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2012-05-16 04:39:04.671864156 -0500
+++ linux-2.6/mm/slob.c	2012-05-16 04:40:24.143862602 -0500
@@ -538,13 +538,6 @@ size_t ksize(const void *block)
 }
 EXPORT_SYMBOL(ksize);
 
-struct kmem_cache {
-	unsigned int size, align;
-	unsigned long flags;
-	const char *name;
-	void (*ctor)(void *);
-};
-
 struct kmem_cache *kmem_cache_create(const char *name, size_t size,
 	size_t align, unsigned long flags, void (*ctor)(void *))
 {
Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-05-16 04:39:08.435864090 -0500
+++ linux-2.6/mm/slab.c	2012-05-16 04:40:24.143862602 -0500
@@ -1153,7 +1153,7 @@ static int init_cache_nodelists_node(int
 	struct kmem_list3 *l3;
 	const int memsize = sizeof(struct kmem_list3);
 
-	list_for_each_entry(cachep, &cache_chain, next) {
+	list_for_each_entry(cachep, &cache_chain, list) {
 		/*
 		 * Set up the size64 kmemlist for cpu before we can
 		 * begin anything. Make sure some other cpu on this
@@ -1191,7 +1191,7 @@ static void __cpuinit cpuup_canceled(lon
 	int node = cpu_to_mem(cpu);
 	const struct cpumask *mask = cpumask_of_node(node);
 
-	list_for_each_entry(cachep, &cache_chain, next) {
+	list_for_each_entry(cachep, &cache_chain, list) {
 		struct array_cache *nc;
 		struct array_cache *shared;
 		struct array_cache **alien;
@@ -1241,7 +1241,7 @@ free_array_cache:
 	 * the respective cache's slabs,  now we can go ahead and
 	 * shrink each nodelist to its limit.
 	 */
-	list_for_each_entry(cachep, &cache_chain, next) {
+	list_for_each_entry(cachep, &cache_chain, list) {
 		l3 = cachep->nodelists[node];
 		if (!l3)
 			continue;
@@ -1270,7 +1270,7 @@ static int __cpuinit cpuup_prepare(long
 	 * Now we can go ahead with allocating the shared arrays and
 	 * array caches
 	 */
-	list_for_each_entry(cachep, &cache_chain, next) {
+	list_for_each_entry(cachep, &cache_chain, list) {
 		struct array_cache *nc;
 		struct array_cache *shared = NULL;
 		struct array_cache **alien = NULL;
@@ -1402,7 +1402,7 @@ static int __meminit drain_cache_nodelis
 	struct kmem_cache *cachep;
 	int ret = 0;
 
-	list_for_each_entry(cachep, &cache_chain, next) {
+	list_for_each_entry(cachep, &cache_chain, list) {
 		struct kmem_list3 *l3;
 
 		l3 = cachep->nodelists[node];
@@ -1545,7 +1545,7 @@ void __init kmem_cache_init(void)
 
 	/* 1) create the cache_cache */
 	INIT_LIST_HEAD(&cache_chain);
-	list_add(&cache_cache.next, &cache_chain);
+	list_add(&cache_cache.list, &cache_chain);
 	cache_cache.colour_off = cache_line_size();
 	cache_cache.array[smp_processor_id()] = &initarray_cache.cache;
 	cache_cache.nodelists[node] = &initkmem_list3[CACHE_CACHE + node];
@@ -1690,7 +1690,7 @@ void __init kmem_cache_init_late(void)
 
 	/* 6) resize the head arrays to their final sizes */
 	mutex_lock(&cache_chain_mutex);
-	list_for_each_entry(cachep, &cache_chain, next)
+	list_for_each_entry(cachep, &cache_chain, list)
 		if (enable_cpucache(cachep, GFP_NOWAIT))
 			BUG();
 	mutex_unlock(&cache_chain_mutex);
@@ -2300,7 +2300,7 @@ kmem_cache_create (const char *name, siz
 		mutex_lock(&cache_chain_mutex);
 	}
 
-	list_for_each_entry(pc, &cache_chain, next) {
+	list_for_each_entry(pc, &cache_chain, list) {
 		char tmp;
 		int res;
 
@@ -2545,7 +2545,7 @@ kmem_cache_create (const char *name, siz
 	}
 
 	/* cache setup completed, link it into the list */
-	list_add(&cachep->next, &cache_chain);
+	list_add(&cachep->list, &cache_chain);
 oops:
 	if (!cachep && (flags & SLAB_PANIC))
 		panic("kmem_cache_create(): failed to create slab `%s'\n",
@@ -2740,10 +2740,10 @@ void kmem_cache_destroy(struct kmem_cach
 	/*
 	 * the chain is never empty, cache_cache is never destroyed
 	 */
-	list_del(&cachep->next);
+	list_del(&cachep->list);
 	if (__cache_shrink(cachep)) {
 		slab_error(cachep, "Can't free all objects");
-		list_add(&cachep->next, &cache_chain);
+		list_add(&cachep->list, &cache_chain);
 		mutex_unlock(&cache_chain_mutex);
 		put_online_cpus();
 		return;
@@ -4030,7 +4030,7 @@ static int alloc_kmemlist(struct kmem_ca
 	return 0;
 
 fail:
-	if (!cachep->next.next) {
+	if (!cachep->list.next) {
 		/* Cache is not active yet. Roll back what we did */
 		node--;
 		while (node >= 0) {
@@ -4215,7 +4215,7 @@ static void cache_reap(struct work_struc
 		/* Give up. Setup the next iteration. */
 		goto out;
 
-	list_for_each_entry(searchp, &cache_chain, next) {
+	list_for_each_entry(searchp, &cache_chain, list) {
 		check_irq_on();
 
 		/*
@@ -4308,7 +4308,7 @@ static void s_stop(struct seq_file *m, v
 
 static int s_show(struct seq_file *m, void *p)
 {
-	struct kmem_cache *cachep = list_entry(p, struct kmem_cache, next);
+	struct kmem_cache *cachep = list_entry(p, struct kmem_cache, list);
 	struct slab *slabp;
 	unsigned long active_objs;
 	unsigned long num_objs;
@@ -4456,7 +4456,7 @@ static ssize_t slabinfo_write(struct fil
 	/* Find the cache in the chain of caches. */
 	mutex_lock(&cache_chain_mutex);
 	res = -EINVAL;
-	list_for_each_entry(cachep, &cache_chain, next) {
+	list_for_each_entry(cachep, &cache_chain, list) {
 		if (!strcmp(cachep->name, kbuf)) {
 			if (limit < 1 || batchcount < 1 ||
 					batchcount > limit || shared < 0) {
Index: linux-2.6/include/linux/slob_def.h
===================================================================
--- linux-2.6.orig/include/linux/slob_def.h	2012-05-16 04:36:53.243866880 -0500
+++ linux-2.6/include/linux/slob_def.h	2012-05-16 04:40:52.439862271 -0500
@@ -1,6 +1,10 @@
 #ifndef __LINUX_SLOB_DEF_H
 #define __LINUX_SLOB_DEF_H
 
+struct kmem_cache {
+	SLAB_COMMON
+};
+
 void *kmem_cache_alloc_node(struct kmem_cache *, gfp_t flags, int node);
 
 static __always_inline void *kmem_cache_alloc(struct kmem_cache *cachep,

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Re: [RFC] Common code 03/12] Extract common fields from struct kmem_cache

[Glauber Costa]

On 05/18/2012 08:19 PM, Christoph Lameter wrote:
> Define "COMMON" to include definitions for fields used in all
> slab allocators. After that it will be possible to share code that
> only operates on those fields of kmem_cache.
>
> The patch basically takes the slob definition of kmem cache and
> uses the field namees for the other allocators.
>
> The slob definition of kmem_cache is moved from slob.c to slob_def.h
> so that the location of the kmem_cache definition is the same for
> all allocators.
>
> Signed-off-by: Christoph Lameter<cl@linux.com>

Reviewed-by: Glauber Costa <glommer@parallels.com>

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Re: [RFC] Common code 03/12] Extract common fields from struct kmem_cache

[JoonSoo Kim]

> On 05/18/2012 08:19 PM, Christoph Lameter wrote:
>>
>> Define "COMMON" to include definitions for fields used in all
>> slab allocators. After that it will be possible to share code that
>> only operates on those fields of kmem_cache.
>>
>> The patch basically takes the slob definition of kmem cache and
>> uses the field namees for the other allocators.
>>
>> The slob definition of kmem_cache is moved from slob.c to slob_def.h
>> so that the location of the kmem_cache definition is the same for
>> all allocators.
>>
>> Signed-off-by: Christoph Lameter<cl@linux.com>
>
>
> Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>

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[RFC] Common code 04/12] slabs: Extract common code for kmem_cache_create

[Christoph Lameter]

[-- Attachment #1: common_kmem_cache_checks --]
[-- Type: text/plain, Size: 9749 bytes --]

Kmem_cache_create does a variety of sanity checks but those
vary depending on the allocator. Use the strictest tests and put them into
a slab_common file. Make the tests conditional on CONFIG_DEBUG_VM.

This patch has the effect of adding sanity checks for SLUB and SLOB
under CONFIG_DEBUG_VM and removes the checks in SLAB for !CONFIG_DEBUG_VM.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 include/linux/slab.h |    4 +++
 mm/Makefile          |    2 -
 mm/slab.c            |   24 ++++++------------
 mm/slab_common.c     |   67 +++++++++++++++++++++++++++++++++++++++++++++++++++
 mm/slob.c            |    8 ++----
 mm/slub.c            |   11 --------
 6 files changed, 85 insertions(+), 31 deletions(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-05-11 09:36:35.308445605 -0500
+++ linux-2.6/mm/slab.c	2012-05-11 09:43:33.160436947 -0500
@@ -1585,7 +1585,7 @@ void __init kmem_cache_init(void)
 	 * bug.
 	 */
 
-	sizes[INDEX_AC].cs_cachep = kmem_cache_create(names[INDEX_AC].name,
+	sizes[INDEX_AC].cs_cachep = __kmem_cache_create(names[INDEX_AC].name,
 					sizes[INDEX_AC].cs_size,
 					ARCH_KMALLOC_MINALIGN,
 					ARCH_KMALLOC_FLAGS|SLAB_PANIC,
@@ -1593,7 +1593,7 @@ void __init kmem_cache_init(void)
 
 	if (INDEX_AC != INDEX_L3) {
 		sizes[INDEX_L3].cs_cachep =
-			kmem_cache_create(names[INDEX_L3].name,
+			__kmem_cache_create(names[INDEX_L3].name,
 				sizes[INDEX_L3].cs_size,
 				ARCH_KMALLOC_MINALIGN,
 				ARCH_KMALLOC_FLAGS|SLAB_PANIC,
@@ -1611,14 +1611,14 @@ void __init kmem_cache_init(void)
 		 * allow tighter packing of the smaller caches.
 		 */
 		if (!sizes->cs_cachep) {
-			sizes->cs_cachep = kmem_cache_create(names->name,
+			sizes->cs_cachep = __kmem_cache_create(names->name,
 					sizes->cs_size,
 					ARCH_KMALLOC_MINALIGN,
 					ARCH_KMALLOC_FLAGS|SLAB_PANIC,
 					NULL);
 		}
 #ifdef CONFIG_ZONE_DMA
-		sizes->cs_dmacachep = kmem_cache_create(
+		sizes->cs_dmacachep = __kmem_cache_create(
 					names->name_dma,
 					sizes->cs_size,
 					ARCH_KMALLOC_MINALIGN,
@@ -2247,7 +2247,7 @@ static int __init_refok setup_cpu_cache(
 }
 
 /**
- * kmem_cache_create - Create a cache.
+ * __kmem_cache_create - Create a cache.
  * @name: A string which is used in /proc/slabinfo to identify this cache.
  * @size: The size of objects to be created in this cache.
  * @align: The required alignment for the objects.
@@ -2274,7 +2274,7 @@ static int __init_refok setup_cpu_cache(
  * as davem.
  */
 struct kmem_cache *
-kmem_cache_create (const char *name, size_t size, size_t align,
+__kmem_cache_create (const char *name, size_t size, size_t align,
 	unsigned long flags, void (*ctor)(void *))
 {
 	size_t left_over, slab_size, ralign;
@@ -2415,7 +2415,7 @@ kmem_cache_create (const char *name, siz
 	/* Get cache's description obj. */
 	cachep = kmem_cache_zalloc(&cache_cache, gfp);
 	if (!cachep)
-		goto oops;
+		return NULL;
 
 	cachep->nodelists = (struct kmem_list3 **)&cachep->array[nr_cpu_ids];
 #if DEBUG
@@ -2471,8 +2471,7 @@ kmem_cache_create (const char *name, siz
 		printk(KERN_ERR
 		       "kmem_cache_create: couldn't create cache %s.\n", name);
 		kmem_cache_free(&cache_cache, cachep);
-		cachep = NULL;
-		goto oops;
+		return NULL;
 	}
 	slab_size = ALIGN(cachep->num * sizeof(kmem_bufctl_t)
 			  + sizeof(struct slab), align);
@@ -2530,8 +2529,7 @@ kmem_cache_create (const char *name, siz
 
 	if (setup_cpu_cache(cachep, gfp)) {
 		__kmem_cache_destroy(cachep);
-		cachep = NULL;
-		goto oops;
+		return NULL;
 	}
 
 	if (flags & SLAB_DEBUG_OBJECTS) {
@@ -2547,16 +2545,12 @@ kmem_cache_create (const char *name, siz
 	/* cache setup completed, link it into the list */
 	list_add(&cachep->list, &cache_chain);
 oops:
-	if (!cachep && (flags & SLAB_PANIC))
-		panic("kmem_cache_create(): failed to create slab `%s'\n",
-		      name);
 	if (slab_is_available()) {
 		mutex_unlock(&cache_chain_mutex);
 		put_online_cpus();
 	}
 	return cachep;
 }
-EXPORT_SYMBOL(kmem_cache_create);
 
 #if DEBUG
 static void check_irq_off(void)
Index: linux-2.6/mm/slab_common.c
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/mm/slab_common.c	2012-05-11 09:43:33.160436947 -0500
@@ -0,0 +1,67 @@
+/*
+ * Slab allocator functions that are independent of the allocator strategy
+ *
+ * (C) 2012 Christoph Lameter <cl@linux.com>
+ */
+#include <linux/slab.h>
+
+#include <linux/mm.h>
+#include <linux/poison.h>
+#include <linux/interrupt.h>
+#include <linux/memory.h>
+#include <linux/compiler.h>
+#include <linux/module.h>
+
+#include <asm/cacheflush.h>
+#include <asm/tlbflush.h>
+#include <asm/page.h>
+
+/*
+ * kmem_cache_create - Create a cache.
+ * @name: A string which is used in /proc/slabinfo to identify this cache.
+ * @size: The size of objects to be created in this cache.
+ * @align: The required alignment for the objects.
+ * @flags: SLAB flags
+ * @ctor: A constructor for the objects.
+ *
+ * Returns a ptr to the cache on success, NULL on failure.
+ * Cannot be called within a interrupt, but can be interrupted.
+ * The @ctor is run when new pages are allocated by the cache.
+ *
+ * The flags are
+ *
+ * %SLAB_POISON - Poison the slab with a known test pattern (a5a5a5a5)
+ * to catch references to uninitialised memory.
+ *
+ * %SLAB_RED_ZONE - Insert `Red' zones around the allocated memory to check
+ * for buffer overruns.
+ *
+ * %SLAB_HWCACHE_ALIGN - Align the objects in this cache to a hardware
+ * cacheline.  This can be beneficial if you're counting cycles as closely
+ * as davem.
+ */
+
+struct kmem_cache *kmem_cache_create(const char *name, size_t size, size_t align,
+		unsigned long flags, void (*ctor)(void *))
+{
+	struct kmem_cache *s = NULL;
+
+#ifdef CONFIG_DEBUG_VM
+	if (!name || in_interrupt() || size < sizeof(void *) ||
+		size > KMALLOC_MAX_SIZE) {
+		printk(KERN_ERR "kmem_cache_create(%s) integrity check"
+			" failed\n", name);
+		goto out;
+	}
+#endif
+
+	s = __kmem_cache_create(name, size, align, flags, ctor);
+
+out:
+	if (!s && (flags & SLAB_PANIC))
+		panic("kmem_cache_create: Failed to create slab '%s'\n", name);
+
+	return s;
+}
+EXPORT_SYMBOL(kmem_cache_create);
+
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-05-11 09:36:35.320445605 -0500
+++ linux-2.6/mm/slub.c	2012-05-11 09:43:33.164436947 -0500
@@ -3921,15 +3921,12 @@ static struct kmem_cache *find_mergeable
 	return NULL;
 }
 
-struct kmem_cache *kmem_cache_create(const char *name, size_t size,
+struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 		size_t align, unsigned long flags, void (*ctor)(void *))
 {
 	struct kmem_cache *s;
 	char *n;
 
-	if (WARN_ON(!name))
-		return NULL;
-
 	down_write(&slub_lock);
 	s = find_mergeable(size, align, flags, name, ctor);
 	if (s) {
@@ -3973,14 +3970,8 @@ struct kmem_cache *kmem_cache_create(con
 	}
 err:
 	up_write(&slub_lock);
-
-	if (flags & SLAB_PANIC)
-		panic("Cannot create slabcache %s\n", name);
-	else
-		s = NULL;
 	return s;
 }
-EXPORT_SYMBOL(kmem_cache_create);
 
 #ifdef CONFIG_SMP
 /*
Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2012-05-11 09:42:52.032437799 -0500
+++ linux-2.6/mm/slob.c	2012-05-11 09:43:33.164436947 -0500
@@ -538,7 +538,7 @@ size_t ksize(const void *block)
 }
 EXPORT_SYMBOL(ksize);
 
-struct kmem_cache *kmem_cache_create(const char *name, size_t size,
+struct kmem_cache *__kmem_cache_create(const char *name, size_t size,
 	size_t align, unsigned long flags, void (*ctor)(void *))
 {
 	struct kmem_cache *c;
@@ -561,13 +561,11 @@ struct kmem_cache *kmem_cache_create(con
 			c->align = ARCH_SLAB_MINALIGN;
 		if (c->align < align)
 			c->align = align;
-	} else if (flags & SLAB_PANIC)
-		panic("Cannot create slab cache %s\n", name);
 
-	kmemleak_alloc(c, sizeof(struct kmem_cache), 1, GFP_KERNEL);
+		kmemleak_alloc(c, sizeof(struct kmem_cache), 1, GFP_KERNEL);
+	}
 	return c;
 }
-EXPORT_SYMBOL(kmem_cache_create);
 
 void kmem_cache_destroy(struct kmem_cache *c)
 {
Index: linux-2.6/mm/Makefile
===================================================================
--- linux-2.6.orig/mm/Makefile	2012-05-11 09:36:35.328445605 -0500
+++ linux-2.6/mm/Makefile	2012-05-11 09:43:33.164436947 -0500
@@ -13,7 +13,7 @@ obj-y			:= filemap.o mempool.o oom_kill.
 			   readahead.o swap.o truncate.o vmscan.o shmem.o \
 			   prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
 			   page_isolation.o mm_init.o mmu_context.o percpu.o \
-			   $(mmu-y)
+			   slab_common.o $(mmu-y)
 obj-y += init-mm.o
 
 ifdef CONFIG_NO_BOOTMEM
Index: linux-2.6/include/linux/slab.h
===================================================================
--- linux-2.6.orig/include/linux/slab.h	2012-05-11 09:36:35.292445608 -0500
+++ linux-2.6/include/linux/slab.h	2012-05-11 09:43:33.164436947 -0500
@@ -117,6 +117,10 @@ int kmem_cache_shrink(struct kmem_cache
 void kmem_cache_free(struct kmem_cache *, void *);
 unsigned int kmem_cache_size(struct kmem_cache *);
 
+/* Slab internal function */
+struct kmem_cache *__kmem_cache_create(const char *, size_t, size_t,
+			unsigned long,
+			void (*)(void *));
 /*
  * Please use this macro to create slab caches. Simply specify the
  * name of the structure and maybe some flags that are listed above.

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Re: [RFC] Common code 04/12] slabs: Extract common code for kmem_cache_create

[Glauber Costa]

On 05/18/2012 08:19 PM, Christoph Lameter wrote:
> Index: linux-2.6/mm/slab.c
> ===================================================================
> --- linux-2.6.orig/mm/slab.c	2012-05-11 09:36:35.308445605 -0500
> +++ linux-2.6/mm/slab.c	2012-05-11 09:43:33.160436947 -0500
> @@ -1585,7 +1585,7 @@ void __init kmem_cache_init(void)
>   	 * bug.
>   	 */
>
> -	sizes[INDEX_AC].cs_cachep = kmem_cache_create(names[INDEX_AC].name,
> +	sizes[INDEX_AC].cs_cachep = __kmem_cache_create(names[INDEX_AC].name,
>   					sizes[INDEX_AC].cs_size,
>   					ARCH_KMALLOC_MINALIGN,
>   					ARCH_KMALLOC_FLAGS|SLAB_PANIC,

So, before your patch, the kmalloc caches were getting all the sanity 
checking done. No we're skipping them. Any particular reason?


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Re: [RFC] Common code 04/12] slabs: Extract common code for kmem_cache_create

[Christoph Lameter]

On Mon, 21 May 2012, Glauber Costa wrote:

> On 05/18/2012 08:19 PM, Christoph Lameter wrote:
> > Index: linux-2.6/mm/slab.c
> > ===================================================================
> > --- linux-2.6.orig/mm/slab.c	2012-05-11 09:36:35.308445605 -0500
> > +++ linux-2.6/mm/slab.c	2012-05-11 09:43:33.160436947 -0500
> > @@ -1585,7 +1585,7 @@ void __init kmem_cache_init(void)
> >   	 * bug.
> >   	 */
> >
> > -	sizes[INDEX_AC].cs_cachep = kmem_cache_create(names[INDEX_AC].name,
> > +	sizes[INDEX_AC].cs_cachep = __kmem_cache_create(names[INDEX_AC].name,
> >   					sizes[INDEX_AC].cs_size,
> >   					ARCH_KMALLOC_MINALIGN,
> >   					ARCH_KMALLOC_FLAGS|SLAB_PANIC,
>
> So, before your patch, the kmalloc caches were getting all the sanity checking
> done. No we're skipping them. Any particular reason?

I can visually do the sanity checking since the parameters are all in the
source. No need to do these checks again at runtime.


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Re: [RFC] Common code 04/12] slabs: Extract common code for kmem_cache_create

[JoonSoo Kim]

2012/5/19 Christoph Lameter <cl@linux.com>:
> This patch has the effect of adding sanity checks for SLUB and SLOB
> under CONFIG_DEBUG_VM and removes the checks in SLAB for !CONFIG_DEBUG_VM.

If !CONFIG_DEBUG_VM,
code for sanity checks remain in __kmem_cache_create in slab.c, doesn't it?

> +#ifdef CONFIG_DEBUG_VM
> +       if (!name || in_interrupt() || size < sizeof(void *) ||
> +               size > KMALLOC_MAX_SIZE) {
> +               printk(KERN_ERR "kmem_cache_create(%s) integrity check"
> +                       " failed\n", name);
> +               goto out;
> +       }
> +#endif

Currently, when !CONFIG_DEBUG_VM, name check is handled differently in
sl[aou]bs.
slob worked with !name, but slab, slub return NULL.
So I think some change is needed for name handling.

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Re: [RFC] Common code 04/12] slabs: Extract common code for kmem_cache_create

[Glauber Costa]

On 05/22/2012 07:08 PM, JoonSoo Kim wrote:
>> +#ifdef CONFIG_DEBUG_VM
>> >  +       if (!name || in_interrupt() || size<  sizeof(void *) ||
>> >  +               size>  KMALLOC_MAX_SIZE) {
>> >  +               printk(KERN_ERR "kmem_cache_create(%s) integrity check"
>> >  +                       " failed\n", name);
>> >  +               goto out;
>> >  +       }
>> >  +#endif
> Currently, when !CONFIG_DEBUG_VM, name check is handled differently in
> sl[aou]bs.
> slob worked with !name, but slab, slub return NULL.
> So I think some change is needed for name handling

Just because slob works without a name, it doesn't mean that calling 
kmem_cache_create() without a name is even a bit close to being sane.

Any user of this interface, has no way to know which allocator will be 
used in the end. So the guarantees given by the interface should be 
sanity checked, whether or not the particular cache uses it.

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Re: [RFC] Common code 04/12] slabs: Extract common code for kmem_cache_create

[Christoph Lameter]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1010 bytes --]

On Wed, 23 May 2012, JoonSoo Kim wrote:

> 2012/5/19 Christoph Lameter <cl@linux.com>:
> > This patch has the effect of adding sanity checks for SLUB and SLOB
> > under CONFIG_DEBUG_VM and removes the checks in SLAB for !CONFIG_DEBUG_VM.
>
> If !CONFIG_DEBUG_VM,
> code for sanity checks remain in __kmem_cache_create in slab.c, doesn't it?

Some sanity checks remain after this patch and are moved later.

>
> > +#ifdef CONFIG_DEBUG_VM
> > +       if (!name || in_interrupt() || size < sizeof(void *) ||
> > +               size > KMALLOC_MAX_SIZE) {
> > +               printk(KERN_ERR "kmem_cache_create(%s) integrity check"
> > +                       " failed\n", name);
> > +               goto out;
> > +       }
> > +#endif
>
> Currently, when !CONFIG_DEBUG_VM, name check is handled differently in
> sl[aou]bs.
> slob worked with !name, but slab, slub return NULL.
> So I think some change is needed for name handling.

Right. All should check for !name and fail on that.

[RFC] Common code 05/12] slabs: Common definition for boot state of the slab allocators

[Christoph Lameter]

[-- Attachment #1: slab_internal --]
[-- Type: text/plain, Size: 9064 bytes --]

All allocators have some sort of support for the bootstrap status.

Setup a common definition for the boot states and make all slab
allocators use that definition.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 include/linux/slab.h |    4 ----
 mm/slab.c            |   42 +++++++++++-------------------------------
 mm/slab.h            |   30 ++++++++++++++++++++++++++++++
 mm/slab_common.c     |    9 +++++++++
 mm/slob.c            |   14 +++++---------
 mm/slub.c            |   21 +++++----------------
 6 files changed, 60 insertions(+), 60 deletions(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-05-11 09:43:33.160436947 -0500
+++ linux-2.6/mm/slab.c	2012-05-11 09:43:53.448436526 -0500
@@ -87,6 +87,7 @@
  */
 
 #include	<linux/slab.h>
+#include	"slab.h"
 #include	<linux/mm.h>
 #include	<linux/poison.h>
 #include	<linux/swap.h>
@@ -590,27 +591,6 @@ static struct kmem_cache cache_cache = {
 
 #define BAD_ALIEN_MAGIC 0x01020304ul
 
-/*
- * chicken and egg problem: delay the per-cpu array allocation
- * until the general caches are up.
- */
-static enum {
-	NONE,
-	PARTIAL_AC,
-	PARTIAL_L3,
-	EARLY,
-	LATE,
-	FULL
-} g_cpucache_up;
-
-/*
- * used by boot code to determine if it can use slab based allocator
- */
-int slab_is_available(void)
-{
-	return g_cpucache_up >= EARLY;
-}
-
 #ifdef CONFIG_LOCKDEP
 
 /*
@@ -676,7 +656,7 @@ static void init_node_lock_keys(int q)
 {
 	struct cache_sizes *s = malloc_sizes;
 
-	if (g_cpucache_up < LATE)
+	if (slab_state < UP)
 		return;
 
 	for (s = malloc_sizes; s->cs_size != ULONG_MAX; s++) {
@@ -1676,14 +1656,14 @@ void __init kmem_cache_init(void)
 		}
 	}
 
-	g_cpucache_up = EARLY;
+	slab_state = UP;
 }
 
 void __init kmem_cache_init_late(void)
 {
 	struct kmem_cache *cachep;
 
-	g_cpucache_up = LATE;
+	slab_state = UP;
 
 	/* Annotate slab for lockdep -- annotate the malloc caches */
 	init_lock_keys();
@@ -1696,7 +1676,7 @@ void __init kmem_cache_init_late(void)
 	mutex_unlock(&cache_chain_mutex);
 
 	/* Done! */
-	g_cpucache_up = FULL;
+	slab_state = FULL;
 
 	/*
 	 * Register a cpu startup notifier callback that initializes
@@ -2194,10 +2174,10 @@ static size_t calculate_slab_order(struc
 
 static int __init_refok setup_cpu_cache(struct kmem_cache *cachep, gfp_t gfp)
 {
-	if (g_cpucache_up == FULL)
+	if (slab_state == FULL)
 		return enable_cpucache(cachep, gfp);
 
-	if (g_cpucache_up == NONE) {
+	if (slab_state == DOWN) {
 		/*
 		 * Note: the first kmem_cache_create must create the cache
 		 * that's used by kmalloc(24), otherwise the creation of
@@ -2212,16 +2192,16 @@ static int __init_refok setup_cpu_cache(
 		 */
 		set_up_list3s(cachep, SIZE_AC);
 		if (INDEX_AC == INDEX_L3)
-			g_cpucache_up = PARTIAL_L3;
+			slab_state = PARTIAL_L3;
 		else
-			g_cpucache_up = PARTIAL_AC;
+			slab_state = PARTIAL_ARRAYCACHE;
 	} else {
 		cachep->array[smp_processor_id()] =
 			kmalloc(sizeof(struct arraycache_init), gfp);
 
-		if (g_cpucache_up == PARTIAL_AC) {
+		if (slab_state == PARTIAL_ARRAYCACHE) {
 			set_up_list3s(cachep, SIZE_L3);
-			g_cpucache_up = PARTIAL_L3;
+			slab_state = PARTIAL_L3;
 		} else {
 			int node;
 			for_each_online_node(node) {
Index: linux-2.6/mm/slab.h
===================================================================
--- /dev/null	1970-01-01 00:00:00.000000000 +0000
+++ linux-2.6/mm/slab.h	2012-05-11 09:43:53.448436526 -0500
@@ -0,0 +1,30 @@
+#ifndef MM_SLAB_H
+#define MM_SLAB_H
+/*
+ * Internal slab definitions
+ */
+
+/*
+ * State of the slab allocator.
+ *
+ * This is used to describe the states of the allocator during bootup.
+ * Allocators use this to gradually bootstrap themselves. Most allocators
+ * have the problem that the structures used for managing slab caches are
+ * allocated from slab caches themselves.
+ */
+enum slab_state {
+	DOWN,			/* No slab functionality yet */
+	PARTIAL,		/* SLUB: kmem_cache_node available */
+	PARTIAL_ARRAYCACHE,	/* SLAB: kmalloc size for arraycache available */
+	PARTIAL_L3,		/* SLAB: kmalloc size for l3 struct available */
+	UP,			/* Slab caches usable but not all extras yet */
+	FULL			/* Everything is working */
+};
+
+extern enum slab_state slab_state;
+
+struct kmem_cache *__kmem_cache_create (const char *name, size_t size,
+	size_t align, unsigned long flags, void (*ctor)(void *));
+
+#endif
+
Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2012-05-11 09:43:33.164436947 -0500
+++ linux-2.6/mm/slob.c	2012-05-11 09:43:53.448436526 -0500
@@ -59,6 +59,8 @@
 
 #include <linux/kernel.h>
 #include <linux/slab.h>
+#include "slab.h"
+
 #include <linux/mm.h>
 #include <linux/swap.h> /* struct reclaim_state */
 #include <linux/cache.h>
@@ -563,6 +565,7 @@ struct kmem_cache *__kmem_cache_create(c
 			c->align = align;
 
 		kmemleak_alloc(c, sizeof(struct kmem_cache), 1, GFP_KERNEL);
+		c->refcount = 1;
 	}
 	return c;
 }
@@ -648,19 +651,12 @@ int kmem_cache_shrink(struct kmem_cache
 }
 EXPORT_SYMBOL(kmem_cache_shrink);
 
-static unsigned int slob_ready __read_mostly;
-
-int slab_is_available(void)
-{
-	return slob_ready;
-}
-
 void __init kmem_cache_init(void)
 {
-	slob_ready = 1;
+	slab_state = UP;
 }
 
 void __init kmem_cache_init_late(void)
 {
-	/* Nothing to do */
+	slab_state = FULL;
 }
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-05-11 09:43:33.164436947 -0500
+++ linux-2.6/mm/slub.c	2012-05-11 09:43:53.448436526 -0500
@@ -16,6 +16,7 @@
 #include <linux/interrupt.h>
 #include <linux/bitops.h>
 #include <linux/slab.h>
+#include "slab.h"
 #include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/kmemcheck.h>
@@ -182,13 +183,6 @@ static int kmem_size = sizeof(struct kme
 static struct notifier_block slab_notifier;
 #endif
 
-static enum {
-	DOWN,		/* No slab functionality available */
-	PARTIAL,	/* Kmem_cache_node works */
-	UP,		/* Everything works but does not show up in sysfs */
-	SYSFS		/* Sysfs up */
-} slab_state = DOWN;
-
 /* A list of all slab caches on the system */
 static DECLARE_RWSEM(slub_lock);
 static LIST_HEAD(slab_caches);
@@ -237,11 +231,6 @@ static inline void stat(const struct kme
  * 			Core slab cache functions
  *******************************************************************/
 
-int slab_is_available(void)
-{
-	return slab_state >= UP;
-}
-
 static inline struct kmem_cache_node *get_node(struct kmem_cache *s, int node)
 {
 	return s->node[node];
@@ -5274,7 +5263,7 @@ static int sysfs_slab_add(struct kmem_ca
 	const char *name;
 	int unmergeable;
 
-	if (slab_state < SYSFS)
+	if (slab_state < FULL)
 		/* Defer until later */
 		return 0;
 
@@ -5319,7 +5308,7 @@ static int sysfs_slab_add(struct kmem_ca
 
 static void sysfs_slab_remove(struct kmem_cache *s)
 {
-	if (slab_state < SYSFS)
+	if (slab_state < FULL)
 		/*
 		 * Sysfs has not been setup yet so no need to remove the
 		 * cache from sysfs.
@@ -5347,7 +5336,7 @@ static int sysfs_slab_alias(struct kmem_
 {
 	struct saved_alias *al;
 
-	if (slab_state == SYSFS) {
+	if (slab_state == FULL) {
 		/*
 		 * If we have a leftover link then remove it.
 		 */
@@ -5380,7 +5369,7 @@ static int __init slab_sysfs_init(void)
 		return -ENOSYS;
 	}
 
-	slab_state = SYSFS;
+	slab_state = FULL;
 
 	list_for_each_entry(s, &slab_caches, list) {
 		err = sysfs_slab_add(s);
Index: linux-2.6/mm/slab_common.c
===================================================================
--- linux-2.6.orig/mm/slab_common.c	2012-05-11 09:43:33.160436947 -0500
+++ linux-2.6/mm/slab_common.c	2012-05-11 09:43:53.448436526 -0500
@@ -16,6 +16,10 @@
 #include <asm/tlbflush.h>
 #include <asm/page.h>
 
+#include "slab.h"
+
+enum slab_state slab_state;
+
 /*
  * kmem_cache_create - Create a cache.
  * @name: A string which is used in /proc/slabinfo to identify this cache.
@@ -65,3 +69,8 @@ out:
 }
 EXPORT_SYMBOL(kmem_cache_create);
 
+int slab_is_available(void)
+{
+	return slab_state >= UP;
+}
+
Index: linux-2.6/include/linux/slab.h
===================================================================
--- linux-2.6.orig/include/linux/slab.h	2012-05-11 09:43:33.164436947 -0500
+++ linux-2.6/include/linux/slab.h	2012-05-11 09:43:53.448436526 -0500
@@ -117,10 +117,6 @@ int kmem_cache_shrink(struct kmem_cache
 void kmem_cache_free(struct kmem_cache *, void *);
 unsigned int kmem_cache_size(struct kmem_cache *);
 
-/* Slab internal function */
-struct kmem_cache *__kmem_cache_create(const char *, size_t, size_t,
-			unsigned long,
-			void (*)(void *));
 /*
  * Please use this macro to create slab caches. Simply specify the
  * name of the structure and maybe some flags that are listed above.

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Re: [RFC] Common code 05/12] slabs: Common definition for boot state of the slab allocators

[Glauber Costa]

On 05/18/2012 08:19 PM, Christoph Lameter wrote:
> All allocators have some sort of support for the bootstrap status.
>
> Setup a common definition for the boot states and make all slab
> allocators use that definition.
>
> Signed-off-by: Christoph Lameter<cl@linux.com>
Reviewed-by: Glauber Costa <glommer@parallels.com>

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Re: [RFC] Common code 05/12] slabs: Common definition for boot state of the slab allocators

[JoonSoo Kim]

2012/5/21 Glauber Costa <glommer@parallels.com>:
> On 05/18/2012 08:19 PM, Christoph Lameter wrote:
>>
>> All allocators have some sort of support for the bootstrap status.
>>
>> Setup a common definition for the boot states and make all slab
>> allocators use that definition.
>>
>> Signed-off-by: Christoph Lameter<cl@linux.com>
>
> Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>

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[RFC] Common code 06/12] slabs: Use a common mutex definition

[Christoph Lameter]

[-- Attachment #1: common_mutex --]
[-- Type: text/plain, Size: 18730 bytes --]

Use the mutex definition from SLAB and make it the common way to take a sleeping lock.

This has the effect of using a mutex instead of a rw semaphore for SLUB.

SLOB gains the use of a mutex for kmem_cache_create serialization.
Not needed now but SLOB may acquire some more features later (like slabinfo
/ sysfs support) through the expansion of the common code that will
need this.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>

---
 mm/slab.c        |  104 +++++++++++++++++++++++++------------------------------
 mm/slab.h        |    4 ++
 mm/slab_common.c |    2 +
 mm/slub.c        |   54 +++++++++++++---------------
 4 files changed, 80 insertions(+), 84 deletions(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-05-11 09:43:53.448436526 -0500
+++ linux-2.6/mm/slab.c	2012-05-11 09:43:58.984436408 -0500
@@ -68,7 +68,7 @@
  * Further notes from the original documentation:
  *
  * 11 April '97.  Started multi-threading - markhe
- *	The global cache-chain is protected by the mutex 'cache_chain_mutex'.
+ *	The global cache-chain is protected by the mutex 'slab_mutex'.
  *	The sem is only needed when accessing/extending the cache-chain, which
  *	can never happen inside an interrupt (kmem_cache_create(),
  *	kmem_cache_shrink() and kmem_cache_reap()).
@@ -696,12 +696,6 @@ static void slab_set_debugobj_lock_class
 }
 #endif
 
-/*
- * Guard access to the cache-chain.
- */
-static DEFINE_MUTEX(cache_chain_mutex);
-static struct list_head cache_chain;
-
 static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
 
 static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
@@ -1125,7 +1119,7 @@ static inline int cache_free_alien(struc
  * When hotplugging memory or a cpu, existing nodelists are not replaced if
  * already in use.
  *
- * Must hold cache_chain_mutex.
+ * Must hold slab_mutex.
  */
 static int init_cache_nodelists_node(int node)
 {
@@ -1133,7 +1127,7 @@ static int init_cache_nodelists_node(int
 	struct kmem_list3 *l3;
 	const int memsize = sizeof(struct kmem_list3);
 
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		/*
 		 * Set up the size64 kmemlist for cpu before we can
 		 * begin anything. Make sure some other cpu on this
@@ -1149,7 +1143,7 @@ static int init_cache_nodelists_node(int
 
 			/*
 			 * The l3s don't come and go as CPUs come and
-			 * go.  cache_chain_mutex is sufficient
+			 * go.  slab_mutex is sufficient
 			 * protection here.
 			 */
 			cachep->nodelists[node] = l3;
@@ -1171,7 +1165,7 @@ static void __cpuinit cpuup_canceled(lon
 	int node = cpu_to_mem(cpu);
 	const struct cpumask *mask = cpumask_of_node(node);
 
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		struct array_cache *nc;
 		struct array_cache *shared;
 		struct array_cache **alien;
@@ -1221,7 +1215,7 @@ free_array_cache:
 	 * the respective cache's slabs,  now we can go ahead and
 	 * shrink each nodelist to its limit.
 	 */
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		l3 = cachep->nodelists[node];
 		if (!l3)
 			continue;
@@ -1250,7 +1244,7 @@ static int __cpuinit cpuup_prepare(long
 	 * Now we can go ahead with allocating the shared arrays and
 	 * array caches
 	 */
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		struct array_cache *nc;
 		struct array_cache *shared = NULL;
 		struct array_cache **alien = NULL;
@@ -1318,9 +1312,9 @@ static int __cpuinit cpuup_callback(stru
 	switch (action) {
 	case CPU_UP_PREPARE:
 	case CPU_UP_PREPARE_FROZEN:
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 		err = cpuup_prepare(cpu);
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		break;
 	case CPU_ONLINE:
 	case CPU_ONLINE_FROZEN:
@@ -1330,7 +1324,7 @@ static int __cpuinit cpuup_callback(stru
   	case CPU_DOWN_PREPARE:
   	case CPU_DOWN_PREPARE_FROZEN:
 		/*
-		 * Shutdown cache reaper. Note that the cache_chain_mutex is
+		 * Shutdown cache reaper. Note that the slab_mutex is
 		 * held so that if cache_reap() is invoked it cannot do
 		 * anything expensive but will only modify reap_work
 		 * and reschedule the timer.
@@ -1357,9 +1351,9 @@ static int __cpuinit cpuup_callback(stru
 #endif
 	case CPU_UP_CANCELED:
 	case CPU_UP_CANCELED_FROZEN:
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 		cpuup_canceled(cpu);
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		break;
 	}
 	return notifier_from_errno(err);
@@ -1375,14 +1369,14 @@ static struct notifier_block __cpuinitda
  * Returns -EBUSY if all objects cannot be drained so that the node is not
  * removed.
  *
- * Must hold cache_chain_mutex.
+ * Must hold slab_mutex.
  */
 static int __meminit drain_cache_nodelists_node(int node)
 {
 	struct kmem_cache *cachep;
 	int ret = 0;
 
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		struct kmem_list3 *l3;
 
 		l3 = cachep->nodelists[node];
@@ -1413,14 +1407,14 @@ static int __meminit slab_memory_callbac
 
 	switch (action) {
 	case MEM_GOING_ONLINE:
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 		ret = init_cache_nodelists_node(nid);
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		break;
 	case MEM_GOING_OFFLINE:
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 		ret = drain_cache_nodelists_node(nid);
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		break;
 	case MEM_ONLINE:
 	case MEM_OFFLINE:
@@ -1524,8 +1518,8 @@ void __init kmem_cache_init(void)
 	node = numa_mem_id();
 
 	/* 1) create the cache_cache */
-	INIT_LIST_HEAD(&cache_chain);
-	list_add(&cache_cache.list, &cache_chain);
+	INIT_LIST_HEAD(&slab_caches);
+	list_add(&cache_cache.list, &slab_caches);
 	cache_cache.colour_off = cache_line_size();
 	cache_cache.array[smp_processor_id()] = &initarray_cache.cache;
 	cache_cache.nodelists[node] = &initkmem_list3[CACHE_CACHE + node];
@@ -1669,11 +1663,11 @@ void __init kmem_cache_init_late(void)
 	init_lock_keys();
 
 	/* 6) resize the head arrays to their final sizes */
-	mutex_lock(&cache_chain_mutex);
-	list_for_each_entry(cachep, &cache_chain, list)
+	mutex_lock(&slab_mutex);
+	list_for_each_entry(cachep, &slab_caches, list)
 		if (enable_cpucache(cachep, GFP_NOWAIT))
 			BUG();
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 
 	/* Done! */
 	slab_state = FULL;
@@ -2523,10 +2517,10 @@ __kmem_cache_create (const char *name, s
 	}
 
 	/* cache setup completed, link it into the list */
-	list_add(&cachep->list, &cache_chain);
+	list_add(&cachep->list, &slab_caches);
 oops:
 	if (slab_is_available()) {
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		put_online_cpus();
 	}
 	return cachep;
@@ -2645,7 +2639,7 @@ out:
 	return nr_freed;
 }
 
-/* Called with cache_chain_mutex held to protect against cpu hotplug */
+/* Called with slab_mutex held to protect against cpu hotplug */
 static int __cache_shrink(struct kmem_cache *cachep)
 {
 	int ret = 0, i = 0;
@@ -2680,9 +2674,9 @@ int kmem_cache_shrink(struct kmem_cache
 	BUG_ON(!cachep || in_interrupt());
 
 	get_online_cpus();
-	mutex_lock(&cache_chain_mutex);
+	mutex_lock(&slab_mutex);
 	ret = __cache_shrink(cachep);
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 	put_online_cpus();
 	return ret;
 }
@@ -2710,15 +2704,15 @@ void kmem_cache_destroy(struct kmem_cach
 
 	/* Find the cache in the chain of caches. */
 	get_online_cpus();
-	mutex_lock(&cache_chain_mutex);
+	mutex_lock(&slab_mutex);
 	/*
 	 * the chain is never empty, cache_cache is never destroyed
 	 */
 	list_del(&cachep->list);
 	if (__cache_shrink(cachep)) {
 		slab_error(cachep, "Can't free all objects");
-		list_add(&cachep->list, &cache_chain);
-		mutex_unlock(&cache_chain_mutex);
+		list_add(&cachep->list, &slab_caches);
+		mutex_unlock(&slab_mutex);
 		put_online_cpus();
 		return;
 	}
@@ -2727,7 +2721,7 @@ void kmem_cache_destroy(struct kmem_cach
 		rcu_barrier();
 
 	__kmem_cache_destroy(cachep);
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 	put_online_cpus();
 }
 EXPORT_SYMBOL(kmem_cache_destroy);
@@ -4039,7 +4033,7 @@ static void do_ccupdate_local(void *info
 	new->new[smp_processor_id()] = old;
 }
 
-/* Always called with the cache_chain_mutex held */
+/* Always called with the slab_mutex held */
 static int do_tune_cpucache(struct kmem_cache *cachep, int limit,
 				int batchcount, int shared, gfp_t gfp)
 {
@@ -4083,7 +4077,7 @@ static int do_tune_cpucache(struct kmem_
 	return alloc_kmemlist(cachep, gfp);
 }
 
-/* Called with cache_chain_mutex held always */
+/* Called with slab_mutex held always */
 static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
 {
 	int err;
@@ -4185,11 +4179,11 @@ static void cache_reap(struct work_struc
 	int node = numa_mem_id();
 	struct delayed_work *work = to_delayed_work(w);
 
-	if (!mutex_trylock(&cache_chain_mutex))
+	if (!mutex_trylock(&slab_mutex))
 		/* Give up. Setup the next iteration. */
 		goto out;
 
-	list_for_each_entry(searchp, &cache_chain, list) {
+	list_for_each_entry(searchp, &slab_caches, list) {
 		check_irq_on();
 
 		/*
@@ -4227,7 +4221,7 @@ next:
 		cond_resched();
 	}
 	check_irq_on();
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 	next_reap_node();
 out:
 	/* Set up the next iteration */
@@ -4263,21 +4257,21 @@ static void *s_start(struct seq_file *m,
 {
 	loff_t n = *pos;
 
-	mutex_lock(&cache_chain_mutex);
+	mutex_lock(&slab_mutex);
 	if (!n)
 		print_slabinfo_header(m);
 
-	return seq_list_start(&cache_chain, *pos);
+	return seq_list_start(&slab_caches, *pos);
 }
 
 static void *s_next(struct seq_file *m, void *p, loff_t *pos)
 {
-	return seq_list_next(p, &cache_chain, pos);
+	return seq_list_next(p, &slab_caches, pos);
 }
 
 static void s_stop(struct seq_file *m, void *p)
 {
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 }
 
 static int s_show(struct seq_file *m, void *p)
@@ -4428,9 +4422,9 @@ static ssize_t slabinfo_write(struct fil
 		return -EINVAL;
 
 	/* Find the cache in the chain of caches. */
-	mutex_lock(&cache_chain_mutex);
+	mutex_lock(&slab_mutex);
 	res = -EINVAL;
-	list_for_each_entry(cachep, &cache_chain, list) {
+	list_for_each_entry(cachep, &slab_caches, list) {
 		if (!strcmp(cachep->name, kbuf)) {
 			if (limit < 1 || batchcount < 1 ||
 					batchcount > limit || shared < 0) {
@@ -4443,7 +4437,7 @@ static ssize_t slabinfo_write(struct fil
 			break;
 		}
 	}
-	mutex_unlock(&cache_chain_mutex);
+	mutex_unlock(&slab_mutex);
 	if (res >= 0)
 		res = count;
 	return res;
@@ -4466,8 +4460,8 @@ static const struct file_operations proc
 
 static void *leaks_start(struct seq_file *m, loff_t *pos)
 {
-	mutex_lock(&cache_chain_mutex);
-	return seq_list_start(&cache_chain, *pos);
+	mutex_lock(&slab_mutex);
+	return seq_list_start(&slab_caches, *pos);
 }
 
 static inline int add_caller(unsigned long *n, unsigned long v)
@@ -4566,17 +4560,17 @@ static int leaks_show(struct seq_file *m
 	name = cachep->name;
 	if (n[0] == n[1]) {
 		/* Increase the buffer size */
-		mutex_unlock(&cache_chain_mutex);
+		mutex_unlock(&slab_mutex);
 		m->private = kzalloc(n[0] * 4 * sizeof(unsigned long), GFP_KERNEL);
 		if (!m->private) {
 			/* Too bad, we are really out */
 			m->private = n;
-			mutex_lock(&cache_chain_mutex);
+			mutex_lock(&slab_mutex);
 			return -ENOMEM;
 		}
 		*(unsigned long *)m->private = n[0] * 2;
 		kfree(n);
-		mutex_lock(&cache_chain_mutex);
+		mutex_lock(&slab_mutex);
 		/* Now make sure this entry will be retried */
 		m->count = m->size;
 		return 0;
Index: linux-2.6/mm/slab.h
===================================================================
--- linux-2.6.orig/mm/slab.h	2012-05-11 09:43:53.448436526 -0500
+++ linux-2.6/mm/slab.h	2012-05-11 09:43:58.988436412 -0500
@@ -23,6 +23,10 @@ enum slab_state {
 
 extern enum slab_state slab_state;
 
+/* The slab cache mutex protects the management structures during changes */
+extern struct mutex slab_mutex;
+extern struct list_head slab_caches;
+
 struct kmem_cache *__kmem_cache_create (const char *name, size_t size,
 	size_t align, unsigned long flags, void (*ctor)(void *));
 
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-05-11 09:43:53.448436526 -0500
+++ linux-2.6/mm/slub.c	2012-05-11 09:43:58.988436412 -0500
@@ -36,13 +36,13 @@
 
 /*
  * Lock order:
- *   1. slub_lock (Global Semaphore)
+ *   1. slab_mutex (Global Mutex)
  *   2. node->list_lock
  *   3. slab_lock(page) (Only on some arches and for debugging)
  *
- *   slub_lock
+ *   slab_mutex
  *
- *   The role of the slub_lock is to protect the list of all the slabs
+ *   The role of the slab_mutex is to protect the list of all the slabs
  *   and to synchronize major metadata changes to slab cache structures.
  *
  *   The slab_lock is only used for debugging and on arches that do not
@@ -183,10 +183,6 @@ static int kmem_size = sizeof(struct kme
 static struct notifier_block slab_notifier;
 #endif
 
-/* A list of all slab caches on the system */
-static DECLARE_RWSEM(slub_lock);
-static LIST_HEAD(slab_caches);
-
 /*
  * Tracking user of a slab.
  */
@@ -3178,11 +3174,11 @@ static inline int kmem_cache_close(struc
  */
 void kmem_cache_destroy(struct kmem_cache *s)
 {
-	down_write(&slub_lock);
+	mutex_lock(&slab_mutex);
 	s->refcount--;
 	if (!s->refcount) {
 		list_del(&s->list);
-		up_write(&slub_lock);
+		mutex_unlock(&slab_mutex);
 		if (kmem_cache_close(s)) {
 			printk(KERN_ERR "SLUB %s: %s called for cache that "
 				"still has objects.\n", s->name, __func__);
@@ -3192,7 +3188,7 @@ void kmem_cache_destroy(struct kmem_cach
 			rcu_barrier();
 		sysfs_slab_remove(s);
 	} else
-		up_write(&slub_lock);
+		mutex_unlock(&slab_mutex);
 }
 EXPORT_SYMBOL(kmem_cache_destroy);
 
@@ -3254,7 +3250,7 @@ static struct kmem_cache *__init create_
 
 	/*
 	 * This function is called with IRQs disabled during early-boot on
-	 * single CPU so there's no need to take slub_lock here.
+	 * single CPU so there's no need to take slab_mutex here.
 	 */
 	if (!kmem_cache_open(s, name, size, ARCH_KMALLOC_MINALIGN,
 								flags, NULL))
@@ -3539,10 +3535,10 @@ static int slab_mem_going_offline_callba
 {
 	struct kmem_cache *s;
 
-	down_read(&slub_lock);
+	mutex_lock(&slab_mutex);
 	list_for_each_entry(s, &slab_caches, list)
 		kmem_cache_shrink(s);
-	up_read(&slub_lock);
+	mutex_unlock(&slab_mutex);
 
 	return 0;
 }
@@ -3563,7 +3559,7 @@ static void slab_mem_offline_callback(vo
 	if (offline_node < 0)
 		return;
 
-	down_read(&slub_lock);
+	mutex_lock(&slab_mutex);
 	list_for_each_entry(s, &slab_caches, list) {
 		n = get_node(s, offline_node);
 		if (n) {
@@ -3579,7 +3575,7 @@ static void slab_mem_offline_callback(vo
 			kmem_cache_free(kmem_cache_node, n);
 		}
 	}
-	up_read(&slub_lock);
+	mutex_unlock(&slab_mutex);
 }
 
 static int slab_mem_going_online_callback(void *arg)
@@ -3602,7 +3598,7 @@ static int slab_mem_going_online_callbac
 	 * allocate a kmem_cache_node structure in order to bring the node
 	 * online.
 	 */
-	down_read(&slub_lock);
+	mutex_lock(&slab_mutex);
 	list_for_each_entry(s, &slab_caches, list) {
 		/*
 		 * XXX: kmem_cache_alloc_node will fallback to other nodes
@@ -3618,7 +3614,7 @@ static int slab_mem_going_online_callbac
 		s->node[nid] = n;
 	}
 out:
-	up_read(&slub_lock);
+	mutex_unlock(&slab_mutex);
 	return ret;
 }
 
@@ -3916,7 +3912,7 @@ struct kmem_cache *__kmem_cache_create(c
 	struct kmem_cache *s;
 	char *n;
 
-	down_write(&slub_lock);
+	mutex_lock(&slab_mutex);
 	s = find_mergeable(size, align, flags, name, ctor);
 	if (s) {
 		s->refcount++;
@@ -3931,7 +3927,7 @@ struct kmem_cache *__kmem_cache_create(c
 			s->refcount--;
 			goto err;
 		}
-		up_write(&slub_lock);
+		mutex_unlock(&slab_mutex);
 		return s;
 	}
 
@@ -3944,9 +3940,9 @@ struct kmem_cache *__kmem_cache_create(c
 		if (kmem_cache_open(s, n,
 				size, align, flags, ctor)) {
 			list_add(&s->list, &slab_caches);
-			up_write(&slub_lock);
+			mutex_unlock(&slab_mutex);
 			if (sysfs_slab_add(s)) {
-				down_write(&slub_lock);
+				mutex_lock(&slab_mutex);
 				list_del(&s->list);
 				kfree(n);
 				kfree(s);
@@ -3958,7 +3954,7 @@ struct kmem_cache *__kmem_cache_create(c
 		kfree(s);
 	}
 err:
-	up_write(&slub_lock);
+	mutex_unlock(&slab_mutex);
 	return s;
 }
 
@@ -3979,13 +3975,13 @@ static int __cpuinit slab_cpuup_callback
 	case CPU_UP_CANCELED_FROZEN:
 	case CPU_DEAD:
 	case CPU_DEAD_FROZEN:
-		down_read(&slub_lock);
+		mutex_lock(&slab_mutex);
 		list_for_each_entry(s, &slab_caches, list) {
 			local_irq_save(flags);
 			__flush_cpu_slab(s, cpu);
 			local_irq_restore(flags);
 		}
-		up_read(&slub_lock);
+		mutex_unlock(&slab_mutex);
 		break;
 	default:
 		break;
@@ -5360,11 +5356,11 @@ static int __init slab_sysfs_init(void)
 	struct kmem_cache *s;
 	int err;
 
-	down_write(&slub_lock);
+	mutex_lock(&slab_mutex);
 
 	slab_kset = kset_create_and_add("slab", &slab_uevent_ops, kernel_kobj);
 	if (!slab_kset) {
-		up_write(&slub_lock);
+		mutex_unlock(&slab_mutex);
 		printk(KERN_ERR "Cannot register slab subsystem.\n");
 		return -ENOSYS;
 	}
@@ -5389,7 +5385,7 @@ static int __init slab_sysfs_init(void)
 		kfree(al);
 	}
 
-	up_write(&slub_lock);
+	mutex_unlock(&slab_mutex);
 	resiliency_test();
 	return 0;
 }
@@ -5415,7 +5411,7 @@ static void *s_start(struct seq_file *m,
 {
 	loff_t n = *pos;
 
-	down_read(&slub_lock);
+	mutex_lock(&slab_mutex);
 	if (!n)
 		print_slabinfo_header(m);
 
@@ -5429,7 +5425,7 @@ static void *s_next(struct seq_file *m,
 
 static void s_stop(struct seq_file *m, void *p)
 {
-	up_read(&slub_lock);
+	mutex_unlock(&slab_mutex);
 }
 
 static int s_show(struct seq_file *m, void *p)
Index: linux-2.6/mm/slab_common.c
===================================================================
--- linux-2.6.orig/mm/slab_common.c	2012-05-11 09:43:53.448436526 -0500
+++ linux-2.6/mm/slab_common.c	2012-05-11 09:43:58.988436412 -0500
@@ -19,6 +19,8 @@
 #include "slab.h"
 
 enum slab_state slab_state;
+LIST_HEAD(slab_caches);
+DEFINE_MUTEX(slab_mutex);
 
 /*
  * kmem_cache_create - Create a cache.

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Re: [RFC] Common code 06/12] slabs: Use a common mutex definition

[JoonSoo Kim]

2012/5/19 Christoph Lameter <cl@linux.com>:
> Use the mutex definition from SLAB and make it the common way to take a sleeping lock.
>
> This has the effect of using a mutex instead of a rw semaphore for SLUB.
>
> SLOB gains the use of a mutex for kmem_cache_create serialization.
> Not needed now but SLOB may acquire some more features later (like slabinfo
> / sysfs support) through the expansion of the common code that will
> need this.
>
> Reviewed-by: Glauber Costa <glommer@parallels.com>
> Signed-off-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>

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[RFC] Common code 07/12] slabs: Move kmem_cache_create mutex handling to common code

[Christoph Lameter]

[-- Attachment #1: move_mutex_to_common --]
[-- Type: text/plain, Size: 5658 bytes --]

Move the mutex handling into the common kmem_cache_create()
function.

Then we can also move more checks out of SLAB's kmem_cache_create()
into the common code.

Reviewed-by: Glauber Costa <glommer@parallels.com>
Signed-off-by: Christoph Lameter <cl@linux.com>

---
 mm/slab.c        |   52 +---------------------------------------------------
 mm/slab_common.c |   41 ++++++++++++++++++++++++++++++++++++++++-
 mm/slub.c        |   30 ++++++++++++++----------------
 3 files changed, 55 insertions(+), 68 deletions(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-05-14 08:51:51.819130415 -0500
+++ linux-2.6/mm/slab.c	2012-05-14 08:52:41.707129382 -0500
@@ -2252,55 +2252,10 @@ __kmem_cache_create (const char *name, s
 	unsigned long flags, void (*ctor)(void *))
 {
 	size_t left_over, slab_size, ralign;
-	struct kmem_cache *cachep = NULL, *pc;
+	struct kmem_cache *cachep = NULL;
 	gfp_t gfp;
 
-	/*
-	 * Sanity checks... these are all serious usage bugs.
-	 */
-	if (!name || in_interrupt() || (size < BYTES_PER_WORD) ||
-	    size > KMALLOC_MAX_SIZE) {
-		printk(KERN_ERR "%s: Early error in slab %s\n", __func__,
-				name);
-		BUG();
-	}
-
-	/*
-	 * We use cache_chain_mutex to ensure a consistent view of
-	 * cpu_online_mask as well.  Please see cpuup_callback
-	 */
-	if (slab_is_available()) {
-		get_online_cpus();
-		mutex_lock(&cache_chain_mutex);
-	}
-
-	list_for_each_entry(pc, &cache_chain, list) {
-		char tmp;
-		int res;
-
-		/*
-		 * This happens when the module gets unloaded and doesn't
-		 * destroy its slab cache and no-one else reuses the vmalloc
-		 * area of the module.  Print a warning.
-		 */
-		res = probe_kernel_address(pc->name, tmp);
-		if (res) {
-			printk(KERN_ERR
-			       "SLAB: cache with size %d has lost its name\n",
-			       pc->buffer_size);
-			continue;
-		}
-
-		if (!strcmp(pc->name, name)) {
-			printk(KERN_ERR
-			       "kmem_cache_create: duplicate cache %s\n", name);
-			dump_stack();
-			goto oops;
-		}
-	}
-
 #if DEBUG
-	WARN_ON(strchr(name, ' '));	/* It confuses parsers */
 #if FORCED_DEBUG
 	/*
 	 * Enable redzoning and last user accounting, except for caches with
@@ -2518,11 +2473,6 @@ __kmem_cache_create (const char *name, s
 
 	/* cache setup completed, link it into the list */
 	list_add(&cachep->list, &slab_caches);
-oops:
-	if (slab_is_available()) {
-		mutex_unlock(&slab_mutex);
-		put_online_cpus();
-	}
 	return cachep;
 }
 
Index: linux-2.6/mm/slab_common.c
===================================================================
--- linux-2.6.orig/mm/slab_common.c	2012-05-14 08:51:51.839130415 -0500
+++ linux-2.6/mm/slab_common.c	2012-05-14 08:52:11.407130009 -0500
@@ -11,7 +11,8 @@
 #include <linux/memory.h>
 #include <linux/compiler.h>
 #include <linux/module.h>
-
+#include <linux/cpu.h>
+#include <linux/uaccess.h>
 #include <asm/cacheflush.h>
 #include <asm/tlbflush.h>
 #include <asm/page.h>
@@ -61,8 +62,46 @@ struct kmem_cache *kmem_cache_create(con
 	}
 #endif
 
+	get_online_cpus();
+	mutex_lock(&slab_mutex);
+
+#ifdef CONFIG_DEBUG_VM
+	list_for_each_entry(s, &slab_caches, list) {
+		char tmp;
+		int res;
+
+		/*
+		 * This happens when the module gets unloaded and doesn't
+		 * destroy its slab cache and no-one else reuses the vmalloc
+		 * area of the module.  Print a warning.
+		 */
+		res = probe_kernel_address(s->name, tmp);
+		if (res) {
+			printk(KERN_ERR
+			       "Slab cache with size %d has lost its name\n",
+			       s->size);
+			continue;
+		}
+
+		if (!strcmp(s->name, name)) {
+			printk(KERN_ERR "kmem_cache_create(%s): Cache name"
+				" already exists.\n",
+				name);
+			dump_stack();
+			s = NULL;
+			goto oops;
+		}
+	}
+
+	WARN_ON(strchr(name, ' '));	/* It confuses parsers */
+#endif
+
 	s = __kmem_cache_create(name, size, align, flags, ctor);
 
+oops:
+	mutex_unlock(&slab_mutex);
+	put_online_cpus();
+
 out:
 	if (!s && (flags & SLAB_PANIC))
 		panic("kmem_cache_create: Failed to create slab '%s'\n", name);
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-05-14 08:51:51.827130415 -0500
+++ linux-2.6/mm/slub.c	2012-05-14 08:52:11.411130009 -0500
@@ -3912,7 +3912,6 @@ struct kmem_cache *__kmem_cache_create(c
 	struct kmem_cache *s;
 	char *n;
 
-	mutex_lock(&slab_mutex);
 	s = find_mergeable(size, align, flags, name, ctor);
 	if (s) {
 		s->refcount++;
@@ -3925,37 +3924,36 @@ struct kmem_cache *__kmem_cache_create(c
 
 		if (sysfs_slab_alias(s, name)) {
 			s->refcount--;
-			goto err;
+			return NULL;
 		}
-		mutex_unlock(&slab_mutex);
 		return s;
 	}
 
 	n = kstrdup(name, GFP_KERNEL);
 	if (!n)
-		goto err;
+		return NULL;
 
 	s = kmalloc(kmem_size, GFP_KERNEL);
 	if (s) {
 		if (kmem_cache_open(s, n,
 				size, align, flags, ctor)) {
+			int r;
+
 			list_add(&s->list, &slab_caches);
 			mutex_unlock(&slab_mutex);
-			if (sysfs_slab_add(s)) {
-				mutex_lock(&slab_mutex);
-				list_del(&s->list);
-				kfree(n);
-				kfree(s);
-				goto err;
-			}
-			return s;
+			r = sysfs_slab_add(s);
+			mutex_lock(&slab_mutex);
+
+			if (!r)
+				return s;
+
+			list_del(&s->list);
+			kmem_cache_close(s);
 		}
-		kfree(n);
 		kfree(s);
 	}
-err:
-	mutex_unlock(&slab_mutex);
-	return s;
+	kfree(n);
+	return NULL;
 }
 
 #ifdef CONFIG_SMP

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Re: [RFC] Common code 07/12] slabs: Move kmem_cache_create mutex handling to common code

[JoonSoo Kim]

2012/5/19 Christoph Lameter <cl@linux.com>:
> Move the mutex handling into the common kmem_cache_create()
> function.
>
>                        list_add(&s->list, &slab_caches);
>                        mutex_unlock(&slab_mutex);
> -                       if (sysfs_slab_add(s)) {
> -                               mutex_lock(&slab_mutex);
> -                               list_del(&s->list);
> -                               kfree(n);
> -                               kfree(s);
> -                               goto err;
> -                       }
> -                       return s;
> +                       r = sysfs_slab_add(s);
> +                       mutex_lock(&slab_mutex);
> +
> +                       if (!r)
> +                               return s;
> +
> +                       list_del(&s->list);
> +                       kmem_cache_close(s);
>                }
> -               kfree(n);
>                kfree(s);
>        }

Before this patch is applied, can we move calling 'sysfs_slab_add' to
common code
for removing slab_mutex entirely in kmem_cache_create?

Re: [RFC] Common code 07/12] slabs: Move kmem_cache_create mutex handling to common code

[Christoph Lameter]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 1330 bytes --]

On Wed, 23 May 2012, JoonSoo Kim wrote:

> 2012/5/19 Christoph Lameter <cl@linux.com>:
> > Move the mutex handling into the common kmem_cache_create()
> > function.
> >
> >                        list_add(&s->list, &slab_caches);
> >                        mutex_unlock(&slab_mutex);
> > -                       if (sysfs_slab_add(s)) {
> > -                               mutex_lock(&slab_mutex);
> > -                               list_del(&s->list);
> > -                               kfree(n);
> > -                               kfree(s);
> > -                               goto err;
> > -                       }
> > -                       return s;
> > +                       r = sysfs_slab_add(s);
> > +                       mutex_lock(&slab_mutex);
> > +
> > +                       if (!r)
> > +                               return s;
> > +
> > +                       list_del(&s->list);
> > +                       kmem_cache_close(s);
> >                }
> > -               kfree(n);
> >                kfree(s);
> >        }
>
> Before this patch is applied, can we move calling 'sysfs_slab_add' to
> common code
> for removing slab_mutex entirely in kmem_cache_create?

Hmmm... its difficult to do that before this patch since sysfs_slab_add
requires dropping the mutex.

[RFC] Common code 09/12] slabs: Extract a common function for kmem_cache_destroy

[Christoph Lameter]

[-- Attachment #1: kmem_cache_destroy --]
[-- Type: text/plain, Size: 6831 bytes --]

kmem_cache_destroy does basically the same in all allocators.

Extract common code which is easy since we already have common mutex handling.

Signed-off-by: Christoph Lameter <cl@linux.com>


---
 mm/slab.c        |   55 +++----------------------------------------------------
 mm/slab.h        |    4 +++-
 mm/slab_common.c |   22 ++++++++++++++++++++++
 mm/slob.c        |   11 +++++++----
 mm/slub.c        |   29 ++++++++---------------------
 5 files changed, 43 insertions(+), 78 deletions(-)

Index: linux-2.6/mm/slab_common.c
===================================================================
--- linux-2.6.orig/mm/slab_common.c	2012-05-17 03:31:18.246158143 -0500
+++ linux-2.6/mm/slab_common.c	2012-05-17 05:16:20.726027559 -0500
@@ -117,6 +117,28 @@ out:
 }
 EXPORT_SYMBOL(kmem_cache_create);
 
+void kmem_cache_destroy(struct kmem_cache *s)
+{
+	get_online_cpus();
+	mutex_lock(&slab_mutex);
+	list_del(&s->list);
+
+	if (!__kmem_cache_shutdown(s)) {
+		if (s->flags & SLAB_DESTROY_BY_RCU)
+			rcu_barrier();
+
+		__kmem_cache_destroy(s);
+	} else {
+		list_add(&s->list, &slab_caches);
+		printk(KERN_ERR "kmem_cache_destroy %s: Slab cache still has objects\n",
+			s->name);
+		dump_stack();
+	}
+	mutex_unlock(&slab_mutex);
+	put_online_cpus();
+}
+EXPORT_SYMBOL(kmem_cache_destroy);
+
 int slab_is_available(void)
 {
 	return slab_state >= UP;
Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-05-17 03:30:39.154158963 -0500
+++ linux-2.6/mm/slab.c	2012-05-17 05:16:20.726027559 -0500
@@ -804,16 +804,6 @@ static void cache_estimate(unsigned long
 	*left_over = slab_size - nr_objs*buffer_size - mgmt_size;
 }
 
-#define slab_error(cachep, msg) __slab_error(__func__, cachep, msg)
-
-static void __slab_error(const char *function, struct kmem_cache *cachep,
-			char *msg)
-{
-	printk(KERN_ERR "slab error in %s(): cache `%s': %s\n",
-	       function, cachep->name, msg);
-	dump_stack();
-}
-
 /*
  * By default on NUMA we use alien caches to stage the freeing of
  * objects allocated from other nodes. This causes massive memory
@@ -2079,7 +2069,7 @@ static void slab_destroy(struct kmem_cac
 	}
 }
 
-static void __kmem_cache_destroy(struct kmem_cache *cachep)
+void __kmem_cache_destroy(struct kmem_cache *cachep)
 {
 	int i;
 	struct kmem_list3 *l3;
@@ -2635,49 +2625,10 @@ int kmem_cache_shrink(struct kmem_cache
 }
 EXPORT_SYMBOL(kmem_cache_shrink);
 
-/**
- * kmem_cache_destroy - delete a cache
- * @cachep: the cache to destroy
- *
- * Remove a &struct kmem_cache object from the slab cache.
- *
- * It is expected this function will be called by a module when it is
- * unloaded.  This will remove the cache completely, and avoid a duplicate
- * cache being allocated each time a module is loaded and unloaded, if the
- * module doesn't have persistent in-kernel storage across loads and unloads.
- *
- * The cache must be empty before calling this function.
- *
- * The caller must guarantee that no one will allocate memory from the cache
- * during the kmem_cache_destroy().
- */
-void kmem_cache_destroy(struct kmem_cache *cachep)
+int __kmem_cache_shutdown(struct kmem_cache *cachep)
 {
-	BUG_ON(!cachep || in_interrupt());
-
-	/* Find the cache in the chain of caches. */
-	get_online_cpus();
-	mutex_lock(&slab_mutex);
-	/*
-	 * the chain is never empty, cache_cache is never destroyed
-	 */
-	list_del(&cachep->list);
-	if (__cache_shrink(cachep)) {
-		slab_error(cachep, "Can't free all objects");
-		list_add(&cachep->list, &slab_caches);
-		mutex_unlock(&slab_mutex);
-		put_online_cpus();
-		return;
-	}
-
-	if (unlikely(cachep->flags & SLAB_DESTROY_BY_RCU))
-		rcu_barrier();
-
-	__kmem_cache_destroy(cachep);
-	mutex_unlock(&slab_mutex);
-	put_online_cpus();
+	return __cache_shrink(cachep);
 }
-EXPORT_SYMBOL(kmem_cache_destroy);
 
 /*
  * Get the memory for a slab management obj.
Index: linux-2.6/mm/slab.h
===================================================================
--- linux-2.6.orig/mm/slab.h	2012-05-17 03:30:15.986159442 -0500
+++ linux-2.6/mm/slab.h	2012-05-17 05:16:20.726027559 -0500
@@ -30,5 +30,7 @@ extern struct list_head slab_caches;
 struct kmem_cache *__kmem_cache_create (const char *name, size_t size,
 	size_t align, unsigned long flags, void (*ctor)(void *));
 
-#endif
+int __kmem_cache_shutdown(struct kmem_cache *);
+void __kmem_cache_destroy(struct kmem_cache *);
 
+#endif
Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2012-05-17 03:30:00.018159771 -0500
+++ linux-2.6/mm/slob.c	2012-05-17 05:16:20.726027559 -0500
@@ -570,14 +570,11 @@ struct kmem_cache *__kmem_cache_create(c
 	return c;
 }
 
-void kmem_cache_destroy(struct kmem_cache *c)
+void __kmem_cache_destroy(struct kmem_cache *c)
 {
 	kmemleak_free(c);
-	if (c->flags & SLAB_DESTROY_BY_RCU)
-		rcu_barrier();
 	slob_free(c, sizeof(struct kmem_cache));
 }
-EXPORT_SYMBOL(kmem_cache_destroy);
 
 void *kmem_cache_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
 {
@@ -645,6 +642,12 @@ unsigned int kmem_cache_size(struct kmem
 }
 EXPORT_SYMBOL(kmem_cache_size);
 
+int __kmem_cache_shutdown(struct kmem_cache *c)
+{
+	/* No way to check for remaining objects */
+	return 0;
+}
+
 int kmem_cache_shrink(struct kmem_cache *d)
 {
 	return 0;
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-05-17 03:30:39.154158963 -0500
+++ linux-2.6/mm/slub.c	2012-05-17 05:16:20.726027559 -0500
@@ -3168,29 +3168,16 @@ static inline int kmem_cache_close(struc
 	return 0;
 }
 
-/*
- * Close a cache and release the kmem_cache structure
- * (must be used for caches created using kmem_cache_create)
- */
-void kmem_cache_destroy(struct kmem_cache *s)
+int __kmem_cache_shutdown(struct kmem_cache *s)
 {
-	mutex_lock(&slab_mutex);
-	s->refcount--;
-	if (!s->refcount) {
-		list_del(&s->list);
-		mutex_unlock(&slab_mutex);
-		if (kmem_cache_close(s)) {
-			printk(KERN_ERR "SLUB %s: %s called for cache that "
-				"still has objects.\n", s->name, __func__);
-			dump_stack();
-		}
-		if (s->flags & SLAB_DESTROY_BY_RCU)
-			rcu_barrier();
-		sysfs_slab_remove(s);
-	} else
-		mutex_unlock(&slab_mutex);
+	return kmem_cache_close(s);
+}
+
+void __kmem_cache_destroy(struct kmem_cache *s)
+{
+	kfree(s);
+	sysfs_slab_remove(s);
 }
-EXPORT_SYMBOL(kmem_cache_destroy);
 
 /********************************************************************
  *		Kmalloc subsystem

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Re: [RFC] Common code 09/12] slabs: Extract a common function for kmem_cache_destroy

[Glauber Costa]

On 05/18/2012 08:19 PM, Christoph Lameter wrote:
> -/*
> - * Close a cache and release the kmem_cache structure
> - * (must be used for caches created using kmem_cache_create)
> - */
> -void kmem_cache_destroy(struct kmem_cache *s)
> +int __kmem_cache_shutdown(struct kmem_cache *s)
>   {
> -	mutex_lock(&slab_mutex);
> -	s->refcount--;
> -	if (!s->refcount) {
> -		list_del(&s->list);
> -		mutex_unlock(&slab_mutex);
> -		if (kmem_cache_close(s)) {
> -			printk(KERN_ERR "SLUB %s: %s called for cache that "
> -				"still has objects.\n", s->name, __func__);
> -			dump_stack();
> -		}
> -		if (s->flags&  SLAB_DESTROY_BY_RCU)
> -			rcu_barrier();
> -		sysfs_slab_remove(s);
> -	} else
> -		mutex_unlock(&slab_mutex);
> +	return kmem_cache_close(s);
> +}

Something doesn't smell right here. It seems that we're now closing the 
caches right away. That wasn't the case before, nor it should be: For 
aliases, we should only decrease the refcount.

So unless I am missing something, it seems to me the correct code would be:

s->refcount--;
if (!s->refcount)
     return kmem_cache_close;
return 0;

And while we're on that, that makes the sequence list_del() -> if it 
fails -> list_add() in the common kmem_cache_destroy a bit clumsy. 
Aliases will be re-added to the list quite frequently. Not that it is a 
big problem, but still...

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Re: [RFC] Common code 09/12] slabs: Extract a common function for kmem_cache_destroy

[Christoph Lameter]

On Mon, 21 May 2012, Glauber Costa wrote:

> Something doesn't smell right here. It seems that we're now closing the caches
> right away. That wasn't the case before, nor it should be: For aliases, we
> should only decrease the refcount.

Why not? The only thing that could be left pending are frees to the page
allocator. We can do those frees with just the kmem_cache structure
hanging on for awhile.

> So unless I am missing something, it seems to me the correct code would be:
>
> s->refcount--;
> if (!s->refcount)
>     return kmem_cache_close;
> return 0;
>
> And while we're on that, that makes the sequence list_del() -> if it fails ->
> list_add() in the common kmem_cache_destroy a bit clumsy. Aliases will be
> re-added to the list quite frequently. Not that it is a big problem, but
> still...

True but this is just an intermediate step. Ultimately the series will
move sysfs processing into slab_common.c and then this is going away.

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Re: [RFC] Common code 09/12] slabs: Extract a common function for kmem_cache_destroy

[Glauber Costa]

On 05/21/2012 10:13 PM, Christoph Lameter wrote:
>> So unless I am missing something, it seems to me the correct code would be:
>> >
>> >  s->refcount--;
>> >  if (!s->refcount)
>> >       return kmem_cache_close;
>> >  return 0;
>> >
>> >  And while we're on that, that makes the sequence list_del() ->  if it fails ->
>> >  list_add() in the common kmem_cache_destroy a bit clumsy. Aliases will be
>> >  re-added to the list quite frequently. Not that it is a big problem, but
>> >  still...
> True but this is just an intermediate step. Ultimately the series will
> move sysfs processing into slab_common.c and then this is going away.
>

But until then, people bisecting into this patch will find a broken 
state, right?

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Re: [RFC] Common code 09/12] slabs: Extract a common function for kmem_cache_destroy

[Christoph Lameter]

On Mon, 21 May 2012, Glauber Costa wrote:

> On 05/21/2012 10:13 PM, Christoph Lameter wrote:
> > > So unless I am missing something, it seems to me the correct code would
> > > be:
> > > >
> > > >  s->refcount--;
> > > >  if (!s->refcount)
> > > >       return kmem_cache_close;
> > > >  return 0;
> > > >
> > > >  And while we're on that, that makes the sequence list_del() ->  if it
> > > fails ->
> > > >  list_add() in the common kmem_cache_destroy a bit clumsy. Aliases will
> > > be
> > > >  re-added to the list quite frequently. Not that it is a big problem,
> > > but
> > > >  still...
> > True but this is just an intermediate step. Ultimately the series will
> > move sysfs processing into slab_common.c and then this is going away.
> >
>
> But until then, people bisecting into this patch will find a broken state,
> right?

I thought this was about clumsiness not breakage. What is broken? Aliases
do not affect the call to __kmem_cache_shutdown. Its only called if there
are no aliases anymore.


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Re: [RFC] Common code 09/12] slabs: Extract a common function for kmem_cache_destroy

[Glauber Costa]

On 05/21/2012 11:31 PM, Christoph Lameter wrote:
>> >  But until then, people bisecting into this patch will find a broken state,
>> >  right?
> I thought this was about clumsiness not breakage. What is broken? Aliases
> do not affect the call to __kmem_cache_shutdown. Its only called if there
> are no aliases anymore.
>
>
Well, that I missed - might be my fault. Can you point me to the exact 
point where you guarantee aliases are ignored, just so we're in the same 
page?

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Re: [RFC] Common code 09/12] slabs: Extract a common function for kmem_cache_destroy

[Christoph Lameter]

On Tue, 22 May 2012, Glauber Costa wrote:

> On 05/21/2012 11:31 PM, Christoph Lameter wrote:
> > > >  But until then, people bisecting into this patch will find a broken
> > > state,
> > > >  right?
> > I thought this was about clumsiness not breakage. What is broken? Aliases
> > do not affect the call to __kmem_cache_shutdown. Its only called if there
> > are no aliases anymore.
> >
> >
> Well, that I missed - might be my fault. Can you point me to the exact point
> where you guarantee aliases are ignored, just so we're in the same page?

Look at the refcount checks. Aliases create additional refcounts.
kmem_cache_shutdown is only called if the refcount reaches zero.

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Re: [RFC] Common code 09/12] slabs: Extract a common function for kmem_cache_destroy

[JoonSoo Kim]

> +void __kmem_cache_destroy(struct kmem_cache *s)
> +{
> +       kfree(s);
> +       sysfs_slab_remove(s);
>  }
> -EXPORT_SYMBOL(kmem_cache_destroy);

sysfs_slab_remove(s) -> kfree(s) is correct order.
If not, it will break the system.

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Re: [RFC] Common code 09/12] slabs: Extract a common function for kmem_cache_destroy

[Christoph Lameter]

[-- Attachment #1: Type: TEXT/PLAIN, Size: 322 bytes --]

On Thu, 24 May 2012, JoonSoo Kim wrote:

> > +void __kmem_cache_destroy(struct kmem_cache *s)
> > +{
> > +       kfree(s);
> > +       sysfs_slab_remove(s);
> >  }
> > -EXPORT_SYMBOL(kmem_cache_destroy);
>
> sysfs_slab_remove(s) -> kfree(s) is correct order.
> If not, it will break the system.

Ok. Changed.

[RFC] Common code 10/12] sl[aub]: Use the name "kmem_cache" for the slab cache with the kmem_cache structure.

[Christoph Lameter]

[-- Attachment #1: common_kmem_cache_name --]
[-- Type: text/plain, Size: 9594 bytes --]

Make all allocators use the "kmem_cache" slabname for the "kmem_cache" structure.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 mm/slab.c        |   72 ++++++++++++++++++++++++++++---------------------------
 mm/slab.h        |    6 ++++
 mm/slab_common.c |    1 
 mm/slob.c        |    3 ++
 mm/slub.c        |    2 -
 5 files changed, 47 insertions(+), 37 deletions(-)

Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-05-17 09:31:42.845710077 -0500
+++ linux-2.6/mm/slab.c	2012-05-17 09:33:58.689707249 -0500
@@ -579,9 +579,9 @@ static struct arraycache_init initarray_
     { {0, BOOT_CPUCACHE_ENTRIES, 1, 0} };
 
 /* internal cache of cache description objs */
-static struct kmem_list3 *cache_cache_nodelists[MAX_NUMNODES];
-static struct kmem_cache cache_cache = {
-	.nodelists = cache_cache_nodelists,
+static struct kmem_list3 *kmem_cache_nodelists[MAX_NUMNODES];
+static struct kmem_cache kmem_cache_boot = {
+	.nodelists = kmem_cache_nodelists,
 	.batchcount = 1,
 	.limit = BOOT_CPUCACHE_ENTRIES,
 	.shared = 1,
@@ -1467,15 +1467,17 @@ void __init kmem_cache_init(void)
 	int order;
 	int node;
 
+	kmem_cache = &kmem_cache_boot;
+
 	if (num_possible_nodes() == 1)
 		use_alien_caches = 0;
 
 	for (i = 0; i < NUM_INIT_LISTS; i++) {
 		kmem_list3_init(&initkmem_list3[i]);
 		if (i < MAX_NUMNODES)
-			cache_cache.nodelists[i] = NULL;
+			kmem_cache->nodelists[i] = NULL;
 	}
-	set_up_list3s(&cache_cache, CACHE_CACHE);
+	set_up_list3s(kmem_cache, CACHE_CACHE);
 
 	/*
 	 * Fragmentation resistance on low memory - only use bigger
@@ -1487,9 +1489,9 @@ void __init kmem_cache_init(void)
 
 	/* Bootstrap is tricky, because several objects are allocated
 	 * from caches that do not exist yet:
-	 * 1) initialize the cache_cache cache: it contains the struct
-	 *    kmem_cache structures of all caches, except cache_cache itself:
-	 *    cache_cache is statically allocated.
+	 * 1) initialize the kmem_cache cache: it contains the struct
+	 *    kmem_cache structures of all caches, except kmem_cache itself:
+	 *    kmem_cache is statically allocated.
 	 *    Initially an __init data area is used for the head array and the
 	 *    kmem_list3 structures, it's replaced with a kmalloc allocated
 	 *    array at the end of the bootstrap.
@@ -1498,45 +1500,45 @@ void __init kmem_cache_init(void)
 	 *    An __init data area is used for the head array.
 	 * 3) Create the remaining kmalloc caches, with minimally sized
 	 *    head arrays.
-	 * 4) Replace the __init data head arrays for cache_cache and the first
+	 * 4) Replace the __init data head arrays for kmem_cache and the first
 	 *    kmalloc cache with kmalloc allocated arrays.
-	 * 5) Replace the __init data for kmem_list3 for cache_cache and
+	 * 5) Replace the __init data for kmem_list3 for kmem_cache and
 	 *    the other cache's with kmalloc allocated memory.
 	 * 6) Resize the head arrays of the kmalloc caches to their final sizes.
 	 */
 
 	node = numa_mem_id();
 
-	/* 1) create the cache_cache */
+	/* 1) create the kmem_cache */
 	INIT_LIST_HEAD(&slab_caches);
-	list_add(&cache_cache.list, &slab_caches);
-	cache_cache.colour_off = cache_line_size();
-	cache_cache.array[smp_processor_id()] = &initarray_cache.cache;
-	cache_cache.nodelists[node] = &initkmem_list3[CACHE_CACHE + node];
+	list_add(&kmem_cache->list, &slab_caches);
+	kmem_cache->colour_off = cache_line_size();
+	kmem_cache->array[smp_processor_id()] = &initarray_cache.cache;
+	kmem_cache->nodelists[node] = &initkmem_list3[CACHE_CACHE + node];
 
 	/*
 	 * struct kmem_cache size depends on nr_node_ids & nr_cpu_ids
 	 */
-	cache_cache.buffer_size = offsetof(struct kmem_cache, array[nr_cpu_ids]) +
+	kmem_cache->buffer_size = offsetof(struct kmem_cache, array[nr_cpu_ids]) +
 				  nr_node_ids * sizeof(struct kmem_list3 *);
 #if DEBUG
-	cache_cache.obj_size = cache_cache.buffer_size;
+	kmem_cache->obj_size = kmem_cache->buffer_size;
 #endif
-	cache_cache.buffer_size = ALIGN(cache_cache.buffer_size,
+	kmem_cache->buffer_size = ALIGN(kmem_cache->buffer_size,
 					cache_line_size());
-	cache_cache.reciprocal_buffer_size =
-		reciprocal_value(cache_cache.buffer_size);
+	kmem_cache->reciprocal_buffer_size =
+		reciprocal_value(kmem_cache->buffer_size);
 
 	for (order = 0; order < MAX_ORDER; order++) {
-		cache_estimate(order, cache_cache.buffer_size,
-			cache_line_size(), 0, &left_over, &cache_cache.num);
-		if (cache_cache.num)
+		cache_estimate(order, kmem_cache->buffer_size,
+			cache_line_size(), 0, &left_over, &kmem_cache->num);
+		if (kmem_cache->num)
 			break;
 	}
-	BUG_ON(!cache_cache.num);
-	cache_cache.gfporder = order;
-	cache_cache.colour = left_over / cache_cache.colour_off;
-	cache_cache.slab_size = ALIGN(cache_cache.num * sizeof(kmem_bufctl_t) +
+	BUG_ON(!kmem_cache->num);
+	kmem_cache->gfporder = order;
+	kmem_cache->colour = left_over / kmem_cache->colour_off;
+	kmem_cache->slab_size = ALIGN(kmem_cache->num * sizeof(kmem_bufctl_t) +
 				      sizeof(struct slab), cache_line_size());
 
 	/* 2+3) create the kmalloc caches */
@@ -1603,15 +1605,15 @@ void __init kmem_cache_init(void)
 
 		ptr = kmalloc(sizeof(struct arraycache_init), GFP_NOWAIT);
 
-		BUG_ON(cpu_cache_get(&cache_cache) != &initarray_cache.cache);
-		memcpy(ptr, cpu_cache_get(&cache_cache),
+		BUG_ON(cpu_cache_get(kmem_cache) != &initarray_cache.cache);
+		memcpy(ptr, cpu_cache_get(kmem_cache),
 		       sizeof(struct arraycache_init));
 		/*
 		 * Do not assume that spinlocks can be initialized via memcpy:
 		 */
 		spin_lock_init(&ptr->lock);
 
-		cache_cache.array[smp_processor_id()] = ptr;
+		kmem_cache->array[smp_processor_id()] = ptr;
 
 		ptr = kmalloc(sizeof(struct arraycache_init), GFP_NOWAIT);
 
@@ -1632,7 +1634,7 @@ void __init kmem_cache_init(void)
 		int nid;
 
 		for_each_online_node(nid) {
-			init_list(&cache_cache, &initkmem_list3[CACHE_CACHE + nid], nid);
+			init_list(kmem_cache, &initkmem_list3[CACHE_CACHE + nid], nid);
 
 			init_list(malloc_sizes[INDEX_AC].cs_cachep,
 				  &initkmem_list3[SIZE_AC + nid], nid);
@@ -2086,7 +2088,7 @@ void __kmem_cache_destroy(struct kmem_ca
 			kfree(l3);
 		}
 	}
-	kmem_cache_free(&cache_cache, cachep);
+	kmem_cache_free(kmem_cache, cachep);
 }
 
 
@@ -2336,7 +2338,7 @@ __kmem_cache_create (const char *name, s
 		gfp = GFP_NOWAIT;
 
 	/* Get cache's description obj. */
-	cachep = kmem_cache_zalloc(&cache_cache, gfp);
+	cachep = kmem_cache_zalloc(kmem_cache, gfp);
 	if (!cachep)
 		return NULL;
 
@@ -2393,7 +2395,7 @@ __kmem_cache_create (const char *name, s
 	if (!cachep->num) {
 		printk(KERN_ERR
 		       "kmem_cache_create: couldn't create cache %s.\n", name);
-		kmem_cache_free(&cache_cache, cachep);
+		kmem_cache_free(kmem_cache, cachep);
 		return NULL;
 	}
 	slab_size = ALIGN(cachep->num * sizeof(kmem_bufctl_t)
@@ -3154,7 +3156,7 @@ static void *cache_alloc_debugcheck_afte
 
 static bool slab_should_failslab(struct kmem_cache *cachep, gfp_t flags)
 {
-	if (cachep == &cache_cache)
+	if (cachep == kmem_cache)
 		return false;
 
 	return should_failslab(obj_size(cachep), flags, cachep->flags);
Index: linux-2.6/mm/slab.h
===================================================================
--- linux-2.6.orig/mm/slab.h	2012-05-17 09:31:42.865710074 -0500
+++ linux-2.6/mm/slab.h	2012-05-17 09:32:42.765708833 -0500
@@ -25,8 +25,14 @@ extern enum slab_state slab_state;
 
 /* The slab cache mutex protects the management structures during changes */
 extern struct mutex slab_mutex;
+
+/* The list of all slab caches on the system */
 extern struct list_head slab_caches;
 
+/* The slab cache that manages slab cache information */
+extern struct kmem_cache *kmem_cache;
+
+/* Functions provided by the slab allocators */
 struct kmem_cache *__kmem_cache_create (const char *name, size_t size,
 	size_t align, unsigned long flags, void (*ctor)(void *));
 
Index: linux-2.6/mm/slab_common.c
===================================================================
--- linux-2.6.orig/mm/slab_common.c	2012-05-17 09:31:42.873710074 -0500
+++ linux-2.6/mm/slab_common.c	2012-05-17 09:33:48.425707474 -0500
@@ -22,6 +22,7 @@
 enum slab_state slab_state;
 LIST_HEAD(slab_caches);
 DEFINE_MUTEX(slab_mutex);
+struct kmem_cache *kmem_cache;
 
 /*
  * kmem_cache_create - Create a cache.
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-05-17 09:31:42.853710075 -0500
+++ linux-2.6/mm/slub.c	2012-05-17 09:33:48.413707474 -0500
@@ -3186,8 +3186,6 @@ void __kmem_cache_destroy(struct kmem_ca
 struct kmem_cache *kmalloc_caches[SLUB_PAGE_SHIFT];
 EXPORT_SYMBOL(kmalloc_caches);
 
-static struct kmem_cache *kmem_cache;
-
 #ifdef CONFIG_ZONE_DMA
 static struct kmem_cache *kmalloc_dma_caches[SLUB_PAGE_SHIFT];
 #endif
Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2012-05-17 09:31:42.837710074 -0500
+++ linux-2.6/mm/slob.c	2012-05-17 09:33:48.397707473 -0500
@@ -656,6 +656,9 @@ EXPORT_SYMBOL(kmem_cache_shrink);
 
 void __init kmem_cache_init(void)
 {
+	kmem_cache = __kmem_cache_create("kmem_cache",
+		sizeof(struct kmem_cache), 0, SLAB_PANIC, NULL);
+	BUG_ON(!kmem_cache);
 	slab_state = UP;
 }
 

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Re: [RFC] Common code 10/12] sl[aub]: Use the name "kmem_cache" for the slab cache with the kmem_cache structure.

[Glauber Costa]

On 05/18/2012 08:19 PM, Christoph Lameter wrote:
> Make all allocators use the "kmem_cache" slabname for the "kmem_cache" structure.
>
> Signed-off-by: Christoph Lameter<cl@linux.com>
This is a good change.

Reviewed-by: Glauber Costa <glommer@parallels.com>

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Re: [RFC] Common code 10/12] sl[aub]: Use the name "kmem_cache" for the slab cache with the kmem_cache structure.

[JoonSoo Kim]

2012/5/21 Glauber Costa <glommer@parallels.com>:
> On 05/18/2012 08:19 PM, Christoph Lameter wrote:
>>
>> Make all allocators use the "kmem_cache" slabname for the "kmem_cache"
>> structure.
>>
>> Signed-off-by: Christoph Lameter<cl@linux.com>
>
> This is a good change.
>
> Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>

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[RFC] Common code 11/12] Move freeing of kmem_cache structure to common code

[Christoph Lameter]

[-- Attachment #1: common_kmem_cache_destroy --]
[-- Type: text/plain, Size: 2350 bytes --]

The freeing action is basically the same in all slab allocators.
Move to the common kmem_cache_destroy() function.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 mm/slab.c        |    1 -
 mm/slab_common.c |    1 +
 mm/slob.c        |    2 --
 mm/slub.c        |    1 -
 4 files changed, 1 insertion(+), 4 deletions(-)

Index: linux-2.6/mm/slab_common.c
===================================================================
--- linux-2.6.orig/mm/slab_common.c	2012-05-18 03:37:23.772360311 -0500
+++ linux-2.6/mm/slab_common.c	2012-05-18 03:38:54.592358430 -0500
@@ -129,6 +129,7 @@ void kmem_cache_destroy(struct kmem_cach
 			rcu_barrier();
 
 		__kmem_cache_destroy(s);
+		kmem_cache_free(kmem_cache, s);
 	} else {
 		list_add(&s->list, &slab_caches);
 		printk(KERN_ERR "kmem_cache_destroy %s: Slab cache still has objects\n",
Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2012-05-18 03:37:23.740360312 -0500
+++ linux-2.6/mm/slob.c	2012-05-18 03:37:48.184359806 -0500
@@ -572,8 +572,6 @@ struct kmem_cache *__kmem_cache_create(c
 
 void __kmem_cache_destroy(struct kmem_cache *c)
 {
-	kmemleak_free(c);
-	slob_free(c, sizeof(struct kmem_cache));
 }
 
 void *kmem_cache_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-05-18 03:37:23.760360314 -0500
+++ linux-2.6/mm/slub.c	2012-05-18 03:37:48.184359806 -0500
@@ -3175,7 +3175,6 @@ int __kmem_cache_shutdown(struct kmem_ca
 
 void __kmem_cache_destroy(struct kmem_cache *s)
 {
-	kfree(s);
 	sysfs_slab_remove(s);
 }
 
Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-05-18 03:37:23.752360313 -0500
+++ linux-2.6/mm/slab.c	2012-05-18 03:37:48.188359801 -0500
@@ -2088,7 +2088,6 @@ void __kmem_cache_destroy(struct kmem_ca
 			kfree(l3);
 		}
 	}
-	kmem_cache_free(kmem_cache, cachep);
 }
 
 

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Re: [RFC] Common code 11/12] Move freeing of kmem_cache structure to common code

[JoonSoo Kim]

2012/5/19 Christoph Lameter <cl@linux.com>:
> The freeing action is basically the same in all slab allocators.
> Move to the common kmem_cache_destroy() function.
>
> Signed-off-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>

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[RFC] Common code 12/12] [slauob]: Get rid of __kmem_cache_destroy

[Christoph Lameter]

[-- Attachment #1: no_slab_specific_kmem_cache_destroy --]
[-- Type: text/plain, Size: 4380 bytes --]

Actions done there can be done in __kmem_cache_shutdown.

This affects RCU handling somewhat. On rcu free all slab allocators
do not refer to other management structures than the kmem_cache structure.
Therefore these other structures can be freed before the rcu deferred
free to the page allocator occurs.

Signed-off-by: Christoph Lameter <cl@linux.com>

---
 mm/slab.c        |   43 +++++++++++++++++++++----------------------
 mm/slab.h        |    1 -
 mm/slab_common.c |    1 -
 mm/slob.c        |    4 ----
 mm/slub.c        |   10 +++++-----
 5 files changed, 26 insertions(+), 33 deletions(-)

Index: linux-2.6/mm/slob.c
===================================================================
--- linux-2.6.orig/mm/slob.c	2012-05-18 03:37:48.184359806 -0500
+++ linux-2.6/mm/slob.c	2012-05-18 03:39:12.100358071 -0500
@@ -570,10 +570,6 @@ struct kmem_cache *__kmem_cache_create(c
 	return c;
 }
 
-void __kmem_cache_destroy(struct kmem_cache *c)
-{
-}
-
 void *kmem_cache_alloc_node(struct kmem_cache *c, gfp_t flags, int node)
 {
 	void *b;
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2012-05-18 03:37:48.184359806 -0500
+++ linux-2.6/mm/slub.c	2012-05-18 03:39:12.104358068 -0500
@@ -3170,12 +3170,12 @@ static inline int kmem_cache_close(struc
 
 int __kmem_cache_shutdown(struct kmem_cache *s)
 {
-	return kmem_cache_close(s);
-}
+	int rc = kmem_cache_close(s);
 
-void __kmem_cache_destroy(struct kmem_cache *s)
-{
-	sysfs_slab_remove(s);
+	if (!rc)
+		sysfs_slab_remove(s);
+
+	return rc;
 }
 
 /********************************************************************
Index: linux-2.6/mm/slab.c
===================================================================
--- linux-2.6.orig/mm/slab.c	2012-05-18 03:37:48.188359801 -0500
+++ linux-2.6/mm/slab.c	2012-05-18 03:39:12.104358068 -0500
@@ -2071,26 +2071,6 @@ static void slab_destroy(struct kmem_cac
 	}
 }
 
-void __kmem_cache_destroy(struct kmem_cache *cachep)
-{
-	int i;
-	struct kmem_list3 *l3;
-
-	for_each_online_cpu(i)
-	    kfree(cachep->array[i]);
-
-	/* NUMA: free the list3 structures */
-	for_each_online_node(i) {
-		l3 = cachep->nodelists[i];
-		if (l3) {
-			kfree(l3->shared);
-			free_alien_cache(l3->alien);
-			kfree(l3);
-		}
-	}
-}
-
-
 /**
  * calculate_slab_order - calculate size (page order) of slabs
  * @cachep: pointer to the cache that is being created
@@ -2453,7 +2433,7 @@ __kmem_cache_create (const char *name, s
 	cachep->refcount = 1;
 
 	if (setup_cpu_cache(cachep, gfp)) {
-		__kmem_cache_destroy(cachep);
+		__kmem_cache_shutdown(cachep);
 		return NULL;
 	}
 
@@ -2628,7 +2608,26 @@ EXPORT_SYMBOL(kmem_cache_shrink);
 
 int __kmem_cache_shutdown(struct kmem_cache *cachep)
 {
-	return __cache_shrink(cachep);
+	int i;
+	struct kmem_list3 *l3;
+	int rc = __cache_shrink(cachep);
+
+	if (rc)
+		return rc;
+
+	for_each_online_cpu(i)
+	    kfree(cachep->array[i]);
+
+	/* NUMA: free the list3 structures */
+	for_each_online_node(i) {
+		l3 = cachep->nodelists[i];
+		if (l3) {
+			kfree(l3->shared);
+			free_alien_cache(l3->alien);
+			kfree(l3);
+		}
+	}
+	return 0;
 }
 
 /*
Index: linux-2.6/mm/slab.h
===================================================================
--- linux-2.6.orig/mm/slab.h	2012-05-18 03:36:21.724361601 -0500
+++ linux-2.6/mm/slab.h	2012-05-18 03:39:12.104358068 -0500
@@ -37,6 +37,5 @@ struct kmem_cache *__kmem_cache_create (
 	size_t align, unsigned long flags, void (*ctor)(void *));
 
 int __kmem_cache_shutdown(struct kmem_cache *);
-void __kmem_cache_destroy(struct kmem_cache *);
 
 #endif
Index: linux-2.6/mm/slab_common.c
===================================================================
--- linux-2.6.orig/mm/slab_common.c	2012-05-18 04:08:38.324321471 -0500
+++ linux-2.6/mm/slab_common.c	2012-05-18 04:16:04.928312217 -0500
@@ -128,7 +128,6 @@ void kmem_cache_destroy(struct kmem_cach
 		if (s->flags & SLAB_DESTROY_BY_RCU)
 			rcu_barrier();
 
-		__kmem_cache_destroy(s);
 		kmem_cache_free(kmem_cache, s);
 	} else {
 		list_add(&s->list, &slab_caches);

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Re: [RFC] Common code 12/12] [slauob]: Get rid of __kmem_cache_destroy

[JoonSoo Kim]

2012/5/19 Christoph Lameter <cl@linux.com>:
> Actions done there can be done in __kmem_cache_shutdown.
>
> This affects RCU handling somewhat. On rcu free all slab allocators
> do not refer to other management structures than the kmem_cache structure.
> Therefore these other structures can be freed before the rcu deferred
> free to the page allocator occurs.
>
> Signed-off-by: Christoph Lameter <cl@linux.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>

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Re: [RFC] Common code 08/12] slabs: list addition move to slab_common

[Glauber Costa]

On 05/18/2012 08:19 PM, Christoph Lameter wrote:
> Move the code to append the new kmem_cache to the list of slab caches to
> the kmem_cache_create code in the shared code.
>
> This is possible now since the acquisition of the mutex was moved into
> kmem_cache_create().
>
> Signed-off-by: Christoph Lameter<cl@linux.com>
Reviewed-by: Glauber Costa <glommer@parallels.com>

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Re: [RFC] Common code 08/12] slabs: list addition move to slab_common

[JoonSoo Kim]

> On 05/18/2012 08:19 PM, Christoph Lameter wrote:
>>
>> Move the code to append the new kmem_cache to the list of slab caches to
>> the kmem_cache_create code in the shared code.
>>
>> This is possible now since the acquisition of the mutex was moved into
>> kmem_cache_create().
>>
>> Signed-off-by: Christoph Lameter<cl@linux.com>
>
> Reviewed-by: Glauber Costa <glommer@parallels.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>

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Re: [RFC] Common code 00/12] Sl[auo]b: Common functionality V2

[Glauber Costa]

On 05/18/2012 08:19 PM, Christoph Lameter wrote:
> V1->V2:
> - Incorporate glommers feedback.
> - Add 2 more patches dealing with common code in kmem_cache_destroy
>
> This is a series of patches that extracts common functionality from
> slab allocators into a common code base. The intend is to standardize
> as much as possible of the allocator behavior while keeping the
> distinctive features of each allocator which are mostly due to their
> storage format and serialization approaches.
>
> This patchset makes a beginning by extracting common functionality in
> kmem_cache_create() and kmem_cache_destroy(). However, there are
> numerous other areas where such work could be beneficial:
>
> 1. Extract the sysfs support from SLUB and make it common. That way
>     all allocators have a common sysfs API and are handleable in the same
>     way regardless of the allocator chose.
>
> 2. Extract the error reporting and checking from SLUB and make
>     it available for all allocators. This means that all allocators
>     will gain the resiliency and error handling capabilties.
>
> 3. Extract the memory hotplug and cpu hotplug handling. It seems that
>     SLAB may be more sophisticated here. Having common code here will
>     make it easier to maintain the special code.
>
> 4. Extract the aliasing capability of SLUB. This will enable fast
>     slab creation without creating too many additional slab caches.
>     The arrays of caches of varying sizes in numerous subsystems
>     do not cause the creation of numerous slab caches. Storage
>     density is increased and the cache footprint is reduced.
>
> Ultimately it is to be hoped that the special code for each allocator
> shrinks to a mininum. This will also make it easier to make modification
> to allocators.
>
> In the far future one could envision that the current allocators will
> just become storage algorithms that can be chosen based on the need of
> the subsystem. F.e.
>
> Cpu cache dependend performance		= Bonwick allocator (SLAB)
> Minimal cycle count and cache footprint	= SLUB
> Maximum storage density			= K&R allocator (SLOB)
>
> But that could be controversial and inefficient if indirect calls are needed.

While we're at it, can one of my patches for consistent name string 
handling among caches be applied?

Once you guys reach a decision about what is the best behavior: 
strdup'ing it in all caches, or not strduping it for the slub, I can 
provide an updated patch that also updates the slob accordingly.


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Re: [RFC] Common code 00/12] Sl[auo]b: Common functionality V2

[Christoph Lameter]

On Mon, 21 May 2012, Glauber Costa wrote:

> While we're at it, can one of my patches for consistent name string handling
> among caches be applied?
>
> Once you guys reach a decision about what is the best behavior: strdup'ing it
> in all caches, or not strduping it for the slub, I can provide an updated
> patch that also updates the slob accordingly.

strduping is the safest approach. If slabs keep a pointer to string data
around then slabs also need their private copy.


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Re: [RFC] Common code 00/12] Sl[auo]b: Common functionality V2

[Glauber Costa]

On 05/21/2012 05:51 PM, Christoph Lameter wrote:
> On Mon, 21 May 2012, Glauber Costa wrote:
>
>> While we're at it, can one of my patches for consistent name string handling
>> among caches be applied?
>>
>> Once you guys reach a decision about what is the best behavior: strdup'ing it
>> in all caches, or not strduping it for the slub, I can provide an updated
>> patch that also updates the slob accordingly.
>
> strduping is the safest approach. If slabs keep a pointer to string data
> around then slabs also need their private copy.

You told me that once, but David seemed to disagree.

David, do you agree with this ?


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Re: [RFC] Common code 00/12] Sl[auo]b: Common functionality V2

[Alex Shi]

On 05/19/2012 12:19 AM, Christoph Lameter wrote:

> V1->V2:
> - Incorporate glommers feedback.
> - Add 2 more patches dealing with common code in kmem_cache_destroy


I tested the patchset on 3.4 kernel with hackbench process/thread:
$hackbench 100 process/thread 2000

on Romely EP machine. 32 LCPUs, with 64GB memory
hackbench process	slub	0%
hackbench thread	slub	0%
hackbench process	slab	-6.0%
hackbench thread	slab	-0.5%

on NHM EP machine, 16 cpus, with 12GB memory
hackbench process	slub	-1.0%
hackbench thread	slub	-1.5%
hackbench process	slab	+1.0%
hackbench thread	slab	+1.0%
hackbench process	slob	0%
hackbench thread	slob	0%

on 4 sockets Quad-core Xeon, 16 cpus, with 16 GB memory
hackbench process	slub	0%
hackbench thread	slub	0%
hackbench process	slab	-0.5%
hackbench thread	slab	-0.5%
hackbench process	slob	0%
hackbench thread	slob	0%


On netperf loopback, 2048 threads testing. In general, compare tcp/udp
results, no clear performance change on above three machines.

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Re: [RFC] Common code 00/12] Sl[auo]b: Common functionality V2

[Alex Shi]

On 06/11/2012 10:25 AM, Alex Shi wrote:

> On 05/19/2012 12:19 AM, Christoph Lameter wrote:
> 
>> V1->V2:
>> - Incorporate glommers feedback.
>> - Add 2 more patches dealing with common code in kmem_cache_destroy
> 
> 
> I tested the patchset on 3.4 kernel with hackbench process/thread:
> $hackbench 100 process/thread 2000
> 
> on Romely EP machine. 32 LCPUs, with 64GB memory
> hackbench process	slub	0%
> hackbench thread	slub	0%
> hackbench process	slab	-6.0%
> hackbench thread	slab	-0.5%
> 
> on NHM EP machine, 16 cpus, with 12GB memory
> hackbench process	slub	-1.0%
> hackbench thread	slub	-1.5%
> hackbench process	slab	+1.0%
> hackbench thread	slab	+1.0%
> hackbench process	slob	0%
> hackbench thread	slob	0%
> 
> on 4 sockets Quad-core Xeon, 16 cpus, with 16 GB memory
> hackbench process	slub	0%
> hackbench thread	slub	0%
> hackbench process	slab	-0.5%
> hackbench thread	slab	-0.5%
> hackbench process	slob	0%
> hackbench thread	slob	0%
> 
> 
> On netperf loopback, 2048 threads testing. In general, compare tcp/udp
> results, no clear performance change on above three machines.


Generally, I think the patchset is qualified for LKP. :)

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