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Commit 41ecc55b authored by Christoph Lameter's avatar Christoph Lameter Committed by Linus Torvalds
Browse files

SLUB: add CONFIG_SLUB_DEBUG 



CONFIG_SLUB_DEBUG can be used to switch off the debugging and sysfs components
of SLUB.  Thus SLUB will be able to replace SLOB.  SLUB can arrange objects in
a denser way than SLOB and the code size should be minimal without debugging
and sysfs support.

Note that CONFIG_SLUB_DEBUG is materially different from CONFIG_SLAB_DEBUG.
CONFIG_SLAB_DEBUG is used to enable slab debugging in SLAB.  SLUB enables
debugging via a boot parameter.  SLUB debug code should always be present.

CONFIG_SLUB_DEBUG can be modified in the embedded config section.

Signed-off-by: default avatarChristoph Lameter <clameter@sgi.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 02cbc874

init/Kconfig

+9 −0
Original line number Diff line number Diff line
@@ -504,6 +504,15 @@ config VM_EVENT_COUNTERS 
	  on EMBEDDED systems.  /proc/vmstat will only show page counts

	  if VM event counters are disabled.



config SLUB_DEBUG

	default y

	bool "Enable SLUB debugging support" if EMBEDDED

	help

	  SLUB has extensive debug support features. Disabling these can

	  result in significant savings in code size. This also disables

	  SLUB sysfs support. /sys/slab will not exist and there will be

	  no support for cache validation etc.



choice

	prompt "Choose SLAB allocator"

	default SLAB

mm/slub.c

+114 −75
Original line number Diff line number Diff line
@@ -89,17 +89,25 @@ 


static inline int SlabDebug(struct page *page)

{

#ifdef CONFIG_SLUB_DEBUG

	return PageError(page);

#else

	return 0;

#endif

}



static inline void SetSlabDebug(struct page *page)

{

#ifdef CONFIG_SLUB_DEBUG

	SetPageError(page);

#endif

}



static inline void ClearSlabDebug(struct page *page)

{

#ifdef CONFIG_SLUB_DEBUG

	ClearPageError(page);

#endif

}



/*
@@ -207,7 +215,7 @@ struct track { 


enum track_item { TRACK_ALLOC, TRACK_FREE };



#ifdef CONFIG_SYSFS

#if defined(CONFIG_SYSFS) && defined(CONFIG_SLUB_DEBUG)

static int sysfs_slab_add(struct kmem_cache *);

static int sysfs_slab_alias(struct kmem_cache *, const char *);

static void sysfs_slab_remove(struct kmem_cache *);
@@ -284,6 +292,14 @@ static inline int slab_index(void *p, struct kmem_cache *s, void *addr) 
	return (p - addr) / s->size;

}



#ifdef CONFIG_SLUB_DEBUG

/*

 * Debug settings:

 */

static int slub_debug;



static char *slub_debug_slabs;



/*

 * Object debugging

 */
@@ -821,6 +837,97 @@ static void trace(struct kmem_cache *s, struct page *page, void *object, int all 
	}

}



static int __init setup_slub_debug(char *str)

{

	if (!str || *str != '=')

		slub_debug = DEBUG_DEFAULT_FLAGS;

	else {

		str++;

		if (*str == 0 || *str == ',')

			slub_debug = DEBUG_DEFAULT_FLAGS;

		else

		for( ;*str && *str != ','; str++)

			switch (*str) {

			case 'f' : case 'F' :

				slub_debug |= SLAB_DEBUG_FREE;

				break;

			case 'z' : case 'Z' :

				slub_debug |= SLAB_RED_ZONE;

				break;

			case 'p' : case 'P' :

				slub_debug |= SLAB_POISON;

				break;

			case 'u' : case 'U' :

				slub_debug |= SLAB_STORE_USER;

				break;

			case 't' : case 'T' :

				slub_debug |= SLAB_TRACE;

				break;

			default:

				printk(KERN_ERR "slub_debug option '%c' "

					"unknown. skipped\n",*str);

			}

	}



	if (*str == ',')

		slub_debug_slabs = str + 1;

	return 1;

}



__setup("slub_debug", setup_slub_debug);



static void kmem_cache_open_debug_check(struct kmem_cache *s)

{

	/*

	 * The page->offset field is only 16 bit wide. This is an offset

	 * in units of words from the beginning of an object. If the slab

	 * size is bigger then we cannot move the free pointer behind the

	 * object anymore.

	 *

	 * On 32 bit platforms the limit is 256k. On 64bit platforms

	 * the limit is 512k.

	 *

	 * Debugging or ctor/dtors may create a need to move the free

	 * pointer. Fail if this happens.

	 */

	if (s->size >= 65535 * sizeof(void *)) {

		BUG_ON(s->flags & (SLAB_RED_ZONE | SLAB_POISON |

				SLAB_STORE_USER | SLAB_DESTROY_BY_RCU));

		BUG_ON(s->ctor || s->dtor);

	}

	else

		/*

		 * Enable debugging if selected on the kernel commandline.

		 */

		if (slub_debug && (!slub_debug_slabs ||

		    strncmp(slub_debug_slabs, s->name,

		    	strlen(slub_debug_slabs)) == 0))

				s->flags |= slub_debug;

}

#else



static inline int alloc_object_checks(struct kmem_cache *s,

		struct page *page, void *object) { return 0; }



static inline int free_object_checks(struct kmem_cache *s,

		struct page *page, void *object) { return 0; }



static inline void add_full(struct kmem_cache_node *n, struct page *page) {}

static inline void remove_full(struct kmem_cache *s, struct page *page) {}

static inline void trace(struct kmem_cache *s, struct page *page,

			void *object, int alloc) {}

static inline void init_object(struct kmem_cache *s,

			void *object, int active) {}

static inline void init_tracking(struct kmem_cache *s, void *object) {}

static inline int slab_pad_check(struct kmem_cache *s, struct page *page)

			{ return 1; }

static inline int check_object(struct kmem_cache *s, struct page *page,

			void *object, int active) { return 1; }

static inline void set_track(struct kmem_cache *s, void *object,

			enum track_item alloc, void *addr) {}

static inline void kmem_cache_open_debug_check(struct kmem_cache *s) {}

#define slub_debug 0

#endif

/*

 * Slab allocation and freeing

 */
@@ -1445,13 +1552,6 @@ static int slub_min_objects = DEFAULT_MIN_OBJECTS; 
 */

static int slub_nomerge;



/*

 * Debug settings:

 */

static int slub_debug;



static char *slub_debug_slabs;



/*

 * Calculate the order of allocation given an slab object size.

 *
@@ -1660,6 +1760,7 @@ static int calculate_sizes(struct kmem_cache *s) 
	 */

	size = ALIGN(size, sizeof(void *));



#ifdef CONFIG_SLUB_DEBUG

	/*

	 * If we are Redzoning then check if there is some space between the

	 * end of the object and the free pointer. If not then add an
@@ -1667,6 +1768,7 @@ static int calculate_sizes(struct kmem_cache *s) 
	 */

	if ((flags & SLAB_RED_ZONE) && size == s->objsize)

		size += sizeof(void *);

#endif



	/*

	 * With that we have determined the number of bytes in actual use
@@ -1674,6 +1776,7 @@ static int calculate_sizes(struct kmem_cache *s) 
	 */

	s->inuse = size;



#ifdef CONFIG_SLUB_DEBUG

	if (((flags & (SLAB_DESTROY_BY_RCU | SLAB_POISON)) ||

		s->ctor || s->dtor)) {

		/*
@@ -1704,6 +1807,7 @@ static int calculate_sizes(struct kmem_cache *s) 
		 * of the object.

		 */

		size += sizeof(void *);

#endif



	/*

	 * Determine the alignment based on various parameters that the
@@ -1753,32 +1857,7 @@ static int kmem_cache_open(struct kmem_cache *s, gfp_t gfpflags, 
	s->objsize = size;

	s->flags = flags;

	s->align = align;



	/*

	 * The page->offset field is only 16 bit wide. This is an offset

	 * in units of words from the beginning of an object. If the slab

	 * size is bigger then we cannot move the free pointer behind the

	 * object anymore.

	 *

	 * On 32 bit platforms the limit is 256k. On 64bit platforms

	 * the limit is 512k.

	 *

	 * Debugging or ctor/dtors may create a need to move the free

	 * pointer. Fail if this happens.

	 */

	if (s->size >= 65535 * sizeof(void *)) {

		BUG_ON(flags & (SLAB_RED_ZONE | SLAB_POISON |

				SLAB_STORE_USER | SLAB_DESTROY_BY_RCU));

		BUG_ON(ctor || dtor);

	}

	else

		/*

		 * Enable debugging if selected on the kernel commandline.

		 */

		if (slub_debug && (!slub_debug_slabs ||

		    strncmp(slub_debug_slabs, name,

		    	strlen(slub_debug_slabs)) == 0))

				s->flags |= slub_debug;

	kmem_cache_open_debug_check(s);



	if (!calculate_sizes(s))

		goto error;
@@ -1949,45 +2028,6 @@ static int __init setup_slub_nomerge(char *str) 


__setup("slub_nomerge", setup_slub_nomerge);



static int __init setup_slub_debug(char *str)

{

	if (!str || *str != '=')

		slub_debug = DEBUG_DEFAULT_FLAGS;

	else {

		str++;

		if (*str == 0 || *str == ',')

			slub_debug = DEBUG_DEFAULT_FLAGS;

		else

		for( ;*str && *str != ','; str++)

			switch (*str) {

			case 'f' : case 'F' :

				slub_debug |= SLAB_DEBUG_FREE;

				break;

			case 'z' : case 'Z' :

				slub_debug |= SLAB_RED_ZONE;

				break;

			case 'p' : case 'P' :

				slub_debug |= SLAB_POISON;

				break;

			case 'u' : case 'U' :

				slub_debug |= SLAB_STORE_USER;

				break;

			case 't' : case 'T' :

				slub_debug |= SLAB_TRACE;

				break;

			default:

				printk(KERN_ERR "slub_debug option '%c' "

					"unknown. skipped\n",*str);

			}

	}



	if (*str == ',')

		slub_debug_slabs = str + 1;

	return 1;

}



__setup("slub_debug", setup_slub_debug);



static struct kmem_cache *create_kmalloc_cache(struct kmem_cache *s,

		const char *name, int size, gfp_t gfp_flags)

{
@@ -2554,8 +2594,7 @@ void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags, 
	return slab_alloc(s, gfpflags, node, caller);

}



#ifdef CONFIG_SYSFS



#if defined(CONFIG_SYSFS) && defined(CONFIG_SLUB_DEBUG)

static int validate_slab(struct kmem_cache *s, struct page *page)

{

	void *p;