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slob: Define page struct fields used in mm_types.h
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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]

Reviewed-by: Glauber Costa <glommer@parallels.com>
Acked-by: David Rientjes <rientjes@google.com>
Reviewed-by: Joonsoo Kim <js1304@gmail.com>
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
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Christoph Lameter authored and Pekka Enberg committed Jun 14, 2012
1 parent 23910c5 commit b8c24c4
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Showing 2 changed files with 42 additions and 60 deletions.
7 changes: 5 additions & 2 deletions include/linux/mm_types.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -53,7 +53,7 @@ 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 {
Expand Down Expand Up @@ -81,11 +81,12 @@ 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. */
};
Expand All @@ -107,6 +108,8 @@ struct page {
short int pobjects;
#endif
};

struct list_head list; /* slobs list of pages */
};

/* Remainder is not double word aligned */
Expand Down
95 changes: 37 additions & 58 deletions mm/slob.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -91,34 +91,13 @@ 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;
}

/*
Expand All @@ -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)
Expand Down Expand Up @@ -267,12 +246,12 @@ static void slob_free_pages(void *b, int order)
/*
* 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) {
Expand All @@ -296,12 +275,12 @@ static void *slob_page_alloc(struct slob_page *sp, size_t size, int align)
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);
}

Expand All @@ -320,7 +299,7 @@ static void *slob_page_alloc(struct slob_page *sp, size_t size, int align)
*/
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;
Expand All @@ -341,7 +320,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
* 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? */
Expand Down Expand Up @@ -374,7 +353,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)

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);
Expand All @@ -392,7 +371,7 @@ static void *slob_alloc(size_t size, gfp_t gfp, int align, int node)
*/
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;
Expand Down Expand Up @@ -421,7 +400,7 @@ static void slob_free(void *block, int size)
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));
Expand All @@ -441,15 +420,15 @@ static void slob_free(void *block, int size)
*/
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;
Expand Down Expand Up @@ -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);

Expand All @@ -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))
Expand All @@ -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);

Expand Down

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