diff options
| -rw-r--r-- | include/linux/mm_types.h | 10 | ||||
| -rw-r--r-- | mm/slab.h | 167 | ||||
| -rw-r--r-- | mm/slub.c | 8 |
3 files changed, 176 insertions, 9 deletions
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index c3a6e6209600..1ae3537c7920 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -56,11 +56,11 @@ struct mem_cgroup; * in each subpage, but you may need to restore some of their values * afterwards. * - * SLUB uses cmpxchg_double() to atomically update its freelist and - * counters. That requires that freelist & counters be adjacent and - * double-word aligned. We align all struct pages to double-word - * boundaries, and ensure that 'freelist' is aligned within the - * struct. + * SLUB uses cmpxchg_double() to atomically update its freelist and counters. + * That requires that freelist & counters in struct slab be adjacent and + * double-word aligned. Because struct slab currently just reinterprets the + * bits of struct page, we align all struct pages to double-word boundaries, + * and ensure that 'freelist' is aligned within struct slab. */ #ifdef CONFIG_HAVE_ALIGNED_STRUCT_PAGE #define _struct_page_alignment __aligned(2 * sizeof(unsigned long)) diff --git a/mm/slab.h b/mm/slab.h index 56ad7eea3ddf..0e67a8cb7f80 100644 --- a/mm/slab.h +++ b/mm/slab.h @@ -5,6 +5,173 @@ * Internal slab definitions */ +/* Reuses the bits in struct page */ +struct slab { + unsigned long __page_flags; + union { + struct list_head slab_list; + struct { /* Partial pages */ + struct slab *next; +#ifdef CONFIG_64BIT + int slabs; /* Nr of slabs left */ +#else + short int slabs; +#endif + }; + struct rcu_head rcu_head; + }; + struct kmem_cache *slab_cache; /* not slob */ + /* Double-word boundary */ + void *freelist; /* first free object */ + union { + void *s_mem; /* slab: first object */ + unsigned long counters; /* SLUB */ + struct { /* SLUB */ + unsigned inuse:16; + unsigned objects:15; + unsigned frozen:1; + }; + }; + + union { + unsigned int active; /* SLAB */ + int units; /* SLOB */ + }; + atomic_t __page_refcount; +#ifdef CONFIG_MEMCG + unsigned long memcg_data; +#endif +}; + +#define SLAB_MATCH(pg, sl) \ + static_assert(offsetof(struct page, pg) == offsetof(struct slab, sl)) +SLAB_MATCH(flags, __page_flags); +SLAB_MATCH(compound_head, slab_list); /* Ensure bit 0 is clear */ +SLAB_MATCH(slab_list, slab_list); +SLAB_MATCH(rcu_head, rcu_head); +SLAB_MATCH(slab_cache, slab_cache); +SLAB_MATCH(s_mem, s_mem); +SLAB_MATCH(active, active); +SLAB_MATCH(_refcount, __page_refcount); +#ifdef CONFIG_MEMCG +SLAB_MATCH(memcg_data, memcg_data); +#endif +#undef SLAB_MATCH +static_assert(sizeof(struct slab) <= sizeof(struct page)); + +/** + * folio_slab - Converts from folio to slab. + * @folio: The folio. + * + * Currently struct slab is a different representation of a folio where + * folio_test_slab() is true. + * + * Return: The slab which contains this folio. + */ +#define folio_slab(folio) (_Generic((folio), \ + const struct folio *: (const struct slab *)(folio), \ + struct folio *: (struct slab *)(folio))) + +/** + * slab_folio - The folio allocated for a slab + * @slab: The slab. + * + * Slabs are allocated as folios that contain the individual objects and are + * using some fields in the first struct page of the folio - those fields are + * now accessed by struct slab. It is occasionally necessary to convert back to + * a folio in order to communicate with the rest of the mm. Please use this + * helper function instead of casting yourself, as the implementation may change + * in the future. + */ +#define slab_folio(s) (_Generic((s), \ + const struct slab *: (const struct folio *)s, \ + struct slab *: (struct folio *)s)) + +/** + * page_slab - Converts from first struct page to slab. + * @p: The first (either head of compound or single) page of slab. + * + * A temporary wrapper to convert struct page to struct slab in situations where + * we know the page is the compound head, or single order-0 page. + * + * Long-term ideally everything would work with struct slab directly or go + * through folio to struct slab. + * + * Return: The slab which contains this page + */ +#define page_slab(p) (_Generic((p), \ + const struct page *: (const struct slab *)(p), \ + struct page *: (struct slab *)(p))) + +/** + * slab_page - The first struct page allocated for a slab + * @slab: The slab. + * + * A convenience wrapper for converting slab to the first struct page of the + * underlying folio, to communicate with code not yet converted to folio or + * struct slab. + */ +#define slab_page(s) folio_page(slab_folio(s), 0) + +/* + * If network-based swap is enabled, sl*b must keep track of whether pages + * were allocated from pfmemalloc reserves. + */ +static inline bool slab_test_pfmemalloc(const struct slab *slab) +{ + return folio_test_active((struct folio *)slab_folio(slab)); +} + +static inline void slab_set_pfmemalloc(struct slab *slab) +{ + folio_set_active(slab_folio(slab)); +} + +static inline void slab_clear_pfmemalloc(struct slab *slab) +{ + folio_clear_active(slab_folio(slab)); +} + +static inline void __slab_clear_pfmemalloc(struct slab *slab) +{ + __folio_clear_active(slab_folio(slab)); +} + +static inline void *slab_address(const struct slab *slab) +{ + return folio_address(slab_folio(slab)); +} + +static inline int slab_nid(const struct slab *slab) +{ + return folio_nid(slab_folio(slab)); +} + +static inline pg_data_t *slab_pgdat(const struct slab *slab) +{ + return folio_pgdat(slab_folio(slab)); +} + +static inline struct slab *virt_to_slab(const void *addr) +{ + struct folio *folio = virt_to_folio(addr); + + if (!folio_test_slab(folio)) + return NULL; + + return folio_slab(folio); +} + +static inline int slab_order(const struct slab *slab) +{ + return folio_order((struct folio *)slab_folio(slab)); +} + +static inline size_t slab_size(const struct slab *slab) +{ + return PAGE_SIZE << slab_order(slab); +} + #ifdef CONFIG_SLOB /* * Common fields provided in kmem_cache by all slab allocators diff --git a/mm/slub.c b/mm/slub.c index 2ccb1c71fc36..a211d96011ba 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -3787,7 +3787,7 @@ static unsigned int slub_min_objects; * requested a higher minimum order then we start with that one instead of * the smallest order which will fit the object. */ -static inline unsigned int slab_order(unsigned int size, +static inline unsigned int calc_slab_order(unsigned int size, unsigned int min_objects, unsigned int max_order, unsigned int fract_leftover) { @@ -3851,7 +3851,7 @@ static inline int calculate_order(unsigned int size) fraction = 16; while (fraction >= 4) { - order = slab_order(size, min_objects, + order = calc_slab_order(size, min_objects, slub_max_order, fraction); if (order <= slub_max_order) return order; @@ -3864,14 +3864,14 @@ static inline int calculate_order(unsigned int size) * We were unable to place multiple objects in a slab. Now * lets see if we can place a single object there. */ - order = slab_order(size, 1, slub_max_order, 1); + order = calc_slab_order(size, 1, slub_max_order, 1); if (order <= slub_max_order) return order; /* * Doh this slab cannot be placed using slub_max_order. */ - order = slab_order(size, 1, MAX_ORDER, 1); + order = calc_slab_order(size, 1, MAX_ORDER, 1); if (order < MAX_ORDER) return order; return -ENOSYS; |