mm/slab: kmalloc: pass requests larger than order-1 page to page allocator

There is not much benefit for serving large objects in kmalloc().
Let's pass large requests to page allocator like SLUB for better
maintenance of common code.

Signed-off-by: Hyeonggon Yoo <42.hyeyoo@gmail.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

diff --git a/include/linux/slab.h b/include/linux/slab.h
index fd2e129fc8130c331903956c4a886faed2f2f171..4ee5b2fed1649b8872b58b2841997a23250d2106 100644 (file)
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -243,27 +243,17 @@ static inline unsigned int arch_slab_minalign(void)
 
 #ifdef CONFIG_SLAB
 /*
- * The largest kmalloc size supported by the SLAB allocators is
- * 32 megabyte (2^25) or the maximum allocatable page order if that is
- * less than 32 MB.
- *
- * WARNING: Its not easy to increase this value since the allocators have
- * to do various tricks to work around compiler limitations in order to
- * ensure proper constant folding.
+ * SLAB and SLUB directly allocates requests fitting in to an order-1 page
+ * (PAGE_SIZE*2).  Larger requests are passed to the page allocator.
  */
-#define KMALLOC_SHIFT_HIGH     ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
-                               (MAX_ORDER + PAGE_SHIFT - 1) : 25)
-#define KMALLOC_SHIFT_MAX      KMALLOC_SHIFT_HIGH
+#define KMALLOC_SHIFT_HIGH     (PAGE_SHIFT + 1)
+#define KMALLOC_SHIFT_MAX      (MAX_ORDER + PAGE_SHIFT - 1)
 #ifndef KMALLOC_SHIFT_LOW
 #define KMALLOC_SHIFT_LOW      5
 #endif
 #endif
 
 #ifdef CONFIG_SLUB
-/*
- * SLUB directly allocates requests fitting in to an order-1 page
- * (PAGE_SIZE*2).  Larger requests are passed to the page allocator.
- */
 #define KMALLOC_SHIFT_HIGH     (PAGE_SHIFT + 1)
 #define KMALLOC_SHIFT_MAX      (MAX_ORDER + PAGE_SHIFT - 1)
 #ifndef KMALLOC_SHIFT_LOW
@@ -415,10 +405,6 @@ static __always_inline unsigned int __kmalloc_index(size_t size,
        if (size <= 512 * 1024) return 19;
        if (size <= 1024 * 1024) return 20;
        if (size <=  2 * 1024 * 1024) return 21;
-       if (size <=  4 * 1024 * 1024) return 22;
-       if (size <=  8 * 1024 * 1024) return 23;
-       if (size <=  16 * 1024 * 1024) return 24;
-       if (size <=  32 * 1024 * 1024) return 25;
 
        if (!IS_ENABLED(CONFIG_PROFILE_ALL_BRANCHES) && size_is_constant)
                BUILD_BUG_ON_MSG(1, "unexpected size in kmalloc_index()");
@@ -428,6 +414,7 @@ static __always_inline unsigned int __kmalloc_index(size_t size,
        /* Will never be reached. Needed because the compiler may complain */
        return -1;
 }
+static_assert(PAGE_SHIFT <= 20);
 #define kmalloc_index(s) __kmalloc_index(s, true)
 #endif /* !CONFIG_SLOB */
 

diff --git a/mm/slab.c b/mm/slab.c
index 8c08d7f3dead9c11753ab73716123d57f06cd724..10c9af904410e1dbe1c7532eaf14dda65a34664e 100644 (file)
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -3585,11 +3585,19 @@ __do_kmalloc_node(size_t size, gfp_t flags, int node, unsigned long caller)
        struct kmem_cache *cachep;
        void *ret;
 
-       if (unlikely(size > KMALLOC_MAX_CACHE_SIZE))
-               return NULL;
+       if (unlikely(size > KMALLOC_MAX_CACHE_SIZE)) {
+               ret = kmalloc_large_node_notrace(size, flags, node);
+
+               trace_kmalloc_node(caller, ret, NULL, size,
+                                  PAGE_SIZE << get_order(size),
+                                  flags, node);
+               return ret;
+       }
+
        cachep = kmalloc_slab(size, flags);
        if (unlikely(ZERO_OR_NULL_PTR(cachep)))
                return cachep;
+
        ret = kmem_cache_alloc_node_trace(cachep, flags, node, size);
        ret = kasan_kmalloc(cachep, ret, size, flags);
 
@@ -3664,17 +3672,27 @@ EXPORT_SYMBOL(kmem_cache_free);
 
 void kmem_cache_free_bulk(struct kmem_cache *orig_s, size_t size, void **p)
 {
-       struct kmem_cache *s;
-       size_t i;
 
        local_irq_disable();
-       for (i = 0; i < size; i++) {
+       for (int i = 0; i < size; i++) {
                void *objp = p[i];
+               struct kmem_cache *s;
 
-               if (!orig_s) /* called via kfree_bulk */
-                       s = virt_to_cache(objp);
-               else
+               if (!orig_s) {
+                       struct folio *folio = virt_to_folio(objp);
+
+                       /* called via kfree_bulk */
+                       if (!folio_test_slab(folio)) {
+                               local_irq_enable();
+                               free_large_kmalloc(folio, objp);
+                               local_irq_disable();
+                               continue;
+                       }
+                       s = folio_slab(folio)->slab_cache;
+               } else {
                        s = cache_from_obj(orig_s, objp);
+               }
+
                if (!s)
                        continue;
 
@@ -3703,20 +3721,24 @@ void kfree(const void *objp)
 {
        struct kmem_cache *c;
        unsigned long flags;
+       struct folio *folio;
 
        trace_kfree(_RET_IP_, objp);
 
        if (unlikely(ZERO_OR_NULL_PTR(objp)))
                return;
-       local_irq_save(flags);
-       kfree_debugcheck(objp);
-       c = virt_to_cache(objp);
-       if (!c) {
-               local_irq_restore(flags);
+
+       folio = virt_to_folio(objp);
+       if (!folio_test_slab(folio)) {
+               free_large_kmalloc(folio, (void *)objp);
                return;
        }
-       debug_check_no_locks_freed(objp, c->object_size);
 
+       c = folio_slab(folio)->slab_cache;
+
+       local_irq_save(flags);
+       kfree_debugcheck(objp);
+       debug_check_no_locks_freed(objp, c->object_size);
        debug_check_no_obj_freed(objp, c->object_size);
        __cache_free(c, (void *)objp, _RET_IP_);
        local_irq_restore(flags);
@@ -4138,15 +4160,17 @@ void __check_heap_object(const void *ptr, unsigned long n,
 size_t __ksize(const void *objp)
 {
        struct kmem_cache *c;
-       size_t size;
+       struct folio *folio;
 
        BUG_ON(!objp);
        if (unlikely(objp == ZERO_SIZE_PTR))
                return 0;
 
-       c = virt_to_cache(objp);
-       size = c ? c->object_size : 0;
+       folio = virt_to_folio(objp);
+       if (!folio_test_slab(folio))
+               return folio_size(folio);
 
-       return size;
+       c = folio_slab(folio)->slab_cache;
+       return c->object_size;
 }
 EXPORT_SYMBOL(__ksize);

diff --git a/mm/slab.h b/mm/slab.h
index 801a207a5cd7ddad4da7c9919cdbef1abc6a9e77..9808d537f6bac21e0d5b190fa737287ad0998619 100644 (file)
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -660,6 +660,9 @@ static inline struct kmem_cache *cache_from_obj(struct kmem_cache *s, void *x)
                print_tracking(cachep, x);
        return cachep;
 }
+
+void free_large_kmalloc(struct folio *folio, void *object);
+
 #endif /* CONFIG_SLOB */
 
 static inline size_t slab_ksize(const struct kmem_cache *s)

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 51ccd0545816278be65b8b34b922f08728b90bad..5a2e81f42ee9abce9b36ba498682b61a2be394d6 100644 (file)
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -744,8 +744,8 @@ struct kmem_cache *kmalloc_slab(size_t size, gfp_t flags)
 
 /*
  * kmalloc_info[] is to make slub_debug=,kmalloc-xx option work at boot time.
- * kmalloc_index() supports up to 2^25=32MB, so the final entry of the table is
- * kmalloc-32M.
+ * kmalloc_index() supports up to 2^21=2MB, so the final entry of the table is
+ * kmalloc-2M.
  */
 const struct kmalloc_info_struct kmalloc_info[] __initconst = {
        INIT_KMALLOC_INFO(0, 0),
@@ -769,11 +769,7 @@ const struct kmalloc_info_struct kmalloc_info[] __initconst = {
        INIT_KMALLOC_INFO(262144, 256k),
        INIT_KMALLOC_INFO(524288, 512k),
        INIT_KMALLOC_INFO(1048576, 1M),
-       INIT_KMALLOC_INFO(2097152, 2M),
-       INIT_KMALLOC_INFO(4194304, 4M),
-       INIT_KMALLOC_INFO(8388608, 8M),
-       INIT_KMALLOC_INFO(16777216, 16M),
-       INIT_KMALLOC_INFO(33554432, 32M)
+       INIT_KMALLOC_INFO(2097152, 2M)
 };
 
 /*
@@ -886,6 +882,21 @@ void __init create_kmalloc_caches(slab_flags_t flags)
        /* Kmalloc array is now usable */
        slab_state = UP;
 }
+
+void free_large_kmalloc(struct folio *folio, void *object)
+{
+       unsigned int order = folio_order(folio);
+
+       if (WARN_ON_ONCE(order == 0))
+               pr_warn_once("object pointer: 0x%p\n", object);
+
+       kmemleak_free(object);
+       kasan_kfree_large(object);
+
+       mod_lruvec_page_state(folio_page(folio, 0), NR_SLAB_UNRECLAIMABLE_B,
+                             -(PAGE_SIZE << order));
+       __free_pages(folio_page(folio, 0), order);
+}
 #endif /* !CONFIG_SLOB */
 
 gfp_t kmalloc_fix_flags(gfp_t flags)

diff --git a/mm/slub.c b/mm/slub.c
index 165fe87af20427d27d70d864897d37d77b291806..a659874c5d44ecfe40374818779f541631150191 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1704,12 +1704,6 @@ static bool freelist_corrupted(struct kmem_cache *s, struct slab *slab,
  * Hooks for other subsystems that check memory allocations. In a typical
  * production configuration these hooks all should produce no code at all.
  */
-static __always_inline void kfree_hook(void *x)
-{
-       kmemleak_free(x);
-       kasan_kfree_large(x);
-}
-
 static __always_inline bool slab_free_hook(struct kmem_cache *s,
                                                void *x, bool init)
 {
@@ -3550,19 +3544,6 @@ struct detached_freelist {
        struct kmem_cache *s;
 };
 
-static inline void free_large_kmalloc(struct folio *folio, void *object)
-{
-       unsigned int order = folio_order(folio);
-
-       if (WARN_ON_ONCE(order == 0))
-               pr_warn_once("object pointer: 0x%p\n", object);
-
-       kfree_hook(object);
-       mod_lruvec_page_state(folio_page(folio, 0), NR_SLAB_UNRECLAIMABLE_B,
-                             -(PAGE_SIZE << order));
-       __free_pages(folio_page(folio, 0), order);
-}
-
 /*
  * This function progressively scans the array with free objects (with
  * a limited look ahead) and extract objects belonging to the same