| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * linux/mm/mempool.c |
| * |
| * memory buffer pool support. Such pools are mostly used |
| * for guaranteed, deadlock-free memory allocations during |
| * extreme VM load. |
| * |
| * started by Ingo Molnar, Copyright (C) 2001 |
| * debugging by David Rientjes, Copyright (C) 2015 |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/slab.h> |
| #include <linux/highmem.h> |
| #include <linux/kasan.h> |
| #include <linux/kmemleak.h> |
| #include <linux/export.h> |
| #include <linux/mempool.h> |
| #include <linux/writeback.h> |
| #include "slab.h" |
| |
| #ifdef CONFIG_SLUB_DEBUG_ON |
| static void poison_error(mempool_t *pool, void *element, size_t size, |
| size_t byte) |
| { |
| const int nr = pool->curr_nr; |
| const int start = max_t(int, byte - (BITS_PER_LONG / 8), 0); |
| const int end = min_t(int, byte + (BITS_PER_LONG / 8), size); |
| int i; |
| |
| pr_err("BUG: mempool element poison mismatch\n"); |
| pr_err("Mempool %p size %zu\n", pool, size); |
| pr_err(" nr=%d @ %p: %s0x", nr, element, start > 0 ? "... " : ""); |
| for (i = start; i < end; i++) |
| pr_cont("%x ", *(u8 *)(element + i)); |
| pr_cont("%s\n", end < size ? "..." : ""); |
| dump_stack(); |
| } |
| |
| static void __check_element(mempool_t *pool, void *element, size_t size) |
| { |
| u8 *obj = element; |
| size_t i; |
| |
| for (i = 0; i < size; i++) { |
| u8 exp = (i < size - 1) ? POISON_FREE : POISON_END; |
| |
| if (obj[i] != exp) { |
| poison_error(pool, element, size, i); |
| return; |
| } |
| } |
| memset(obj, POISON_INUSE, size); |
| } |
| |
| static void check_element(mempool_t *pool, void *element) |
| { |
| /* Skip checking: KASAN might save its metadata in the element. */ |
| if (kasan_enabled()) |
| return; |
| |
| /* Mempools backed by slab allocator */ |
| if (pool->free == mempool_kfree) { |
| __check_element(pool, element, (size_t)pool->pool_data); |
| } else if (pool->free == mempool_free_slab) { |
| __check_element(pool, element, kmem_cache_size(pool->pool_data)); |
| } else if (pool->free == mempool_free_pages) { |
| /* Mempools backed by page allocator */ |
| int order = (int)(long)pool->pool_data; |
| void *addr = kmap_local_page((struct page *)element); |
| |
| __check_element(pool, addr, 1UL << (PAGE_SHIFT + order)); |
| kunmap_local(addr); |
| } |
| } |
| |
| static void __poison_element(void *element, size_t size) |
| { |
| u8 *obj = element; |
| |
| memset(obj, POISON_FREE, size - 1); |
| obj[size - 1] = POISON_END; |
| } |
| |
| static void poison_element(mempool_t *pool, void *element) |
| { |
| /* Skip poisoning: KASAN might save its metadata in the element. */ |
| if (kasan_enabled()) |
| return; |
| |
| /* Mempools backed by slab allocator */ |
| if (pool->alloc == mempool_kmalloc) { |
| __poison_element(element, (size_t)pool->pool_data); |
| } else if (pool->alloc == mempool_alloc_slab) { |
| __poison_element(element, kmem_cache_size(pool->pool_data)); |
| } else if (pool->alloc == mempool_alloc_pages) { |
| /* Mempools backed by page allocator */ |
| int order = (int)(long)pool->pool_data; |
| void *addr = kmap_local_page((struct page *)element); |
| |
| __poison_element(addr, 1UL << (PAGE_SHIFT + order)); |
| kunmap_local(addr); |
| } |
| } |
| #else /* CONFIG_SLUB_DEBUG_ON */ |
| static inline void check_element(mempool_t *pool, void *element) |
| { |
| } |
| static inline void poison_element(mempool_t *pool, void *element) |
| { |
| } |
| #endif /* CONFIG_SLUB_DEBUG_ON */ |
| |
| static __always_inline bool kasan_poison_element(mempool_t *pool, void *element) |
| { |
| if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc) |
| return kasan_mempool_poison_object(element); |
| else if (pool->alloc == mempool_alloc_pages) |
| return kasan_mempool_poison_pages(element, |
| (unsigned long)pool->pool_data); |
| return true; |
| } |
| |
| static void kasan_unpoison_element(mempool_t *pool, void *element) |
| { |
| if (pool->alloc == mempool_kmalloc) |
| kasan_mempool_unpoison_object(element, (size_t)pool->pool_data); |
| else if (pool->alloc == mempool_alloc_slab) |
| kasan_mempool_unpoison_object(element, |
| kmem_cache_size(pool->pool_data)); |
| else if (pool->alloc == mempool_alloc_pages) |
| kasan_mempool_unpoison_pages(element, |
| (unsigned long)pool->pool_data); |
| } |
| |
| static __always_inline void add_element(mempool_t *pool, void *element) |
| { |
| BUG_ON(pool->curr_nr >= pool->min_nr); |
| poison_element(pool, element); |
| if (kasan_poison_element(pool, element)) |
| pool->elements[pool->curr_nr++] = element; |
| } |
| |
| static void *remove_element(mempool_t *pool) |
| { |
| void *element = pool->elements[--pool->curr_nr]; |
| |
| BUG_ON(pool->curr_nr < 0); |
| kasan_unpoison_element(pool, element); |
| check_element(pool, element); |
| return element; |
| } |
| |
| /** |
| * mempool_exit - exit a mempool initialized with mempool_init() |
| * @pool: pointer to the memory pool which was initialized with |
| * mempool_init(). |
| * |
| * Free all reserved elements in @pool and @pool itself. This function |
| * only sleeps if the free_fn() function sleeps. |
| * |
| * May be called on a zeroed but uninitialized mempool (i.e. allocated with |
| * kzalloc()). |
| */ |
| void mempool_exit(mempool_t *pool) |
| { |
| while (pool->curr_nr) { |
| void *element = remove_element(pool); |
| pool->free(element, pool->pool_data); |
| } |
| kfree(pool->elements); |
| pool->elements = NULL; |
| } |
| EXPORT_SYMBOL(mempool_exit); |
| |
| /** |
| * mempool_destroy - deallocate a memory pool |
| * @pool: pointer to the memory pool which was allocated via |
| * mempool_create(). |
| * |
| * Free all reserved elements in @pool and @pool itself. This function |
| * only sleeps if the free_fn() function sleeps. |
| */ |
| void mempool_destroy(mempool_t *pool) |
| { |
| if (unlikely(!pool)) |
| return; |
| |
| mempool_exit(pool); |
| kfree(pool); |
| } |
| EXPORT_SYMBOL(mempool_destroy); |
| |
| int mempool_init_node(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn, |
| mempool_free_t *free_fn, void *pool_data, |
| gfp_t gfp_mask, int node_id) |
| { |
| spin_lock_init(&pool->lock); |
| pool->min_nr = min_nr; |
| pool->pool_data = pool_data; |
| pool->alloc = alloc_fn; |
| pool->free = free_fn; |
| init_waitqueue_head(&pool->wait); |
| |
| pool->elements = kmalloc_array_node(min_nr, sizeof(void *), |
| gfp_mask, node_id); |
| if (!pool->elements) |
| return -ENOMEM; |
| |
| /* |
| * First pre-allocate the guaranteed number of buffers. |
| */ |
| while (pool->curr_nr < pool->min_nr) { |
| void *element; |
| |
| element = pool->alloc(gfp_mask, pool->pool_data); |
| if (unlikely(!element)) { |
| mempool_exit(pool); |
| return -ENOMEM; |
| } |
| add_element(pool, element); |
| } |
| |
| return 0; |
| } |
| EXPORT_SYMBOL(mempool_init_node); |
| |
| /** |
| * mempool_init - initialize a memory pool |
| * @pool: pointer to the memory pool that should be initialized |
| * @min_nr: the minimum number of elements guaranteed to be |
| * allocated for this pool. |
| * @alloc_fn: user-defined element-allocation function. |
| * @free_fn: user-defined element-freeing function. |
| * @pool_data: optional private data available to the user-defined functions. |
| * |
| * Like mempool_create(), but initializes the pool in (i.e. embedded in another |
| * structure). |
| * |
| * Return: %0 on success, negative error code otherwise. |
| */ |
| int mempool_init_noprof(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn, |
| mempool_free_t *free_fn, void *pool_data) |
| { |
| return mempool_init_node(pool, min_nr, alloc_fn, free_fn, |
| pool_data, GFP_KERNEL, NUMA_NO_NODE); |
| |
| } |
| EXPORT_SYMBOL(mempool_init_noprof); |
| |
| /** |
| * mempool_create_node - create a memory pool |
| * @min_nr: the minimum number of elements guaranteed to be |
| * allocated for this pool. |
| * @alloc_fn: user-defined element-allocation function. |
| * @free_fn: user-defined element-freeing function. |
| * @pool_data: optional private data available to the user-defined functions. |
| * @gfp_mask: memory allocation flags |
| * @node_id: numa node to allocate on |
| * |
| * this function creates and allocates a guaranteed size, preallocated |
| * memory pool. The pool can be used from the mempool_alloc() and mempool_free() |
| * functions. This function might sleep. Both the alloc_fn() and the free_fn() |
| * functions might sleep - as long as the mempool_alloc() function is not called |
| * from IRQ contexts. |
| * |
| * Return: pointer to the created memory pool object or %NULL on error. |
| */ |
| mempool_t *mempool_create_node_noprof(int min_nr, mempool_alloc_t *alloc_fn, |
| mempool_free_t *free_fn, void *pool_data, |
| gfp_t gfp_mask, int node_id) |
| { |
| mempool_t *pool; |
| |
| pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id); |
| if (!pool) |
| return NULL; |
| |
| if (mempool_init_node(pool, min_nr, alloc_fn, free_fn, pool_data, |
| gfp_mask, node_id)) { |
| kfree(pool); |
| return NULL; |
| } |
| |
| return pool; |
| } |
| EXPORT_SYMBOL(mempool_create_node_noprof); |
| |
| /** |
| * mempool_resize - resize an existing memory pool |
| * @pool: pointer to the memory pool which was allocated via |
| * mempool_create(). |
| * @new_min_nr: the new minimum number of elements guaranteed to be |
| * allocated for this pool. |
| * |
| * This function shrinks/grows the pool. In the case of growing, |
| * it cannot be guaranteed that the pool will be grown to the new |
| * size immediately, but new mempool_free() calls will refill it. |
| * This function may sleep. |
| * |
| * Note, the caller must guarantee that no mempool_destroy is called |
| * while this function is running. mempool_alloc() & mempool_free() |
| * might be called (eg. from IRQ contexts) while this function executes. |
| * |
| * Return: %0 on success, negative error code otherwise. |
| */ |
| int mempool_resize(mempool_t *pool, int new_min_nr) |
| { |
| void *element; |
| void **new_elements; |
| unsigned long flags; |
| |
| BUG_ON(new_min_nr <= 0); |
| might_sleep(); |
| |
| spin_lock_irqsave(&pool->lock, flags); |
| if (new_min_nr <= pool->min_nr) { |
| while (new_min_nr < pool->curr_nr) { |
| element = remove_element(pool); |
| spin_unlock_irqrestore(&pool->lock, flags); |
| pool->free(element, pool->pool_data); |
| spin_lock_irqsave(&pool->lock, flags); |
| } |
| pool->min_nr = new_min_nr; |
| goto out_unlock; |
| } |
| spin_unlock_irqrestore(&pool->lock, flags); |
| |
| /* Grow the pool */ |
| new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements), |
| GFP_KERNEL); |
| if (!new_elements) |
| return -ENOMEM; |
| |
| spin_lock_irqsave(&pool->lock, flags); |
| if (unlikely(new_min_nr <= pool->min_nr)) { |
| /* Raced, other resize will do our work */ |
| spin_unlock_irqrestore(&pool->lock, flags); |
| kfree(new_elements); |
| goto out; |
| } |
| memcpy(new_elements, pool->elements, |
| pool->curr_nr * sizeof(*new_elements)); |
| kfree(pool->elements); |
| pool->elements = new_elements; |
| pool->min_nr = new_min_nr; |
| |
| while (pool->curr_nr < pool->min_nr) { |
| spin_unlock_irqrestore(&pool->lock, flags); |
| element = pool->alloc(GFP_KERNEL, pool->pool_data); |
| if (!element) |
| goto out; |
| spin_lock_irqsave(&pool->lock, flags); |
| if (pool->curr_nr < pool->min_nr) { |
| add_element(pool, element); |
| } else { |
| spin_unlock_irqrestore(&pool->lock, flags); |
| pool->free(element, pool->pool_data); /* Raced */ |
| goto out; |
| } |
| } |
| out_unlock: |
| spin_unlock_irqrestore(&pool->lock, flags); |
| out: |
| return 0; |
| } |
| EXPORT_SYMBOL(mempool_resize); |
| |
| /** |
| * mempool_alloc - allocate an element from a specific memory pool |
| * @pool: pointer to the memory pool which was allocated via |
| * mempool_create(). |
| * @gfp_mask: the usual allocation bitmask. |
| * |
| * this function only sleeps if the alloc_fn() function sleeps or |
| * returns NULL. Note that due to preallocation, this function |
| * *never* fails when called from process contexts. (it might |
| * fail if called from an IRQ context.) |
| * Note: using __GFP_ZERO is not supported. |
| * |
| * Return: pointer to the allocated element or %NULL on error. |
| */ |
| void *mempool_alloc_noprof(mempool_t *pool, gfp_t gfp_mask) |
| { |
| void *element; |
| unsigned long flags; |
| wait_queue_entry_t wait; |
| gfp_t gfp_temp; |
| |
| VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO); |
| might_alloc(gfp_mask); |
| |
| gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */ |
| gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */ |
| gfp_mask |= __GFP_NOWARN; /* failures are OK */ |
| |
| gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO); |
| |
| repeat_alloc: |
| |
| element = pool->alloc(gfp_temp, pool->pool_data); |
| if (likely(element != NULL)) |
| return element; |
| |
| spin_lock_irqsave(&pool->lock, flags); |
| if (likely(pool->curr_nr)) { |
| element = remove_element(pool); |
| spin_unlock_irqrestore(&pool->lock, flags); |
| /* paired with rmb in mempool_free(), read comment there */ |
| smp_wmb(); |
| /* |
| * Update the allocation stack trace as this is more useful |
| * for debugging. |
| */ |
| kmemleak_update_trace(element); |
| return element; |
| } |
| |
| /* |
| * We use gfp mask w/o direct reclaim or IO for the first round. If |
| * alloc failed with that and @pool was empty, retry immediately. |
| */ |
| if (gfp_temp != gfp_mask) { |
| spin_unlock_irqrestore(&pool->lock, flags); |
| gfp_temp = gfp_mask; |
| goto repeat_alloc; |
| } |
| |
| /* We must not sleep if !__GFP_DIRECT_RECLAIM */ |
| if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) { |
| spin_unlock_irqrestore(&pool->lock, flags); |
| return NULL; |
| } |
| |
| /* Let's wait for someone else to return an element to @pool */ |
| init_wait(&wait); |
| prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE); |
| |
| spin_unlock_irqrestore(&pool->lock, flags); |
| |
| /* |
| * FIXME: this should be io_schedule(). The timeout is there as a |
| * workaround for some DM problems in 2.6.18. |
| */ |
| io_schedule_timeout(5*HZ); |
| |
| finish_wait(&pool->wait, &wait); |
| goto repeat_alloc; |
| } |
| EXPORT_SYMBOL(mempool_alloc_noprof); |
| |
| /** |
| * mempool_alloc_preallocated - allocate an element from preallocated elements |
| * belonging to a specific memory pool |
| * @pool: pointer to the memory pool which was allocated via |
| * mempool_create(). |
| * |
| * This function is similar to mempool_alloc, but it only attempts allocating |
| * an element from the preallocated elements. It does not sleep and immediately |
| * returns if no preallocated elements are available. |
| * |
| * Return: pointer to the allocated element or %NULL if no elements are |
| * available. |
| */ |
| void *mempool_alloc_preallocated(mempool_t *pool) |
| { |
| void *element; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&pool->lock, flags); |
| if (likely(pool->curr_nr)) { |
| element = remove_element(pool); |
| spin_unlock_irqrestore(&pool->lock, flags); |
| /* paired with rmb in mempool_free(), read comment there */ |
| smp_wmb(); |
| /* |
| * Update the allocation stack trace as this is more useful |
| * for debugging. |
| */ |
| kmemleak_update_trace(element); |
| return element; |
| } |
| spin_unlock_irqrestore(&pool->lock, flags); |
| |
| return NULL; |
| } |
| EXPORT_SYMBOL(mempool_alloc_preallocated); |
| |
| /** |
| * mempool_free - return an element to the pool. |
| * @element: pool element pointer. |
| * @pool: pointer to the memory pool which was allocated via |
| * mempool_create(). |
| * |
| * this function only sleeps if the free_fn() function sleeps. |
| */ |
| void mempool_free(void *element, mempool_t *pool) |
| { |
| unsigned long flags; |
| |
| if (unlikely(element == NULL)) |
| return; |
| |
| /* |
| * Paired with the wmb in mempool_alloc(). The preceding read is |
| * for @element and the following @pool->curr_nr. This ensures |
| * that the visible value of @pool->curr_nr is from after the |
| * allocation of @element. This is necessary for fringe cases |
| * where @element was passed to this task without going through |
| * barriers. |
| * |
| * For example, assume @p is %NULL at the beginning and one task |
| * performs "p = mempool_alloc(...);" while another task is doing |
| * "while (!p) cpu_relax(); mempool_free(p, ...);". This function |
| * may end up using curr_nr value which is from before allocation |
| * of @p without the following rmb. |
| */ |
| smp_rmb(); |
| |
| /* |
| * For correctness, we need a test which is guaranteed to trigger |
| * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr |
| * without locking achieves that and refilling as soon as possible |
| * is desirable. |
| * |
| * Because curr_nr visible here is always a value after the |
| * allocation of @element, any task which decremented curr_nr below |
| * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets |
| * incremented to min_nr afterwards. If curr_nr gets incremented |
| * to min_nr after the allocation of @element, the elements |
| * allocated after that are subject to the same guarantee. |
| * |
| * Waiters happen iff curr_nr is 0 and the above guarantee also |
| * ensures that there will be frees which return elements to the |
| * pool waking up the waiters. |
| */ |
| if (unlikely(READ_ONCE(pool->curr_nr) < pool->min_nr)) { |
| spin_lock_irqsave(&pool->lock, flags); |
| if (likely(pool->curr_nr < pool->min_nr)) { |
| add_element(pool, element); |
| spin_unlock_irqrestore(&pool->lock, flags); |
| wake_up(&pool->wait); |
| return; |
| } |
| spin_unlock_irqrestore(&pool->lock, flags); |
| } |
| pool->free(element, pool->pool_data); |
| } |
| EXPORT_SYMBOL(mempool_free); |
| |
| /* |
| * A commonly used alloc and free fn. |
| */ |
| void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data) |
| { |
| struct kmem_cache *mem = pool_data; |
| VM_BUG_ON(mem->ctor); |
| return kmem_cache_alloc_noprof(mem, gfp_mask); |
| } |
| EXPORT_SYMBOL(mempool_alloc_slab); |
| |
| void mempool_free_slab(void *element, void *pool_data) |
| { |
| struct kmem_cache *mem = pool_data; |
| kmem_cache_free(mem, element); |
| } |
| EXPORT_SYMBOL(mempool_free_slab); |
| |
| /* |
| * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory |
| * specified by pool_data |
| */ |
| void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data) |
| { |
| size_t size = (size_t)pool_data; |
| return kmalloc_noprof(size, gfp_mask); |
| } |
| EXPORT_SYMBOL(mempool_kmalloc); |
| |
| void mempool_kfree(void *element, void *pool_data) |
| { |
| kfree(element); |
| } |
| EXPORT_SYMBOL(mempool_kfree); |
| |
| void *mempool_kvmalloc(gfp_t gfp_mask, void *pool_data) |
| { |
| size_t size = (size_t)pool_data; |
| return kvmalloc(size, gfp_mask); |
| } |
| EXPORT_SYMBOL(mempool_kvmalloc); |
| |
| void mempool_kvfree(void *element, void *pool_data) |
| { |
| kvfree(element); |
| } |
| EXPORT_SYMBOL(mempool_kvfree); |
| |
| /* |
| * A simple mempool-backed page allocator that allocates pages |
| * of the order specified by pool_data. |
| */ |
| void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data) |
| { |
| int order = (int)(long)pool_data; |
| return alloc_pages_noprof(gfp_mask, order); |
| } |
| EXPORT_SYMBOL(mempool_alloc_pages); |
| |
| void mempool_free_pages(void *element, void *pool_data) |
| { |
| int order = (int)(long)pool_data; |
| __free_pages(element, order); |
| } |
| EXPORT_SYMBOL(mempool_free_pages); |