v4.19.13 snapshot.
diff --git a/mm/mempool.c b/mm/mempool.c
new file mode 100644
index 0000000..0ef8cc8
--- /dev/null
+++ b/mm/mempool.c
@@ -0,0 +1,549 @@
+// 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/blkdev.h>
+#include <linux/writeback.h>
+#include "slab.h"
+
+#if defined(CONFIG_DEBUG_SLAB) || defined(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)
+{
+ /* Mempools backed by slab allocator */
+ if (pool->free == mempool_free_slab || pool->free == mempool_kfree)
+ __check_element(pool, element, ksize(element));
+
+ /* Mempools backed by page allocator */
+ if (pool->free == mempool_free_pages) {
+ int order = (int)(long)pool->pool_data;
+ void *addr = kmap_atomic((struct page *)element);
+
+ __check_element(pool, addr, 1UL << (PAGE_SHIFT + order));
+ kunmap_atomic(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)
+{
+ /* Mempools backed by slab allocator */
+ if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
+ __poison_element(element, ksize(element));
+
+ /* Mempools backed by page allocator */
+ if (pool->alloc == mempool_alloc_pages) {
+ int order = (int)(long)pool->pool_data;
+ void *addr = kmap_atomic((struct page *)element);
+
+ __poison_element(addr, 1UL << (PAGE_SHIFT + order));
+ kunmap_atomic(addr);
+ }
+}
+#else /* CONFIG_DEBUG_SLAB || 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_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
+
+static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
+{
+ if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
+ kasan_poison_kfree(element, _RET_IP_);
+ if (pool->alloc == mempool_alloc_pages)
+ kasan_free_pages(element, (unsigned long)pool->pool_data);
+}
+
+static void kasan_unpoison_element(mempool_t *pool, void *element)
+{
+ if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
+ kasan_unpoison_slab(element);
+ if (pool->alloc == mempool_alloc_pages)
+ kasan_alloc_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);
+ 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).
+ */
+int mempool_init(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);
+
+/**
+ * mempool_create - 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.
+ *
+ * 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.
+ */
+mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
+ mempool_free_t *free_fn, void *pool_data)
+{
+ return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,
+ GFP_KERNEL, NUMA_NO_NODE);
+}
+EXPORT_SYMBOL(mempool_create);
+
+mempool_t *mempool_create_node(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);
+
+/**
+ * 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.
+ */
+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.
+ */
+void *mempool_alloc(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_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
+
+ 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);
+
+/**
+ * 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(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(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(size, gfp_mask);
+}
+EXPORT_SYMBOL(mempool_kmalloc);
+
+void mempool_kfree(void *element, void *pool_data)
+{
+ kfree(element);
+}
+EXPORT_SYMBOL(mempool_kfree);
+
+/*
+ * 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(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);