From: Peter Zijlstra <a.p.zijlstra@chello.nl> 
Subject: [PATCH 11/31] mm: memory reserve management
Patch-mainline: not yet

Generic reserve management code.

It provides methods to reserve and charge. Upon this, generic alloc/free style
reserve pools could be build, which could fully replace mempool_t
functionality.

It should also allow for a Banker's algorithm replacement of __GFP_NOFAIL.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Suresh Jayaraman <sjayaraman@suse.de>
---
 include/linux/reserve.h |  197 ++++++++++++++
 mm/Makefile             |    2 
 mm/reserve.c            |  637 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 835 insertions(+), 1 deletion(-)

--- /dev/null
+++ b/include/linux/reserve.h
@@ -0,0 +1,197 @@
+/*
+ * Memory reserve management.
+ *
+ *  Copyright (C) 2007-2008 Red Hat, Inc.,
+ *  			    Peter Zijlstra <pzijlstr@redhat.com>
+ *
+ * This file contains the public data structure and API definitions.
+ */
+
+#ifndef _LINUX_RESERVE_H
+#define _LINUX_RESERVE_H
+
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/wait.h>
+#include <linux/slab.h>
+
+struct mem_reserve {
+	struct mem_reserve *parent;
+	struct list_head children;
+	struct list_head siblings;
+
+	const char *name;
+
+	long pages;
+	long limit;
+	long usage;
+	spinlock_t lock;	/* protects limit and usage */
+
+	wait_queue_head_t waitqueue;
+};
+
+extern struct mem_reserve mem_reserve_root;
+
+void mem_reserve_init(struct mem_reserve *res, const char *name,
+		      struct mem_reserve *parent);
+int mem_reserve_connect(struct mem_reserve *new_child,
+			struct mem_reserve *node);
+void mem_reserve_disconnect(struct mem_reserve *node);
+
+int mem_reserve_pages_set(struct mem_reserve *res, long pages);
+int mem_reserve_pages_add(struct mem_reserve *res, long pages);
+int mem_reserve_pages_charge(struct mem_reserve *res, long pages);
+
+int mem_reserve_kmalloc_set(struct mem_reserve *res, long bytes);
+int mem_reserve_kmalloc_charge(struct mem_reserve *res, long bytes);
+
+struct kmem_cache;
+
+int mem_reserve_kmem_cache_set(struct mem_reserve *res,
+			       struct kmem_cache *s,
+			       int objects);
+int mem_reserve_kmem_cache_charge(struct mem_reserve *res,
+				  struct kmem_cache *s, long objs);
+
+void *___kmalloc_reserve(size_t size, gfp_t flags, int node, unsigned long ip,
+			 struct mem_reserve *res, int *emerg);
+
+static inline
+void *__kmalloc_reserve(size_t size, gfp_t flags, int node, unsigned long ip,
+			struct mem_reserve *res, int *emerg)
+{
+	void *obj;
+
+	obj = kmalloc_node_track_caller(size,
+			flags | __GFP_NOMEMALLOC | __GFP_NOWARN, node);
+	if (!obj)
+		obj = ___kmalloc_reserve(size, flags, node, ip, res, emerg);
+
+	return obj;
+}
+
+/**
+ * kmalloc_reserve() - kmalloc() and charge against @res for @emerg allocations
+ * @size - size of the requested memory region
+ * @gfp - allocation flags to use for this allocation
+ * @node - preferred memory node for this allocation
+ * @res - reserve to charge emergency allocations against
+ * @emerg - bit 0 is set when the allocation was an emergency allocation
+ *
+ * Returns NULL on failure
+ */
+#define kmalloc_reserve(size, gfp, node, res, emerg) 			\
+	__kmalloc_reserve(size, gfp, node, _RET_IP_, res, emerg)
+
+void __kfree_reserve(void *obj, struct mem_reserve *res, int emerg);
+
+/**
+ * kfree_reserve() - kfree() and uncharge against @res for @emerg allocations
+ * @obj - memory to free
+ * @res - reserve to uncharge emergency allocations from
+ * @emerg - was this an emergency allocation
+ */
+static inline
+void kfree_reserve(void *obj, struct mem_reserve *res, int emerg)
+{
+	if (unlikely(obj && res && emerg))
+		__kfree_reserve(obj, res, emerg);
+	else
+		kfree(obj);
+}
+
+void *__kmem_cache_alloc_reserve(struct kmem_cache *s, gfp_t flags, int node,
+				 struct mem_reserve *res, int *emerg);
+
+/**
+ * kmem_cache_alloc_reserve() - kmem_cache_alloc() and charge against @res
+ * @s - kmem_cache to allocate from
+ * @gfp - allocation flags to use for this allocation
+ * @node - preferred memory node for this allocation
+ * @res - reserve to charge emergency allocations against
+ * @emerg - bit 0 is set when the allocation was an emergency allocation
+ *
+ * Returns NULL on failure
+ */
+static inline
+void *kmem_cache_alloc_reserve(struct kmem_cache *s, gfp_t flags, int node,
+			       struct mem_reserve *res, int *emerg)
+{
+	void *obj;
+
+	obj = kmem_cache_alloc_node(s,
+			flags | __GFP_NOMEMALLOC | __GFP_NOWARN, node);
+	if (!obj)
+		obj = __kmem_cache_alloc_reserve(s, flags, node, res, emerg);
+
+	return obj;
+}
+
+void __kmem_cache_free_reserve(struct kmem_cache *s, void *obj,
+			       struct mem_reserve *res, int emerg);
+
+/**
+ * kmem_cache_free_reserve() - kmem_cache_free() and uncharge against @res
+ * @s - kmem_cache to free to
+ * @obj - memory to free
+ * @res - reserve to uncharge emergency allocations from
+ * @emerg - was this an emergency allocation
+ */
+static inline
+void kmem_cache_free_reserve(struct kmem_cache *s, void *obj,
+			     struct mem_reserve *res, int emerg)
+{
+	if (unlikely(obj && res && emerg))
+		__kmem_cache_free_reserve(s, obj, res, emerg);
+	else
+		kmem_cache_free(s, obj);
+}
+
+struct page *__alloc_pages_reserve(int node, gfp_t flags, int order,
+				  struct mem_reserve *res, int *emerg);
+
+/**
+ * alloc_pages_reserve() - alloc_pages() and charge against @res
+ * @node - preferred memory node for this allocation
+ * @gfp - allocation flags to use for this allocation
+ * @order - page order
+ * @res - reserve to charge emergency allocations against
+ * @emerg - bit 0 is set when the allocation was an emergency allocation
+ *
+ * Returns NULL on failure
+ */
+static inline
+struct page *alloc_pages_reserve(int node, gfp_t flags, int order,
+				 struct mem_reserve *res, int *emerg)
+{
+	struct page *page;
+
+	page = alloc_pages_node(node,
+			flags | __GFP_NOMEMALLOC | __GFP_NOWARN, order);
+	if (!page)
+		page = __alloc_pages_reserve(node, flags, order, res, emerg);
+
+	return page;
+}
+
+void __free_pages_reserve(struct page *page, int order,
+			  struct mem_reserve *res, int emerg);
+
+/**
+ * free_pages_reserve() - __free_pages() and uncharge against @res
+ * @page - page to free
+ * @order - page order
+ * @res - reserve to uncharge emergency allocations from
+ * @emerg - was this an emergency allocation
+ */
+static inline
+void free_pages_reserve(struct page *page, int order,
+			struct mem_reserve *res, int emerg)
+{
+	if (unlikely(page && res && emerg))
+		__free_pages_reserve(page, order, res, emerg);
+	else
+		__free_pages(page, order);
+}
+
+#endif /* _LINUX_RESERVE_H */
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -12,7 +12,7 @@ obj-y			:= bootmem.o filemap.o mempool.o
 			   readahead.o swap.o truncate.o vmscan.o shmem.o \
 			   prio_tree.o util.o mmzone.o vmstat.o backing-dev.o \
 			   page_isolation.o mm_init.o mmu_context.o percpu.o \
-			   $(mmu-y)
+			   reserve.o $(mmu-y)
 obj-y += init-mm.o
 
 obj-$(CONFIG_HAVE_MEMBLOCK) += memblock.o
--- /dev/null
+++ b/mm/reserve.c
@@ -0,0 +1,639 @@
+/*
+ * Memory reserve management.
+ *
+ *  Copyright (C) 2007-2008, Red Hat, Inc.,
+ *  			     Peter Zijlstra <pzijlstr@redhat.com>
+ *
+ * Description:
+ *
+ * Manage a set of memory reserves.
+ *
+ * A memory reserve is a reserve for a specified number of object of specified
+ * size. Since memory is managed in pages, this reserve demand is then
+ * translated into a page unit.
+ *
+ * So each reserve has a specified object limit, an object usage count and a
+ * number of pages required to back these objects.
+ *
+ * Usage is charged against a reserve, if the charge fails, the resource must
+ * not be allocated/used.
+ *
+ * The reserves are managed in a tree, and the resource demands (pages and
+ * limit) are propagated up the tree. Obviously the object limit will be
+ * meaningless as soon as the unit starts mixing, but the required page reserve
+ * (being of one unit) is still valid at the root.
+ *
+ * It is the page demand of the root node that is used to set the global
+ * reserve (adjust_memalloc_reserve() which sets zone->pages_emerg).
+ *
+ * As long as a subtree has the same usage unit, an aggregate node can be used
+ * to charge against, instead of the leaf nodes. However, do be consistent with
+ * who is charged, resource usage is not propagated up the tree (for
+ * performance reasons).
+ */
+
+#include <linux/reserve.h>
+#include <linux/mutex.h>
+#include <linux/mmzone.h>
+#include <linux/log2.h>
+#include <linux/proc_fs.h>
+#include <linux/seq_file.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include "internal.h"
+
+static DEFINE_MUTEX(mem_reserve_mutex);
+
+/**
+ * @mem_reserve_root - the global reserve root
+ *
+ * The global reserve is empty, and has no limit unit, it merely
+ * acts as an aggregation point for reserves and an interface to
+ * adjust_memalloc_reserve().
+ */
+struct mem_reserve mem_reserve_root = {
+	.children = LIST_HEAD_INIT(mem_reserve_root.children),
+	.siblings = LIST_HEAD_INIT(mem_reserve_root.siblings),
+	.name = "total reserve",
+	.lock = __SPIN_LOCK_UNLOCKED(mem_reserve_root.lock),
+	.waitqueue = __WAIT_QUEUE_HEAD_INITIALIZER(mem_reserve_root.waitqueue),
+};
+EXPORT_SYMBOL_GPL(mem_reserve_root);
+
+/**
+ * mem_reserve_init() - initialize a memory reserve object
+ * @res - the new reserve object
+ * @name - a name for this reserve
+ * @parent - when non NULL, the parent to connect to.
+ */
+void mem_reserve_init(struct mem_reserve *res, const char *name,
+		      struct mem_reserve *parent)
+{
+	memset(res, 0, sizeof(*res));
+	INIT_LIST_HEAD(&res->children);
+	INIT_LIST_HEAD(&res->siblings);
+	res->name = name;
+	spin_lock_init(&res->lock);
+	init_waitqueue_head(&res->waitqueue);
+
+	if (parent)
+		mem_reserve_connect(res, parent);
+}
+EXPORT_SYMBOL_GPL(mem_reserve_init);
+
+/*
+ * propagate the pages and limit changes up the (sub)tree.
+ */
+static void __calc_reserve(struct mem_reserve *res, long pages, long limit)
+{
+	unsigned long flags;
+
+	for ( ; res; res = res->parent) {
+		res->pages += pages;
+
+		if (limit) {
+			spin_lock_irqsave(&res->lock, flags);
+			res->limit += limit;
+			spin_unlock_irqrestore(&res->lock, flags);
+		}
+	}
+}
+
+/**
+ * __mem_reserve_add() - primitive to change the size of a reserve
+ * @res - reserve to change
+ * @pages - page delta
+ * @limit - usage limit delta
+ *
+ * Returns -ENOMEM when a size increase is not possible atm.
+ */
+static int __mem_reserve_add(struct mem_reserve *res, long pages, long limit)
+{
+	int ret = 0;
+	long reserve;
+
+	/*
+	 * This looks more complex than need be, that is because we handle
+	 * the case where @res isn't actually connected to mem_reserve_root.
+	 *
+	 * So, by propagating the new pages up the (sub)tree and computing
+	 * the difference in mem_reserve_root.pages we find if this action
+	 * affects the actual reserve.
+	 *
+	 * The (partial) propagation also makes that mem_reserve_connect()
+	 * needs only look at the direct child, since each disconnected
+	 * sub-tree is fully up-to-date.
+	 */
+	reserve = mem_reserve_root.pages;
+	__calc_reserve(res, pages, 0);
+	reserve = mem_reserve_root.pages - reserve;
+
+	if (reserve) {
+		ret = adjust_memalloc_reserve(reserve);
+		if (ret)
+			__calc_reserve(res, -pages, 0);
+	}
+
+	/*
+	 * Delay updating the limits until we've acquired the resources to
+	 * back it.
+	 */
+	if (!ret)
+		__calc_reserve(res, 0, limit);
+
+	return ret;
+}
+
+/**
+ * __mem_reserve_charge() - primitive to charge object usage of a reserve
+ * @res - reserve to charge
+ * @charge - size of the charge
+ *
+ * Returns non-zero on success, zero on failure.
+ */
+static
+int __mem_reserve_charge(struct mem_reserve *res, long charge)
+{
+	unsigned long flags;
+	int ret = 0;
+
+	spin_lock_irqsave(&res->lock, flags);
+	if (charge < 0 || res->usage + charge < res->limit) {
+		res->usage += charge;
+		if (unlikely(res->usage < 0))
+			res->usage = 0;
+		ret = 1;
+	}
+	if (charge < 0)
+		wake_up_all(&res->waitqueue);
+	spin_unlock_irqrestore(&res->lock, flags);
+
+	return ret;
+}
+
+/**
+ * mem_reserve_connect() - connect a reserve to another in a child-parent relation
+ * @new_child - the reserve node to connect (child)
+ * @node - the reserve node to connect to (parent)
+ *
+ * Connecting a node results in an increase of the reserve by the amount of
+ * pages in @new_child->pages if @node has a connection to mem_reserve_root.
+ *
+ * Returns -ENOMEM when the new connection would increase the reserve (parent
+ * is connected to mem_reserve_root) and there is no memory to do so.
+ *
+ * On error, the child is _NOT_ connected.
+ */
+int mem_reserve_connect(struct mem_reserve *new_child, struct mem_reserve *node)
+{
+	int ret;
+
+	WARN_ON(!new_child->name);
+
+	mutex_lock(&mem_reserve_mutex);
+	if (new_child->parent) {
+		ret = -EEXIST;
+		goto unlock;
+	}
+	new_child->parent = node;
+	list_add(&new_child->siblings, &node->children);
+	ret = __mem_reserve_add(node, new_child->pages, new_child->limit);
+	if (ret) {
+		new_child->parent = NULL;
+		list_del_init(&new_child->siblings);
+	}
+unlock:
+	mutex_unlock(&mem_reserve_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mem_reserve_connect);
+
+/**
+ * mem_reserve_disconnect() - sever a nodes connection to the reserve tree
+ * @node - the node to disconnect
+ *
+ * Disconnecting a node results in a reduction of the reserve by @node->pages
+ * if node had a connection to mem_reserve_root.
+ */
+void mem_reserve_disconnect(struct mem_reserve *node)
+{
+	int ret;
+
+	BUG_ON(!node->parent);
+
+	mutex_lock(&mem_reserve_mutex);
+	if (!node->parent) {
+		ret = -ENOENT;
+		goto unlock;
+	}
+	ret = __mem_reserve_add(node->parent, -node->pages, -node->limit);
+	if (!ret) {
+		node->parent = NULL;
+		list_del_init(&node->siblings);
+	}
+unlock:
+	mutex_unlock(&mem_reserve_mutex);
+
+	/*
+	 * We cannot fail to shrink the reserves, can we?
+	 */
+	WARN_ON(ret);
+}
+EXPORT_SYMBOL_GPL(mem_reserve_disconnect);
+
+#ifdef CONFIG_PROC_FS
+
+/*
+ * Simple output of the reserve tree in: /proc/reserve_info
+ * Example:
+ *
+ * localhost ~ # cat /proc/reserve_info
+ * 1:0 "total reserve" 6232K 0/278581
+ * 2:1 "total network reserve" 6232K 0/278581
+ * 3:2 "network TX reserve" 212K 0/53
+ * 4:3 "protocol TX pages" 212K 0/53
+ * 5:2 "network RX reserve" 6020K 0/278528
+ * 6:5 "IPv4 route cache" 5508K 0/16384
+ * 7:5 "SKB data reserve" 512K 0/262144
+ * 8:7 "IPv4 fragment cache" 512K 0/262144
+ */
+
+static void mem_reserve_show_item(struct seq_file *m, struct mem_reserve *res,
+				  unsigned int parent, unsigned int *id)
+{
+	struct mem_reserve *child;
+	unsigned int my_id = ++*id;
+
+	seq_printf(m, "%d:%d \"%s\" %ldK %ld/%ld\n",
+			my_id, parent, res->name,
+			res->pages << (PAGE_SHIFT - 10),
+			res->usage, res->limit);
+
+	list_for_each_entry(child, &res->children, siblings)
+		mem_reserve_show_item(m, child, my_id, id);
+}
+
+static int mem_reserve_show(struct seq_file *m, void *v)
+{
+	unsigned int ident = 0;
+
+	mutex_lock(&mem_reserve_mutex);
+	mem_reserve_show_item(m, &mem_reserve_root, ident, &ident);
+	mutex_unlock(&mem_reserve_mutex);
+
+	return 0;
+}
+
+static int mem_reserve_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, mem_reserve_show, NULL);
+}
+
+static const struct file_operations mem_reserve_opterations = {
+	.open = mem_reserve_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+static __init int mem_reserve_proc_init(void)
+{
+	proc_create("reserve_info", S_IRUSR, NULL, &mem_reserve_opterations);
+	return 0;
+}
+
+module_init(mem_reserve_proc_init);
+
+#endif
+
+/*
+ * alloc_page helpers
+ */
+
+/**
+ * mem_reserve_pages_set() - set reserves size in pages
+ * @res - reserve to set
+ * @pages - size in pages to set it to
+ *
+ * Returns -ENOMEM when it fails to set the reserve. On failure the old size
+ * is preserved.
+ */
+int mem_reserve_pages_set(struct mem_reserve *res, long pages)
+{
+	int ret;
+
+	mutex_lock(&mem_reserve_mutex);
+	pages -= res->pages;
+	ret = __mem_reserve_add(res, pages, pages * PAGE_SIZE);
+	mutex_unlock(&mem_reserve_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mem_reserve_pages_set);
+
+/**
+ * mem_reserve_pages_add() - change the size in a relative way
+ * @res - reserve to change
+ * @pages - number of pages to add (or subtract when negative)
+ *
+ * Similar to mem_reserve_pages_set, except that the argument is relative
+ * instead of absolute.
+ *
+ * Returns -ENOMEM when it fails to increase.
+ */
+int mem_reserve_pages_add(struct mem_reserve *res, long pages)
+{
+	int ret;
+
+	mutex_lock(&mem_reserve_mutex);
+	ret = __mem_reserve_add(res, pages, pages * PAGE_SIZE);
+	mutex_unlock(&mem_reserve_mutex);
+
+	return ret;
+}
+
+/**
+ * mem_reserve_pages_charge() - charge page usage to a reserve
+ * @res - reserve to charge
+ * @pages - size to charge
+ *
+ * Returns non-zero on success.
+ */
+int mem_reserve_pages_charge(struct mem_reserve *res, long pages)
+{
+	return __mem_reserve_charge(res, pages * PAGE_SIZE);
+}
+EXPORT_SYMBOL_GPL(mem_reserve_pages_charge);
+
+/*
+ * kmalloc helpers
+ */
+
+/**
+ * mem_reserve_kmalloc_set() - set this reserve to bytes worth of kmalloc
+ * @res - reserve to change
+ * @bytes - size in bytes to reserve
+ *
+ * Returns -ENOMEM on failure.
+ */
+int mem_reserve_kmalloc_set(struct mem_reserve *res, long bytes)
+{
+	int ret;
+	long pages;
+
+	mutex_lock(&mem_reserve_mutex);
+	pages = kmalloc_estimate_bytes(GFP_ATOMIC, bytes);
+	pages -= res->pages;
+	bytes -= res->limit;
+	ret = __mem_reserve_add(res, pages, bytes);
+	mutex_unlock(&mem_reserve_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mem_reserve_kmalloc_set);
+
+/**
+ * mem_reserve_kmalloc_charge() - charge bytes to a reserve
+ * @res - reserve to charge
+ * @bytes - bytes to charge
+ *
+ * Returns non-zero on success.
+ */
+int mem_reserve_kmalloc_charge(struct mem_reserve *res, long bytes)
+{
+	if (bytes < 0)
+		bytes = -roundup_pow_of_two(-bytes);
+	else
+		bytes = roundup_pow_of_two(bytes);
+
+	return __mem_reserve_charge(res, bytes);
+}
+EXPORT_SYMBOL_GPL(mem_reserve_kmalloc_charge);
+
+/*
+ * kmem_cache helpers
+ */
+
+/**
+ * mem_reserve_kmem_cache_set() - set reserve to @objects worth of kmem_cache_alloc of @s
+ * @res - reserve to set
+ * @s - kmem_cache to reserve from
+ * @objects - number of objects to reserve
+ *
+ * Returns -ENOMEM on failure.
+ */
+int mem_reserve_kmem_cache_set(struct mem_reserve *res, struct kmem_cache *s,
+			       int objects)
+{
+	int ret;
+	long pages, bytes;
+
+	mutex_lock(&mem_reserve_mutex);
+	pages = kmem_alloc_estimate(s, GFP_ATOMIC, objects);
+	pages -= res->pages;
+	bytes = objects * kmem_cache_size(s) - res->limit;
+	ret = __mem_reserve_add(res, pages, bytes);
+	mutex_unlock(&mem_reserve_mutex);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(mem_reserve_kmem_cache_set);
+
+/**
+ * mem_reserve_kmem_cache_charge() - charge (or uncharge) usage of objs
+ * @res - reserve to charge
+ * @objs - objects to charge for
+ *
+ * Returns non-zero on success.
+ */
+int mem_reserve_kmem_cache_charge(struct mem_reserve *res, struct kmem_cache *s,
+				  long objs)
+{
+	return __mem_reserve_charge(res, objs * kmem_cache_size(s));
+}
+EXPORT_SYMBOL_GPL(mem_reserve_kmem_cache_charge);
+
+/*
+ * Alloc wrappers.
+ *
+ * Actual usage is commented in linux/reserve.h where the interface functions
+ * live. Furthermore, the code is 3 instances of the same paradigm, hence only
+ * the first contains extensive comments.
+ */
+
+/*
+ * kmalloc/kfree
+ */
+
+void *___kmalloc_reserve(size_t size, gfp_t flags, int node, unsigned long ip,
+			 struct mem_reserve *res, int *emerg)
+{
+	void *obj;
+	gfp_t gfp;
+
+	/*
+	 * Try a regular allocation, when that fails and we're not entitled
+	 * to the reserves, fail.
+	 */
+	gfp = flags | __GFP_NOMEMALLOC | __GFP_NOWARN;
+	obj = kmalloc_node_track_caller(size, gfp, node);
+
+	if (obj || !(gfp_to_alloc_flags(flags) & ALLOC_NO_WATERMARKS))
+		goto out;
+
+	/*
+	 * If we were given a reserve to charge against, try that.
+	 */
+	if (res && !mem_reserve_kmalloc_charge(res, size)) {
+		/*
+		 * If we failed to charge and we're not allowed to wait for
+		 * it to succeed, bail.
+		 */
+		if (!(flags & __GFP_WAIT))
+			goto out;
+
+		/*
+		 * Wait for a successfull charge against the reserve. All
+		 * uncharge operations against this reserve will wake us up.
+		 */
+		wait_event(res->waitqueue,
+				mem_reserve_kmalloc_charge(res, size));
+
+		/*
+		 * After waiting for it, again try a regular allocation.
+		 * Pressure could have lifted during our sleep. If this
+		 * succeeds, uncharge the reserve.
+		 */
+		obj = kmalloc_node_track_caller(size, gfp, node);
+		if (obj) {
+			mem_reserve_kmalloc_charge(res, -size);
+			goto out;
+		}
+	}
+
+	/*
+	 * Regular allocation failed, and we've successfully charged our
+	 * requested usage against the reserve. Do the emergency allocation.
+	 */
+	obj = kmalloc_node_track_caller(size, flags, node);
+	WARN_ON(!obj);
+	if (emerg)
+		*emerg = 1;
+
+out:
+	return obj;
+}
+
+void __kfree_reserve(void *obj, struct mem_reserve *res, int emerg)
+{
+	/*
+	 * ksize gives the full allocated size vs the requested size we used to
+	 * charge; however since we round up to the nearest power of two, this
+	 * should all work nicely.
+	 */
+	size_t size = ksize(obj);
+
+	kfree(obj);
+	/*
+	 * Free before uncharge, this ensures memory is actually present when
+	 * a subsequent charge succeeds.
+	 */
+	mem_reserve_kmalloc_charge(res, -size);
+}
+
+/*
+ * kmem_cache_alloc/kmem_cache_free
+ */
+
+void *__kmem_cache_alloc_reserve(struct kmem_cache *s, gfp_t flags, int node,
+				 struct mem_reserve *res, int *emerg)
+{
+	void *obj;
+	gfp_t gfp;
+
+	gfp = flags | __GFP_NOMEMALLOC | __GFP_NOWARN;
+	obj = kmem_cache_alloc_node(s, gfp, node);
+
+	if (obj || !(gfp_to_alloc_flags(flags) & ALLOC_NO_WATERMARKS))
+		goto out;
+
+	if (res && !mem_reserve_kmem_cache_charge(res, s, 1)) {
+		if (!(flags & __GFP_WAIT))
+			goto out;
+
+		wait_event(res->waitqueue,
+				mem_reserve_kmem_cache_charge(res, s, 1));
+
+		obj = kmem_cache_alloc_node(s, gfp, node);
+		if (obj) {
+			mem_reserve_kmem_cache_charge(res, s, -1);
+			goto out;
+		}
+	}
+
+	obj = kmem_cache_alloc_node(s, flags, node);
+	WARN_ON(!obj);
+	if (emerg)
+		*emerg = 1;
+
+out:
+	return obj;
+}
+
+void __kmem_cache_free_reserve(struct kmem_cache *s, void *obj,
+			       struct mem_reserve *res, int emerg)
+{
+	kmem_cache_free(s, obj);
+	mem_reserve_kmem_cache_charge(res, s, -1);
+}
+
+/*
+ * alloc_pages/free_pages
+ */
+
+struct page *__alloc_pages_reserve(int node, gfp_t flags, int order,
+				   struct mem_reserve *res, int *emerg)
+{
+	struct page *page;
+	gfp_t gfp;
+	long pages = 1 << order;
+
+	gfp = flags | __GFP_NOMEMALLOC | __GFP_NOWARN;
+	page = alloc_pages_node(node, gfp, order);
+
+	if (page || !(gfp_to_alloc_flags(flags) & ALLOC_NO_WATERMARKS))
+		goto out;
+
+	if (res && !mem_reserve_pages_charge(res, pages)) {
+		if (!(flags & __GFP_WAIT))
+			goto out;
+
+		wait_event(res->waitqueue,
+				mem_reserve_pages_charge(res, pages));
+
+		page = alloc_pages_node(node, gfp, order);
+		if (page) {
+			mem_reserve_pages_charge(res, -pages);
+			goto out;
+		}
+	}
+
+	page = alloc_pages_node(node, flags, order);
+	WARN_ON(!page);
+	if (emerg)
+		*emerg = 1;
+
+out:
+	return page;
+}
+EXPORT_SYMBOL_GPL(__alloc_pages_reserve);
+
+void __free_pages_reserve(struct page *page, int order,
+			  struct mem_reserve *res, int emerg)
+{
+	__free_pages(page, order);
+	mem_reserve_pages_charge(res, -(1 << order));
+}
+EXPORT_SYMBOL_GPL(__free_pages_reserve);
