diff --git a/mm/filemap.c b/mm/filemap.c
index 81fb9bf..b7a01e9 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -33,6 +33,7 @@
 #include <linux/syscalls.h>
 #include <linux/cpuset.h>
 #include <linux/hardirq.h> /* for BUG_ON(!in_atomic()) only */
+#include <linux/memcontrol.h>
 #include "internal.h"
 
 /*
@@ -118,6 +119,7 @@
 {
 	struct address_space *mapping = page->mapping;
 
+	mem_cgroup_uncharge_page(page);
 	radix_tree_delete(&mapping->page_tree, page->index);
 	page->mapping = NULL;
 	mapping->nrpages--;
@@ -461,6 +463,11 @@
 	int error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
 
 	if (error == 0) {
+
+		error = mem_cgroup_charge(page, current->mm);
+		if (error)
+			goto out;
+
 		write_lock_irq(&mapping->tree_lock);
 		error = radix_tree_insert(&mapping->page_tree, offset, page);
 		if (!error) {
@@ -470,10 +477,13 @@
 			page->index = offset;
 			mapping->nrpages++;
 			__inc_zone_page_state(page, NR_FILE_PAGES);
-		}
+		} else
+			mem_cgroup_uncharge_page(page);
+
 		write_unlock_irq(&mapping->tree_lock);
 		radix_tree_preload_end();
 	}
+out:
 	return error;
 }
 EXPORT_SYMBOL(add_to_page_cache);
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 4d4805e..ebca767 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -21,6 +21,9 @@
 #include <linux/memcontrol.h>
 #include <linux/cgroup.h>
 #include <linux/mm.h>
+#include <linux/page-flags.h>
+#include <linux/bit_spinlock.h>
+#include <linux/rcupdate.h>
 
 struct cgroup_subsys mem_cgroup_subsys;
 
@@ -31,7 +34,9 @@
  * to help the administrator determine what knobs to tune.
  *
  * TODO: Add a water mark for the memory controller. Reclaim will begin when
- * we hit the water mark.
+ * we hit the water mark. May be even add a low water mark, such that
+ * no reclaim occurs from a cgroup at it's low water mark, this is
+ * a feature that will be implemented much later in the future.
  */
 struct mem_cgroup {
 	struct cgroup_subsys_state css;
@@ -49,6 +54,14 @@
 };
 
 /*
+ * We use the lower bit of the page->page_cgroup pointer as a bit spin
+ * lock. We need to ensure that page->page_cgroup is atleast two
+ * byte aligned (based on comments from Nick Piggin)
+ */
+#define PAGE_CGROUP_LOCK_BIT 	0x0
+#define PAGE_CGROUP_LOCK 		(1 << PAGE_CGROUP_LOCK_BIT)
+
+/*
  * A page_cgroup page is associated with every page descriptor. The
  * page_cgroup helps us identify information about the cgroup
  */
@@ -56,6 +69,8 @@
 	struct list_head lru;		/* per cgroup LRU list */
 	struct page *page;
 	struct mem_cgroup *mem_cgroup;
+	atomic_t ref_cnt;		/* Helpful when pages move b/w  */
+					/* mapped and cached states     */
 };
 
 
@@ -88,14 +103,157 @@
 	css_put(&mm->mem_cgroup->css);
 }
 
+static inline int page_cgroup_locked(struct page *page)
+{
+	return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT,
+					&page->page_cgroup);
+}
+
 void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc)
 {
-	page->page_cgroup = (unsigned long)pc;
+	int locked;
+
+	/*
+	 * While resetting the page_cgroup we might not hold the
+	 * page_cgroup lock. free_hot_cold_page() is an example
+	 * of such a scenario
+	 */
+	if (pc)
+		VM_BUG_ON(!page_cgroup_locked(page));
+	locked = (page->page_cgroup & PAGE_CGROUP_LOCK);
+	page->page_cgroup = ((unsigned long)pc | locked);
 }
 
 struct page_cgroup *page_get_page_cgroup(struct page *page)
 {
-	return page->page_cgroup;
+	return (struct page_cgroup *)
+		(page->page_cgroup & ~PAGE_CGROUP_LOCK);
+}
+
+void __always_inline lock_page_cgroup(struct page *page)
+{
+	bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
+	VM_BUG_ON(!page_cgroup_locked(page));
+}
+
+void __always_inline unlock_page_cgroup(struct page *page)
+{
+	bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup);
+}
+
+/*
+ * Charge the memory controller for page usage.
+ * Return
+ * 0 if the charge was successful
+ * < 0 if the cgroup is over its limit
+ */
+int mem_cgroup_charge(struct page *page, struct mm_struct *mm)
+{
+	struct mem_cgroup *mem;
+	struct page_cgroup *pc, *race_pc;
+
+	/*
+	 * Should page_cgroup's go to their own slab?
+	 * One could optimize the performance of the charging routine
+	 * by saving a bit in the page_flags and using it as a lock
+	 * to see if the cgroup page already has a page_cgroup associated
+	 * with it
+	 */
+	lock_page_cgroup(page);
+	pc = page_get_page_cgroup(page);
+	/*
+	 * The page_cgroup exists and the page has already been accounted
+	 */
+	if (pc) {
+		atomic_inc(&pc->ref_cnt);
+		goto done;
+	}
+
+	unlock_page_cgroup(page);
+
+	pc = kzalloc(sizeof(struct page_cgroup), GFP_KERNEL);
+	if (pc == NULL)
+		goto err;
+
+	rcu_read_lock();
+	/*
+	 * We always charge the cgroup the mm_struct belongs to
+	 * the mm_struct's mem_cgroup changes on task migration if the
+	 * thread group leader migrates. It's possible that mm is not
+	 * set, if so charge the init_mm (happens for pagecache usage).
+	 */
+	if (!mm)
+		mm = &init_mm;
+
+	mem = rcu_dereference(mm->mem_cgroup);
+	/*
+	 * For every charge from the cgroup, increment reference
+	 * count
+	 */
+	css_get(&mem->css);
+	rcu_read_unlock();
+
+	/*
+	 * If we created the page_cgroup, we should free it on exceeding
+	 * the cgroup limit.
+	 */
+	if (res_counter_charge(&mem->res, 1)) {
+		css_put(&mem->css);
+		goto free_pc;
+	}
+
+	lock_page_cgroup(page);
+	/*
+	 * Check if somebody else beat us to allocating the page_cgroup
+	 */
+	race_pc = page_get_page_cgroup(page);
+	if (race_pc) {
+		kfree(pc);
+		pc = race_pc;
+		atomic_inc(&pc->ref_cnt);
+		res_counter_uncharge(&mem->res, 1);
+		css_put(&mem->css);
+		goto done;
+	}
+
+	atomic_set(&pc->ref_cnt, 1);
+	pc->mem_cgroup = mem;
+	pc->page = page;
+	page_assign_page_cgroup(page, pc);
+
+done:
+	unlock_page_cgroup(page);
+	return 0;
+free_pc:
+	kfree(pc);
+	return -ENOMEM;
+err:
+	unlock_page_cgroup(page);
+	return -ENOMEM;
+}
+
+/*
+ * Uncharging is always a welcome operation, we never complain, simply
+ * uncharge.
+ */
+void mem_cgroup_uncharge(struct page_cgroup *pc)
+{
+	struct mem_cgroup *mem;
+	struct page *page;
+
+	if (!pc)
+		return;
+
+	if (atomic_dec_and_test(&pc->ref_cnt)) {
+		page = pc->page;
+		lock_page_cgroup(page);
+		mem = pc->mem_cgroup;
+		css_put(&mem->css);
+		page_assign_page_cgroup(page, NULL);
+		unlock_page_cgroup(page);
+		res_counter_uncharge(&mem->res, 1);
+		kfree(pc);
+	}
 }
 
 static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft,
@@ -150,6 +308,8 @@
 		return NULL;
 
 	res_counter_init(&mem->res);
+	INIT_LIST_HEAD(&mem->active_list);
+	INIT_LIST_HEAD(&mem->inactive_list);
 	return &mem->css;
 }
 
diff --git a/mm/memory.c b/mm/memory.c
index 9d073fa..0ba224e 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -50,6 +50,7 @@
 #include <linux/delayacct.h>
 #include <linux/init.h>
 #include <linux/writeback.h>
+#include <linux/memcontrol.h>
 
 #include <asm/pgalloc.h>
 #include <asm/uaccess.h>
@@ -1144,16 +1145,20 @@
 {
 	int retval;
 	pte_t *pte;
-	spinlock_t *ptl;  
+	spinlock_t *ptl;
+
+	retval = mem_cgroup_charge(page, mm);
+	if (retval)
+		goto out;
 
 	retval = -EINVAL;
 	if (PageAnon(page))
-		goto out;
+		goto out_uncharge;
 	retval = -ENOMEM;
 	flush_dcache_page(page);
 	pte = get_locked_pte(mm, addr, &ptl);
 	if (!pte)
-		goto out;
+		goto out_uncharge;
 	retval = -EBUSY;
 	if (!pte_none(*pte))
 		goto out_unlock;
@@ -1165,8 +1170,12 @@
 	set_pte_at(mm, addr, pte, mk_pte(page, prot));
 
 	retval = 0;
+	pte_unmap_unlock(pte, ptl);
+	return retval;
 out_unlock:
 	pte_unmap_unlock(pte, ptl);
+out_uncharge:
+	mem_cgroup_uncharge_page(page);
 out:
 	return retval;
 }
@@ -1641,6 +1650,9 @@
 	cow_user_page(new_page, old_page, address, vma);
 	__SetPageUptodate(new_page);
 
+	if (mem_cgroup_charge(new_page, mm))
+		goto oom_free_new;
+
 	/*
 	 * Re-check the pte - we dropped the lock
 	 */
@@ -1672,7 +1684,9 @@
 		/* Free the old page.. */
 		new_page = old_page;
 		ret |= VM_FAULT_WRITE;
-	}
+	} else
+		mem_cgroup_uncharge_page(new_page);
+
 	if (new_page)
 		page_cache_release(new_page);
 	if (old_page)
@@ -1696,6 +1710,8 @@
 		put_page(dirty_page);
 	}
 	return ret;
+oom_free_new:
+	__free_page(new_page);
 oom:
 	if (old_page)
 		page_cache_release(old_page);
@@ -2036,6 +2052,12 @@
 		count_vm_event(PGMAJFAULT);
 	}
 
+	if (mem_cgroup_charge(page, mm)) {
+		delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
+		ret = VM_FAULT_OOM;
+		goto out;
+	}
+
 	mark_page_accessed(page);
 	lock_page(page);
 	delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
@@ -2073,8 +2095,10 @@
 	if (write_access) {
 		/* XXX: We could OR the do_wp_page code with this one? */
 		if (do_wp_page(mm, vma, address,
-				page_table, pmd, ptl, pte) & VM_FAULT_OOM)
+				page_table, pmd, ptl, pte) & VM_FAULT_OOM) {
+			mem_cgroup_uncharge_page(page);
 			ret = VM_FAULT_OOM;
+		}
 		goto out;
 	}
 
@@ -2085,6 +2109,7 @@
 out:
 	return ret;
 out_nomap:
+	mem_cgroup_uncharge_page(page);
 	pte_unmap_unlock(page_table, ptl);
 	unlock_page(page);
 	page_cache_release(page);
@@ -2114,6 +2139,9 @@
 		goto oom;
 	__SetPageUptodate(page);
 
+	if (mem_cgroup_charge(page, mm))
+		goto oom_free_page;
+
 	entry = mk_pte(page, vma->vm_page_prot);
 	entry = maybe_mkwrite(pte_mkdirty(entry), vma);
 
@@ -2131,8 +2159,11 @@
 	pte_unmap_unlock(page_table, ptl);
 	return 0;
 release:
+	mem_cgroup_uncharge_page(page);
 	page_cache_release(page);
 	goto unlock;
+oom_free_page:
+	__free_page(page);
 oom:
 	return VM_FAULT_OOM;
 }
@@ -2246,6 +2277,11 @@
 
 	}
 
+	if (mem_cgroup_charge(page, mm)) {
+		ret = VM_FAULT_OOM;
+		goto out;
+	}
+
 	page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
 
 	/*
@@ -2281,6 +2317,7 @@
 		/* no need to invalidate: a not-present page won't be cached */
 		update_mmu_cache(vma, address, entry);
 	} else {
+		mem_cgroup_uncharge_page(page);
 		if (anon)
 			page_cache_release(page);
 		else
diff --git a/mm/migrate.c b/mm/migrate.c
index 857a987..417bbda 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -29,6 +29,7 @@
 #include <linux/mempolicy.h>
 #include <linux/vmalloc.h>
 #include <linux/security.h>
+#include <linux/memcontrol.h>
 
 #include "internal.h"
 
@@ -152,6 +153,11 @@
  		return;
  	}
 
+	if (mem_cgroup_charge(new, mm)) {
+		pte_unmap(ptep);
+		return;
+	}
+
  	ptl = pte_lockptr(mm, pmd);
  	spin_lock(ptl);
 	pte = *ptep;
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index 37576b8..26a54a1 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -43,6 +43,7 @@
 #include <linux/backing-dev.h>
 #include <linux/fault-inject.h>
 #include <linux/page-isolation.h>
+#include <linux/memcontrol.h>
 
 #include <asm/tlbflush.h>
 #include <asm/div64.h>
@@ -987,6 +988,7 @@
 
 	if (!PageHighMem(page))
 		debug_check_no_locks_freed(page_address(page), PAGE_SIZE);
+	VM_BUG_ON(page_get_page_cgroup(page));
 	arch_free_page(page, 0);
 	kernel_map_pages(page, 1, 0);
 
@@ -2525,6 +2527,7 @@
 		set_page_links(page, zone, nid, pfn);
 		init_page_count(page);
 		reset_page_mapcount(page);
+		page_assign_page_cgroup(page, NULL);
 		SetPageReserved(page);
 
 		/*
diff --git a/mm/rmap.c b/mm/rmap.c
index 57ad276..4a34879 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -48,6 +48,7 @@
 #include <linux/rcupdate.h>
 #include <linux/module.h>
 #include <linux/kallsyms.h>
+#include <linux/memcontrol.h>
 
 #include <asm/tlbflush.h>
 
@@ -554,8 +555,14 @@
 	VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
 	if (atomic_inc_and_test(&page->_mapcount))
 		__page_set_anon_rmap(page, vma, address);
-	else
+	else {
 		__page_check_anon_rmap(page, vma, address);
+		/*
+		 * We unconditionally charged during prepare, we uncharge here
+		 * This takes care of balancing the reference counts
+		 */
+		mem_cgroup_uncharge_page(page);
+	}
 }
 
 /*
@@ -586,6 +593,12 @@
 {
 	if (atomic_inc_and_test(&page->_mapcount))
 		__inc_zone_page_state(page, NR_FILE_MAPPED);
+	else
+		/*
+		 * We unconditionally charged during prepare, we uncharge here
+		 * This takes care of balancing the reference counts
+		 */
+		mem_cgroup_uncharge_page(page);
 }
 
 #ifdef CONFIG_DEBUG_VM
@@ -646,6 +659,8 @@
 			page_clear_dirty(page);
 			set_page_dirty(page);
 		}
+		mem_cgroup_uncharge_page(page);
+
 		__dec_zone_page_state(page,
 				PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
 	}
diff --git a/mm/swap_state.c b/mm/swap_state.c
index ec42f01..f96e3ff 100644
--- a/mm/swap_state.c
+++ b/mm/swap_state.c
@@ -17,6 +17,7 @@
 #include <linux/backing-dev.h>
 #include <linux/pagevec.h>
 #include <linux/migrate.h>
+#include <linux/memcontrol.h>
 
 #include <asm/pgtable.h>
 
@@ -76,6 +77,11 @@
 	BUG_ON(PagePrivate(page));
 	error = radix_tree_preload(gfp_mask);
 	if (!error) {
+
+		error = mem_cgroup_charge(page, current->mm);
+		if (error)
+			goto out;
+
 		write_lock_irq(&swapper_space.tree_lock);
 		error = radix_tree_insert(&swapper_space.page_tree,
 						entry.val, page);
@@ -86,10 +92,13 @@
 			total_swapcache_pages++;
 			__inc_zone_page_state(page, NR_FILE_PAGES);
 			INC_CACHE_INFO(add_total);
+		} else {
+			mem_cgroup_uncharge_page(page);
 		}
 		write_unlock_irq(&swapper_space.tree_lock);
 		radix_tree_preload_end();
 	}
+out:
 	return error;
 }
 
@@ -104,6 +113,7 @@
 	BUG_ON(PageWriteback(page));
 	BUG_ON(PagePrivate(page));
 
+	mem_cgroup_uncharge_page(page);
 	radix_tree_delete(&swapper_space.page_tree, page_private(page));
 	set_page_private(page, 0);
 	ClearPageSwapCache(page);
diff --git a/mm/swapfile.c b/mm/swapfile.c
index afae7b1..fddc4cc 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -27,6 +27,7 @@
 #include <linux/mutex.h>
 #include <linux/capability.h>
 #include <linux/syscalls.h>
+#include <linux/memcontrol.h>
 
 #include <asm/pgtable.h>
 #include <asm/tlbflush.h>
@@ -506,9 +507,12 @@
  * just let do_wp_page work it out if a write is requested later - to
  * force COW, vm_page_prot omits write permission from any private vma.
  */
-static void unuse_pte(struct vm_area_struct *vma, pte_t *pte,
+static int unuse_pte(struct vm_area_struct *vma, pte_t *pte,
 		unsigned long addr, swp_entry_t entry, struct page *page)
 {
+	if (mem_cgroup_charge(page, vma->vm_mm))
+		return -ENOMEM;
+
 	inc_mm_counter(vma->vm_mm, anon_rss);
 	get_page(page);
 	set_pte_at(vma->vm_mm, addr, pte,
@@ -520,6 +524,7 @@
 	 * immediately swapped out again after swapon.
 	 */
 	activate_page(page);
+	return 1;
 }
 
 static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
@@ -529,7 +534,7 @@
 	pte_t swp_pte = swp_entry_to_pte(entry);
 	pte_t *pte;
 	spinlock_t *ptl;
-	int found = 0;
+	int ret = 0;
 
 	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
 	do {
@@ -538,13 +543,12 @@
 		 * Test inline before going to call unuse_pte.
 		 */
 		if (unlikely(pte_same(*pte, swp_pte))) {
-			unuse_pte(vma, pte++, addr, entry, page);
-			found = 1;
+			ret = unuse_pte(vma, pte++, addr, entry, page);
 			break;
 		}
 	} while (pte++, addr += PAGE_SIZE, addr != end);
 	pte_unmap_unlock(pte - 1, ptl);
-	return found;
+	return ret;
 }
 
 static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud,
@@ -553,14 +557,16 @@
 {
 	pmd_t *pmd;
 	unsigned long next;
+	int ret;
 
 	pmd = pmd_offset(pud, addr);
 	do {
 		next = pmd_addr_end(addr, end);
 		if (pmd_none_or_clear_bad(pmd))
 			continue;
-		if (unuse_pte_range(vma, pmd, addr, next, entry, page))
-			return 1;
+		ret = unuse_pte_range(vma, pmd, addr, next, entry, page);
+		if (ret)
+			return ret;
 	} while (pmd++, addr = next, addr != end);
 	return 0;
 }
@@ -571,14 +577,16 @@
 {
 	pud_t *pud;
 	unsigned long next;
+	int ret;
 
 	pud = pud_offset(pgd, addr);
 	do {
 		next = pud_addr_end(addr, end);
 		if (pud_none_or_clear_bad(pud))
 			continue;
-		if (unuse_pmd_range(vma, pud, addr, next, entry, page))
-			return 1;
+		ret = unuse_pmd_range(vma, pud, addr, next, entry, page);
+		if (ret)
+			return ret;
 	} while (pud++, addr = next, addr != end);
 	return 0;
 }
@@ -588,6 +596,7 @@
 {
 	pgd_t *pgd;
 	unsigned long addr, end, next;
+	int ret;
 
 	if (page->mapping) {
 		addr = page_address_in_vma(page, vma);
@@ -605,8 +614,9 @@
 		next = pgd_addr_end(addr, end);
 		if (pgd_none_or_clear_bad(pgd))
 			continue;
-		if (unuse_pud_range(vma, pgd, addr, next, entry, page))
-			return 1;
+		ret = unuse_pud_range(vma, pgd, addr, next, entry, page);
+		if (ret)
+			return ret;
 	} while (pgd++, addr = next, addr != end);
 	return 0;
 }
@@ -615,6 +625,7 @@
 				swp_entry_t entry, struct page *page)
 {
 	struct vm_area_struct *vma;
+	int ret = 0;
 
 	if (!down_read_trylock(&mm->mmap_sem)) {
 		/*
@@ -627,15 +638,11 @@
 		lock_page(page);
 	}
 	for (vma = mm->mmap; vma; vma = vma->vm_next) {
-		if (vma->anon_vma && unuse_vma(vma, entry, page))
+		if (vma->anon_vma && (ret = unuse_vma(vma, entry, page)))
 			break;
 	}
 	up_read(&mm->mmap_sem);
-	/*
-	 * Currently unuse_mm cannot fail, but leave error handling
-	 * at call sites for now, since we change it from time to time.
-	 */
-	return 0;
+	return (ret < 0)? ret: 0;
 }
 
 /*