Merge branch 'cm-13.0' of https://github.com/CyanogenMod/android_kernel_samsung_smdk4412 into replicant-6.0

15 files changed, 1341 insertions, 276 deletions

diff --git a/mm/Kconfig b/mm/Kconfig
index dcecf12..6c733a7 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -371,6 +371,31 @@ config CLEANCACHE
 
 	  If unsure, say Y to enable cleancache
 
+config ZSMALLOC
+	bool "Memory allocator for compressed pages"
+	depends on MMU
+	default n
+	help
+	  zsmalloc is a slab-based memory allocator designed to store
+	  compressed RAM pages.  zsmalloc uses virtual memory mapping
+	  in order to reduce fragmentation.  However, this results in a
+	  non-standard allocator interface where a handle, not a pointer, is
+	  returned by an alloc().  This handle must be mapped in order to
+	  access the allocated space.
+
+config PGTABLE_MAPPING
+	bool "Use page table mapping to access object in zsmalloc"
+	depends on ZSMALLOC
+	help
+	  By default, zsmalloc uses a copy-based object mapping method to
+	  access allocations that span two pages. However, if a particular
+	  architecture (ex, ARM) performs VM mapping faster than copying,
+	  then you should select this. This causes zsmalloc to use page table
+	  mapping rather than copying for object mapping.
+
+	  You can check speed with zsmalloc benchmark[1].
+	  [1] https://github.com/spartacus06/zsmalloc
+
 config CMA
 	bool "Contiguous Memory Allocator framework"
 	# Currently there is only one allocator so force it on
diff --git a/mm/Makefile b/mm/Makefile
index 9b994ce..47ebf93 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -78,5 +78,7 @@ obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o
 obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o
 obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
 obj-$(CONFIG_CLEANCACHE) += cleancache.o
+obj-$(CONFIG_ZSMALLOC)	+= zsmalloc.o
+
 obj-$(CONFIG_CMA) += cma.o
 obj-$(CONFIG_CMA_BEST_FIT) += cma-best-fit.o
diff --git a/mm/cleancache.c b/mm/cleancache.c
index bcaae4c..83a8241 100644
--- a/mm/cleancache.c
+++ b/mm/cleancache.c
@@ -160,7 +160,8 @@ void __cleancache_flush_page(struct address_space *mapping, struct page *page)
 	if (pool_id >= 0) {
 		VM_BUG_ON(!PageLocked(page));
 		if (cleancache_get_key(mapping->host, &key) >= 0) {
-			(*cleancache_ops.flush_page)(pool_id, key, page->index);
+			(*cleancache_ops.invalidate_page)(pool_id,
+							  key, page->index);
 			cleancache_flushes++;
 		}
 	}
@@ -178,7 +179,7 @@ void __cleancache_flush_inode(struct address_space *mapping)
 	struct cleancache_filekey key = { .u.key = { 0 } };
 
 	if (pool_id >= 0 && cleancache_get_key(mapping->host, &key) >= 0)
-		(*cleancache_ops.flush_inode)(pool_id, key);
+		(*cleancache_ops.invalidate_inode)(pool_id, key);
 }
 EXPORT_SYMBOL(__cleancache_flush_inode);
 
@@ -192,7 +193,7 @@ void __cleancache_flush_fs(struct super_block *sb)
 	if (sb->cleancache_poolid >= 0) {
 		int old_poolid = sb->cleancache_poolid;
 		sb->cleancache_poolid = -1;
-		(*cleancache_ops.flush_fs)(old_poolid);
+		(*cleancache_ops.invalidate_fs)(old_poolid);
 	}
 }
 EXPORT_SYMBOL(__cleancache_flush_fs);
diff --git a/mm/madvise.c b/mm/madvise.c
index deabe5f6..5a273af 100644
--- a/mm/madvise.c
+++ b/mm/madvise.c
@@ -87,7 +87,8 @@ static long madvise_behavior(struct vm_area_struct * vma,
 
 	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
 	*prev = vma_merge(mm, *prev, start, end, new_flags, vma->anon_vma,
-				vma->vm_file, pgoff, vma_policy(vma));
+				vma->vm_file, pgoff, vma_policy(vma),
+				vma_get_anon_name(vma));
 	if (*prev) {
 		vma = *prev;
 		goto success;
diff --git a/mm/memory.c b/mm/memory.c
index 5331e67..29c8112 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1436,6 +1436,16 @@ int zap_vma_ptes(struct vm_area_struct *vma, unsigned long address,
 }
 EXPORT_SYMBOL_GPL(zap_vma_ptes);
 
+/*
+ * FOLL_FORCE can write to even unwritable pte's, but only
+ * after we've gone through a COW cycle and they are dirty.
+ */
+static inline bool can_follow_write_pte(pte_t pte, unsigned int flags)
+{
+	return pte_write(pte) ||
+		((flags & FOLL_FORCE) && (flags & FOLL_COW) && pte_dirty(pte));
+}
+
 /**
  * follow_page - look up a page descriptor from a user-virtual address
  * @vma: vm_area_struct mapping @address
@@ -1518,7 +1528,7 @@ split_fallthrough:
 	pte = *ptep;
 	if (!pte_present(pte))
 		goto no_page;
-	if ((flags & FOLL_WRITE) && !pte_write(pte))
+	if ((flags & FOLL_WRITE) && !can_follow_write_pte(pte, flags))
 		goto unlock;
 
 	page = vm_normal_page(vma, address, pte);
@@ -1832,7 +1842,7 @@ int __get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
 				 */
 				if ((ret & VM_FAULT_WRITE) &&
 				    !(vma->vm_flags & VM_WRITE))
-					foll_flags &= ~FOLL_WRITE;
+					foll_flags |= FOLL_COW;
 
 				cond_resched();
 			}
@@ -3140,7 +3150,8 @@ static int do_swap_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	mem_cgroup_commit_charge_swapin(page, ptr);
 
 	swap_free(entry);
-	if (vm_swap_full() || (vma->vm_flags & VM_LOCKED) || PageMlocked(page))
+	if ((PageSwapCache(page) && vm_swap_full(page_swap_info(page))) ||
+		(vma->vm_flags & VM_LOCKED) || PageMlocked(page))
 		try_to_free_swap(page);
 	unlock_page(page);
 	if (swapcache) {
diff --git a/mm/mempolicy.c b/mm/mempolicy.c
index 7065fb3..7c8caa9 100644
--- a/mm/mempolicy.c
+++ b/mm/mempolicy.c
@@ -664,8 +664,9 @@ static int mbind_range(struct mm_struct *mm, unsigned long start,
 		vmend   = min(end, vma->vm_end);
 
 		pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
-		prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
-				  vma->anon_vma, vma->vm_file, pgoff, new_pol);
+                prev = vma_merge(mm, prev, vmstart, vmend, vma->vm_flags,
+                                 vma->anon_vma, vma->vm_file, pgoff,
+                                 new_pol, vma_get_anon_name(name));
 		if (prev) {
 			vma = prev;
 			next = vma->vm_next;
diff --git a/mm/mlock.c b/mm/mlock.c
index b41b3b7..734fd7f 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -321,7 +321,8 @@ static int mlock_fixup(struct vm_area_struct *vma, struct vm_area_struct **prev,
 
 	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
 	*prev = vma_merge(mm, *prev, start, end, newflags, vma->anon_vma,
-			  vma->vm_file, pgoff, vma_policy(vma));
+			  vma->vm_file, pgoff, vma_policy(vma),
+			  vma_get_anon_name(vma));
 	if (*prev) {
 		vma = *prev;
 		goto success;
diff --git a/mm/mmap.c b/mm/mmap.c
index d1cf520..96f124e 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -656,7 +656,8 @@ again:			remove_next = 1 + (end > next->vm_end);
  * per-vma resources, so we don't attempt to merge those.
  */
 static inline int is_mergeable_vma(struct vm_area_struct *vma,
-			struct file *file, unsigned long vm_flags)
+			struct file *file, unsigned long vm_flags,
+			const char __user *anon_name)
 {
 	/* VM_CAN_NONLINEAR may get set later by f_op->mmap() */
 	if ((vma->vm_flags ^ vm_flags) & ~VM_CAN_NONLINEAR)
@@ -665,6 +666,8 @@ static inline int is_mergeable_vma(struct vm_area_struct *vma,
 		return 0;
 	if (vma->vm_ops && vma->vm_ops->close)
 		return 0;
+	if (vma_get_anon_name(vma) != anon_name)
+		return 0;
 	return 1;
 }
 
@@ -695,9 +698,10 @@ static inline int is_mergeable_anon_vma(struct anon_vma *anon_vma1,
  */
 static int
 can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
-	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
+	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff,
+	const char __user *anon_name)
 {
-	if (is_mergeable_vma(vma, file, vm_flags) &&
+	if (is_mergeable_vma(vma, file, vm_flags, anon_name) &&
 	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 		if (vma->vm_pgoff == vm_pgoff)
 			return 1;
@@ -714,9 +718,10 @@ can_vma_merge_before(struct vm_area_struct *vma, unsigned long vm_flags,
  */
 static int
 can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
-	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff)
+	struct anon_vma *anon_vma, struct file *file, pgoff_t vm_pgoff,
+	const char __user *anon_name)
 {
-	if (is_mergeable_vma(vma, file, vm_flags) &&
+	if (is_mergeable_vma(vma, file, vm_flags, anon_name) &&
 	    is_mergeable_anon_vma(anon_vma, vma->anon_vma, vma)) {
 		pgoff_t vm_pglen;
 		vm_pglen = (vma->vm_end - vma->vm_start) >> PAGE_SHIFT;
@@ -727,9 +732,9 @@ can_vma_merge_after(struct vm_area_struct *vma, unsigned long vm_flags,
 }
 
 /*
- * Given a mapping request (addr,end,vm_flags,file,pgoff), figure out
- * whether that can be merged with its predecessor or its successor.
- * Or both (it neatly fills a hole).
+ * Given a mapping request (addr,end,vm_flags,file,pgoff,anon_name),
+ * figure out whether that can be merged with its predecessor or its
+ * successor.  Or both (it neatly fills a hole).
  *
  * In most cases - when called for mmap, brk or mremap - [addr,end) is
  * certain not to be mapped by the time vma_merge is called; but when
@@ -759,7 +764,8 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
 			struct vm_area_struct *prev, unsigned long addr,
 			unsigned long end, unsigned long vm_flags,
 		     	struct anon_vma *anon_vma, struct file *file,
-			pgoff_t pgoff, struct mempolicy *policy)
+			pgoff_t pgoff, struct mempolicy *policy,
+			const char __user *anon_name)
 {
 	pgoff_t pglen = (end - addr) >> PAGE_SHIFT;
 	struct vm_area_struct *area, *next;
@@ -785,15 +791,15 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
 	 */
 	if (prev && prev->vm_end == addr &&
   			mpol_equal(vma_policy(prev), policy) &&
-			can_vma_merge_after(prev, vm_flags,
-						anon_vma, file, pgoff)) {
+			can_vma_merge_after(prev, vm_flags, anon_vma,
+						file, pgoff, anon_name)) {
 		/*
 		 * OK, it can.  Can we now merge in the successor as well?
 		 */
 		if (next && end == next->vm_start &&
 				mpol_equal(policy, vma_policy(next)) &&
-				can_vma_merge_before(next, vm_flags,
-					anon_vma, file, pgoff+pglen) &&
+				can_vma_merge_before(next, vm_flags, anon_vma,
+						file, pgoff+pglen, anon_name) &&
 				is_mergeable_anon_vma(prev->anon_vma,
 						      next->anon_vma, NULL)) {
 							/* cases 1, 6 */
@@ -813,8 +819,8 @@ struct vm_area_struct *vma_merge(struct mm_struct *mm,
 	 */
 	if (next && end == next->vm_start &&
  			mpol_equal(policy, vma_policy(next)) &&
-			can_vma_merge_before(next, vm_flags,
-					anon_vma, file, pgoff+pglen)) {
+			can_vma_merge_before(next, vm_flags, anon_vma,
+					file, pgoff+pglen, anon_name)) {
 		if (prev && addr < prev->vm_end)	/* case 4 */
 			err = vma_adjust(prev, prev->vm_start,
 				addr, prev->vm_pgoff, NULL);
@@ -1251,7 +1257,8 @@ munmap_back:
 	/*
 	 * Can we just expand an old mapping?
 	 */
-	vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff, NULL);
+	vma = vma_merge(mm, prev, addr, addr + len, vm_flags, NULL, file, pgoff,
+			NULL, NULL);
 	if (vma)
 		goto out;
 
@@ -2202,7 +2209,7 @@ unsigned long do_brk(unsigned long addr, unsigned long len)
 
 	/* Can we just expand an old private anonymous mapping? */
 	vma = vma_merge(mm, prev, addr, addr + len, flags,
-					NULL, NULL, pgoff, NULL);
+					NULL, NULL, pgoff, NULL, NULL);
 	if (vma)
 		goto out;
 
@@ -2340,7 +2347,8 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 
 	find_vma_prepare(mm, addr, &prev, &rb_link, &rb_parent);
 	new_vma = vma_merge(mm, prev, addr, addr + len, vma->vm_flags,
-			vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
+			vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
+			vma_get_anon_name(vma));
 	if (new_vma) {
 		/*
 		 * Source vma may have been merged into new_vma
diff --git a/mm/mprotect.c b/mm/mprotect.c
index 5a688a2..5f168eb 100644
--- a/mm/mprotect.c
+++ b/mm/mprotect.c
@@ -179,7 +179,8 @@ mprotect_fixup(struct vm_area_struct *vma, struct vm_area_struct **pprev,
 	 */
 	pgoff = vma->vm_pgoff + ((start - vma->vm_start) >> PAGE_SHIFT);
 	*pprev = vma_merge(mm, *pprev, start, end, newflags,
-			vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma));
+			vma->anon_vma, vma->vm_file, pgoff, vma_policy(vma),
+			vma_get_anon_name(vma));
 	if (*pprev) {
 		vma = *pprev;
 		goto success;
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index 7c72487..678cf2b 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -38,6 +38,28 @@ int sysctl_oom_kill_allocating_task;
 int sysctl_oom_dump_tasks = 1;
 static DEFINE_SPINLOCK(zone_scan_lock);
 
+/*
+ * compare_swap_oom_score_adj() - compare and swap current's oom_score_adj
+ * @old_val: old oom_score_adj for compare
+ * @new_val: new oom_score_adj for swap
+ *
+ * Sets the oom_score_adj value for current to @new_val iff its present value is
+ * @old_val.  Usually used to reinstate a previous value to prevent racing with
+ * userspacing tuning the value in the interim.
+ */
+void compare_swap_oom_score_adj(int old_val, int new_val)
+{
+	struct sighand_struct *sighand = current->sighand;
+
+	spin_lock_irq(&sighand->siglock);
+	if (current->signal->oom_score_adj == old_val) {
+		current->signal->oom_score_adj = new_val;
+		delete_from_adj_tree(current);
+		add_2_adj_tree(current);
+	}
+	spin_unlock_irq(&sighand->siglock);
+}
+
 /**
  * test_set_oom_score_adj() - set current's oom_score_adj and return old value
  * @new_val: new oom_score_adj value
diff --git a/mm/page_io.c b/mm/page_io.c
index dc76b4d..f57da45 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -18,6 +18,8 @@
 #include <linux/bio.h>
 #include <linux/swapops.h>
 #include <linux/writeback.h>
+#include <linux/aio.h>
+#include <linux/blkdev.h>
 #include <asm/pgtable.h>
 
 static struct bio *get_swap_bio(gfp_t gfp_flags,
@@ -78,9 +80,49 @@ void end_swap_bio_read(struct bio *bio, int err)
 				imajor(bio->bi_bdev->bd_inode),
 				iminor(bio->bi_bdev->bd_inode),
 				(unsigned long long)bio->bi_sector);
-	} else {
-		SetPageUptodate(page);
+		goto out;
+	}
+
+	SetPageUptodate(page);
+
+	/*
+	 * There is no guarantee that the page is in swap cache - the software
+	 * suspend code (at least) uses end_swap_bio_read() against a non-
+	 * swapcache page.  So we must check PG_swapcache before proceeding with
+	 * this optimization.
+	 */
+	if (likely(PageSwapCache(page))) {
+		/*
+		 * The swap subsystem performs lazy swap slot freeing,
+		 * expecting that the page will be swapped out again.
+		 * So we can avoid an unnecessary write if the page
+		 * isn't redirtied.
+		 * This is good for real swap storage because we can
+		 * reduce unnecessary I/O and enhance wear-leveling
+		 * if an SSD is used as the as swap device.
+		 * But if in-memory swap device (eg zram) is used,
+		 * this causes a duplicated copy between uncompressed
+		 * data in VM-owned memory and compressed data in
+		 * zram-owned memory.  So let's free zram-owned memory
+		 * and make the VM-owned decompressed page *dirty*,
+		 * so the page should be swapped out somewhere again if
+		 * we again wish to reclaim it.
+		 */
+		struct gendisk *disk = bio->bi_bdev->bd_disk;
+		if (disk->fops->swap_slot_free_notify) {
+			swp_entry_t entry;
+			unsigned long offset;
+
+			entry.val = page_private(page);
+			offset = swp_offset(entry);
+
+			SetPageDirty(page);
+			disk->fops->swap_slot_free_notify(bio->bi_bdev,
+					offset);
+		}
 	}
+
+out:
 	unlock_page(page);
 	bio_put(bio);
 }
diff --git a/mm/shmem.c b/mm/shmem.c
index a858b67..bcfa97d 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -1060,17 +1060,8 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
 	info = SHMEM_I(inode);
 	if (info->flags & VM_LOCKED)
 		goto redirty;
-#ifdef CONFIG_ZRAM_FOR_ANDROID
-	/*
-	 * Modification for compcache
-	 * shmem_writepage can be reason of kernel panic when using swap.
-	 * This modification prevent using swap by shmem.
-	 */
-	goto redirty;
-#else
 	if (!total_swap_pages)
 		goto redirty;
-#endif
 
 	/*
 	 * shmem_backing_dev_info's capabilities prevent regular writeback or
diff --git a/mm/swapfile.c b/mm/swapfile.c
index 3e5a3a7..4add436 100644
--- a/mm/swapfile.c
+++ b/mm/swapfile.c
@@ -69,6 +69,26 @@ static inline unsigned char swap_count(unsigned char ent)
 	return ent & ~SWAP_HAS_CACHE;	/* may include SWAP_HAS_CONT flag */
 }
 
+bool is_swap_fast(swp_entry_t entry)
+{
+	struct swap_info_struct *p;
+	unsigned long type;
+
+	if (non_swap_entry(entry))
+		return false;
+
+	type = swp_type(entry);
+	if (type >= nr_swapfiles)
+		return false;
+
+	p = swap_info[type];
+
+	if (p->flags & SWP_FAST)
+		return true;
+
+	return false;
+}
+
 /* returns 1 if swap entry is freed */
 static int
 __try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset)
@@ -289,7 +309,7 @@ checks:
 		scan_base = offset = si->lowest_bit;
 
 	/* reuse swap entry of cache-only swap if not busy. */
-	if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+	if (vm_swap_full(si) && si->swap_map[offset] == SWAP_HAS_CACHE) {
 		int swap_was_freed;
 		spin_unlock(&swap_lock);
 		swap_was_freed = __try_to_reclaim_swap(si, offset);
@@ -378,7 +398,8 @@ scan:
 			spin_lock(&swap_lock);
 			goto checks;
 		}
-		if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+		if (vm_swap_full(si) &&
+			si->swap_map[offset] == SWAP_HAS_CACHE) {
 			spin_lock(&swap_lock);
 			goto checks;
 		}
@@ -393,7 +414,8 @@ scan:
 			spin_lock(&swap_lock);
 			goto checks;
 		}
-		if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) {
+		if (vm_swap_full(si) &&
+			si->swap_map[offset] == SWAP_HAS_CACHE) {
 			spin_lock(&swap_lock);
 			goto checks;
 		}
@@ -708,7 +730,8 @@ int free_swap_and_cache(swp_entry_t entry)
 		 * Also recheck PageSwapCache now page is locked (above).
 		 */
 		if (PageSwapCache(page) && !PageWriteback(page) &&
-				(!page_mapped(page) || vm_swap_full())) {
+				(!page_mapped(page) ||
+				vm_swap_full(page_swap_info(page)))) {
 			delete_from_swap_cache(page);
 			SetPageDirty(page);
 		}
@@ -2012,159 +2035,6 @@ static int setup_swap_map_and_extents(struct swap_info_struct *p,
 	return nr_extents;
 }
 
-#ifdef CONFIG_ZRAM_FOR_ANDROID
-int swapon(char *name, int swap_flags)
-{
-	struct swap_info_struct *p;
-
-	struct file *swap_file = NULL;
-	struct address_space *mapping;
-	int i;
-	int prio;
-	int error;
-	union swap_header *swap_header;
-	int nr_extents;
-	sector_t span;
-	unsigned long maxpages;
-	unsigned char *swap_map = NULL;
-	struct page *page = NULL;
-	struct inode *inode = NULL;
-
-	p = alloc_swap_info();
-	if (IS_ERR(p))
-		return PTR_ERR(p);
-
-	swap_file = filp_open(name, O_RDWR | O_LARGEFILE, 0);
-	if (IS_ERR(swap_file)) {
-		error = PTR_ERR(swap_file);
-		swap_file = NULL;
-		printk("zfqin, filp_open failed\n");
-		goto bad_swap;
-	}
-
-	printk("zfqin, filp_open succeeded\n");
-	p->swap_file = swap_file;
-	mapping = swap_file->f_mapping;
-
-	for (i = 0; i < nr_swapfiles; i++) {
-		struct swap_info_struct *q = swap_info[i];
-
-		if (q == p || !q->swap_file)
-			continue;
-		if (mapping == q->swap_file->f_mapping) {
-			error = -EBUSY;
-			goto bad_swap;
-		}
-	}
-
-	inode = mapping->host;
-	/* If S_ISREG(inode->i_mode) will do mutex_lock(&inode->i_mutex); */
-	error = claim_swapfile(p, inode);
-	if (unlikely(error))
-		goto bad_swap;
-
-	/*
-	 * Read the swap header.
-	 */
-	if (!mapping->a_ops->readpage) {
-		error = -EINVAL;
-		goto bad_swap;
-	}
-	page = read_mapping_page(mapping, 0, swap_file);
-	if (IS_ERR(page)) {
-		error = PTR_ERR(page);
-		goto bad_swap;
-	}
-	swap_header = kmap(page);
-
-	maxpages = read_swap_header(p, swap_header, inode);
-	if (unlikely(!maxpages)) {
-		error = -EINVAL;
-		goto bad_swap;
-	}
-
-	/* OK, set up the swap map and apply the bad block list */
-	swap_map = vzalloc(maxpages);
-	if (!swap_map) {
-		error = -ENOMEM;
-		goto bad_swap;
-	}
-
-	error = swap_cgroup_swapon(p->type, maxpages);
-	if (error)
-		goto bad_swap;
-
-	nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map,
-						maxpages, &span);
-	if (unlikely(nr_extents < 0)) {
-		error = nr_extents;
-		goto bad_swap;
-	}
-
-	if (p->bdev) {
-		if (blk_queue_nonrot(bdev_get_queue(p->bdev))) {
-			p->flags |= SWP_SOLIDSTATE;
-			p->cluster_next = 1 + (random32() % p->highest_bit);
-		}
-		if (discard_swap(p) == 0 && (swap_flags & SWAP_FLAG_DISCARD))
-			p->flags |= SWP_DISCARDABLE;
-	}
-
-	mutex_lock(&swapon_mutex);
-	prio = -1;
-	if (swap_flags & SWAP_FLAG_PREFER)
-		prio =
-		    (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT;
-	enable_swap_info(p, prio, swap_map);
-
-	printk(KERN_INFO "Adding %uk swap on %s.  "
-	       "Priority:%d extents:%d across:%lluk %s%s\n",
-	       p->pages << (PAGE_SHIFT - 10), name, p->prio,
-	       nr_extents, (unsigned long long)span << (PAGE_SHIFT - 10),
-	       (p->flags & SWP_SOLIDSTATE) ? "SS" : "",
-	       (p->flags & SWP_DISCARDABLE) ? "D" : "");
-
-	mutex_unlock(&swapon_mutex);
-	atomic_inc(&proc_poll_event);
-	wake_up_interruptible(&proc_poll_wait);
-
-	if (S_ISREG(inode->i_mode))
-		inode->i_flags |= S_SWAPFILE;
-	error = 0;
-	goto out;
- bad_swap:
-	if (inode && S_ISBLK(inode->i_mode) && p->bdev) {
-		set_blocksize(p->bdev, p->old_block_size);
-		blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
-	}
-	destroy_swap_extents(p);
-	swap_cgroup_swapoff(p->type);
-	spin_lock(&swap_lock);
-	p->swap_file = NULL;
-	p->flags = 0;
-	spin_unlock(&swap_lock);
-	vfree(swap_map);
-	if (swap_file) {
-		if (inode && S_ISREG(inode->i_mode)) {
-			mutex_unlock(&inode->i_mutex);
-			inode = NULL;
-		}
-		filp_close(swap_file, NULL);
-	}
- out:
-	if (page && !IS_ERR(page)) {
-		kunmap(page);
-		page_cache_release(page);
-	}
-
-	if (inode && S_ISREG(inode->i_mode))
-		mutex_unlock(&inode->i_mutex);
-	return error;
-}
-
-EXPORT_SYMBOL(swapon);
-#endif /* CONFIG_ZRAM_FOR_ANDROID */
-
 SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 {
 	struct swap_info_struct *p;
@@ -2267,6 +2137,8 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
 		}
 		if (discard_swap(p) == 0 && (swap_flags & SWAP_FLAG_DISCARD))
 			p->flags |= SWP_DISCARDABLE;
+		if (blk_queue_fast(bdev_get_queue(p->bdev)))
+			p->flags |= SWP_FAST;
 	}
 
 	mutex_lock(&swapon_mutex);
@@ -2449,6 +2321,13 @@ int swapcache_prepare(swp_entry_t entry)
 	return __swap_duplicate(entry, SWAP_HAS_CACHE);
 }
 
+struct swap_info_struct *page_swap_info(struct page *page)
+{
+	swp_entry_t swap = { .val = page_private(page) };
+	BUG_ON(!PageSwapCache(page));
+	return swap_info[swp_type(swap)];
+}
+
 /*
  * swap_lock prevents swap_map being freed. Don't grab an extra
  * reference on the swaphandle, it doesn't matter if it becomes unused.
diff --git a/mm/vmscan.c b/mm/vmscan.c
index b0d3366..ce6e2e5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -624,6 +624,10 @@ void putback_lru_page(struct page *page)
 	int was_unevictable = PageUnevictable(page);
 
 	VM_BUG_ON(PageLRU(page));
+#ifdef CONFIG_CLEANCACHE
+	if (active)
+		SetPageWasActive(page);
+#endif
 
 redo:
 	ClearPageUnevictable(page);
@@ -771,9 +775,6 @@ static noinline_for_stack void free_page_list(struct list_head *free_pages)
 /*
  * shrink_page_list() returns the number of reclaimed pages
  */
-#ifndef CONFIG_ZRAM_FOR_ANDROID
-static
-#endif /* CONFIG_ZRAM_FOR_ANDROID */
 unsigned long shrink_page_list(struct list_head *page_list,
 				      struct zone *zone,
 				      struct scan_control *sc)
@@ -989,7 +990,7 @@ cull_mlocked:
 
 activate_locked:
 		/* Not a candidate for swapping, so reclaim swap space. */
-		if (PageSwapCache(page) && vm_swap_full())
+		if (PageSwapCache(page) && vm_swap_full(page_swap_info(page)))
 			try_to_free_swap(page);
 		VM_BUG_ON(PageActive(page));
 		SetPageActive(page);
@@ -1281,9 +1282,6 @@ static unsigned long isolate_pages_global(unsigned long nr,
  * clear_active_flags() is a helper for shrink_active_list(), clearing
  * any active bits from the pages in the list.
  */
-#ifndef CONFIG_ZRAM_FOR_ANDROID
-static
-#endif /* CONFIG_ZRAM_FOR_ANDROID */
 unsigned long clear_active_flags(struct list_head *page_list,
 					unsigned int *count)
 {
@@ -1297,6 +1295,9 @@ unsigned long clear_active_flags(struct list_head *page_list,
 		if (PageActive(page)) {
 			lru += LRU_ACTIVE;
 			ClearPageActive(page);
+#ifdef CONFIG_CLEANCACHE
+			SetPageWasActive(page);
+#endif
 			nr_active += numpages;
 		}
 		if (count)
@@ -1354,40 +1355,6 @@ int isolate_lru_page(struct page *page)
 	return ret;
 }
 
-#ifdef CONFIG_ZRAM_FOR_ANDROID
-/**
- * isolate_lru_page_compcache - tries to isolate a page for compcache
- * @page: page to isolate from its LRU list
- *
- * Isolates a @page from an LRU list, clears PageLRU,but
- * does not adjusts the vmstat statistic
- * Returns 0 if the page was removed from an LRU list.
- * Returns -EBUSY if the page was not on an LRU list.
- */
-int isolate_lru_page_compcache(struct page *page)
-{
-	int ret = -EBUSY;
-
-	VM_BUG_ON(!page_count(page));
-
-	if (PageLRU(page)) {
-		struct zone *zone = page_zone(page);
-
-		spin_lock_irq(&zone->lru_lock);
-		if (PageLRU(page)) {
-			int lru = page_lru(page);
-			ret = 0;
-			get_page(page);
-			ClearPageLRU(page);
-			list_del(&page->lru);
-			mem_cgroup_del_lru_list(page, lru);
-		}
-		spin_unlock_irq(&zone->lru_lock);
-	}
-	return ret;
-}
-#endif
-
 /*
  * Are there way too many processes in the direct reclaim path already?
  */
@@ -1624,44 +1591,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct zone *zone,
 	return nr_reclaimed;
 }
 
-#ifdef CONFIG_ZRAM_FOR_ANDROID
-unsigned long
-zone_id_shrink_pagelist(struct zone *zone, struct list_head *page_list)
-{
-	unsigned long nr_reclaimed = 0;
-	unsigned long nr_anon;
-	unsigned long nr_file;
-
-	struct scan_control sc = {
-		.gfp_mask = GFP_USER,
-		.may_writepage = 1,
-		.nr_to_reclaim = SWAP_CLUSTER_MAX,
-		.may_unmap = 1,
-		.may_swap = 1,
-		.swappiness = vm_swappiness,
-		.order = 0,
-		.mem_cgroup = NULL,
-		.nodemask = NULL,
-	};
-
-	spin_lock_irq(&zone->lru_lock);
-
-	update_isolated_counts(zone, &sc, &nr_anon, &nr_file, page_list);
-
-	spin_unlock_irq(&zone->lru_lock);
-
-	nr_reclaimed = shrink_page_list(page_list, zone, &sc);
-
-	__count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
-
-	putback_lru_pages(zone, &sc, nr_anon, nr_file, page_list);
-
-	return nr_reclaimed;
-}
-
-EXPORT_SYMBOL(zone_id_shrink_pagelist);
-#endif /* CONFIG_ZRAM_FOR_ANDROID */
-
 /*
  * This moves pages from the active list to the inactive list.
  *
@@ -1790,6 +1719,9 @@ static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
 		}
 
 		ClearPageActive(page);	/* we are de-activating */
+#ifdef CONFIG_CLEANCACHE
+		SetPageWasActive(page);
+#endif
 		list_add(&page->lru, &l_inactive);
 	}
 
diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c
new file mode 100644
index 0000000..5e17643
--- /dev/null
+++ b/mm/zsmalloc.c
@@ -0,0 +1,1148 @@
+/*
+ * zsmalloc memory allocator
+ *
+ * Copyright (C) 2011  Nitin Gupta
+ * Copyright (C) 2012, 2013 Minchan Kim
+ *
+ * This code is released using a dual license strategy: BSD/GPL
+ * You can choose the license that better fits your requirements.
+ *
+ * Released under the terms of 3-clause BSD License
+ * Released under the terms of GNU General Public License Version 2.0
+ */
+
+/*
+ * This allocator is designed for use with zram. Thus, the allocator is
+ * supposed to work well under low memory conditions. In particular, it
+ * never attempts higher order page allocation which is very likely to
+ * fail under memory pressure. On the other hand, if we just use single
+ * (0-order) pages, it would suffer from very high fragmentation --
+ * any object of size PAGE_SIZE/2 or larger would occupy an entire page.
+ * This was one of the major issues with its predecessor (xvmalloc).
+ *
+ * To overcome these issues, zsmalloc allocates a bunch of 0-order pages
+ * and links them together using various 'struct page' fields. These linked
+ * pages act as a single higher-order page i.e. an object can span 0-order
+ * page boundaries. The code refers to these linked pages as a single entity
+ * called zspage.
+ *
+ * For simplicity, zsmalloc can only allocate objects of size up to PAGE_SIZE
+ * since this satisfies the requirements of all its current users (in the
+ * worst case, page is incompressible and is thus stored "as-is" i.e. in
+ * uncompressed form). For allocation requests larger than this size, failure
+ * is returned (see zs_malloc).
+ *
+ * Additionally, zs_malloc() does not return a dereferenceable pointer.
+ * Instead, it returns an opaque handle (unsigned long) which encodes actual
+ * location of the allocated object. The reason for this indirection is that
+ * zsmalloc does not keep zspages permanently mapped since that would cause
+ * issues on 32-bit systems where the VA region for kernel space mappings
+ * is very small. So, before using the allocating memory, the object has to
+ * be mapped using zs_map_object() to get a usable pointer and subsequently
+ * unmapped using zs_unmap_object().
+ *
+ * Following is how we use various fields and flags of underlying
+ * struct page(s) to form a zspage.
+ *
+ * Usage of struct page fields:
+ *	page->first_page: points to the first component (0-order) page
+ *	page->index (union with page->freelist): offset of the first object
+ *		starting in this page. For the first page, this is
+ *		always 0, so we use this field (aka freelist) to point
+ *		to the first free object in zspage.
+ *	page->lru: links together all component pages (except the first page)
+ *		of a zspage
+ *
+ *	For _first_ page only:
+ *
+ *	page->private (union with page->first_page): refers to the
+ *		component page after the first page
+ *	page->freelist: points to the first free object in zspage.
+ *		Free objects are linked together using in-place
+ *		metadata.
+ *	page->objects: maximum number of objects we can store in this
+ *		zspage (class->zspage_order * PAGE_SIZE / class->size)
+ *	page->lru: links together first pages of various zspages.
+ *		Basically forming list of zspages in a fullness group.
+ *	page->mapping: class index and fullness group of the zspage
+ *
+ * Usage of struct page flags:
+ *	PG_private: identifies the first component page
+ *	PG_private2: identifies the last component page
+ *
+ */
+
+#ifdef CONFIG_ZSMALLOC_DEBUG
+#define DEBUG
+#endif
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/bitops.h>
+#include <linux/errno.h>
+#include <linux/highmem.h>
+#include <linux/init.h>
+#include <linux/string.h>
+#include <linux/slab.h>
+#include <asm/tlbflush.h>
+#include <asm/pgtable.h>
+#include <linux/cpumask.h>
+#include <linux/cpu.h>
+#include <linux/vmalloc.h>
+#include <linux/hardirq.h>
+#include <linux/spinlock.h>
+#include <linux/types.h>
+#include <linux/zsmalloc.h>
+
+/*
+ * This must be power of 2 and greater than of equal to sizeof(link_free).
+ * These two conditions ensure that any 'struct link_free' itself doesn't
+ * span more than 1 page which avoids complex case of mapping 2 pages simply
+ * to restore link_free pointer values.
+ */
+#define ZS_ALIGN		8
+
+/*
+ * A single 'zspage' is composed of up to 2^N discontiguous 0-order (single)
+ * pages. ZS_MAX_ZSPAGE_ORDER defines upper limit on N.
+ */
+#define ZS_MAX_ZSPAGE_ORDER 2
+#define ZS_MAX_PAGES_PER_ZSPAGE (_AC(1, UL) << ZS_MAX_ZSPAGE_ORDER)
+
+/*
+ * Object location (<PFN>, <obj_idx>) is encoded as
+ * as single (unsigned long) handle value.
+ *
+ * Note that object index <obj_idx> is relative to system
+ * page <PFN> it is stored in, so for each sub-page belonging
+ * to a zspage, obj_idx starts with 0.
+ *
+ * This is made more complicated by various memory models and PAE.
+ */
+
+#ifndef MAX_PHYSMEM_BITS
+#ifdef CONFIG_HIGHMEM64G
+#define MAX_PHYSMEM_BITS 36
+#else /* !CONFIG_HIGHMEM64G */
+/*
+ * If this definition of MAX_PHYSMEM_BITS is used, OBJ_INDEX_BITS will just
+ * be PAGE_SHIFT
+ */
+#define MAX_PHYSMEM_BITS BITS_PER_LONG
+#endif
+#endif
+#define _PFN_BITS		(MAX_PHYSMEM_BITS - PAGE_SHIFT)
+#define OBJ_INDEX_BITS	(BITS_PER_LONG - _PFN_BITS)
+#define OBJ_INDEX_MASK	((_AC(1, UL) << OBJ_INDEX_BITS) - 1)
+
+#define MAX(a, b) ((a) >= (b) ? (a) : (b))
+/* ZS_MIN_ALLOC_SIZE must be multiple of ZS_ALIGN */
+#define ZS_MIN_ALLOC_SIZE \
+	MAX(32, (ZS_MAX_PAGES_PER_ZSPAGE << PAGE_SHIFT >> OBJ_INDEX_BITS))
+#define ZS_MAX_ALLOC_SIZE	PAGE_SIZE
+
+/*
+ * On systems with 4K page size, this gives 254 size classes! There is a
+ * trader-off here:
+ *  - Large number of size classes is potentially wasteful as free page are
+ *    spread across these classes
+ *  - Small number of size classes causes large internal fragmentation
+ *  - Probably its better to use specific size classes (empirically
+ *    determined). NOTE: all those class sizes must be set as multiple of
+ *    ZS_ALIGN to make sure link_free itself never has to span 2 pages.
+ *
+ *  ZS_MIN_ALLOC_SIZE and ZS_SIZE_CLASS_DELTA must be multiple of ZS_ALIGN
+ *  (reason above)
+ */
+#define ZS_SIZE_CLASS_DELTA	(PAGE_SIZE >> 8)
+#define ZS_SIZE_CLASSES		((ZS_MAX_ALLOC_SIZE - ZS_MIN_ALLOC_SIZE) / \
+					ZS_SIZE_CLASS_DELTA + 1)
+
+/*
+ * We do not maintain any list for completely empty or full pages
+ */
+enum fullness_group {
+	ZS_ALMOST_FULL,
+	ZS_ALMOST_EMPTY,
+	_ZS_NR_FULLNESS_GROUPS,
+
+	ZS_EMPTY,
+	ZS_FULL
+};
+
+/*
+ * We assign a page to ZS_ALMOST_EMPTY fullness group when:
+ *	n <= N / f, where
+ * n = number of allocated objects
+ * N = total number of objects zspage can store
+ * f = 1/fullness_threshold_frac
+ *
+ * Similarly, we assign zspage to:
+ *	ZS_ALMOST_FULL	when n > N / f
+ *	ZS_EMPTY	when n == 0
+ *	ZS_FULL		when n == N
+ *
+ * (see: fix_fullness_group())
+ */
+static const int fullness_threshold_frac = 4;
+
+struct size_class {
+	/*
+	 * Size of objects stored in this class. Must be multiple
+	 * of ZS_ALIGN.
+	 */
+	int size;
+	unsigned int index;
+
+	/* Number of PAGE_SIZE sized pages to combine to form a 'zspage' */
+	int pages_per_zspage;
+
+	spinlock_t lock;
+
+	struct page *fullness_list[_ZS_NR_FULLNESS_GROUPS];
+};
+
+/*
+ * Placed within free objects to form a singly linked list.
+ * For every zspage, first_page->freelist gives head of this list.
+ *
+ * This must be power of 2 and less than or equal to ZS_ALIGN
+ */
+struct link_free {
+	/* Handle of next free chunk (encodes <PFN, obj_idx>) */
+	void *next;
+};
+
+struct zs_pool {
+	struct size_class *size_class[ZS_SIZE_CLASSES];
+
+	gfp_t flags;	/* allocation flags used when growing pool */
+	atomic_long_t pages_allocated;
+};
+
+/*
+ * A zspage's class index and fullness group
+ * are encoded in its (first)page->mapping
+ */
+#define CLASS_IDX_BITS	28
+#define FULLNESS_BITS	4
+#define CLASS_IDX_MASK	((1 << CLASS_IDX_BITS) - 1)
+#define FULLNESS_MASK	((1 << FULLNESS_BITS) - 1)
+
+struct mapping_area {
+#ifdef CONFIG_PGTABLE_MAPPING
+	struct vm_struct *vm; /* vm area for mapping object that span pages */
+#else
+	char *vm_buf; /* copy buffer for objects that span pages */
+#endif
+	char *vm_addr; /* address of kmap_atomic()'ed pages */
+	enum zs_mapmode vm_mm; /* mapping mode */
+};
+
+/* per-cpu VM mapping areas for zspage accesses that cross page boundaries */
+static DEFINE_PER_CPU(struct mapping_area, zs_map_area);
+
+static int is_first_page(struct page *page)
+{
+	return PagePrivate(page);
+}
+
+static int is_last_page(struct page *page)
+{
+	return PagePrivate2(page);
+}
+
+static void get_zspage_mapping(struct page *page, unsigned int *class_idx,
+				enum fullness_group *fullness)
+{
+	unsigned long m;
+	BUG_ON(!is_first_page(page));
+
+	m = (unsigned long)page->mapping;
+	*fullness = m & FULLNESS_MASK;
+	*class_idx = (m >> FULLNESS_BITS) & CLASS_IDX_MASK;
+}
+
+static void set_zspage_mapping(struct page *page, unsigned int class_idx,
+				enum fullness_group fullness)
+{
+	unsigned long m;
+	BUG_ON(!is_first_page(page));
+
+	m = ((class_idx & CLASS_IDX_MASK) << FULLNESS_BITS) |
+			(fullness & FULLNESS_MASK);
+	page->mapping = (struct address_space *)m;
+}
+
+/*
+ * zsmalloc divides the pool into various size classes where each
+ * class maintains a list of zspages where each zspage is divided
+ * into equal sized chunks. Each allocation falls into one of these
+ * classes depending on its size. This function returns index of the
+ * size class which has chunk size big enough to hold the give size.
+ */
+static int get_size_class_index(int size)
+{
+	int idx = 0;
+
+	if (likely(size > ZS_MIN_ALLOC_SIZE))
+		idx = DIV_ROUND_UP(size - ZS_MIN_ALLOC_SIZE,
+				ZS_SIZE_CLASS_DELTA);
+
+	return idx;
+}
+
+/*
+ * For each size class, zspages are divided into different groups
+ * depending on how "full" they are. This was done so that we could
+ * easily find empty or nearly empty zspages when we try to shrink
+ * the pool (not yet implemented). This function returns fullness
+ * status of the given page.
+ */
+static enum fullness_group get_fullness_group(struct page *page)
+{
+	int inuse, max_objects;
+	enum fullness_group fg;
+	BUG_ON(!is_first_page(page));
+
+	inuse = page->inuse;
+	max_objects = page->objects;
+
+	if (inuse == 0)
+		fg = ZS_EMPTY;
+	else if (inuse == max_objects)
+		fg = ZS_FULL;
+	else if (inuse <= max_objects / fullness_threshold_frac)
+		fg = ZS_ALMOST_EMPTY;
+	else
+		fg = ZS_ALMOST_FULL;
+
+	return fg;
+}
+
+/*
+ * Each size class maintains various freelists and zspages are assigned
+ * to one of these freelists based on the number of live objects they
+ * have. This functions inserts the given zspage into the freelist
+ * identified by <class, fullness_group>.
+ */
+static void insert_zspage(struct page *page, struct size_class *class,
+				enum fullness_group fullness)
+{
+	struct page **head;
+
+	BUG_ON(!is_first_page(page));
+
+	if (fullness >= _ZS_NR_FULLNESS_GROUPS)
+		return;
+
+	head = &class->fullness_list[fullness];
+	if (*head)
+		list_add_tail(&page->lru, &(*head)->lru);
+
+	*head = page;
+}
+
+/*
+ * This function removes the given zspage from the freelist identified
+ * by <class, fullness_group>.
+ */
+static void remove_zspage(struct page *page, struct size_class *class,
+				enum fullness_group fullness)
+{
+	struct page **head;
+
+	BUG_ON(!is_first_page(page));
+
+	if (fullness >= _ZS_NR_FULLNESS_GROUPS)
+		return;
+
+	head = &class->fullness_list[fullness];
+	BUG_ON(!*head);
+	if (list_empty(&(*head)->lru))
+		*head = NULL;
+	else if (*head == page)
+		*head = (struct page *)list_entry((*head)->lru.next,
+					struct page, lru);
+
+	list_del_init(&page->lru);
+}
+
+/*
+ * Each size class maintains zspages in different fullness groups depending
+ * on the number of live objects they contain. When allocating or freeing
+ * objects, the fullness status of the page can change, say, from ALMOST_FULL
+ * to ALMOST_EMPTY when freeing an object. This function checks if such
+ * a status change has occurred for the given page and accordingly moves the
+ * page from the freelist of the old fullness group to that of the new
+ * fullness group.
+ */
+static enum fullness_group fix_fullness_group(struct zs_pool *pool,
+						struct page *page)
+{
+	int class_idx;
+	struct size_class *class;
+	enum fullness_group currfg, newfg;
+
+	BUG_ON(!is_first_page(page));
+
+	get_zspage_mapping(page, &class_idx, &currfg);
+	newfg = get_fullness_group(page);
+	if (newfg == currfg)
+		goto out;
+
+	class = pool->size_class[class_idx];
+	remove_zspage(page, class, currfg);
+	insert_zspage(page, class, newfg);
+	set_zspage_mapping(page, class_idx, newfg);
+
+out:
+	return newfg;
+}
+
+/*
+ * We have to decide on how many pages to link together
+ * to form a zspage for each size class. This is important
+ * to reduce wastage due to unusable space left at end of
+ * each zspage which is given as:
+ *	wastage = Zp - Zp % size_class
+ * where Zp = zspage size = k * PAGE_SIZE where k = 1, 2, ...
+ *
+ * For example, for size class of 3/8 * PAGE_SIZE, we should
+ * link together 3 PAGE_SIZE sized pages to form a zspage
+ * since then we can perfectly fit in 8 such objects.
+ */
+static int get_pages_per_zspage(int class_size)
+{
+	int i, max_usedpc = 0;
+	/* zspage order which gives maximum used size per KB */
+	int max_usedpc_order = 1;
+
+	for (i = 1; i <= ZS_MAX_PAGES_PER_ZSPAGE; i++) {
+		int zspage_size;
+		int waste, usedpc;
+
+		zspage_size = i * PAGE_SIZE;
+		waste = zspage_size % class_size;
+		usedpc = (zspage_size - waste) * 100 / zspage_size;
+
+		if (usedpc > max_usedpc) {
+			max_usedpc = usedpc;
+			max_usedpc_order = i;
+		}
+	}
+
+	return max_usedpc_order;
+}
+
+/*
+ * A single 'zspage' is composed of many system pages which are
+ * linked together using fields in struct page. This function finds
+ * the first/head page, given any component page of a zspage.
+ */
+static struct page *get_first_page(struct page *page)
+{
+	if (is_first_page(page))
+		return page;
+	else
+		return page->first_page;
+}
+
+static struct page *get_next_page(struct page *page)
+{
+	struct page *next;
+
+	if (is_last_page(page))
+		next = NULL;
+	else if (is_first_page(page))
+		next = (struct page *)page_private(page);
+	else
+		next = list_entry(page->lru.next, struct page, lru);
+
+	return next;
+}
+
+/*
+ * Encode <page, obj_idx> as a single handle value.
+ * On hardware platforms with physical memory starting at 0x0 the pfn
+ * could be 0 so we ensure that the handle will never be 0 by adjusting the
+ * encoded obj_idx value before encoding.
+ */
+static void *obj_location_to_handle(struct page *page, unsigned long obj_idx)
+{
+	unsigned long handle;
+
+	if (!page) {
+		BUG_ON(obj_idx);
+		return NULL;
+	}
+
+	handle = page_to_pfn(page) << OBJ_INDEX_BITS;
+	handle |= ((obj_idx + 1) & OBJ_INDEX_MASK);
+
+	return (void *)handle;
+}
+
+/*
+ * Decode <page, obj_idx> pair from the given object handle. We adjust the
+ * decoded obj_idx back to its original value since it was adjusted in
+ * obj_location_to_handle().
+ */
+static void obj_handle_to_location(unsigned long handle, struct page **page,
+				unsigned long *obj_idx)
+{
+	*page = pfn_to_page(handle >> OBJ_INDEX_BITS);
+	*obj_idx = (handle & OBJ_INDEX_MASK) - 1;
+}
+
+static unsigned long obj_idx_to_offset(struct page *page,
+				unsigned long obj_idx, int class_size)
+{
+	unsigned long off = 0;
+
+	if (!is_first_page(page))
+		off = page->index;
+
+	return off + obj_idx * class_size;
+}
+
+static void reset_page(struct page *page)
+{
+	clear_bit(PG_private, &page->flags);
+	clear_bit(PG_private_2, &page->flags);
+	set_page_private(page, 0);
+	page->mapping = NULL;
+	page->freelist = NULL;
+	reset_page_mapcount(page);
+}
+
+static void free_zspage(struct page *first_page)
+{
+	struct page *nextp, *tmp, *head_extra;
+
+	BUG_ON(!is_first_page(first_page));
+	BUG_ON(first_page->inuse);
+
+	head_extra = (struct page *)page_private(first_page);
+
+	reset_page(first_page);
+	__free_page(first_page);
+
+	/* zspage with only 1 system page */
+	if (!head_extra)
+		return;
+
+	list_for_each_entry_safe(nextp, tmp, &head_extra->lru, lru) {
+		list_del(&nextp->lru);
+		reset_page(nextp);
+		__free_page(nextp);
+	}
+	reset_page(head_extra);
+	__free_page(head_extra);
+}
+
+/* Initialize a newly allocated zspage */
+static void init_zspage(struct page *first_page, struct size_class *class)
+{
+	unsigned long off = 0;
+	struct page *page = first_page;
+
+	BUG_ON(!is_first_page(first_page));
+	while (page) {
+		struct page *next_page;
+		struct link_free *link;
+		unsigned int i = 1;
+		void *vaddr;
+
+		/*
+		 * page->index stores offset of first object starting
+		 * in the page. For the first page, this is always 0,
+		 * so we use first_page->index (aka ->freelist) to store
+		 * head of corresponding zspage's freelist.
+		 */
+		if (page != first_page)
+			page->index = off;
+
+		vaddr = kmap_atomic(page);
+		link = (struct link_free *)vaddr + off / sizeof(*link);
+
+		while ((off += class->size) < PAGE_SIZE) {
+			link->next = obj_location_to_handle(page, i++);
+			link += class->size / sizeof(*link);
+		}
+
+		/*
+		 * We now come to the last (full or partial) object on this
+		 * page, which must point to the first object on the next
+		 * page (if present)
+		 */
+		next_page = get_next_page(page);
+		link->next = obj_location_to_handle(next_page, 0);
+		kunmap_atomic(vaddr);
+		page = next_page;
+		off %= PAGE_SIZE;
+	}
+}
+
+/*
+ * Allocate a zspage for the given size class
+ */
+static struct page *alloc_zspage(struct size_class *class, gfp_t flags)
+{
+	int i, error;
+	struct page *first_page = NULL, *uninitialized_var(prev_page);
+
+	/*
+	 * Allocate individual pages and link them together as:
+	 * 1. first page->private = first sub-page
+	 * 2. all sub-pages are linked together using page->lru
+	 * 3. each sub-page is linked to the first page using page->first_page
+	 *
+	 * For each size class, First/Head pages are linked together using
+	 * page->lru. Also, we set PG_private to identify the first page
+	 * (i.e. no other sub-page has this flag set) and PG_private_2 to
+	 * identify the last page.
+	 */
+	error = -ENOMEM;
+	for (i = 0; i < class->pages_per_zspage; i++) {
+		struct page *page;
+
+		page = alloc_page(flags);
+		if (!page)
+			goto cleanup;
+
+		INIT_LIST_HEAD(&page->lru);
+		if (i == 0) {	/* first page */
+			SetPagePrivate(page);
+			set_page_private(page, 0);
+			first_page = page;
+			first_page->inuse = 0;
+		}
+		if (i == 1)
+			set_page_private(first_page, (unsigned long)page);
+		if (i >= 1)
+			page->first_page = first_page;
+		if (i >= 2)
+			list_add(&page->lru, &prev_page->lru);
+		if (i == class->pages_per_zspage - 1)	/* last page */
+			SetPagePrivate2(page);
+		prev_page = page;
+	}
+
+	init_zspage(first_page, class);
+
+	first_page->freelist = obj_location_to_handle(first_page, 0);
+	/* Maximum number of objects we can store in this zspage */
+	first_page->objects = class->pages_per_zspage * PAGE_SIZE / class->size;
+
+	error = 0; /* Success */
+
+cleanup:
+	if (unlikely(error) && first_page) {
+		free_zspage(first_page);
+		first_page = NULL;
+	}
+
+	return first_page;
+}
+
+static struct page *find_get_zspage(struct size_class *class)
+{
+	int i;
+	struct page *page;
+
+	for (i = 0; i < _ZS_NR_FULLNESS_GROUPS; i++) {
+		page = class->fullness_list[i];
+		if (page)
+			break;
+	}
+
+	return page;
+}
+
+#ifdef CONFIG_PGTABLE_MAPPING
+static inline int __zs_cpu_up(struct mapping_area *area)
+{
+	/*
+	 * Make sure we don't leak memory if a cpu UP notification
+	 * and zs_init() race and both call zs_cpu_up() on the same cpu
+	 */
+	if (area->vm)
+		return 0;
+	area->vm = alloc_vm_area(PAGE_SIZE * 2, NULL);
+	if (!area->vm)
+		return -ENOMEM;
+	return 0;
+}
+
+static inline void __zs_cpu_down(struct mapping_area *area)
+{
+	if (area->vm)
+		free_vm_area(area->vm);
+	area->vm = NULL;
+}
+
+static inline void *__zs_map_object(struct mapping_area *area,
+				struct page *pages[2], int off, int size)
+{
+	BUG_ON(map_vm_area(area->vm, PAGE_KERNEL, &pages));
+	area->vm_addr = area->vm->addr;
+	return area->vm_addr + off;
+}
+
+static inline void __zs_unmap_object(struct mapping_area *area,
+				struct page *pages[2], int off, int size)
+{
+	unsigned long addr = (unsigned long)area->vm_addr;
+
+	unmap_kernel_range(addr, PAGE_SIZE * 2);
+}
+
+#else /* CONFIG_PGTABLE_MAPPING */
+
+static inline int __zs_cpu_up(struct mapping_area *area)
+{
+	/*
+	 * Make sure we don't leak memory if a cpu UP notification
+	 * and zs_init() race and both call zs_cpu_up() on the same cpu
+	 */
+	if (area->vm_buf)
+		return 0;
+	area->vm_buf = (char *)__get_free_page(GFP_KERNEL);
+	if (!area->vm_buf)
+		return -ENOMEM;
+	return 0;
+}
+
+static inline void __zs_cpu_down(struct mapping_area *area)
+{
+	if (area->vm_buf)
+		free_page((unsigned long)area->vm_buf);
+	area->vm_buf = NULL;
+}
+
+static void *__zs_map_object(struct mapping_area *area,
+			struct page *pages[2], int off, int size)
+{
+	int sizes[2];
+	void *addr;
+	char *buf = area->vm_buf;
+
+	/* disable page faults to match kmap_atomic() return conditions */
+	pagefault_disable();
+
+	/* no read fastpath */
+	if (area->vm_mm == ZS_MM_WO)
+		goto out;
+
+	sizes[0] = PAGE_SIZE - off;
+	sizes[1] = size - sizes[0];
+
+	/* copy object to per-cpu buffer */
+	addr = kmap_atomic(pages[0]);
+	memcpy(buf, addr + off, sizes[0]);
+	kunmap_atomic(addr);
+	addr = kmap_atomic(pages[1]);
+	memcpy(buf + sizes[0], addr, sizes[1]);
+	kunmap_atomic(addr);
+out:
+	return area->vm_buf;
+}
+
+static void __zs_unmap_object(struct mapping_area *area,
+			struct page *pages[2], int off, int size)
+{
+	int sizes[2];
+	void *addr;
+	char *buf = area->vm_buf;
+
+	/* no write fastpath */
+	if (area->vm_mm == ZS_MM_RO)
+		goto out;
+
+	sizes[0] = PAGE_SIZE - off;
+	sizes[1] = size - sizes[0];
+
+	/* copy per-cpu buffer to object */
+	addr = kmap_atomic(pages[0]);
+	memcpy(addr + off, buf, sizes[0]);
+	kunmap_atomic(addr);
+	addr = kmap_atomic(pages[1]);
+	memcpy(addr, buf + sizes[0], sizes[1]);
+	kunmap_atomic(addr);
+
+out:
+	/* enable page faults to match kunmap_atomic() return conditions */
+	pagefault_enable();
+}
+
+#endif /* CONFIG_PGTABLE_MAPPING */
+
+static int zs_cpu_notifier(struct notifier_block *nb, unsigned long action,
+				void *pcpu)
+{
+	int ret, cpu = (long)pcpu;
+	struct mapping_area *area;
+
+	switch (action) {
+	case CPU_UP_PREPARE:
+		area = &per_cpu(zs_map_area, cpu);
+		ret = __zs_cpu_up(area);
+		if (ret)
+			return notifier_from_errno(ret);
+		break;
+	case CPU_DEAD:
+	case CPU_UP_CANCELED:
+		area = &per_cpu(zs_map_area, cpu);
+		__zs_cpu_down(area);
+		break;
+	}
+
+	return NOTIFY_OK;
+}
+
+static struct notifier_block zs_cpu_nb = {
+	.notifier_call = zs_cpu_notifier
+};
+
+static void zs_exit(void)
+{
+	int cpu;
+
+	for_each_online_cpu(cpu)
+		zs_cpu_notifier(NULL, CPU_DEAD, (void *)(long)cpu);
+	unregister_cpu_notifier(&zs_cpu_nb);
+}
+
+static int zs_init(void)
+{
+	int cpu, ret;
+
+	register_cpu_notifier(&zs_cpu_nb);
+	for_each_online_cpu(cpu) {
+		ret = zs_cpu_notifier(NULL, CPU_UP_PREPARE, (void *)(long)cpu);
+		if (notifier_to_errno(ret))
+			goto fail;
+	}
+	return 0;
+fail:
+	zs_exit();
+	return notifier_to_errno(ret);
+}
+
+static unsigned int get_maxobj_per_zspage(int size, int pages_per_zspage)
+{
+	return pages_per_zspage * PAGE_SIZE / size;
+}
+
+static bool can_merge(struct size_class *prev, int size, int pages_per_zspage)
+{
+	if (prev->pages_per_zspage != pages_per_zspage)
+		return false;
+
+	if (get_maxobj_per_zspage(prev->size, prev->pages_per_zspage)
+		!= get_maxobj_per_zspage(size, pages_per_zspage))
+		return false;
+
+	return true;
+}
+
+/**
+ * zs_create_pool - Creates an allocation pool to work from.
+ * @flags: allocation flags used to allocate pool metadata
+ *
+ * This function must be called before anything when using
+ * the zsmalloc allocator.
+ *
+ * On success, a pointer to the newly created pool is returned,
+ * otherwise NULL.
+ */
+struct zs_pool *zs_create_pool(gfp_t flags)
+{
+	int i;
+	struct zs_pool *pool;
+
+	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
+	if (!pool)
+		return NULL;
+
+	/*
+	 * Iterate reversly, because, size of size_class that we want to use
+	 * for merging should be larger or equal to current size.
+	 */
+	for (i = ZS_SIZE_CLASSES - 1; i >= 0; i--) {
+		int size;
+		int pages_per_zspage;
+		struct size_class *class;
+		struct size_class *prev_class;
+
+		size = ZS_MIN_ALLOC_SIZE + i * ZS_SIZE_CLASS_DELTA;
+		if (size > ZS_MAX_ALLOC_SIZE)
+			size = ZS_MAX_ALLOC_SIZE;
+		pages_per_zspage = get_pages_per_zspage(size);
+
+		/*
+		 * size_class is used for normal zsmalloc operation such
+		 * as alloc/free for that size. Although it is natural that we
+		 * have one size_class for each size, there is a chance that we
+		 * can get more memory utilization if we use one size_class for
+		 * many different sizes whose size_class have same
+		 * characteristics. So, we makes size_class point to
+		 * previous size_class if possible.
+		 */
+		if (i < ZS_SIZE_CLASSES - 1) {
+			prev_class = pool->size_class[i + 1];
+			if (can_merge(prev_class, size, pages_per_zspage)) {
+				pool->size_class[i] = prev_class;
+				continue;
+			}
+		}
+
+		class = kzalloc(sizeof(struct size_class), GFP_KERNEL);
+		if (!class)
+			goto err;
+
+		class->size = size;
+		class->index = i;
+		class->pages_per_zspage = pages_per_zspage;
+		spin_lock_init(&class->lock);
+		pool->size_class[i] = class;
+	}
+
+	pool->flags = flags;
+
+	return pool;
+
+err:
+	zs_destroy_pool(pool);
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(zs_create_pool);
+
+void zs_destroy_pool(struct zs_pool *pool)
+{
+	int i;
+
+	for (i = 0; i < ZS_SIZE_CLASSES; i++) {
+		int fg;
+		struct size_class *class = pool->size_class[i];
+
+		if (!class)
+			continue;
+
+		if (class->index != i)
+			continue;
+
+		for (fg = 0; fg < _ZS_NR_FULLNESS_GROUPS; fg++) {
+			if (class->fullness_list[fg]) {
+				pr_info("Freeing non-empty class with size %db, fullness group %d\n",
+					class->size, fg);
+			}
+		}
+		kfree(class);
+	}
+	kfree(pool);
+}
+EXPORT_SYMBOL_GPL(zs_destroy_pool);
+
+/**
+ * zs_malloc - Allocate block of given size from pool.
+ * @pool: pool to allocate from
+ * @size: size of block to allocate
+ *
+ * On success, handle to the allocated object is returned,
+ * otherwise 0.
+ * Allocation requests with size > ZS_MAX_ALLOC_SIZE will fail.
+ */
+unsigned long zs_malloc(struct zs_pool *pool, size_t size)
+{
+	unsigned long obj;
+	struct link_free *link;
+	struct size_class *class;
+	void *vaddr;
+
+	struct page *first_page, *m_page;
+	unsigned long m_objidx, m_offset;
+
+	if (unlikely(!size || size > ZS_MAX_ALLOC_SIZE))
+		return 0;
+
+	class = pool->size_class[get_size_class_index(size)];
+
+	spin_lock(&class->lock);
+	first_page = find_get_zspage(class);
+
+	if (!first_page) {
+		spin_unlock(&class->lock);
+		first_page = alloc_zspage(class, pool->flags);
+		if (unlikely(!first_page))
+			return 0;
+
+		set_zspage_mapping(first_page, class->index, ZS_EMPTY);
+		atomic_long_add(class->pages_per_zspage,
+					&pool->pages_allocated);
+		spin_lock(&class->lock);
+	}
+
+	obj = (unsigned long)first_page->freelist;
+	obj_handle_to_location(obj, &m_page, &m_objidx);
+	m_offset = obj_idx_to_offset(m_page, m_objidx, class->size);
+
+	vaddr = kmap_atomic(m_page);
+	link = (struct link_free *)vaddr + m_offset / sizeof(*link);
+	first_page->freelist = link->next;
+	memset(link, POISON_INUSE, sizeof(*link));
+	kunmap_atomic(vaddr);
+
+	first_page->inuse++;
+	/* Now move the zspage to another fullness group, if required */
+	fix_fullness_group(pool, first_page);
+	spin_unlock(&class->lock);
+
+	return obj;
+}
+EXPORT_SYMBOL_GPL(zs_malloc);
+
+void zs_free(struct zs_pool *pool, unsigned long obj)
+{
+	struct link_free *link;
+	struct page *first_page, *f_page;
+	unsigned long f_objidx, f_offset;
+	void *vaddr;
+
+	int class_idx;
+	struct size_class *class;
+	enum fullness_group fullness;
+
+	if (unlikely(!obj))
+		return;
+
+	obj_handle_to_location(obj, &f_page, &f_objidx);
+	first_page = get_first_page(f_page);
+
+	get_zspage_mapping(first_page, &class_idx, &fullness);
+	class = pool->size_class[class_idx];
+	f_offset = obj_idx_to_offset(f_page, f_objidx, class->size);
+
+	spin_lock(&class->lock);
+
+	/* Insert this object in containing zspage's freelist */
+	vaddr = kmap_atomic(f_page);
+	link = (struct link_free *)(vaddr + f_offset);
+	link->next = first_page->freelist;
+	kunmap_atomic(vaddr);
+	first_page->freelist = (void *)obj;
+
+	first_page->inuse--;
+	fullness = fix_fullness_group(pool, first_page);
+	spin_unlock(&class->lock);
+
+	if (fullness == ZS_EMPTY) {
+		atomic_long_sub(class->pages_per_zspage,
+				&pool->pages_allocated);
+		free_zspage(first_page);
+	}
+}
+EXPORT_SYMBOL_GPL(zs_free);
+
+/**
+ * zs_map_object - get address of allocated object from handle.
+ * @pool: pool from which the object was allocated
+ * @handle: handle returned from zs_malloc
+ *
+ * Before using an object allocated from zs_malloc, it must be mapped using
+ * this function. When done with the object, it must be unmapped using
+ * zs_unmap_object.
+ *
+ * Only one object can be mapped per cpu at a time. There is no protection
+ * against nested mappings.
+ *
+ * This function returns with preemption and page faults disabled.
+ */
+void *zs_map_object(struct zs_pool *pool, unsigned long handle,
+			enum zs_mapmode mm)
+{
+	struct page *page;
+	unsigned long obj_idx, off;
+
+	unsigned int class_idx;
+	enum fullness_group fg;
+	struct size_class *class;
+	struct mapping_area *area;
+	struct page *pages[2];
+
+	BUG_ON(!handle);
+
+	/*
+	 * Because we use per-cpu mapping areas shared among the
+	 * pools/users, we can't allow mapping in interrupt context
+	 * because it can corrupt another users mappings.
+	 */
+	BUG_ON(in_interrupt());
+
+	obj_handle_to_location(handle, &page, &obj_idx);
+	get_zspage_mapping(get_first_page(page), &class_idx, &fg);
+	class = pool->size_class[class_idx];
+	off = obj_idx_to_offset(page, obj_idx, class->size);
+
+	area = &get_cpu_var(zs_map_area);
+	area->vm_mm = mm;
+	if (off + class->size <= PAGE_SIZE) {
+		/* this object is contained entirely within a page */
+		area->vm_addr = kmap_atomic(page);
+		return area->vm_addr + off;
+	}
+
+	/* this object spans two pages */
+	pages[0] = page;
+	pages[1] = get_next_page(page);
+	BUG_ON(!pages[1]);
+
+	return __zs_map_object(area, pages, off, class->size);
+}
+EXPORT_SYMBOL_GPL(zs_map_object);
+
+void zs_unmap_object(struct zs_pool *pool, unsigned long handle)
+{
+	struct page *page;
+	unsigned long obj_idx, off;
+
+	unsigned int class_idx;
+	enum fullness_group fg;
+	struct size_class *class;
+	struct mapping_area *area;
+
+	BUG_ON(!handle);
+
+	obj_handle_to_location(handle, &page, &obj_idx);
+	get_zspage_mapping(get_first_page(page), &class_idx, &fg);
+	class = pool->size_class[class_idx];
+	off = obj_idx_to_offset(page, obj_idx, class->size);
+
+	area = &__get_cpu_var(zs_map_area);
+	if (off + class->size <= PAGE_SIZE)
+		kunmap_atomic(area->vm_addr);
+	else {
+		struct page *pages[2];
+
+		pages[0] = page;
+		pages[1] = get_next_page(page);
+		BUG_ON(!pages[1]);
+
+		__zs_unmap_object(area, pages, off, class->size);
+	}
+	put_cpu_var(zs_map_area);
+}
+EXPORT_SYMBOL_GPL(zs_unmap_object);
+
+unsigned long zs_get_total_pages(struct zs_pool *pool)
+{
+	return atomic_long_read(&pool->pages_allocated);
+}
+EXPORT_SYMBOL_GPL(zs_get_total_pages);
+
+module_init(zs_init);
+module_exit(zs_exit);
+
+MODULE_LICENSE("Dual BSD/GPL");
+MODULE_AUTHOR("Nitin Gupta <ngupta@vflare.org>");