1 files changed, 302 insertions, 94 deletions

diff --git a/drivers/android/binder_alloc.c b/drivers/android/binder_alloc.c
index aabfebac6e57..1c1a7d9c86ed 100644
--- a/drivers/android/binder_alloc.c
+++ b/drivers/android/binder_alloc.c
@@ -27,9 +27,12 @@
 #include <linux/vmalloc.h>
 #include <linux/slab.h>
 #include <linux/sched.h>
+#include <linux/list_lru.h>
 #include "binder_alloc.h"
 #include "binder_trace.h"
 
+struct list_lru binder_alloc_lru;
+
 static DEFINE_MUTEX(binder_alloc_mmap_lock);
 
 enum {
@@ -48,14 +51,23 @@ module_param_named(debug_mask, binder_alloc_debug_mask,
 			pr_info(x); \
 	} while (0)
 
+static struct binder_buffer *binder_buffer_next(struct binder_buffer *buffer)
+{
+	return list_entry(buffer->entry.next, struct binder_buffer, entry);
+}
+
+static struct binder_buffer *binder_buffer_prev(struct binder_buffer *buffer)
+{
+	return list_entry(buffer->entry.prev, struct binder_buffer, entry);
+}
+
 static size_t binder_alloc_buffer_size(struct binder_alloc *alloc,
 				       struct binder_buffer *buffer)
 {
 	if (list_is_last(&buffer->entry, &alloc->buffers))
-		return alloc->buffer +
-		       alloc->buffer_size - (void *)buffer->data;
-	return (size_t)list_entry(buffer->entry.next,
-			  struct binder_buffer, entry) - (size_t)buffer->data;
+		return (u8 *)alloc->buffer +
+			alloc->buffer_size - (u8 *)buffer->data;
+	return (u8 *)binder_buffer_next(buffer)->data - (u8 *)buffer->data;
 }
 
 static void binder_insert_free_buffer(struct binder_alloc *alloc,
@@ -105,9 +117,9 @@ static void binder_insert_allocated_buffer_locked(
 		buffer = rb_entry(parent, struct binder_buffer, rb_node);
 		BUG_ON(buffer->free);
 
-		if (new_buffer < buffer)
+		if (new_buffer->data < buffer->data)
 			p = &parent->rb_left;
-		else if (new_buffer > buffer)
+		else if (new_buffer->data > buffer->data)
 			p = &parent->rb_right;
 		else
 			BUG();
@@ -122,18 +134,17 @@ static struct binder_buffer *binder_alloc_prepare_to_free_locked(
 {
 	struct rb_node *n = alloc->allocated_buffers.rb_node;
 	struct binder_buffer *buffer;
-	struct binder_buffer *kern_ptr;
+	void *kern_ptr;
 
-	kern_ptr = (struct binder_buffer *)(user_ptr - alloc->user_buffer_offset
-		- offsetof(struct binder_buffer, data));
+	kern_ptr = (void *)(user_ptr - alloc->user_buffer_offset);
 
 	while (n) {
 		buffer = rb_entry(n, struct binder_buffer, rb_node);
 		BUG_ON(buffer->free);
 
-		if (kern_ptr < buffer)
+		if (kern_ptr < buffer->data)
 			n = n->rb_left;
-		else if (kern_ptr > buffer)
+		else if (kern_ptr > buffer->data)
 			n = n->rb_right;
 		else {
 			/*
@@ -180,8 +191,9 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 {
 	void *page_addr;
 	unsigned long user_page_addr;
-	struct page **page;
-	struct mm_struct *mm;
+	struct binder_lru_page *page;
+	struct mm_struct *mm = NULL;
+	bool need_mm = false;
 
 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 		     "%d: %s pages %pK-%pK\n", alloc->pid,
@@ -192,9 +204,18 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 
 	trace_binder_update_page_range(alloc, allocate, start, end);
 
-	if (vma)
-		mm = NULL;
-	else
+	if (allocate == 0)
+		goto free_range;
+
+	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
+		page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE];
+		if (!page->page_ptr) {
+			need_mm = true;
+			break;
+		}
+	}
+
+	if (!vma && need_mm)
 		mm = get_task_mm(alloc->tsk);
 
 	if (mm) {
@@ -207,10 +228,7 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 		}
 	}
 
-	if (allocate == 0)
-		goto free_range;
-
-	if (vma == NULL) {
+	if (!vma && need_mm) {
 		pr_err("%d: binder_alloc_buf failed to map pages in userspace, no vma\n",
 			alloc->pid);
 		goto err_no_vma;
@@ -218,18 +236,40 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 
 	for (page_addr = start; page_addr < end; page_addr += PAGE_SIZE) {
 		int ret;
+		bool on_lru;
+		size_t index;
 
-		page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE];
+		index = (page_addr - alloc->buffer) / PAGE_SIZE;
+		page = &alloc->pages[index];
+
+		if (page->page_ptr) {
+			trace_binder_alloc_lru_start(alloc, index);
 
-		BUG_ON(*page);
-		*page = alloc_page(GFP_KERNEL | __GFP_HIGHMEM | __GFP_ZERO);
-		if (*page == NULL) {
+			on_lru = list_lru_del(&binder_alloc_lru, &page->lru);
+			WARN_ON(!on_lru);
+
+			trace_binder_alloc_lru_end(alloc, index);
+			continue;
+		}
+
+		if (WARN_ON(!vma))
+			goto err_page_ptr_cleared;
+
+		trace_binder_alloc_page_start(alloc, index);
+		page->page_ptr = alloc_page(GFP_KERNEL |
+					    __GFP_HIGHMEM |
+					    __GFP_ZERO);
+		if (!page->page_ptr) {
 			pr_err("%d: binder_alloc_buf failed for page at %pK\n",
 				alloc->pid, page_addr);
 			goto err_alloc_page_failed;
 		}
+		page->alloc = alloc;
+		INIT_LIST_HEAD(&page->lru);
+
 		ret = map_kernel_range_noflush((unsigned long)page_addr,
-					PAGE_SIZE, PAGE_KERNEL, page);
+					       PAGE_SIZE, PAGE_KERNEL,
+					       &page->page_ptr);
 		flush_cache_vmap((unsigned long)page_addr,
 				(unsigned long)page_addr + PAGE_SIZE);
 		if (ret != 1) {
@@ -239,12 +279,14 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 		}
 		user_page_addr =
 			(uintptr_t)page_addr + alloc->user_buffer_offset;
-		ret = vm_insert_page(vma, user_page_addr, page[0]);
+		ret = vm_insert_page(vma, user_page_addr, page[0].page_ptr);
 		if (ret) {
 			pr_err("%d: binder_alloc_buf failed to map page at %lx in userspace\n",
 			       alloc->pid, user_page_addr);
 			goto err_vm_insert_page_failed;
 		}
+
+		trace_binder_alloc_page_end(alloc, index);
 		/* vm_insert_page does not seem to increment the refcount */
 	}
 	if (mm) {
@@ -256,16 +298,27 @@ static int binder_update_page_range(struct binder_alloc *alloc, int allocate,
 free_range:
 	for (page_addr = end - PAGE_SIZE; page_addr >= start;
 	     page_addr -= PAGE_SIZE) {
-		page = &alloc->pages[(page_addr - alloc->buffer) / PAGE_SIZE];
-		if (vma)
-			zap_page_range(vma, (uintptr_t)page_addr +
-				alloc->user_buffer_offset, PAGE_SIZE, NULL);
+		bool ret;
+		size_t index;
+
+		index = (page_addr - alloc->buffer) / PAGE_SIZE;
+		page = &alloc->pages[index];
+
+		trace_binder_free_lru_start(alloc, index);
+
+		ret = list_lru_add(&binder_alloc_lru, &page->lru);
+		WARN_ON(!ret);
+
+		trace_binder_free_lru_end(alloc, index);
+		continue;
+
 err_vm_insert_page_failed:
 		unmap_kernel_range((unsigned long)page_addr, PAGE_SIZE);
 err_map_kernel_failed:
-		__free_page(*page);
-		*page = NULL;
+		__free_page(page->page_ptr);
+		page->page_ptr = NULL;
 err_alloc_page_failed:
+err_page_ptr_cleared:
 		;
 	}
 err_no_vma:
@@ -321,6 +374,9 @@ struct binder_buffer *binder_alloc_new_buf_locked(struct binder_alloc *alloc,
 		return ERR_PTR(-ENOSPC);
 	}
 
+	/* Pad 0-size buffers so they get assigned unique addresses */
+	size = max(size, sizeof(void *));
+
 	while (n) {
 		buffer = rb_entry(n, struct binder_buffer, rb_node);
 		BUG_ON(!buffer->free);
@@ -380,14 +436,9 @@ struct binder_buffer *binder_alloc_new_buf_locked(struct binder_alloc *alloc,
 
 	has_page_addr =
 		(void *)(((uintptr_t)buffer->data + buffer_size) & PAGE_MASK);
-	if (n == NULL) {
-		if (size + sizeof(struct binder_buffer) + 4 >= buffer_size)
-			buffer_size = size; /* no room for other buffers */
-		else
-			buffer_size = size + sizeof(struct binder_buffer);
-	}
+	WARN_ON(n && buffer_size != size);
 	end_page_addr =
-		(void *)PAGE_ALIGN((uintptr_t)buffer->data + buffer_size);
+		(void *)PAGE_ALIGN((uintptr_t)buffer->data + size);
 	if (end_page_addr > has_page_addr)
 		end_page_addr = has_page_addr;
 	ret = binder_update_page_range(alloc, 1,
@@ -395,17 +446,25 @@ struct binder_buffer *binder_alloc_new_buf_locked(struct binder_alloc *alloc,
 	if (ret)
 		return ERR_PTR(ret);
 
-	rb_erase(best_fit, &alloc->free_buffers);
-	buffer->free = 0;
-	buffer->free_in_progress = 0;
-	binder_insert_allocated_buffer_locked(alloc, buffer);
 	if (buffer_size != size) {
-		struct binder_buffer *new_buffer = (void *)buffer->data + size;
+		struct binder_buffer *new_buffer;
 
+		new_buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
+		if (!new_buffer) {
+			pr_err("%s: %d failed to alloc new buffer struct\n",
+			       __func__, alloc->pid);
+			goto err_alloc_buf_struct_failed;
+		}
+		new_buffer->data = (u8 *)buffer->data + size;
 		list_add(&new_buffer->entry, &buffer->entry);
 		new_buffer->free = 1;
 		binder_insert_free_buffer(alloc, new_buffer);
 	}
+
+	rb_erase(best_fit, &alloc->free_buffers);
+	buffer->free = 0;
+	buffer->free_in_progress = 0;
+	binder_insert_allocated_buffer_locked(alloc, buffer);
 	binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
 		     "%d: binder_alloc_buf size %zd got %pK\n",
 		      alloc->pid, size, buffer);
@@ -420,6 +479,12 @@ struct binder_buffer *binder_alloc_new_buf_locked(struct binder_alloc *alloc,
 			      alloc->pid, size, alloc->free_async_space);
 	}
 	return buffer;
+
+err_alloc_buf_struct_failed:
+	binder_update_page_range(alloc, 0,
+				 (void *)PAGE_ALIGN((uintptr_t)buffer->data),
+				 end_page_addr, NULL);
+	return ERR_PTR(-ENOMEM);
 }
 
 /**
@@ -454,57 +519,59 @@ struct binder_buffer *binder_alloc_new_buf(struct binder_alloc *alloc,
 
 static void *buffer_start_page(struct binder_buffer *buffer)
 {
-	return (void *)((uintptr_t)buffer & PAGE_MASK);
+	return (void *)((uintptr_t)buffer->data & PAGE_MASK);
 }
 
-static void *buffer_end_page(struct binder_buffer *buffer)
+static void *prev_buffer_end_page(struct binder_buffer *buffer)
 {
-	return (void *)(((uintptr_t)(buffer + 1) - 1) & PAGE_MASK);
+	return (void *)(((uintptr_t)(buffer->data) - 1) & PAGE_MASK);
 }
 
 static void binder_delete_free_buffer(struct binder_alloc *alloc,
 				      struct binder_buffer *buffer)
 {
 	struct binder_buffer *prev, *next = NULL;
-	int free_page_end = 1;
-	int free_page_start = 1;
-
+	bool to_free = true;
 	BUG_ON(alloc->buffers.next == &buffer->entry);
-	prev = list_entry(buffer->entry.prev, struct binder_buffer, entry);
+	prev = binder_buffer_prev(buffer);
 	BUG_ON(!prev->free);
-	if (buffer_end_page(prev) == buffer_start_page(buffer)) {
-		free_page_start = 0;
-		if (buffer_end_page(prev) == buffer_end_page(buffer))
-			free_page_end = 0;
+	if (prev_buffer_end_page(prev) == buffer_start_page(buffer)) {
+		to_free = false;
 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
-			     "%d: merge free, buffer %pK share page with %pK\n",
-			      alloc->pid, buffer, prev);
+				   "%d: merge free, buffer %pK share page with %pK\n",
+				   alloc->pid, buffer->data, prev->data);
 	}
 
 	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
-		next = list_entry(buffer->entry.next,
-				  struct binder_buffer, entry);
-		if (buffer_start_page(next) == buffer_end_page(buffer)) {
-			free_page_end = 0;
-			if (buffer_start_page(next) ==
-			    buffer_start_page(buffer))
-				free_page_start = 0;
+		next = binder_buffer_next(buffer);
+		if (buffer_start_page(next) == buffer_start_page(buffer)) {
+			to_free = false;
 			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
-				     "%d: merge free, buffer %pK share page with %pK\n",
-				      alloc->pid, buffer, prev);
+					   "%d: merge free, buffer %pK share page with %pK\n",
+					   alloc->pid,
+					   buffer->data,
+					   next->data);
 		}
 	}
-	list_del(&buffer->entry);
-	if (free_page_start || free_page_end) {
+
+	if (PAGE_ALIGNED(buffer->data)) {
 		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
-			     "%d: merge free, buffer %pK do not share page%s%s with %pK or %pK\n",
-			     alloc->pid, buffer, free_page_start ? "" : " end",
-			     free_page_end ? "" : " start", prev, next);
-		binder_update_page_range(alloc, 0, free_page_start ?
-			buffer_start_page(buffer) : buffer_end_page(buffer),
-			(free_page_end ? buffer_end_page(buffer) :
-			buffer_start_page(buffer)) + PAGE_SIZE, NULL);
+				   "%d: merge free, buffer start %pK is page aligned\n",
+				   alloc->pid, buffer->data);
+		to_free = false;
 	}
+
+	if (to_free) {
+		binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
+				   "%d: merge free, buffer %pK do not share page with %pK or %pK\n",
+				   alloc->pid, buffer->data,
+				   prev->data, next->data);
+		binder_update_page_range(alloc, 0, buffer_start_page(buffer),
+					 buffer_start_page(buffer) + PAGE_SIZE,
+					 NULL);
+	}
+	list_del(&buffer->entry);
+	kfree(buffer);
 }
 
 static void binder_free_buf_locked(struct binder_alloc *alloc,
@@ -525,8 +592,8 @@ static void binder_free_buf_locked(struct binder_alloc *alloc,
 	BUG_ON(buffer->free);
 	BUG_ON(size > buffer_size);
 	BUG_ON(buffer->transaction != NULL);
-	BUG_ON((void *)buffer < alloc->buffer);
-	BUG_ON((void *)buffer > alloc->buffer + alloc->buffer_size);
+	BUG_ON(buffer->data < alloc->buffer);
+	BUG_ON(buffer->data > alloc->buffer + alloc->buffer_size);
 
 	if (buffer->async_transaction) {
 		alloc->free_async_space += size + sizeof(struct binder_buffer);
@@ -544,8 +611,7 @@ static void binder_free_buf_locked(struct binder_alloc *alloc,
 	rb_erase(&buffer->rb_node, &alloc->allocated_buffers);
 	buffer->free = 1;
 	if (!list_is_last(&buffer->entry, &alloc->buffers)) {
-		struct binder_buffer *next = list_entry(buffer->entry.next,
-						struct binder_buffer, entry);
+		struct binder_buffer *next = binder_buffer_next(buffer);
 
 		if (next->free) {
 			rb_erase(&next->rb_node, &alloc->free_buffers);
@@ -553,8 +619,7 @@ static void binder_free_buf_locked(struct binder_alloc *alloc,
 		}
 	}
 	if (alloc->buffers.next != &buffer->entry) {
-		struct binder_buffer *prev = list_entry(buffer->entry.prev,
-						struct binder_buffer, entry);
+		struct binder_buffer *prev = binder_buffer_prev(buffer);
 
 		if (prev->free) {
 			binder_delete_free_buffer(alloc, buffer);
@@ -640,14 +705,14 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 	}
 	alloc->buffer_size = vma->vm_end - vma->vm_start;
 
-	if (binder_update_page_range(alloc, 1, alloc->buffer,
-				     alloc->buffer + PAGE_SIZE, vma)) {
+	buffer = kzalloc(sizeof(*buffer), GFP_KERNEL);
+	if (!buffer) {
 		ret = -ENOMEM;
-		failure_string = "alloc small buf";
-		goto err_alloc_small_buf_failed;
+		failure_string = "alloc buffer struct";
+		goto err_alloc_buf_struct_failed;
 	}
-	buffer = alloc->buffer;
-	INIT_LIST_HEAD(&alloc->buffers);
+
+	buffer->data = alloc->buffer;
 	list_add(&buffer->entry, &alloc->buffers);
 	buffer->free = 1;
 	binder_insert_free_buffer(alloc, buffer);
@@ -658,7 +723,7 @@ int binder_alloc_mmap_handler(struct binder_alloc *alloc,
 
 	return 0;
 
-err_alloc_small_buf_failed:
+err_alloc_buf_struct_failed:
 	kfree(alloc->pages);
 	alloc->pages = NULL;
 err_alloc_pages_failed:
@@ -678,14 +743,13 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
 {
 	struct rb_node *n;
 	int buffers, page_count;
+	struct binder_buffer *buffer;
 
 	BUG_ON(alloc->vma);
 
 	buffers = 0;
 	mutex_lock(&alloc->mutex);
 	while ((n = rb_first(&alloc->allocated_buffers))) {
-		struct binder_buffer *buffer;
-
 		buffer = rb_entry(n, struct binder_buffer, rb_node);
 
 		/* Transaction should already have been freed */
@@ -695,22 +759,36 @@ void binder_alloc_deferred_release(struct binder_alloc *alloc)
 		buffers++;
 	}
 
+	while (!list_empty(&alloc->buffers)) {
+		buffer = list_first_entry(&alloc->buffers,
+					  struct binder_buffer, entry);
+		WARN_ON(!buffer->free);
+
+		list_del(&buffer->entry);
+		WARN_ON_ONCE(!list_empty(&alloc->buffers));
+		kfree(buffer);
+	}
+
 	page_count = 0;
 	if (alloc->pages) {
 		int i;
 
 		for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
 			void *page_addr;
+			bool on_lru;
 
-			if (!alloc->pages[i])
+			if (!alloc->pages[i].page_ptr)
 				continue;
 
+			on_lru = list_lru_del(&binder_alloc_lru,
+					      &alloc->pages[i].lru);
 			page_addr = alloc->buffer + i * PAGE_SIZE;
 			binder_alloc_debug(BINDER_DEBUG_BUFFER_ALLOC,
-				     "%s: %d: page %d at %pK not freed\n",
-				     __func__, alloc->pid, i, page_addr);
+				     "%s: %d: page %d at %pK %s\n",
+				     __func__, alloc->pid, i, page_addr,
+				     on_lru ? "on lru" : "active");
 			unmap_kernel_range((unsigned long)page_addr, PAGE_SIZE);
-			__free_page(alloc->pages[i]);
+			__free_page(alloc->pages[i].page_ptr);
 			page_count++;
 		}
 		kfree(alloc->pages);
@@ -754,6 +832,34 @@ void binder_alloc_print_allocated(struct seq_file *m,
 }
 
 /**
+ * binder_alloc_print_pages() - print page usage
+ * @m:     seq_file for output via seq_printf()
+ * @alloc: binder_alloc for this proc
+ */
+void binder_alloc_print_pages(struct seq_file *m,
+			      struct binder_alloc *alloc)
+{
+	struct binder_lru_page *page;
+	int i;
+	int active = 0;
+	int lru = 0;
+	int free = 0;
+
+	mutex_lock(&alloc->mutex);
+	for (i = 0; i < alloc->buffer_size / PAGE_SIZE; i++) {
+		page = &alloc->pages[i];
+		if (!page->page_ptr)
+			free++;
+		else if (list_empty(&page->lru))
+			active++;
+		else
+			lru++;
+	}
+	mutex_unlock(&alloc->mutex);
+	seq_printf(m, "  pages: %d:%d:%d\n", active, lru, free);
+}
+
+/**
  * binder_alloc_get_allocated_count() - return count of buffers
  * @alloc: binder_alloc for this proc
  *
@@ -787,6 +893,102 @@ void binder_alloc_vma_close(struct binder_alloc *alloc)
 }
 
 /**
+ * binder_alloc_free_page() - shrinker callback to free pages
+ * @item:   item to free
+ * @lock:   lock protecting the item
+ * @cb_arg: callback argument
+ *
+ * Called from list_lru_walk() in binder_shrink_scan() to free
+ * up pages when the system is under memory pressure.
+ */
+enum lru_status binder_alloc_free_page(struct list_head *item,
+				       struct list_lru_one *lru,
+				       spinlock_t *lock,
+				       void *cb_arg)
+{
+	struct mm_struct *mm = NULL;
+	struct binder_lru_page *page = container_of(item,
+						    struct binder_lru_page,
+						    lru);
+	struct binder_alloc *alloc;
+	uintptr_t page_addr;
+	size_t index;
+
+	alloc = page->alloc;
+	if (!mutex_trylock(&alloc->mutex))
+		goto err_get_alloc_mutex_failed;
+
+	if (!page->page_ptr)
+		goto err_page_already_freed;
+
+	index = page - alloc->pages;
+	page_addr = (uintptr_t)alloc->buffer + index * PAGE_SIZE;
+	if (alloc->vma) {
+		mm = get_task_mm(alloc->tsk);
+		if (!mm)
+			goto err_get_task_mm_failed;
+		if (!down_write_trylock(&mm->mmap_sem))
+			goto err_down_write_mmap_sem_failed;
+
+		trace_binder_unmap_user_start(alloc, index);
+
+		zap_page_range(alloc->vma,
+			       page_addr +
+			       alloc->user_buffer_offset,
+			       PAGE_SIZE, NULL);
+
+		trace_binder_unmap_user_end(alloc, index);
+
+		up_write(&mm->mmap_sem);
+		mmput(mm);
+	}
+
+	trace_binder_unmap_kernel_start(alloc, index);
+
+	unmap_kernel_range(page_addr, PAGE_SIZE);
+	__free_page(page->page_ptr);
+	page->page_ptr = NULL;
+
+	trace_binder_unmap_kernel_end(alloc, index);
+
+	list_lru_isolate(lru, item);
+
+	mutex_unlock(&alloc->mutex);
+	return LRU_REMOVED;
+
+err_down_write_mmap_sem_failed:
+	mmput(mm);
+err_get_task_mm_failed:
+err_page_already_freed:
+	mutex_unlock(&alloc->mutex);
+err_get_alloc_mutex_failed:
+	return LRU_SKIP;
+}
+
+static unsigned long
+binder_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
+{
+	unsigned long ret = list_lru_count(&binder_alloc_lru);
+	return ret;
+}
+
+static unsigned long
+binder_shrink_scan(struct shrinker *shrink, struct shrink_control *sc)
+{
+	unsigned long ret;
+
+	ret = list_lru_walk(&binder_alloc_lru, binder_alloc_free_page,
+			    NULL, sc->nr_to_scan);
+	return ret;
+}
+
+struct shrinker binder_shrinker = {
+	.count_objects = binder_shrink_count,
+	.scan_objects = binder_shrink_scan,
+	.seeks = DEFAULT_SEEKS,
+};
+
+/**
  * binder_alloc_init() - called by binder_open() for per-proc initialization
  * @alloc: binder_alloc for this proc
  *
@@ -798,5 +1000,11 @@ void binder_alloc_init(struct binder_alloc *alloc)
 	alloc->tsk = current->group_leader;
 	alloc->pid = current->group_leader->pid;
 	mutex_init(&alloc->mutex);
+	INIT_LIST_HEAD(&alloc->buffers);
 }
 
+void binder_alloc_shrinker_init(void)
+{
+	list_lru_init(&binder_alloc_lru);
+	register_shrinker(&binder_shrinker);
+}