From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Antonino A. Daplas" Subject: [PATCH 8/9] fbdev: mm: Deferred IO support Date: Sun, 25 Feb 2007 17:09:26 +0800 Message-ID: <1172394566.16179.47.camel@daplas> Reply-To: linux-fbdev-devel@lists.sourceforge.net Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============1231304648==" Return-path: Received: from sc8-sf-mx2-b.sourceforge.net ([10.3.1.92] helo=mail.sourceforge.net) by sc8-sf-list1-new.sourceforge.net with esmtp (Exim 4.43) id 1HLFOg-00074e-Kt for linux-fbdev-devel@lists.sourceforge.net; Sun, 25 Feb 2007 01:10:22 -0800 Received: from py-out-1112.google.com ([64.233.166.178]) by mail.sourceforge.net with esmtp (Exim 4.44) id 1HLFOf-0005hh-Hz for linux-fbdev-devel@lists.sourceforge.net; Sun, 25 Feb 2007 01:10:22 -0800 Received: by py-out-1112.google.com with SMTP id a29so528629pyi for ; Sun, 25 Feb 2007 01:10:21 -0800 (PST) List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: linux-fbdev-devel-bounces@lists.sourceforge.net Errors-To: linux-fbdev-devel-bounces@lists.sourceforge.net To: Andrew Morton Cc: Jaya Kumar , Linux Fbdev development list --===============1231304648== Content-Type: multipart/alternative; boundary="=-lCbQDIS0JZwtHTPcWETV" --=-lCbQDIS0JZwtHTPcWETV Content-Type: text/plain Content-Transfer-Encoding: 7bit From: Jaya Kumar This implements deferred IO support in fbdev. Deferred IO is a way to delay and repurpose IO. This implementation is done using mm's page_mkwrite and page_mkclean hooks in order to detect, delay and then rewrite IO. This functionality is used by hecubafb. [adaplas] This is useful for graphics hardware with no directly addressable/mappable framebuffer. Implementing this will allow the "framebuffer" to be accesible from user space via mmap(). Signed-off-by: Jaya Kumar Signed-off-by: Antonino Daplas --- Documentation/fb/deferred_io.txt | 75 +++++++++++++++++++++ drivers/video/Kconfig | 5 + drivers/video/Makefile | 1 drivers/video/fb_defio.c | 137 ++++++++++++++++++++++++++++++++++++++ include/linux/fb.h | 20 ++++++ mm/rmap.c | 1 6 files changed, 239 insertions(+), 0 deletions(-) diff --git a/Documentation/fb/deferred_io.txt b/Documentation/fb/deferred_io.txt new file mode 100644 index 0000000..73cf9fb --- /dev/null +++ b/Documentation/fb/deferred_io.txt @@ -0,0 +1,75 @@ +Deferred IO +----------- + +Deferred IO is a way to delay and repurpose IO. It uses host memory as a +buffer and the MMU pagefault as a pretrigger for when to perform the device +IO. The following example may be a useful explaination of how one such setup +works: + +- userspace app like Xfbdev mmaps framebuffer +- deferred IO and driver sets up nopage and page_mkwrite handlers +- userspace app tries to write to mmaped vaddress +- we get pagefault and reach nopage handler +- nopage handler finds and returns physical page +- we get page_mkwrite where we add this page to a list +- schedule a workqueue task to be run after a delay +- app continues writing to that page with no additional cost. this is + the key benefit. +- the workqueue task comes in and mkcleans the pages on the list, then + completes the work associated with updating the framebuffer. this is + the real work talking to the device. +- app tries to write to the address (that has now been mkcleaned) +- get pagefault and the above sequence occurs again + +As can be seen from above, one benefit is roughly to allow bursty framebuffer +writes to occur at minimum cost. Then after some time when hopefully things +have gone quiet, we go and really update the framebuffer which would be +a relatively more expensive operation. + +For some types of nonvolatile high latency displays, the desired image is +the final image rather than the intermediate stages which is why it's okay +to not update for each write that is occuring. + +It may be the case that this is useful in other scenarios as well. Paul Mundt +has mentioned a case where it is beneficial to use the page count to decide +whether to coalesce and issue SG DMA or to do memory bursts. + +Another one may be if one has a device framebuffer that is in an usual format, +say diagonally shifting RGB, this may then be a mechanism for you to allow +apps to pretend to have a normal framebuffer but reswizzle for the device +framebuffer at vsync time based on the touched pagelist. + +How to use it: (for applications) +--------------------------------- +No changes needed. mmap the framebuffer like normal and just use it. + +How to use it: (for fbdev drivers) +---------------------------------- +The following example may be helpful. + +1. Setup your structure. Eg: + +static struct fb_deferred_io hecubafb_defio = { + .delay = HZ, + .deferred_io = hecubafb_dpy_deferred_io, +}; + +The delay is the minimum delay between when the page_mkwrite trigger occurs +and when the deferred_io callback is called. The deferred_io callback is +explained below. + +2. Setup your deferred IO callback. Eg: +static void hecubafb_dpy_deferred_io(struct fb_info *info, + struct list_head *pagelist) + +The deferred_io callback is where you would perform all your IO to the display +device. You receive the pagelist which is the list of pages that were written +to during the delay. You must not modify this list. This callback is called +from a workqueue. + +3. Call init + info->fbdefio = &hecubafb_defio; + fb_deferred_io_init(info); + +4. Call cleanup + fb_deferred_io_cleanup(info); diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig index 9fcd67f..dd9541f 100644 --- a/drivers/video/Kconfig +++ b/drivers/video/Kconfig @@ -92,6 +92,11 @@ config FB_CFB_IMAGEBLIT blitting. This is used by drivers that don't provide their own (accelerated) version. +config FB_DEFERRED_IO + bool + depends on FB + default y + config FB_SVGALIB tristate depends on FB diff --git a/drivers/video/Makefile b/drivers/video/Makefile index f6a2b60..b1020c3 100644 --- a/drivers/video/Makefile +++ b/drivers/video/Makefile @@ -20,6 +20,7 @@ obj-$(CONFIG_FB_CFB_IMAGEBLIT) += cfbimg obj-$(CONFIG_FB_SVGALIB) += svgalib.o obj-$(CONFIG_FB_MACMODES) += macmodes.o obj-$(CONFIG_FB_DDC) += fb_ddc.o +obj-$(CONFIG_FB_DEFERRED_IO) += fb_defio.o # Hardware specific drivers go first obj-$(CONFIG_FB_AMIGA) += amifb.o c2p.o diff --git a/drivers/video/fb_defio.c b/drivers/video/fb_defio.c new file mode 100644 index 0000000..cc780f4 --- /dev/null +++ b/drivers/video/fb_defio.c @@ -0,0 +1,137 @@ +/* + * linux/drivers/video/fb_defio.c + * + * Copyright (C) 2006 Jaya Kumar + * + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file COPYING in the main directory of this archive + * for more details. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* to support deferred IO */ +#include +#include + +/* this is to find and return the vmalloc-ed fb pages */ +static struct page* fb_deferred_io_nopage(struct vm_area_struct *vma, + unsigned long vaddr, int *type) +{ + unsigned long offset; + struct page *page; + struct fb_info *info = vma->vm_private_data; + + offset = (vaddr - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT); + if (offset >= info->fix.smem_len) + return NOPAGE_SIGBUS; + + page = vmalloc_to_page(info->screen_base + offset); + if (!page) + return NOPAGE_OOM; + + get_page(page); + if (type) + *type = VM_FAULT_MINOR; + return page; +} + +/* vm_ops->page_mkwrite handler */ +static int fb_deferred_io_mkwrite(struct vm_area_struct *vma, + struct page *page) +{ + struct fb_info *info = vma->vm_private_data; + struct fb_deferred_io *fbdefio = info->fbdefio; + + /* this is a callback we get when userspace first tries to + write to the page. we schedule a workqueue. that workqueue + will eventually mkclean the touched pages and execute the + deferred framebuffer IO. then if userspace touches a page + again, we repeat the same scheme */ + + /* protect against the workqueue changing the page list */ + mutex_lock(&fbdefio->lock); + list_add(&page->lru, &fbdefio->pagelist); + mutex_unlock(&fbdefio->lock); + + /* come back after delay to process the deferred IO */ + schedule_delayed_work(&info->deferred_work, fbdefio->delay); + return 0; +} + +static struct vm_operations_struct fb_deferred_io_vm_ops = { + .nopage = fb_deferred_io_nopage, + .page_mkwrite = fb_deferred_io_mkwrite, +}; + +static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma) +{ + vma->vm_ops = &fb_deferred_io_vm_ops; + vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND ); + vma->vm_private_data = info; + return 0; +} + +/* workqueue callback */ +static void fb_deferred_io_work(struct work_struct *work) +{ + struct fb_info *info = container_of(work, struct fb_info, + deferred_work.work); + struct list_head *node, *next; + struct page *cur; + struct fb_deferred_io *fbdefio = info->fbdefio; + + /* here we mkclean the pages, then do all deferred IO */ + mutex_lock(&fbdefio->lock); + list_for_each_entry(cur, &fbdefio->pagelist, lru) { + lock_page(cur); + page_mkclean(cur); + unlock_page(cur); + } + + /* driver's callback with pagelist */ + fbdefio->deferred_io(info, &fbdefio->pagelist); + + /* clear the list */ + list_for_each_safe(node, next, &fbdefio->pagelist) { + list_del(node); + } + mutex_unlock(&fbdefio->lock); +} + +void fb_deferred_io_init(struct fb_info *info) +{ + struct fb_deferred_io *fbdefio = info->fbdefio; + + BUG_ON(!fbdefio); + mutex_init(&fbdefio->lock); + info->fbops->fb_mmap = fb_deferred_io_mmap; + INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work); + INIT_LIST_HEAD(&fbdefio->pagelist); + if (fbdefio->delay == 0) /* set a default of 1 s */ + fbdefio->delay = HZ; +} +EXPORT_SYMBOL_GPL(fb_deferred_io_init); + +void fb_deferred_io_cleanup(struct fb_info *info) +{ + struct fb_deferred_io *fbdefio = info->fbdefio; + + BUG_ON(!fbdefio); + cancel_delayed_work(&info->deferred_work); + flush_scheduled_work(); +} +EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup); + +MODULE_LICENSE("GPL"); diff --git a/include/linux/fb.h b/include/linux/fb.h index be913ec..8a8255b 100644 --- a/include/linux/fb.h +++ b/include/linux/fb.h @@ -561,6 +561,16 @@ struct fb_pixmap { void (*readio) (struct fb_info *info, void *dst, void __iomem *src, unsigned int size); }; +#ifdef CONFIG_FB_DEFERRED_IO +struct fb_deferred_io { + /* delay between mkwrite and deferred handler */ + unsigned long delay; + struct mutex lock; /* mutex that protects the page list */ + struct list_head pagelist; /* list of touched pages */ + /* callback */ + void (*deferred_io)(struct fb_info *info, struct list_head *pagelist); +}; +#endif /* * Frame buffer operations @@ -778,6 +788,10 @@ #ifdef CONFIG_FB_BACKLIGHT struct mutex bl_curve_mutex; u8 bl_curve[FB_BACKLIGHT_LEVELS]; #endif +#ifdef CONFIG_FB_DEFERRED_IO + struct delayed_work deferred_work; + struct fb_deferred_io *fbdefio; +#endif struct fb_ops *fbops; struct device *device; /* This is the parent */ @@ -913,6 +927,12 @@ static inline void __fb_pad_aligned_buff } } +#ifdef CONFIG_FB_DEFERRED_IO +/* drivers/video/fb_defio.c */ +extern void fb_deferred_io_init(struct fb_info *info); +extern void fb_deferred_io_cleanup(struct fb_info *info); +#endif + /* drivers/video/fbsysfs.c */ extern struct fb_info *framebuffer_alloc(size_t size, struct device *dev); extern void framebuffer_release(struct fb_info *info); diff --git a/mm/rmap.c b/mm/rmap.c index 3bffd67..7d58c77 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -496,6 +496,7 @@ int page_mkclean(struct page *page) return ret; } +EXPORT_SYMBOL_GPL(page_mkclean); /** * page_set_anon_rmap - setup new anonymous rmap --=-lCbQDIS0JZwtHTPcWETV Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: 7bit 
From:  Jaya Kumar <jayakumar.lkml@gmail.com>

This implements deferred IO support in fbdev. Deferred IO is a way to
delay and repurpose IO. This implementation is done using mm's page_mkwrite
and page_mkclean hooks in order to detect, delay and then rewrite IO. This
functionality is used by hecubafb.

[adaplas]
This is useful for graphics hardware with no directly addressable/mappable
framebuffer. Implementing this will allow the "framebuffer" to be accesible
from user space via mmap().

Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com>
Signed-off-by: Antonino Daplas <adaplas@gmail.com>
---

 Documentation/fb/deferred_io.txt |   75 +++++++++++++++++++++
 drivers/video/Kconfig            |    5 +
 drivers/video/Makefile           |    1 
 drivers/video/fb_defio.c         |  137 ++++++++++++++++++++++++++++++++++++++
 include/linux/fb.h               |   20 ++++++
 mm/rmap.c                        |    1 
 6 files changed, 239 insertions(+), 0 deletions(-)

diff --git a/Documentation/fb/deferred_io.txt b/Documentation/fb/deferred_io.txt
new file mode 100644
index 0000000..73cf9fb
--- /dev/null
+++ b/Documentation/fb/deferred_io.txt
@@ -0,0 +1,75 @@
+Deferred IO
+-----------
+
+Deferred IO is a way to delay and repurpose IO. It uses host memory as a
+buffer and the MMU pagefault as a pretrigger for when to perform the device
+IO. The following example may be a useful explaination of how one such setup
+works:
+
+- userspace app like Xfbdev mmaps framebuffer
+- deferred IO and driver sets up nopage and page_mkwrite handlers
+- userspace app tries to write to mmaped vaddress
+- we get pagefault and reach nopage handler
+- nopage handler finds and returns physical page
+- we get page_mkwrite where we add this page to a list
+- schedule a workqueue task to be run after a delay
+- app continues writing to that page with no additional cost. this is
+  the key benefit.
+- the workqueue task comes in and mkcleans the pages on the list, then
+ completes the work associated with updating the framebuffer. this is
+  the real work talking to the device.
+- app tries to write to the address (that has now been mkcleaned)
+- get pagefault and the above sequence occurs again
+
+As can be seen from above, one benefit is roughly to allow bursty framebuffer
+writes to occur at minimum cost. Then after some time when hopefully things
+have gone quiet, we go and really update the framebuffer which would be
+a relatively more expensive operation.
+
+For some types of nonvolatile high latency displays, the desired image is
+the final image rather than the intermediate stages which is why it's okay
+to not update for each write that is occuring.
+
+It may be the case that this is useful in other scenarios as well. Paul Mundt
+has mentioned a case where it is beneficial to use the page count to decide
+whether to coalesce and issue SG DMA or to do memory bursts.
+
+Another one may be if one has a device framebuffer that is in an usual format,
+say diagonally shifting RGB, this may then be a mechanism for you to allow
+apps to pretend to have a normal framebuffer but reswizzle for the device
+framebuffer at vsync time based on the touched pagelist.
+
+How to use it: (for applications)
+---------------------------------
+No changes needed. mmap the framebuffer like normal and just use it.
+
+How to use it: (for fbdev drivers)
+----------------------------------
+The following example may be helpful.
+
+1. Setup your structure. Eg:
+
+static struct fb_deferred_io hecubafb_defio = {
+	.delay		= HZ,
+	.deferred_io	= hecubafb_dpy_deferred_io,
+};
+
+The delay is the minimum delay between when the page_mkwrite trigger occurs
+and when the deferred_io callback is called. The deferred_io callback is
+explained below.
+
+2. Setup your deferred IO callback. Eg:
+static void hecubafb_dpy_deferred_io(struct fb_info *info,
+				struct list_head *pagelist)
+
+The deferred_io callback is where you would perform all your IO to the display
+device. You receive the pagelist which is the list of pages that were written
+to during the delay. You must not modify this list. This callback is called
+from a workqueue.
+
+3. Call init
+	info->fbdefio = &hecubafb_defio;
+	fb_deferred_io_init(info);
+
+4. Call cleanup
+	fb_deferred_io_cleanup(info);
diff --git a/drivers/video/Kconfig b/drivers/video/Kconfig
index 9fcd67f..dd9541f 100644
--- a/drivers/video/Kconfig
+++ b/drivers/video/Kconfig
@@ -92,6 +92,11 @@ config FB_CFB_IMAGEBLIT
 	  blitting. This is used by drivers that don't provide their own
 	  (accelerated) version.
 
+config FB_DEFERRED_IO
+	bool
+	depends on FB
+	default y
+
 config FB_SVGALIB
 	tristate
 	depends on FB
diff --git a/drivers/video/Makefile b/drivers/video/Makefile
index f6a2b60..b1020c3 100644
--- a/drivers/video/Makefile
+++ b/drivers/video/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_FB_CFB_IMAGEBLIT) += cfbimg
 obj-$(CONFIG_FB_SVGALIB)       += svgalib.o
 obj-$(CONFIG_FB_MACMODES)      += macmodes.o
 obj-$(CONFIG_FB_DDC)           += fb_ddc.o
+obj-$(CONFIG_FB_DEFERRED_IO)   += fb_defio.o
 
 # Hardware specific drivers go first
 obj-$(CONFIG_FB_AMIGA)            += amifb.o c2p.o
diff --git a/drivers/video/fb_defio.c b/drivers/video/fb_defio.c
new file mode 100644
index 0000000..cc780f4
--- /dev/null
+++ b/drivers/video/fb_defio.c
@@ -0,0 +1,137 @@
+/*
+ *  linux/drivers/video/fb_defio.c
+ *
+ *  Copyright (C) 2006 Jaya Kumar
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/string.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/delay.h>
+#include <linux/interrupt.h>
+#include <linux/fb.h>
+#include <linux/list.h>
+#include <asm/uaccess.h>
+
+/* to support deferred IO */
+#include <linux/rmap.h>
+#include <linux/pagemap.h>
+
+/* this is to find and return the vmalloc-ed fb pages */
+static struct page* fb_deferred_io_nopage(struct vm_area_struct *vma,
+					unsigned long vaddr, int *type)
+{
+	unsigned long offset;
+	struct page *page;
+	struct fb_info *info = vma->vm_private_data;
+
+	offset = (vaddr - vma->vm_start) + (vma->vm_pgoff << PAGE_SHIFT);
+	if (offset >= info->fix.smem_len)
+		return NOPAGE_SIGBUS;
+
+	page = vmalloc_to_page(info->screen_base + offset);
+	if (!page)
+		return NOPAGE_OOM;
+
+	get_page(page);
+	if (type)
+		*type = VM_FAULT_MINOR;
+	return page;
+}
+
+/* vm_ops->page_mkwrite handler */
+static int fb_deferred_io_mkwrite(struct vm_area_struct *vma,
+					struct page *page)
+{
+	struct fb_info *info = vma->vm_private_data;
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	/* this is a callback we get when userspace first tries to
+	write to the page. we schedule a workqueue. that workqueue
+	will eventually mkclean the touched pages and execute the
+	deferred framebuffer IO. then if userspace touches a page
+	again, we repeat the same scheme */
+
+	/* protect against the workqueue changing the page list */
+	mutex_lock(&fbdefio->lock);
+	list_add(&page->lru, &fbdefio->pagelist);
+	mutex_unlock(&fbdefio->lock);
+
+	/* come back after delay to process the deferred IO */
+	schedule_delayed_work(&info->deferred_work, fbdefio->delay);
+	return 0;
+}
+
+static struct vm_operations_struct fb_deferred_io_vm_ops = {
+	.nopage   	= fb_deferred_io_nopage,
+	.page_mkwrite	= fb_deferred_io_mkwrite,
+};
+
+static int fb_deferred_io_mmap(struct fb_info *info, struct vm_area_struct *vma)
+{
+	vma->vm_ops = &fb_deferred_io_vm_ops;
+	vma->vm_flags |= ( VM_IO | VM_RESERVED | VM_DONTEXPAND );
+	vma->vm_private_data = info;
+	return 0;
+}
+
+/* workqueue callback */
+static void fb_deferred_io_work(struct work_struct *work)
+{
+	struct fb_info *info = container_of(work, struct fb_info,
+						deferred_work.work);
+	struct list_head *node, *next;
+	struct page *cur;
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	/* here we mkclean the pages, then do all deferred IO */
+	mutex_lock(&fbdefio->lock);
+	list_for_each_entry(cur, &fbdefio->pagelist, lru) {
+		lock_page(cur);
+		page_mkclean(cur);
+		unlock_page(cur);
+	}
+
+	/* driver's callback with pagelist */
+	fbdefio->deferred_io(info, &fbdefio->pagelist);
+
+	/* clear the list */
+	list_for_each_safe(node, next, &fbdefio->pagelist) {
+		list_del(node);
+	}
+	mutex_unlock(&fbdefio->lock);
+}
+
+void fb_deferred_io_init(struct fb_info *info)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	BUG_ON(!fbdefio);
+	mutex_init(&fbdefio->lock);
+	info->fbops->fb_mmap = fb_deferred_io_mmap;
+	INIT_DELAYED_WORK(&info->deferred_work, fb_deferred_io_work);
+	INIT_LIST_HEAD(&fbdefio->pagelist);
+	if (fbdefio->delay == 0) /* set a default of 1 s */
+		fbdefio->delay = HZ;
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_init);
+
+void fb_deferred_io_cleanup(struct fb_info *info)
+{
+	struct fb_deferred_io *fbdefio = info->fbdefio;
+
+	BUG_ON(!fbdefio);
+	cancel_delayed_work(&info->deferred_work);
+	flush_scheduled_work();
+}
+EXPORT_SYMBOL_GPL(fb_deferred_io_cleanup);
+
+MODULE_LICENSE("GPL");
diff --git a/include/linux/fb.h b/include/linux/fb.h
index be913ec..8a8255b 100644
--- a/include/linux/fb.h
+++ b/include/linux/fb.h
@@ -561,6 +561,16 @@ struct fb_pixmap {
 	void (*readio) (struct fb_info *info, void *dst, void __iomem *src, unsigned int size);
 };
 
+#ifdef CONFIG_FB_DEFERRED_IO
+struct fb_deferred_io {
+	/* delay between mkwrite and deferred handler */
+	unsigned long delay;
+	struct mutex lock; /* mutex that protects the page list */
+	struct list_head pagelist; /* list of touched pages */
+	/* callback */
+	void (*deferred_io)(struct fb_info *info, struct list_head *pagelist);
+};
+#endif
 
 /*
  * Frame buffer operations
@@ -778,6 +788,10 @@ #ifdef CONFIG_FB_BACKLIGHT
 	struct mutex bl_curve_mutex;	
 	u8 bl_curve[FB_BACKLIGHT_LEVELS];
 #endif
+#ifdef CONFIG_FB_DEFERRED_IO
+	struct delayed_work deferred_work;
+	struct fb_deferred_io *fbdefio;
+#endif
 
 	struct fb_ops *fbops;
 	struct device *device;		/* This is the parent */
@@ -913,6 +927,12 @@ static inline void __fb_pad_aligned_buff
 	}
 }
 
+#ifdef CONFIG_FB_DEFERRED_IO
+/* drivers/video/fb_defio.c */
+extern void fb_deferred_io_init(struct fb_info *info);
+extern void fb_deferred_io_cleanup(struct fb_info *info);
+#endif
+
 /* drivers/video/fbsysfs.c */
 extern struct fb_info *framebuffer_alloc(size_t size, struct device *dev);
 extern void framebuffer_release(struct fb_info *info);
diff --git a/mm/rmap.c b/mm/rmap.c
index 3bffd67..7d58c77 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -496,6 +496,7 @@ int page_mkclean(struct page *page)
 
 	return ret;
 }
+EXPORT_SYMBOL_GPL(page_mkclean);
 
 /**
  * page_set_anon_rmap - setup new anonymous rmap
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