[PATCH 3.11 3.12] Avoid high-order allocations in evdev

[Josh Boyer]

Daniel pointed me to this patch the other day and asked to get it into
Fedora.

josh

Bugzilla: N/A
Upstream-status: Queued for 3.13

>From 92eb77d0ffbaa71b501a0a8dabf09a351bf4267f Mon Sep 17 00:00:00 2001
From: Daniel Stone <daniel at fooishbar.org>
Date: Thu, 31 Oct 2013 07:25:34 +0000
Subject: Input: evdev - fall back to vmalloc for client event buffer

evdev always tries to allocate the event buffer for clients using
kzalloc rather than vmalloc, presumably to avoid mapping overhead where
possible.  However, drivers like bcm5974, which claims support for
reporting 16 fingers simultaneously, can have an extraordinarily large
buffer.  The resultant contiguous order-4 allocation attempt fails due
to fragmentation, and the device is thus unusable until reboot.

Try kzalloc if we can to avoid the mapping overhead, but if that fails,
fall back to vzalloc.

Signed-off-by: Daniel Stone <daniels at collabora.com>
Signed-off-by: Dmitry Torokhov <dmitry.torokhov at gmail.com>
---
diff --git a/drivers/input/evdev.c b/drivers/input/evdev.c
index b6ded17..a06e125 100644
--- a/drivers/input/evdev.c
+++ b/drivers/input/evdev.c
@@ -18,6 +18,8 @@
 #include <linux/poll.h>
 #include <linux/sched.h>
 #include <linux/slab.h>
+#include <linux/vmalloc.h>
+#include <linux/mm.h>
 #include <linux/module.h>
 #include <linux/init.h>
 #include <linux/input/mt.h>
@@ -369,7 +371,11 @@ static int evdev_release(struct inode *inode, struct file *file)
 	mutex_unlock(&evdev->mutex);
 
 	evdev_detach_client(evdev, client);
-	kfree(client);
+
+	if (is_vmalloc_addr(client))
+		vfree(client);
+	else
+		kfree(client);
 
 	evdev_close_device(evdev);
 
@@ -389,12 +395,14 @@ static int evdev_open(struct inode *inode, struct file *file)
 {
 	struct evdev *evdev = container_of(inode->i_cdev, struct evdev, cdev);
 	unsigned int bufsize = evdev_compute_buffer_size(evdev->handle.dev);
+	unsigned int size = sizeof(struct evdev_client) +
+					bufsize * sizeof(struct input_event);
 	struct evdev_client *client;
 	int error;
 
-	client = kzalloc(sizeof(struct evdev_client) +
-				bufsize * sizeof(struct input_event),
-			 GFP_KERNEL);
+	client = kzalloc(size, GFP_KERNEL | __GFP_NOWARN);
+	if (!client)
+		client = vzalloc(size);
 	if (!client)
 		return -ENOMEM;
 
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