Staging: android: add lowmemorykiller driver

From: San Mehat <san@android.com>
Cc: Brian Swetland <swetland@google.com>
Cc: Robert Love <rlove@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

3 files changed, 126 insertions, 0 deletions

diff --git a/drivers/staging/android/Kconfig b/drivers/staging/android/Kconfig
index 502c283eedcc..934f6f2019b3 100644
--- a/drivers/staging/android/Kconfig
+++ b/drivers/staging/android/Kconfig
@@ -77,4 +77,10 @@ config ANDROID_TIMED_GPIO
         depends on GENERIC_GPIO
         default n
 
+config ANDROID_LOW_MEMORY_KILLER
+        bool "Android Low Memory Killer"
+        default N
+        ---help---
+          Register processes to be killed when memory is low
+
 endmenu
diff --git a/drivers/staging/android/Makefile b/drivers/staging/android/Makefile
index 7ea6fbe92f4b..95209d6273a1 100644
--- a/drivers/staging/android/Makefile
+++ b/drivers/staging/android/Makefile
@@ -2,3 +2,4 @@ obj-$(CONFIG_ANDROID_BINDER_IPC)	+= binder.o
 obj-$(CONFIG_ANDROID_LOGGER)            += logger.o
 obj-$(CONFIG_ANDROID_RAM_CONSOLE)       += ram_console.o
 obj-$(CONFIG_ANDROID_TIMED_GPIO)        += timed_gpio.o
+obj-$(CONFIG_ANDROID_LOW_MEMORY_KILLER) += lowmemorykiller.o
diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
new file mode 100644
index 000000000000..3715d56ca96b
--- /dev/null
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -0,0 +1,119 @@
+/* drivers/misc/lowmemorykiller.c
+ *
+ * Copyright (C) 2007-2008 Google, Inc.
+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/oom.h>
+#include <linux/sched.h>
+
+static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask);
+
+static struct shrinker lowmem_shrinker = {
+        .shrink = lowmem_shrink,
+        .seeks = DEFAULT_SEEKS * 16
+};
+static uint32_t lowmem_debug_level = 2;
+static int lowmem_adj[6] = {
+        0,
+        1,
+        6,
+        12,
+};
+static int lowmem_adj_size = 4;
+static size_t lowmem_minfree[6] = {
+        3*512, // 6MB
+        2*1024, // 8MB
+        4*1024, // 16MB
+        16*1024, // 64MB
+};
+static int lowmem_minfree_size = 4;
+
+#define lowmem_print(level, x...) do { if(lowmem_debug_level >= (level)) printk(x); } while(0)
+
+module_param_named(cost, lowmem_shrinker.seeks, int, S_IRUGO | S_IWUSR);
+module_param_array_named(adj, lowmem_adj, int, &lowmem_adj_size, S_IRUGO | S_IWUSR);
+module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size, S_IRUGO | S_IWUSR);
+module_param_named(debug_level, lowmem_debug_level, uint, S_IRUGO | S_IWUSR);
+
+static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask)
+{
+        struct task_struct *p;
+        struct task_struct *selected = NULL;
+        int rem = 0;
+        int tasksize;
+        int i;
+        int min_adj = OOM_ADJUST_MAX + 1;
+        int selected_tasksize = 0;
+        int array_size = ARRAY_SIZE(lowmem_adj);
+        int other_free = global_page_state(NR_FREE_PAGES) + global_page_state(NR_FILE_PAGES);
+        if(lowmem_adj_size < array_size)
+                array_size = lowmem_adj_size;
+        if(lowmem_minfree_size < array_size)
+                array_size = lowmem_minfree_size;
+        for(i = 0; i < array_size; i++) {
+                if(other_free < lowmem_minfree[i]) {
+                        min_adj = lowmem_adj[i];
+                        break;
+                }
+        }
+        if(nr_to_scan > 0)
+                lowmem_print(3, "lowmem_shrink %d, %x, ofree %d, ma %d\n", nr_to_scan, gfp_mask, other_free, min_adj);
+        read_lock(&tasklist_lock);
+        for_each_process(p) {
+                if(p->oomkilladj >= 0 && p->mm) {
+                        tasksize = get_mm_rss(p->mm);
+                        if(nr_to_scan > 0 && tasksize > 0 && p->oomkilladj >= min_adj) {
+                                if(selected == NULL ||
+                                   p->oomkilladj > selected->oomkilladj ||
+                                   (p->oomkilladj == selected->oomkilladj &&
+                                    tasksize > selected_tasksize)) {
+                                        selected = p;
+                                        selected_tasksize = tasksize;
+                                        lowmem_print(2, "select %d (%s), adj %d, size %d, to kill\n",
+                                                     p->pid, p->comm, p->oomkilladj, tasksize);
+                                }
+                        }
+                        rem += tasksize;
+                }
+        }
+        if(selected != NULL) {
+                lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",
+                             selected->pid, selected->comm,
+                             selected->oomkilladj, selected_tasksize);
+                force_sig(SIGKILL, selected);
+                rem -= selected_tasksize;
+        }
+        lowmem_print(4, "lowmem_shrink %d, %x, return %d\n", nr_to_scan, gfp_mask, rem);
+        read_unlock(&tasklist_lock);
+        return rem;
+}
+
+static int __init lowmem_init(void)
+{
+        register_shrinker(&lowmem_shrinker);
+        return 0;
+}
+
+static void __exit lowmem_exit(void)
+{
+        unregister_shrinker(&lowmem_shrinker);
+}
+
+module_init(lowmem_init);
+module_exit(lowmem_exit);
+
+MODULE_LICENSE("GPL");
+