Revert "staging, android: remove lowmemory killer from the tree"

This reverts commit 915e70f.

Signed-off-by: youling257 <youling257@gmail.com>

drivers/staging/android/Kconfig

@@ -14,6 +14,16 @@ config ASHMEM
 	  It is, in theory, a good memory allocator for low-memory devices,
 	  because it can discard shared memory units when under memory pressure.
 
+config ANDROID_LOW_MEMORY_KILLER
+	bool "Android Low Memory Killer"
+	---help---
+	  Registers processes to be killed when low memory conditions, this is useful
+	  as there is no particular swap space on android.
+
+	  The registered process will kill according to the priorities in android init
+	  scripts (/init.rc), and it defines priority values with minimum free memory size
+	  for each priority.
+
 source "drivers/staging/android/ion/Kconfig"
 
 endif # if ANDROID

drivers/staging/android/Makefile

@@ -3,3 +3,4 @@ ccflags-y += -I$(src)			# needed for trace events
 obj-y					+= ion/
 
 obj-$(CONFIG_ASHMEM)			+= ashmem.o
+obj-$(CONFIG_ANDROID_LOW_MEMORY_KILLER)	+= lowmemorykiller.o

drivers/staging/android/lowmemorykiller.c

@@ -0,0 +1,212 @@
+/* drivers/misc/lowmemorykiller.c
+ *
+ * The lowmemorykiller driver lets user-space specify a set of memory thresholds
+ * where processes with a range of oom_score_adj values will get killed. Specify
+ * the minimum oom_score_adj values in
+ * /sys/module/lowmemorykiller/parameters/adj and the number of free pages in
+ * /sys/module/lowmemorykiller/parameters/minfree. Both files take a comma
+ * separated list of numbers in ascending order.
+ *
+ * For example, write "0,8" to /sys/module/lowmemorykiller/parameters/adj and
+ * "1024,4096" to /sys/module/lowmemorykiller/parameters/minfree to kill
+ * processes with a oom_score_adj value of 8 or higher when the free memory
+ * drops below 4096 pages and kill processes with a oom_score_adj value of 0 or
+ * higher when the free memory drops below 1024 pages.
+ *
+ * The driver considers memory used for caches to be free, but if a large
+ * percentage of the cached memory is locked this can be very inaccurate
+ * and processes may not get killed until the normal oom killer is triggered.
+ *
+ * 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.
+ *
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/init.h>
+#include <linux/moduleparam.h>
+#include <linux/kernel.h>
+#include <linux/mm.h>
+#include <linux/oom.h>
+#include <linux/sched/signal.h>
+#include <linux/swap.h>
+#include <linux/rcupdate.h>
+#include <linux/profile.h>
+#include <linux/notifier.h>
+
+static u32 lowmem_debug_level = 1;
+static short lowmem_adj[6] = {
+	0,
+	1,
+	6,
+	12,
+};
+
+static int lowmem_adj_size = 4;
+static int lowmem_minfree[6] = {
+	3 * 512,	/* 6MB */
+	2 * 1024,	/* 8MB */
+	4 * 1024,	/* 16MB */
+	16 * 1024,	/* 64MB */
+};
+
+static int lowmem_minfree_size = 4;
+
+static unsigned long lowmem_deathpending_timeout;
+
+#define lowmem_print(level, x...)			\
+	do {						\
+		if (lowmem_debug_level >= (level))	\
+			pr_info(x);			\
+	} while (0)
+
+static unsigned long lowmem_count(struct shrinker *s,
+				  struct shrink_control *sc)
+{
+	return global_node_page_state(NR_ACTIVE_ANON) +
+		global_node_page_state(NR_ACTIVE_FILE) +
+		global_node_page_state(NR_INACTIVE_ANON) +
+		global_node_page_state(NR_INACTIVE_FILE);
+}
+
+static unsigned long lowmem_scan(struct shrinker *s, struct shrink_control *sc)
+{
+	struct task_struct *tsk;
+	struct task_struct *selected = NULL;
+	unsigned long rem = 0;
+	int tasksize;
+	int i;
+	short min_score_adj = OOM_SCORE_ADJ_MAX + 1;
+	int minfree = 0;
+	int selected_tasksize = 0;
+	short selected_oom_score_adj;
+	int array_size = ARRAY_SIZE(lowmem_adj);
+	int other_free = global_page_state(NR_FREE_PAGES) - totalreserve_pages;
+	int other_file = global_node_page_state(NR_FILE_PAGES) -
+				global_node_page_state(NR_SHMEM) -
+				total_swapcache_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++) {
+		minfree = lowmem_minfree[i];
+		if (other_free < minfree && other_file < minfree) {
+			min_score_adj = lowmem_adj[i];
+			break;
+		}
+	}
+
+	lowmem_print(3, "lowmem_scan %lu, %x, ofree %d %d, ma %hd\n",
+		     sc->nr_to_scan, sc->gfp_mask, other_free,
+		     other_file, min_score_adj);
+
+	if (min_score_adj == OOM_SCORE_ADJ_MAX + 1) {
+		lowmem_print(5, "lowmem_scan %lu, %x, return 0\n",
+			     sc->nr_to_scan, sc->gfp_mask);
+		return 0;
+	}
+
+	selected_oom_score_adj = min_score_adj;
+
+	rcu_read_lock();
+	for_each_process(tsk) {
+		struct task_struct *p;
+		short oom_score_adj;
+
+		if (tsk->flags & PF_KTHREAD)
+			continue;
+
+		p = find_lock_task_mm(tsk);
+		if (!p)
+			continue;
+
+		if (task_lmk_waiting(p) &&
+		    time_before_eq(jiffies, lowmem_deathpending_timeout)) {
+			task_unlock(p);
+			rcu_read_unlock();
+			return 0;
+		}
+		oom_score_adj = p->signal->oom_score_adj;
+		if (oom_score_adj < min_score_adj) {
+			task_unlock(p);
+			continue;
+		}
+		tasksize = get_mm_rss(p->mm);
+		task_unlock(p);
+		if (tasksize <= 0)
+			continue;
+		if (selected) {
+			if (oom_score_adj < selected_oom_score_adj)
+				continue;
+			if (oom_score_adj == selected_oom_score_adj &&
+			    tasksize <= selected_tasksize)
+				continue;
+		}
+		selected = p;
+		selected_tasksize = tasksize;
+		selected_oom_score_adj = oom_score_adj;
+		lowmem_print(2, "select '%s' (%d), adj %hd, size %d, to kill\n",
+			     p->comm, p->pid, oom_score_adj, tasksize);
+	}
+	if (selected) {
+		task_lock(selected);
+		send_sig(SIGKILL, selected, 0);
+		if (selected->mm)
+			task_set_lmk_waiting(selected);
+		task_unlock(selected);
+		lowmem_print(1, "Killing '%s' (%d), adj %hd,\n"
+				 "   to free %ldkB on behalf of '%s' (%d) because\n"
+				 "   cache %ldkB is below limit %ldkB for oom_score_adj %hd\n"
+				 "   Free memory is %ldkB above reserved\n",
+			     selected->comm, selected->pid,
+			     selected_oom_score_adj,
+			     selected_tasksize * (long)(PAGE_SIZE / 1024),
+			     current->comm, current->pid,
+			     other_file * (long)(PAGE_SIZE / 1024),
+			     minfree * (long)(PAGE_SIZE / 1024),
+			     min_score_adj,
+			     other_free * (long)(PAGE_SIZE / 1024));
+		lowmem_deathpending_timeout = jiffies + HZ;
+		rem += selected_tasksize;
+	}
+
+	lowmem_print(4, "lowmem_scan %lu, %x, return %lu\n",
+		     sc->nr_to_scan, sc->gfp_mask, rem);
+	rcu_read_unlock();
+	return rem;
+}
+
+static struct shrinker lowmem_shrinker = {
+	.scan_objects = lowmem_scan,
+	.count_objects = lowmem_count,
+	.seeks = DEFAULT_SEEKS * 16
+};
+
+static int __init lowmem_init(void)
+{
+	register_shrinker(&lowmem_shrinker);
+	return 0;
+}
+device_initcall(lowmem_init);
+
+/*
+ * not really modular, but the easiest way to keep compat with existing
+ * bootargs behaviour is to continue using module_param here.
+ */
+module_param_named(cost, lowmem_shrinker.seeks, int, 0644);
+module_param_array_named(adj, lowmem_adj, short, &lowmem_adj_size, 0644);
+module_param_array_named(minfree, lowmem_minfree, uint, &lowmem_minfree_size,
+			 0644);
+module_param_named(debug_level, lowmem_debug_level, uint, 0644);
+

include/linux/sched.h

@@ -1269,6 +1269,7 @@ extern struct pid *cad_pid;
 #define PFA_NO_NEW_PRIVS		0	/* May not gain new privileges. */
 #define PFA_SPREAD_PAGE			1	/* Spread page cache over cpuset */
 #define PFA_SPREAD_SLAB			2	/* Spread some slab caches over cpuset */
+#define PFA_LMK_WAITING			3	/* Lowmemorykiller is waiting */
 
 
 #define TASK_PFA_TEST(name, func)					\
@@ -1294,6 +1295,9 @@ TASK_PFA_TEST(SPREAD_SLAB, spread_slab)
 TASK_PFA_SET(SPREAD_SLAB, spread_slab)
 TASK_PFA_CLEAR(SPREAD_SLAB, spread_slab)
 
+TASK_PFA_TEST(LMK_WAITING, lmk_waiting)
+TASK_PFA_SET(LMK_WAITING, lmk_waiting)
+
 static inline void
 current_restore_flags(unsigned long orig_flags, unsigned long flags)
 {