[patch 1/4] lowmemorykiller: Only iterate over process list whenneeded.

[David Rientjes]

From: Arve HjÃnnevÃg <arve@xxxxxxxxxxx>

Use NR_ACTIVE plus NR_INACTIVE as a size estimate for our fake cache
instead the sum of rss. Neither method is accurate.

Also skip the process scan, if the amount of memory available is above
the largest threshold set.

Signed-off-by: Arve HjÃnnevÃg <arve@xxxxxxxxxxx>
---
 drivers/staging/android/lowmemorykiller.c |   35 +++++++++++++++++-----------
 1 files changed, 21 insertions(+), 14 deletions(-)

diff --git a/drivers/staging/android/lowmemorykiller.c b/drivers/staging/android/lowmemorykiller.c
--- a/drivers/staging/android/lowmemorykiller.c
+++ b/drivers/staging/android/lowmemorykiller.c
@@ -71,23 +71,30 @@ static int lowmem_shrink(int nr_to_scan, gfp_t gfp_mask)
 	}
 	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);
+	rem = global_page_state(NR_ACTIVE) + global_page_state(NR_INACTIVE);
+	if (nr_to_scan <= 0 || min_adj == OOM_ADJUST_MAX + 1) {
+		lowmem_print(5, "lowmem_shrink %d, %x, return %d\n", nr_to_scan, gfp_mask, rem);
+		return rem;
+	}
+
 	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 (p->oomkilladj < min_adj || !p->mm)
+			continue;
+		tasksize = get_mm_rss(p->mm);
+		if (tasksize <= 0)
+			continue;
+		if (selected) {
+			if (p->oomkilladj < selected->oomkilladj)
+				continue;
+			if (p->oomkilladj == selected->oomkilladj &&
+			    tasksize <= selected_tasksize)
+				continue;
 		}
+		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);
 	}
 	if(selected != NULL) {
 		lowmem_print(1, "send sigkill to %d (%s), adj %d, size %d\n",