lmkd: kill multiple tasks

The task selected to die may be small, add its approximate size
to other_free and other_file and keep killing until all thresholds
are met.

Bug: 16236289
Change-Id: Iceeca4c63fec98cae2bf53e258f7707cea408b07

1 files changed, 88 insertions, 53 deletions

diff --git a/lmkd/lmkd.c b/lmkd/lmkd.c
index b276f0a..2362cbf 100644
--- a/lmkd/lmkd.c
+++ b/lmkd/lmkd.c
@@ -560,29 +560,57 @@ static struct proc *proc_adj_lru(int oomadj) {
     return (struct proc *)adjslot_tail(&procadjslot_list[ADJTOSLOT(oomadj)]);
 }
 
-static void mp_event(uint32_t events __unused) {
-    int i;
-    int ret;
-    unsigned long long evcount;
-    struct sysmeminfo mi;
-    int other_free;
-    int other_file;
-    int minfree = 0;
-    int min_score_adj = OOM_ADJUST_MAX + 1;
+/* Kill one process specified by procp.  Returns the size of the process killed */
+static int kill_one_process(struct proc *procp, int other_free, int other_file,
+        int minfree, int min_score_adj, bool first)
+{
+    int pid = procp->pid;
+    uid_t uid = procp->uid;
+    char *taskname;
+    int tasksize;
+    int r;
+
+    taskname = proc_get_name(pid);
+    if (!taskname) {
+        pid_remove(pid);
+        return -1;
+    }
 
-    ret = read(mpevfd, &evcount, sizeof(evcount));
-    if (ret < 0)
-        ALOGE("Error reading memory pressure event fd; errno=%d",
-              errno);
+    tasksize = proc_get_size(pid);
+    if (tasksize <= 0) {
+        pid_remove(pid);
+        return -1;
+    }
 
-    if (time(NULL) - kill_lasttime < KILL_TIMEOUT)
-        return;
+    ALOGI("Killing '%s' (%d), uid %d, adj %d\n"
+          "   to free %ldkB because cache %s%ldkB is below limit %ldkB for oom_adj %d\n"
+          "   Free memory is %s%ldkB %s reserved",
+          taskname, pid, uid, procp->oomadj, tasksize * page_k,
+          first ? "" : "~", other_file * page_k, minfree * page_k, min_score_adj,
+          first ? "" : "~", other_free * page_k, other_free >= 0 ? "above" : "below");
+    r = kill(pid, SIGKILL);
+    killProcessGroup(uid, pid, SIGKILL);
+    pid_remove(pid);
 
-    if (zoneinfo_parse(&mi) < 0)
-        return;
+    if (r) {
+        ALOGE("kill(%d): errno=%d", procp->pid, errno);
+        return -1;
+    } else {
+        return tasksize;
+    }
+}
 
-    other_free = mi.nr_free_pages - mi.totalreserve_pages;
-    other_file = mi.nr_file_pages - mi.nr_shmem;
+/*
+ * Find a process to kill based on the current (possibly estimated) free memory
+ * and cached memory sizes.  Returns the size of the killed processes.
+ */
+static int find_and_kill_process(int other_free, int other_file, bool first)
+{
+    int i;
+    int r;
+    int min_score_adj = OOM_ADJUST_MAX + 1;
+    int minfree = 0;
+    int killed_size = 0;
 
     for (i = 0; i < lowmem_targets_size; i++) {
         minfree = lowmem_minfree[i];
@@ -593,52 +621,59 @@ static void mp_event(uint32_t events __unused) {
     }
 
     if (min_score_adj == OOM_ADJUST_MAX + 1)
-        return;
+        return 0;
 
     for (i = OOM_ADJUST_MAX; i >= min_score_adj; i--) {
         struct proc *procp;
 
-    retry:
+retry:
         procp = proc_adj_lru(i);
 
         if (procp) {
-            int pid = procp->pid;
-            uid_t uid = procp->uid;
-            char *taskname;
-            int tasksize;
-            int r;
-
-            taskname = proc_get_name(pid);
-            if (!taskname) {
-                pid_remove(pid);
-                goto retry;
-            }
-
-            tasksize = proc_get_size(pid);
-            if (tasksize < 0) {
-                pid_remove(pid);
-                goto retry;
-            }
-
-            ALOGI("Killing '%s' (%d), uid %d, adj %d\n"
-                  "   to free %ldkB because cache %ldkB is below limit %ldkB for oom_adj %d\n"
-                  "   Free memory is %ldkB %s reserved",
-                  taskname, pid, uid, procp->oomadj, tasksize * page_k,
-                  other_file * page_k, minfree * page_k, min_score_adj,
-                  other_free * page_k, other_free >= 0 ? "above" : "below");
-            r = kill(pid, SIGKILL);
-            killProcessGroup(uid, pid, SIGKILL);
-            pid_remove(pid);
-
-            if (r) {
-                ALOGE("kill(%d): errno=%d", procp->pid, errno);
+            killed_size = kill_one_process(procp, other_free, other_file, minfree, min_score_adj, first);
+            if (killed_size < 0) {
                 goto retry;
             } else {
-                time(&kill_lasttime);
-                break;
+                return killed_size;
             }
         }
     }
+
+    return 0;
+}
+
+static void mp_event(uint32_t events __unused) {
+    int i;
+    int ret;
+    unsigned long long evcount;
+    struct sysmeminfo mi;
+    int other_free;
+    int other_file;
+    int killed_size;
+    bool first = true;
+
+    ret = read(mpevfd, &evcount, sizeof(evcount));
+    if (ret < 0)
+        ALOGE("Error reading memory pressure event fd; errno=%d",
+              errno);
+
+    if (time(NULL) - kill_lasttime < KILL_TIMEOUT)
+        return;
+
+    if (zoneinfo_parse(&mi) < 0)
+        return;
+
+    other_free = mi.nr_free_pages - mi.totalreserve_pages;
+    other_file = mi.nr_file_pages - mi.nr_shmem;
+
+    do {
+        killed_size = find_and_kill_process(other_free, other_file, first);
+        if (killed_size > 0) {
+            first = false;
+            other_free += killed_size;
+            other_file += killed_size;
+        }
+    } while (killed_size > 0);
 }
 
 static int init_mp(char *levelstr, void *event_handler)