Add lmkd low memory killer daemon

Move kernel low memory killer logic to new daemon lmkd.  ActivityManager
communicates with this daemon over a named socket.

Change-Id: Ie957da7e9b1f7150e23c689fdadf23ff260b47be

lmkd/Android.mk

@@ -0,0 +1,10 @@
+LOCAL_PATH:= $(call my-dir)
+include $(CLEAR_VARS)
+
+LOCAL_SRC_FILES := lmkd.c
+LOCAL_STATIC_LIBRARIES := libcutils liblog libm libc
+LOCAL_FORCE_STATIC_EXECUTABLE := true
+
+LOCAL_MODULE := lmkd
+
+include $(BUILD_EXECUTABLE)

lmkd/lmkd.c

@@ -0,0 +1,735 @@
+/*
+ * Copyright (C) 2013 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#define LOG_TAG "lowmemorykiller"
+
+#include <errno.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+#include <unistd.h>
+#include <arpa/inet.h>
+#include <sys/epoll.h>
+#include <sys/eventfd.h>
+#include <sys/socket.h>
+#include <sys/types.h>
+#include <cutils/log.h>
+#include <cutils/sockets.h>
+
+#define MEMCG_SYSFS_PATH "/dev/memcg/"
+#define MEMPRESSURE_WATCH_LEVEL "medium"
+#define ZONEINFO_PATH "/proc/zoneinfo"
+#define LINE_MAX 128
+
+#define INKERNEL_MINFREE_PATH "/sys/module/lowmemorykiller/parameters/minfree"
+#define INKERNEL_ADJ_PATH "/sys/module/lowmemorykiller/parameters/adj"
+
+#define ARRAY_SIZE(x)   (sizeof(x) / sizeof(*(x)))
+
+enum lmk_cmd {
+    LMK_TARGET,
+    LMK_PROCPRIO,
+    LMK_PROCREMOVE,
+};
+
+#define MAX_TARGETS 6
+/*
+ * longest is LMK_TARGET followed by MAX_TARGETS each minfree and minkillprio
+ * values
+ */
+#define CTRL_PACKET_MAX (sizeof(int) * (MAX_TARGETS * 2 + 1))
+
+/* default to old in-kernel interface if no memory pressure events */
+static int use_inkernel_interface = 1;
+
+/* memory pressure level medium event */
+static int mpevfd;
+
+/* control socket listen and data */
+static int ctrl_lfd;
+static int ctrl_dfd = -1;
+static int ctrl_dfd_reopened; /* did we reopen ctrl conn on this loop? */
+
+/* 1 memory pressure level, 1 ctrl listen socket, 1 ctrl data socket */
+#define MAX_EPOLL_EVENTS 3
+static int epollfd;
+static int maxevents;
+
+#define OOM_DISABLE (-17)
+/* inclusive */
+#define OOM_ADJUST_MIN (-16)
+#define OOM_ADJUST_MAX 15
+
+static int lowmem_adj[MAX_TARGETS];
+static int lowmem_minfree[MAX_TARGETS];
+static int lowmem_targets_size;
+
+struct sysmeminfo {
+    int nr_free_pages;
+    int nr_file_pages;
+    int nr_shmem;
+    int totalreserve_pages;
+};
+
+struct adjslot_list {
+    struct adjslot_list *next;
+    struct adjslot_list *prev;
+};
+
+struct proc {
+    struct adjslot_list asl;
+    int pid;
+    int oomadj;
+    struct proc *pidhash_next;
+};
+
+#define PIDHASH_SZ 1024
+static struct proc *pidhash[PIDHASH_SZ];
+#define pid_hashfn(x) ((((x) >> 8) ^ (x)) & (PIDHASH_SZ - 1))
+
+#define ADJTOSLOT(adj) (adj + -OOM_ADJUST_MIN)
+static struct adjslot_list procadjslot_list[ADJTOSLOT(OOM_ADJUST_MAX) + 1];
+
+/*
+ * Wait 1-2 seconds for the death report of a killed process prior to
+ * considering killing more processes.
+ */
+#define KILL_TIMEOUT 2
+/* Time of last process kill we initiated, stop me before I kill again */
+static time_t kill_lasttime;
+
+/* PAGE_SIZE / 1024 */
+static long page_k;
+
+static struct proc *pid_lookup(int pid) {
+    struct proc *procp;
+
+    for (procp = pidhash[pid_hashfn(pid)]; procp && procp->pid != pid;
+         procp = procp->pidhash_next)
+            ;
+
+    return procp;
+}
+
+static void adjslot_insert(struct adjslot_list *head, struct adjslot_list *new)
+{
+    struct adjslot_list *next = head->next;
+    new->prev = head;
+    new->next = next;
+    next->prev = new;
+    head->next = new;
+}
+
+static void adjslot_remove(struct adjslot_list *old)
+{
+    struct adjslot_list *prev = old->prev;
+    struct adjslot_list *next = old->next;
+    next->prev = prev;
+    prev->next = next;
+}
+
+static struct adjslot_list *adjslot_tail(struct adjslot_list *head) {
+    struct adjslot_list *asl = head->prev;
+
+    return asl == head ? NULL : asl;
+}
+
+static void proc_slot(struct proc *procp) {
+    int adjslot = ADJTOSLOT(procp->oomadj);
+
+    adjslot_insert(&procadjslot_list[adjslot], &procp->asl);
+}
+
+static void proc_unslot(struct proc *procp) {
+    adjslot_remove(&procp->asl);
+}
+
+static void proc_insert(struct proc *procp) {
+    int hval = pid_hashfn(procp->pid);
+
+    procp->pidhash_next = pidhash[hval];
+    pidhash[hval] = procp;
+    proc_slot(procp);
+}
+
+static int pid_remove(int pid) {
+    int hval = pid_hashfn(pid);
+    struct proc *procp;
+    struct proc *prevp;
+
+    for (procp = pidhash[hval], prevp = NULL; procp && procp->pid != pid;
+         procp = procp->pidhash_next)
+            prevp = procp;
+
+    if (!procp)
+        return -1;
+
+    if (!prevp)
+        pidhash[hval] = procp->pidhash_next;
+    else
+        prevp->pidhash_next = procp->pidhash_next;
+
+    proc_unslot(procp);
+    free(procp);
+    return 0;
+}
+
+static void writefilestring(char *path, char *s) {
+    int fd = open(path, O_WRONLY);
+    int len = strlen(s);
+    int ret;
+
+    if (fd < 0) {
+        ALOGE("Error opening %s; errno=%d", path, errno);
+        return;
+    }
+
+    ret = write(fd, s, len);
+    if (ret < 0) {
+        ALOGE("Error writing %s; errno=%d", path, errno);
+    } else if (ret < len) {
+        ALOGE("Short write on %s; length=%d", path, ret);
+    }
+
+    close(fd);
+}
+
+static void cmd_procprio(int pid, int oomadj) {
+    struct proc *procp;
+    char path[80];
+    char val[20];
+
+    if (oomadj < OOM_DISABLE || oomadj > OOM_ADJUST_MAX) {
+        ALOGE("Invalid PROCPRIO oomadj argument %d", oomadj);
+        return;
+    }
+
+    snprintf(path, sizeof(path), "/proc/%d/oom_adj", pid);
+    snprintf(val, sizeof(val), "%d", oomadj);
+    writefilestring(path, val);
+
+    if (use_inkernel_interface)
+        return;
+
+    procp = pid_lookup(pid);
+    if (!procp) {
+            procp = malloc(sizeof(struct proc));
+            if (!procp) {
+                // Oh, the irony.  May need to rebuild our state.
+                return;
+            }
+
+            procp->pid = pid;
+            procp->oomadj = oomadj;
+            proc_insert(procp);
+    } else {
+        proc_unslot(procp);
+        procp->oomadj = oomadj;
+        proc_slot(procp);
+    }
+}
+
+static void cmd_procremove(int pid) {
+    struct proc *procp;
+
+    if (use_inkernel_interface)
+        return;
+
+    pid_remove(pid);
+    kill_lasttime = 0;
+}
+
+static void cmd_target(int ntargets, int *params) {
+    int i;
+
+    if (ntargets > (int)ARRAY_SIZE(lowmem_adj))
+        return;
+
+    for (i = 0; i < ntargets; i++) {
+        lowmem_minfree[i] = ntohl(*params++);
+        lowmem_adj[i] = ntohl(*params++);
+    }
+
+    lowmem_targets_size = ntargets;
+
+    if (use_inkernel_interface) {
+        char minfreestr[128];
+        char killpriostr[128];
+
+        minfreestr[0] = '\0';
+        killpriostr[0] = '\0';
+
+        for (i = 0; i < lowmem_targets_size; i++) {
+            char val[40];
+
+            if (i) {
+                strlcat(minfreestr, ",", sizeof(minfreestr));
+                strlcat(killpriostr, ",", sizeof(killpriostr));
+            }
+
+            snprintf(val, sizeof(val), "%d", lowmem_minfree[i]);
+            strlcat(minfreestr, val, sizeof(minfreestr));
+            snprintf(val, sizeof(val), "%d", lowmem_adj[i]);
+            strlcat(killpriostr, val, sizeof(killpriostr));
+        }
+
+        writefilestring(INKERNEL_MINFREE_PATH, minfreestr);
+        writefilestring(INKERNEL_ADJ_PATH, killpriostr);
+    }
+}
+
+static void ctrl_data_close(void) {
+    ALOGI("Closing Activity Manager data connection");
+    close(ctrl_dfd);
+    ctrl_dfd = -1;
+    maxevents--;
+}
+
+static int ctrl_data_read(char *buf, size_t bufsz) {
+    int ret = 0;
+
+    ret = read(ctrl_dfd, buf, bufsz);
+
+    if (ret == -1) {
+        ALOGE("control data socket read failed; errno=%d", errno);
+    } else if (ret == 0) {
+        ALOGE("Got EOF on control data socket");
+        ret = -1;
+    }
+
+    return ret;
+}
+
+static void ctrl_command_handler(void) {
+    int ibuf[CTRL_PACKET_MAX / sizeof(int)];
+    int len;
+    int cmd = -1;
+    int nargs;
+    int targets;
+
+    len = ctrl_data_read((char *)ibuf, CTRL_PACKET_MAX);
+    if (len <= 0)
+        return;
+
+    nargs = len / sizeof(int) - 1;
+    if (nargs < 0)
+        goto wronglen;
+
+    cmd = ntohl(ibuf[0]);
+
+    switch(cmd) {
+    case LMK_TARGET:
+        targets = nargs / 2;
+        if (nargs & 0x1 || targets > (int)ARRAY_SIZE(lowmem_adj))
+            goto wronglen;
+        cmd_target(targets, &ibuf[1]);
+        break;
+    case LMK_PROCPRIO:
+        if (nargs != 2)
+            goto wronglen;
+        cmd_procprio(ntohl(ibuf[1]), ntohl(ibuf[2]));
+        break;
+    case LMK_PROCREMOVE:
+        if (nargs != 1)
+            goto wronglen;
+        cmd_procremove(ntohl(ibuf[1]));
+        break;
+    default:
+        ALOGE("Received unknown command code %d", cmd);
+        return;
+    }
+
+    return;
+
+wronglen:
+    ALOGE("Wrong control socket read length cmd=%d len=%d", cmd, len);
+}
+
+static void ctrl_data_handler(uint32_t events) {
+    if (events & EPOLLHUP) {
+        ALOGI("ActivityManager disconnected");
+        if (!ctrl_dfd_reopened)
+            ctrl_data_close();
+    } else if (events & EPOLLIN) {
+        ctrl_command_handler();
+    }
+}
+
+static void ctrl_connect_handler(uint32_t events) {
+    struct sockaddr addr;
+    socklen_t alen;
+    struct epoll_event epev;
+
+    if (ctrl_dfd >= 0) {
+        ctrl_data_close();
+        ctrl_dfd_reopened = 1;
+    }
+
+    alen = sizeof(addr);
+    ctrl_dfd = accept(ctrl_lfd, &addr, &alen);
+
+    if (ctrl_dfd < 0) {
+        ALOGE("lmkd control socket accept failed; errno=%d", errno);
+        return;
+    }
+
+    ALOGI("ActivityManager connected");
+    maxevents++;
+    epev.events = EPOLLIN;
+    epev.data.ptr = (void *)ctrl_data_handler;
+    if (epoll_ctl(epollfd, EPOLL_CTL_ADD, ctrl_dfd, &epev) == -1) {
+        ALOGE("epoll_ctl for data connection socket failed; errno=%d", errno);
+        ctrl_data_close();
+        return;
+    }
+}
+
+static int zoneinfo_parse_protection(char *cp) {
+    int max = 0;
+    int zoneval;
+
+    if (*cp++ != '(')
+        return 0;
+
+    do {
+        zoneval = strtol(cp, &cp, 0);
+        if ((*cp != ',') && (*cp != ')'))
+            return 0;
+        if (zoneval > max)
+            max = zoneval;
+    } while (cp = strtok(NULL, " "));
+
+    return max;
+}
+
+static void zoneinfo_parse_line(char *line, struct sysmeminfo *mip) {
+    char *cp = line;
+    char *ap;
+
+    cp = strtok(line, " ");
+    if (!cp)
+        return;
+
+    ap = strtok(NULL, " ");
+    if (!ap)
+        return;
+
+    if (!strcmp(cp, "nr_free_pages"))
+        mip->nr_free_pages += strtol(ap, NULL, 0);
+    else if (!strcmp(cp, "nr_file_pages"))
+        mip->nr_file_pages += strtol(ap, NULL, 0);
+    else if (!strcmp(cp, "nr_shmem"))
+        mip->nr_shmem += strtol(ap, NULL, 0);
+    else if (!strcmp(cp, "high"))
+        mip->totalreserve_pages += strtol(ap, NULL, 0);
+    else if (!strcmp(cp, "protection:"))
+        mip->totalreserve_pages += zoneinfo_parse_protection(ap);
+}
+
+static int zoneinfo_parse(struct sysmeminfo *mip) {
+    FILE *f;
+    char *cp;
+    char line[LINE_MAX];
+
+    memset(mip, 0, sizeof(struct sysmeminfo));
+    f = fopen(ZONEINFO_PATH, "r");
+    if (!f) {
+        ALOGE("%s open: errno=%d", ZONEINFO_PATH, errno);
+        return -1;
+    }
+
+    while (fgets(line, LINE_MAX, f))
+            zoneinfo_parse_line(line, mip);
+
+    fclose(f);
+    return 0;
+}
+
+static int proc_get_size(int pid) {
+    char path[PATH_MAX];
+    char line[LINE_MAX];
+    FILE *f;
+    int rss = 0;
+    int total;
+
+    snprintf(path, PATH_MAX, "/proc/%d/statm", pid);
+    f = fopen(path, "r");
+    if (!f)
+        return -1;
+    if (!fgets(line, LINE_MAX, f)) {
+        fclose(f);
+        return -1;
+    }
+
+    sscanf(line, "%d %d ", &total, &rss);
+    fclose(f);
+    return rss;
+}
+
+static char *proc_get_name(int pid) {
+    char path[PATH_MAX];
+    static char line[LINE_MAX];
+    FILE *f;
+    char *cp;
+
+    snprintf(path, PATH_MAX, "/proc/%d/cmdline", pid);
+    f = fopen(path, "r");
+    if (!f)
+        return NULL;
+    if (!fgets(line, LINE_MAX, f)) {
+        fclose(f);
+        return NULL;
+    }
+
+    cp = strchr(line, ' ');
+    if (cp)
+        *cp = '\0';
+
+    return line;
+}
+
+static struct proc *proc_adj_lru(int oomadj) {
+    return (struct proc *)adjslot_tail(&procadjslot_list[ADJTOSLOT(oomadj)]);
+}
+
+static void mp_event(uint32_t events) {
+    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;
+
+    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;
+
+    for (i = 0; i < lowmem_targets_size; i++) {
+        minfree = lowmem_minfree[i];
+        if (other_free < minfree && other_file < minfree) {
+            min_score_adj = lowmem_adj[i];
+            break;
+        }
+    }
+
+    if (min_score_adj == OOM_ADJUST_MAX + 1)
+        return;
+
+    for (i = OOM_ADJUST_MAX; i >= min_score_adj; i--) {
+        struct proc *procp;
+
+    retry:
+        procp = proc_adj_lru(i);
+
+        if (procp) {
+            int pid = procp->pid;
+            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), 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, 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);
+            pid_remove(pid);
+
+            if (r) {
+                ALOGE("kill(%d): errno=%d", procp->pid, errno);
+                goto retry;
+            } else {
+                time(&kill_lasttime);
+                break;
+            }
+        }
+    }
+}
+
+static int init_mp(char *levelstr, void *event_handler)
+{
+    int mpfd;
+    int evfd;
+    int evctlfd;
+    char buf[256];
+    struct epoll_event epev;
+    int ret;
+
+    mpfd = open(MEMCG_SYSFS_PATH "memory.pressure_level", O_RDONLY);
+    if (mpfd < 0) {
+        ALOGI("No kernel memory.pressure_level support (errno=%d)", errno);
+        goto err_open_mpfd;
+    }
+
+    evctlfd = open(MEMCG_SYSFS_PATH "cgroup.event_control", O_WRONLY);
+    if (evctlfd < 0) {
+        ALOGI("No kernel memory cgroup event control (errno=%d)", errno);
+        goto err_open_evctlfd;
+    }
+
+    evfd = eventfd(0, EFD_NONBLOCK);
+    if (evfd < 0) {
+        ALOGE("eventfd failed for level %s; errno=%d", levelstr, errno);
+        goto err_eventfd;
+    }
+
+    ret = snprintf(buf, sizeof(buf), "%d %d %s", evfd, mpfd, levelstr);
+    if (ret >= (ssize_t)sizeof(buf)) {
+        ALOGE("cgroup.event_control line overflow for level %s", levelstr);
+        goto err;
+    }
+
+    ret = write(evctlfd, buf, strlen(buf) + 1);
+    if (ret == -1) {
+        ALOGE("cgroup.event_control write failed for level %s; errno=%d",
+              levelstr, errno);
+        goto err;
+    }
+
+    epev.events = EPOLLIN;
+    epev.data.ptr = event_handler;
+    ret = epoll_ctl(epollfd, EPOLL_CTL_ADD, evfd, &epev);
+    if (ret == -1) {
+        ALOGE("epoll_ctl for level %s failed; errno=%d", levelstr, errno);
+        goto err;
+    }
+    maxevents++;
+    mpevfd = evfd;
+    return 0;
+
+err:
+    close(evfd);
+err_eventfd:
+    close(evctlfd);
+err_open_evctlfd:
+    close(mpfd);
+err_open_mpfd:
+    return -1;
+}
+
+static int init(void) {
+    struct epoll_event epev;
+    int i;
+    int ret;
+
+    page_k = sysconf(_SC_PAGESIZE);
+    if (page_k == -1)
+        page_k = PAGE_SIZE;
+    page_k /= 1024;
+
+    epollfd = epoll_create(MAX_EPOLL_EVENTS);
+    if (epollfd == -1) {
+        ALOGE("epoll_create failed (errno=%d)", errno);
+        return -1;
+    }
+
+    ctrl_lfd = android_get_control_socket("lmkd");
+    if (ctrl_lfd < 0) {
+        ALOGE("get lmkd control socket failed");
+        return -1;
+    }
+
+    ret = listen(ctrl_lfd, 1);
+    if (ret < 0) {
+        ALOGE("lmkd control socket listen failed (errno=%d)", errno);
+        return -1;
+    }
+
+    epev.events = EPOLLIN;
+    epev.data.ptr = (void *)ctrl_connect_handler;
+    if (epoll_ctl(epollfd, EPOLL_CTL_ADD, ctrl_lfd, &epev) == -1) {
+        ALOGE("epoll_ctl for lmkd control socket failed (errno=%d)", errno);
+        return -1;
+    }
+    maxevents++;
+
+    use_inkernel_interface = !access(INKERNEL_MINFREE_PATH, W_OK);
+
+    if (use_inkernel_interface) {
+        ALOGI("Using in-kernel low memory killer interface");
+    } else {
+        ret = init_mp(MEMPRESSURE_WATCH_LEVEL, (void *)&mp_event);
+        if (ret)
+            ALOGE("Kernel does not support memory pressure events or in-kernel low memory killer");
+    }
+
+    for (i = 0; i <= ADJTOSLOT(OOM_ADJUST_MAX); i++) {
+        procadjslot_list[i].next = &procadjslot_list[i];
+        procadjslot_list[i].prev = &procadjslot_list[i];
+    }
+
+    return 0;
+}
+
+static void mainloop(void) {
+    while (1) {
+        struct epoll_event events[maxevents];
+        int nevents;
+        int i;
+
+        ctrl_dfd_reopened = 0;
+        nevents = epoll_wait(epollfd, events, maxevents, -1);
+
+        if (nevents == -1) {
+            if (errno == EINTR)
+                continue;
+            ALOGE("epoll_wait failed (errno=%d)", errno);
+            continue;
+        }
+
+        for (i = 0; i < nevents; ++i) {
+            if (events[i].events & EPOLLERR)
+                ALOGD("EPOLLERR on event #%d", i);
+            if (events[i].data.ptr)
+                (*(void (*)(uint32_t))events[i].data.ptr)(events[i].events);
+        }
+    }
+}
+
+int main(int argc, char **argv) {
+    if (!init())
+        mainloop();
+
+    ALOGI("exiting");
+    return 0;
+}