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platform_system_core/lmkd/lmkd.c

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/*
* 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 <arpa/inet.h>
#include <errno.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <time.h>
#include <sys/cdefs.h>
#include <sys/epoll.h>
#include <sys/eventfd.h>
#include <sys/mman.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <unistd.h>
#include <cutils/sockets.h>
#include <log/log.h>
#include <processgroup/processgroup.h>
#ifndef __unused
#define __unused __attribute__((__unused__))
#endif
#define MEMCG_SYSFS_PATH "/dev/memcg/"
#define MEMPRESSURE_WATCH_LEVEL "low"
#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;
/* OOM score values used by both kernel and framework */
#define OOM_SCORE_ADJ_MIN (-1000)
#define OOM_SCORE_ADJ_MAX 1000
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;
uid_t uid;
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_SCORE_ADJ_MIN)
static struct adjslot_list procadjslot_list[ADJTOSLOT(OOM_SCORE_ADJ_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 ssize_t read_all(int fd, char *buf, size_t max_len)
{
ssize_t ret = 0;
while (max_len > 0) {
ssize_t r = read(fd, buf, max_len);
if (r == 0) {
break;
}
if (r == -1) {
return -1;
}
ret += r;
buf += r;
max_len -= r;
}
return ret;
}
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 | O_CLOEXEC);
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 uid, int oomadj) {
struct proc *procp;
char path[80];
char val[20];
if (oomadj < OOM_SCORE_ADJ_MIN || oomadj > OOM_SCORE_ADJ_MAX) {
ALOGE("Invalid PROCPRIO oomadj argument %d", oomadj);
return;
}
snprintf(path, sizeof(path), "/proc/%d/oom_score_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->uid = uid;
procp->oomadj = oomadj;
proc_insert(procp);
} else {
proc_unslot(procp);
procp->oomadj = oomadj;
proc_slot(procp);
}
}
static void cmd_procremove(int pid) {
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 != 3)
goto wronglen;
cmd_procprio(ntohl(ibuf[1]), ntohl(ibuf[2]), ntohl(ibuf[3]));
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 __unused) {
struct sockaddr_storage ss;
struct sockaddr *addrp = (struct sockaddr *)&ss;
socklen_t alen;
struct epoll_event epev;
if (ctrl_dfd >= 0) {
ctrl_data_close();
ctrl_dfd_reopened = 1;
}
alen = sizeof(ss);
ctrl_dfd = accept(ctrl_lfd, addrp, &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;
char *save_ptr;
for (cp = strtok_r(cp, "(), ", &save_ptr); cp; cp = strtok_r(NULL, "), ", &save_ptr)) {
zoneval = strtol(cp, &cp, 0);
if (zoneval > max)
max = zoneval;
}
return max;
}
static void zoneinfo_parse_line(char *line, struct sysmeminfo *mip) {
char *cp = line;
char *ap;
char *save_ptr;
cp = strtok_r(line, " ", &save_ptr);
if (!cp)
return;
ap = strtok_r(NULL, " ", &save_ptr);
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) {
int fd;
ssize_t size;
char buf[PAGE_SIZE];
char *save_ptr;
char *line;
memset(mip, 0, sizeof(struct sysmeminfo));
fd = open(ZONEINFO_PATH, O_RDONLY | O_CLOEXEC);
if (fd == -1) {
ALOGE("%s open: errno=%d", ZONEINFO_PATH, errno);
return -1;
}
size = read_all(fd, buf, sizeof(buf) - 1);
if (size < 0) {
ALOGE("%s read: errno=%d", ZONEINFO_PATH, errno);
close(fd);
return -1;
}
ALOG_ASSERT((size_t)size < sizeof(buf) - 1, "/proc/zoneinfo too large");
buf[size] = 0;
for (line = strtok_r(buf, "\n", &save_ptr); line; line = strtok_r(NULL, "\n", &save_ptr))
zoneinfo_parse_line(line, mip);
close(fd);
return 0;
}
static int proc_get_size(int pid) {
char path[PATH_MAX];
char line[LINE_MAX];
int fd;
int rss = 0;
int total;
ssize_t ret;
snprintf(path, PATH_MAX, "/proc/%d/statm", pid);
fd = open(path, O_RDONLY | O_CLOEXEC);
if (fd == -1)
return -1;
ret = read_all(fd, line, sizeof(line) - 1);
if (ret < 0) {
close(fd);
return -1;
}
sscanf(line, "%d %d ", &total, &rss);
close(fd);
return rss;
}
static char *proc_get_name(int pid) {
char path[PATH_MAX];
static char line[LINE_MAX];
int fd;
char *cp;
ssize_t ret;
snprintf(path, PATH_MAX, "/proc/%d/cmdline", pid);
fd = open(path, O_RDONLY | O_CLOEXEC);
if (fd == -1)
return NULL;
ret = read_all(fd, line, sizeof(line) - 1);
close(fd);
if (ret < 0) {
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)]);
}
/* 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;
}
tasksize = proc_get_size(pid);
if (tasksize <= 0) {
pid_remove(pid);
return -1;
}
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 (r) {
ALOGE("kill(%d): errno=%d", procp->pid, errno);
return -1;
} else {
return tasksize;
}
}
/*
* 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 min_score_adj = OOM_SCORE_ADJ_MAX + 1;
int minfree = 0;
int killed_size = 0;
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_SCORE_ADJ_MAX + 1)
return 0;
for (i = OOM_SCORE_ADJ_MAX; i >= min_score_adj; i--) {
struct proc *procp;
retry:
procp = proc_adj_lru(i);
if (procp) {
killed_size = kill_one_process(procp, other_free, other_file, minfree, min_score_adj, first);
if (killed_size < 0) {
goto retry;
} else {
return killed_size;
}
}
}
return 0;
}
static void mp_event(uint32_t events __unused) {
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;
while (zoneinfo_parse(&mi) < 0) {
// Failed to read /proc/zoneinfo, assume ENOMEM and kill something
find_and_kill_process(0, 0, true);
}
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)
{
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 | O_CLOEXEC);
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 | O_CLOEXEC);
if (evctlfd < 0) {
ALOGI("No kernel memory cgroup event control (errno=%d)", errno);
goto err_open_evctlfd;
}
evfd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
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_SCORE_ADJ_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 __unused, char **argv __unused) {
struct sched_param param = {
.sched_priority = 1,
};
mlockall(MCL_FUTURE);
sched_setscheduler(0, SCHED_FIFO, &param);
if (!init())
mainloop();
ALOGI("exiting");
return 0;
}
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