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core-out-of-memory.c
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core-out-of-memory.c
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/*
* Copyright (C) 2013-2021 Canonical, Ltd.
* Copyright (C) 2022-2023 Colin Ian King.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* 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.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#include "stress-ng.h"
#include "core-killpid.h"
#include "core-out-of-memory.h"
#if defined(__linux__)
#define OOM_SCORE_ADJ_MIN "-1000"
#define OOM_SCORE_ADJ_MAX "1000"
#define OOM_ADJ_NO_OOM "-17"
#define OOM_ADJ_MIN "-16"
#define OOM_ADJ_MAX "15"
/*
* stress_process_oomed()
* check if a process has been logged as OOM killed
*/
bool stress_process_oomed(const pid_t pid)
{
int fd;
bool oomed = false;
fd = open("/dev/kmsg", O_RDONLY | O_NONBLOCK);
if (fd < 0)
return oomed;
for (;;) {
char buf[4096], *ptr;
ssize_t ret;
ret = read(fd, buf, sizeof(buf) - 1);
if (ret < 0)
break;
buf[ret] = '\0';
/*
* Look for 'Out of memory: Kill process 22566'
*/
ptr = strstr(buf, "process");
if (ptr && (strstr(buf, "Out of memory") ||
strstr(buf, "oom_reaper"))) {
intmax_t oom_pid;
if (sscanf(ptr + 7, "%10" SCNdMAX, &oom_pid) == 1) {
if (oom_pid == (intmax_t)pid) {
oomed = true;
break;
}
}
}
}
(void)close(fd);
return oomed;
}
static const char *stress_args_name(stress_args_t *args)
{
if (!args)
return "main";
return args->name;
}
/*
* stress_set_adjustment()
* try to set OOM adjustment, retry if EAGAIN or EINTR, give up
* after multiple retries. Returns 0 for success, -errno for
* on failure.
*/
static int stress_set_adjustment(
stress_args_t *args,
const char *procname,
const char *str)
{
const size_t len = strlen(str);
int i, saved_errno = 0;
for (i = 0; i < 32; i++) {
ssize_t n;
int fd;
fd = open(procname, O_WRONLY);
if (fd < 0)
return -errno;
n = write(fd, str, len);
saved_errno = errno;
(void)close(fd);
if (n > 0)
return 0;
if (n < 0) {
if ((saved_errno != EAGAIN) &&
(saved_errno != EINTR) &&
(saved_errno != EACCES)) {
if (args && args->instance == 0)
pr_dbg("%s: can't set oom_score_adj, errno=%d (%s)\n",
stress_args_name(args), saved_errno, strerror(saved_errno));
return -saved_errno;
}
}
}
/* Unexpected failure, report why */
if ((args && args->instance == 0) && (saved_errno != EACCES))
pr_dbg("%s: can't set oom_score_adj, errno=%d (%s)\n", stress_args_name(args),
saved_errno, strerror(saved_errno));
return -1;
}
/*
* stress_set_oom_adjustment()
* attempt to stop oom killer
* if we have root privileges then try and make process
* unkillable by oom killer
* NOTE: null args -> main stress-ng process, otherwise a stressor
*/
void stress_set_oom_adjustment(stress_args_t *args, const bool killable)
{
bool high_priv;
bool make_killable = killable;
char *str;
int ret;
/*
* --no-oom-adjust option ignores any oom adjustments
*/
if (g_opt_flags & OPT_FLAGS_NO_OOM_ADJUST)
return;
high_priv = (getuid() == 0) && (geteuid() == 0);
/*
* main cannot be killable; if OPT_FLAGS_OOMABLE set make
* all child procs easily OOMable
*/
if (args && (g_opt_flags & OPT_FLAGS_OOMABLE))
make_killable = true;
/*
* Try modern oom interface
*/
if (make_killable)
str = OOM_SCORE_ADJ_MAX;
else
str = high_priv ? OOM_SCORE_ADJ_MIN : "0";
ret = stress_set_adjustment(args, "/proc/self/oom_score_adj", str);
/*
* Success or some random failure that's not -ENOENT
*/
if ((ret == 0) || (ret != -ENOENT))
return;
/*
* Fall back to old oom interface if we got -ENOENT
*/
if (make_killable)
str = OOM_ADJ_MAX;
else
str = high_priv ? OOM_ADJ_NO_OOM : OOM_ADJ_MIN;
(void)stress_set_adjustment(args, "/proc/self/oom_adj", str);
}
#else
void stress_set_oom_adjustment(stress_args_t *args, const bool killable)
{
(void)args;
(void)killable;
}
bool stress_process_oomed(const pid_t pid)
{
(void)pid;
return false;
}
#endif
/*
* stress_oomable_child()
* generic way to run a process that is possibly going to be
* OOM'd and we retry if it gets killed.
*/
int stress_oomable_child(
stress_args_t *args,
void *context,
stress_oomable_child_func_t func,
const int flag)
{
pid_t pid;
int ooms = 0;
int segvs = 0;
int buserrs = 0;
int rc = EXIT_SUCCESS;
size_t signal_idx = 0;
const bool not_quiet = !(flag & STRESS_OOMABLE_QUIET);
const bool valid_timeout = (g_opt_timeout > 0);
/*
* Kill child multiple times, start with SIGALRM and work up
*/
static const int signals[] = {
SIGALRM,
SIGALRM,
SIGALRM,
SIGALRM,
SIGTERM,
SIGKILL
};
again:
if (!stress_continue(args))
return EXIT_SUCCESS;
if (valid_timeout && (stress_time_now() > args->time_end)) {
return EXIT_SUCCESS;
}
pid = fork();
if (pid < 0) {
/* Keep trying if we are out of resources */
if ((errno == EAGAIN) || (errno == ENOMEM)) {
/* don't retry for 1/10th sec */
(void)shim_usleep(100000);
goto again;
}
if (not_quiet)
pr_err("%s: fork failed: errno=%d: (%s)\n",
args->name, errno, strerror(errno));
return -1;
} else if (pid > 0) {
/* Parent, wait for child */
int status, ret;
rewait:
stress_set_proc_state(args->name, STRESS_STATE_WAIT);
ret = waitpid(pid, &status, 0);
if (ret < 0) {
stress_set_proc_state(args->name, STRESS_STATE_RUN);
/* No longer alive? */
if (errno == ECHILD)
goto report;
if ((errno != EINTR) && not_quiet)
pr_dbg("%s: waitpid(): errno=%d (%s)\n",
args->name, errno, strerror(errno));
(void)stress_kill_sig(pid, signals[signal_idx]);
if (++signal_idx >= SIZEOF_ARRAY(signals))
goto report;
/*
* First time round do fast re-wait
* in case child can be reaped quickly,
* there after do slow backoff on each
* iteration until we give up and do
* the final SIGKILL
*/
if (signal_idx > 1)
(void)shim_usleep(500000);
goto rewait;
} else if (WIFSIGNALED(status)) {
stress_set_proc_state(args->name, STRESS_STATE_RUN);
if (not_quiet)
pr_dbg("%s: child died: %s (instance %d)\n",
args->name, stress_strsignal(WTERMSIG(status)),
args->instance);
/* Bus error death? retry */
if (WTERMSIG(status) == SIGBUS) {
buserrs++;
goto again;
}
/* If we got killed by OOM killer, re-start */
if ((signals[signal_idx] != SIGKILL) && (WTERMSIG(status) == SIGKILL)) {
/*
* The --oomable flag was enabled, so
* the behaviour here is to no longer
* retry. The exit return is EXIT_SUCCESS
* because the child is allowed to terminate
* by being OOM'd.
*/
if (g_opt_flags & OPT_FLAGS_OOMABLE) {
stress_log_system_mem_info();
if (not_quiet)
pr_dbg("%s: assuming killed by OOM "
"killer, bailing out "
"(instance %d)\n",
args->name, args->instance);
stress_clean_dir(args->name, args->pid, args->instance);
return EXIT_SUCCESS;
} else {
stress_log_system_mem_info();
if (not_quiet)
pr_dbg("%s: assuming killed by OOM "
"killer, restarting again "
"(instance %d)\n",
args->name, args->instance);
ooms++;
goto again;
}
}
/* If we got killed by sigsegv, re-start */
if (WTERMSIG(status) == SIGSEGV) {
if (not_quiet)
pr_dbg("%s: killed by SIGSEGV, "
"restarting again "
"(instance %d)\n",
args->name, args->instance);
segvs++;
goto again;
}
}
rc = WEXITSTATUS(status);
} else {
/* Child */
int ret;
if (!stress_continue(args)) {
stress_set_proc_state(args->name, STRESS_STATE_EXIT);
_exit(EXIT_SUCCESS);
}
stress_parent_died_alarm();
/* Make sure this is killable by OOM killer */
stress_set_oom_adjustment(args, true);
/* Explicitly drop capabilities, makes it more OOM-able */
if (flag & STRESS_OOMABLE_DROP_CAP) {
VOID_RET(int, stress_drop_capabilities(args->name));
}
/*
* Process may have exceeded run time by the time it was
* fully runnable, so check for this before doing expensive
* stressor invocation
*/
if (!stress_continue(args) ||
(valid_timeout && (stress_time_now() > args->time_end))) {
stress_set_proc_state(args->name, STRESS_STATE_EXIT);
_exit(EXIT_SUCCESS);
}
/* ..and finally re-start the stressor */
ret = func(args, context);
pr_fail_check(&rc);
if (rc != EXIT_SUCCESS)
ret = rc;
stress_set_proc_state(args->name, STRESS_STATE_EXIT);
_exit(ret);
}
report:
if ((ooms + segvs + buserrs > 0) && not_quiet) {
pr_dbg("%s: OOM restarts: %d"
", SIGSEGV restarts: %d"
", SIGBUS restarts: %d\n",
args->name, ooms, segvs, buserrs);
}
return rc;
}