oom: move oom_adj value from task_struct to signal_struct
Currently, OOM logic callflow is here.
__out_of_memory()
select_bad_process() for each task
badness() calculate badness of one task
oom_kill_process() search child
oom_kill_task() kill target task and mm shared tasks with it
example, process-A have two thread, thread-A and thread-B and it have very
fat memory and each thread have following oom_adj and oom_score.
thread-A: oom_adj = OOM_DISABLE, oom_score = 0
thread-B: oom_adj = 0, oom_score = very-high
Then, select_bad_process() select thread-B, but oom_kill_task() refuse
kill the task because thread-A have OOM_DISABLE. Thus __out_of_memory()
call select_bad_process() again. but select_bad_process() select the same
task. It mean kernel fall in livelock.
The fact is, select_bad_process() must select killable task. otherwise
OOM logic go into livelock.
And root cause is, oom_adj shouldn't be per-thread value. it should be
per-process value because OOM-killer kill a process, not thread. Thus
This patch moves oomkilladj (now more appropriately named oom_adj) from
struct task_struct to struct signal_struct. it naturally prevent
select_bad_process() choose wrong task.
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6f742f6..81cfff8 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -999,11 +999,17 @@
struct task_struct *task = get_proc_task(file->f_path.dentry->d_inode);
char buffer[PROC_NUMBUF];
size_t len;
- int oom_adjust;
+ int oom_adjust = OOM_DISABLE;
+ unsigned long flags;
if (!task)
return -ESRCH;
- oom_adjust = task->oomkilladj;
+
+ if (lock_task_sighand(task, &flags)) {
+ oom_adjust = task->signal->oom_adj;
+ unlock_task_sighand(task, &flags);
+ }
+
put_task_struct(task);
len = snprintf(buffer, sizeof(buffer), "%i\n", oom_adjust);
@@ -1017,6 +1023,7 @@
struct task_struct *task;
char buffer[PROC_NUMBUF], *end;
int oom_adjust;
+ unsigned long flags;
memset(buffer, 0, sizeof(buffer));
if (count > sizeof(buffer) - 1)
@@ -1032,11 +1039,20 @@
task = get_proc_task(file->f_path.dentry->d_inode);
if (!task)
return -ESRCH;
- if (oom_adjust < task->oomkilladj && !capable(CAP_SYS_RESOURCE)) {
+ if (!lock_task_sighand(task, &flags)) {
+ put_task_struct(task);
+ return -ESRCH;
+ }
+
+ if (oom_adjust < task->signal->oom_adj && !capable(CAP_SYS_RESOURCE)) {
+ unlock_task_sighand(task, &flags);
put_task_struct(task);
return -EACCES;
}
- task->oomkilladj = oom_adjust;
+
+ task->signal->oom_adj = oom_adjust;
+
+ unlock_task_sighand(task, &flags);
put_task_struct(task);
if (end - buffer == 0)
return -EIO;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 899d730..17e9a8e 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -639,6 +639,8 @@
unsigned audit_tty;
struct tty_audit_buf *tty_audit_buf;
#endif
+
+ int oom_adj; /* OOM kill score adjustment (bit shift) */
};
/* Context switch must be unlocked if interrupts are to be enabled */
@@ -1221,7 +1223,6 @@
* a short time
*/
unsigned char fpu_counter;
- s8 oomkilladj; /* OOM kill score adjustment (bit shift). */
#ifdef CONFIG_BLK_DEV_IO_TRACE
unsigned int btrace_seq;
#endif
diff --git a/kernel/fork.c b/kernel/fork.c
index 73a442b..1020977 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -880,6 +880,8 @@
tty_audit_fork(sig);
+ sig->oom_adj = current->signal->oom_adj;
+
return 0;
}
diff --git a/mm/oom_kill.c b/mm/oom_kill.c
index da4c342..630b77f 100644
--- a/mm/oom_kill.c
+++ b/mm/oom_kill.c
@@ -58,6 +58,10 @@
unsigned long points, cpu_time, run_time;
struct mm_struct *mm;
struct task_struct *child;
+ int oom_adj = p->signal->oom_adj;
+
+ if (oom_adj == OOM_DISABLE)
+ return 0;
task_lock(p);
mm = p->mm;
@@ -148,15 +152,15 @@
points /= 8;
/*
- * Adjust the score by oomkilladj.
+ * Adjust the score by oom_adj.
*/
- if (p->oomkilladj) {
- if (p->oomkilladj > 0) {
+ if (oom_adj) {
+ if (oom_adj > 0) {
if (!points)
points = 1;
- points <<= p->oomkilladj;
+ points <<= oom_adj;
} else
- points >>= -(p->oomkilladj);
+ points >>= -(oom_adj);
}
#ifdef DEBUG
@@ -251,7 +255,7 @@
*ppoints = ULONG_MAX;
}
- if (p->oomkilladj == OOM_DISABLE)
+ if (p->signal->oom_adj == OOM_DISABLE)
continue;
points = badness(p, uptime.tv_sec);
@@ -304,7 +308,7 @@
}
printk(KERN_INFO "[%5d] %5d %5d %8lu %8lu %3d %3d %s\n",
p->pid, __task_cred(p)->uid, p->tgid, mm->total_vm,
- get_mm_rss(mm), (int)task_cpu(p), p->oomkilladj,
+ get_mm_rss(mm), (int)task_cpu(p), p->signal->oom_adj,
p->comm);
task_unlock(p);
} while_each_thread(g, p);
@@ -359,18 +363,9 @@
* change to NULL at any time since we do not hold task_lock(p).
* However, this is of no concern to us.
*/
-
- if (mm == NULL)
+ if (!mm || p->signal->oom_adj == OOM_DISABLE)
return 1;
- /*
- * Don't kill the process if any threads are set to OOM_DISABLE
- */
- do_each_thread(g, q) {
- if (q->mm == mm && q->oomkilladj == OOM_DISABLE)
- return 1;
- } while_each_thread(g, q);
-
__oom_kill_task(p, 1);
/*
@@ -394,8 +389,9 @@
if (printk_ratelimit()) {
printk(KERN_WARNING "%s invoked oom-killer: "
- "gfp_mask=0x%x, order=%d, oomkilladj=%d\n",
- current->comm, gfp_mask, order, current->oomkilladj);
+ "gfp_mask=0x%x, order=%d, oom_adj=%d\n",
+ current->comm, gfp_mask, order,
+ current->signal->oom_adj);
task_lock(current);
cpuset_print_task_mems_allowed(current);
task_unlock(current);