/**
* oom_kill - kill the "best" process when we run out of memory
*
* If we run out of memory, we have the choice between either
* killing a random task (bad), letting the system crash (worse)
* OR try to be smart about which process to kill. Note that we
* don't have to be perfect here, we just have to be good.
*/
static void oom_kill(void)
{
struct task_struct *p, *q;
read_lock(&tasklist_lock);
p = select_bad_process();
/* Found nothing?!?! Either we hang forever, or we panic. */
if (p == NULL)
panic("Out of memory and no killable processes...\n");
/* kill all processes that share the ->mm (i.e. all threads) */
for_each_task(q) {
if (q->mm == p->mm)
oom_kill_task(q);
}
read_unlock(&tasklist_lock);
/*
* Make kswapd go out of the way, so "p" has a good chance of
* killing itself before someone else gets the chance to ask
* for more memory.
*/
yield();
return;
}
/**
* oom_kill - kill the "best" process when we run out of memory
*
* If we run out of memory, we have the choice between either
* killing a random task (bad), letting the system crash (worse)
* OR try to be smart about which process to kill. Note that we
* don't have to be perfect here, we just have to be good.
*/
static void oom_kill(void)
{
struct task_struct *p = select_bad_process(), *q;
panic("Out of memory... our AP is an embedded system, every single process is useful, just panic NOW ! \n");
#if 0
/* Found nothing?!?! Either we hang forever, or we panic. */
if (p == NULL)
panic("Out of memory and no killable processes...\n");
#endif
/* kill all processes that share the ->mm (i.e. all threads) */
read_lock(&tasklist_lock);
for_each_task(q) {
if(q->mm == p->mm) oom_kill_task(q);
}
read_unlock(&tasklist_lock);
/*
* Make kswapd go out of the way, so "p" has a good chance of
* killing itself before someone else gets the chance to ask
* for more memory.
*/
current->policy |= SCHED_YIELD;
schedule();
return;
}
/**
* out_of_memory - kill the "best" process when we run out of memory
* @oc: pointer to struct oom_control
*
* If we run out of memory, we have the choice between either
* killing a random task (bad), letting the system crash (worse)
* OR try to be smart about which process to kill. Note that we
* don't have to be perfect here, we just have to be good.
*/
bool out_of_memory(struct oom_control *oc)
{
unsigned long freed = 0;
enum oom_constraint constraint = CONSTRAINT_NONE;
if (oom_killer_disabled)
return false;
if (!is_memcg_oom(oc)) {
blocking_notifier_call_chain(&oom_notify_list, 0, &freed);
if (freed > 0)
/* Got some memory back in the last second. */
return true;
}
/*
* If current has a pending SIGKILL or is exiting, then automatically
* select it. The goal is to allow it to allocate so that it may
* quickly exit and free its memory.
*/
if (task_will_free_mem(current)) {
mark_oom_victim(current);
wake_oom_reaper(current);
return true;
}
/*
* The OOM killer does not compensate for IO-less reclaim.
* pagefault_out_of_memory lost its gfp context so we have to
* make sure exclude 0 mask - all other users should have at least
* ___GFP_DIRECT_RECLAIM to get here.
*/
if (oc->gfp_mask && !(oc->gfp_mask & __GFP_FS))
return true;
/*
* Check if there were limitations on the allocation (only relevant for
* NUMA and memcg) that may require different handling.
*/
constraint = constrained_alloc(oc);
if (constraint != CONSTRAINT_MEMORY_POLICY)
oc->nodemask = NULL;
check_panic_on_oom(oc, constraint);
if (!is_memcg_oom(oc) && sysctl_oom_kill_allocating_task &&
current->mm && !oom_unkillable_task(current, NULL, oc->nodemask) &&
current->signal->oom_score_adj != OOM_SCORE_ADJ_MIN) {
get_task_struct(current);
oc->chosen = current;
oom_kill_process(oc, "Out of memory (oom_kill_allocating_task)");
return true;
}
select_bad_process(oc);
/* Found nothing?!?! */
if (!oc->chosen) {
dump_header(oc, NULL);
pr_warn("Out of memory and no killable processes...\n");
/*
* If we got here due to an actual allocation at the
* system level, we cannot survive this and will enter
* an endless loop in the allocator. Bail out now.
*/
if (!is_sysrq_oom(oc) && !is_memcg_oom(oc))
panic("System is deadlocked on memory\n");
}
if (oc->chosen && oc->chosen != (void *)-1UL)
oom_kill_process(oc, !is_memcg_oom(oc) ? "Out of memory" :
"Memory cgroup out of memory");
return !!oc->chosen;
}