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Commit 1f4c00bc authored by Charan Teja Reddy's avatar Charan Teja Reddy
Browse files

mm: check for possibility of ulmk kills in should_ulmk_retry 



Improve the should_ulmk_retry() logic by traversing through the
processes in the system in search for tasks that have the oom_score_adj
>= 0. This can avoid the premature OOM.

Change-Id: I8dd85cc66ab786b979b2a83d03d951e83c75744a
Signed-off-by: default avatarCharan Teja Reddy <charante@codeaurora.org>
parent c7448bfb

mm/oom_kill.c

+36 −0
Original line number Diff line number Diff line
@@ -80,6 +80,28 @@ static atomic64_t ulmk_kill_jiffies = ATOMIC64_INIT(INITIAL_JIFFIES); 
static unsigned long psi_emergency_jiffies = INITIAL_JIFFIES;

static DEFINE_MUTEX(ulmk_retry_lock);



static bool ulmk_kill_possible(void)

{

	struct task_struct *tsk;

	bool ret = false;



	rcu_read_lock();

	for_each_process(tsk) {

		if (tsk->flags & PF_KTHREAD)

			continue;



		task_lock(tsk);

		if (tsk->signal->oom_score_adj >= 0) {

			ret = true;

			task_unlock(tsk);

			break;

		}

		task_unlock(tsk);

	}

	rcu_read_unlock();



	return ret;

}



/*

 * psi_emergency_jiffies represents the last ULMK emergency event.
@@ -107,6 +129,20 @@ bool should_ulmk_retry(void) 
		goto out;

	}



	/*

	 * We reached here means no kill have had happened since the last

	 * emergency trigger for 2*HZ window. We can't derive the status

	 * of the low memory killer here. So, before falling back to OOM,

	 * check for any +ve adj tasks left in the system in repeat for

	 * next 20*HZ. Indirectly the below logic also giving 20HZ window

	 * for the first emergency trigger.

	 */

	if (time_after(psi_emergency_jiffies + 20 * HZ, now) &&

	    ulmk_kill_possible()) {

		ret = true;

		goto out;

	}



out:

	mutex_unlock(&ulmk_retry_lock);

	return ret;