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Commit a7517e81 authored by Patrick Daly's avatar Patrick Daly
Browse files

psi: Add emergency trigger 



Provide a hook for the page allocator to call into before
declaring OOM.

Change-Id: I70e1d19395f8cfba4b56d11446670dd191b0a39f
Signed-off-by: default avatarPatrick Daly <pdaly@codeaurora.org>
parent 8d6e8215

include/linux/psi.h

+4 −0
Original line number Diff line number Diff line
@@ -23,6 +23,8 @@ void psi_memstall_leave(unsigned long *flags); 


int psi_show(struct seq_file *s, struct psi_group *group, enum psi_res res);



void psi_emergency_trigger(void);



#ifdef CONFIG_CGROUPS

int psi_cgroup_alloc(struct cgroup *cgrp);

void psi_cgroup_free(struct cgroup *cgrp);
@@ -43,6 +45,8 @@ static inline void psi_init(void) {} 
static inline void psi_memstall_enter(unsigned long *flags) {}

static inline void psi_memstall_leave(unsigned long *flags) {}



static inline void psi_emergency_trigger(void){}



#ifdef CONFIG_CGROUPS

static inline int psi_cgroup_alloc(struct cgroup *cgrp)

{

kernel/sched/psi.c

+25 −0
Original line number Diff line number Diff line
@@ -587,6 +587,31 @@ static u64 update_triggers(struct psi_group *group, u64 now) 
	return now + group->poll_min_period;

}



void psi_emergency_trigger(void)

{

	struct psi_group *group = &psi_system;

	struct psi_trigger *t;



	if (static_branch_likely(&psi_disabled))

		return;



	/*

	 * In unlikely case that OOM was triggered while adding/

	 * removing triggers.

	 */

	if (!mutex_trylock(&group->trigger_lock))

		return;



	list_for_each_entry(t, &group->triggers, node) {

		trace_psi_event(t->state, t->threshold);



		/* Generate an event */

		if (cmpxchg(&t->event, 0, 1) == 0)

			wake_up_interruptible(&t->event_wait);

	}

	mutex_unlock(&group->trigger_lock);

}



/*

 * Schedule polling if it's not already scheduled. It's safe to call even from

 * hotpath because even though kthread_queue_delayed_work takes worker->lock

mm/oom_kill.c

+29 −2
Original line number Diff line number Diff line
@@ -43,6 +43,7 @@ 
#include <linux/mmu_notifier.h>

#include <linux/memory_hotplug.h>

#include <linux/show_mem_notifier.h>

#include <linux/psi.h>



#include <asm/tlb.h>

#include "internal.h"
@@ -74,13 +75,39 @@ DEFINE_MUTEX(oom_lock); 


#ifdef CONFIG_HAVE_USERSPACE_LOW_MEMORY_KILLER

static atomic64_t ulmk_kill_jiffies = ATOMIC64_INIT(INITIAL_JIFFIES);

static unsigned long psi_emergency_jiffies = INITIAL_JIFFIES;

static DEFINE_MUTEX(ulmk_retry_lock);





/*

 * psi_emergency_jiffies represents the last ULMK emergency event.

 * Give ULMK a 2 second window to handle this event.

 * If ULMK has made some progress since then, send another.

 * Repeat as necessary.

 */

bool should_ulmk_retry(void)

{

	unsigned long j = atomic64_read(&ulmk_kill_jiffies);

	unsigned long now, last_kill;

	bool ret = false;



	mutex_lock(&ulmk_retry_lock);

	now = jiffies;

	last_kill = atomic64_read(&ulmk_kill_jiffies);

	if (time_before(now, psi_emergency_jiffies + 2 * HZ)) {

		ret = true;

		goto out;

	}



	if (time_after_eq(last_kill, psi_emergency_jiffies)) {

		psi_emergency_jiffies = now;

		psi_emergency_trigger();

		ret = true;

		goto out;

	}



	return time_before(jiffies, j + 2 * HZ);

out:

	mutex_unlock(&ulmk_retry_lock);

	return ret;

}



void ulmk_update_last_kill(void)

mm/page_alloc.c

+2 −3
Original line number Diff line number Diff line
@@ -4565,9 +4565,6 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, 
	if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL))

		goto nopage;



	if (order <= PAGE_ALLOC_COSTLY_ORDER && should_ulmk_retry())

		goto retry;



	if (should_reclaim_retry(gfp_mask, order, ac, alloc_flags,

				 did_some_progress > 0, &no_progress_loops))

		goto retry;
@@ -4585,6 +4582,8 @@ __alloc_pages_slowpath(gfp_t gfp_mask, unsigned int order, 
				&compaction_retries))

		goto retry;



	if (order <= PAGE_ALLOC_COSTLY_ORDER && should_ulmk_retry())

		goto retry;



	/* Deal with possible cpuset update races before we start OOM killing */

	if (check_retry_cpuset(cpuset_mems_cookie, ac))