Commit e972a070 authored by David Rientjes's avatar David Rientjes Committed by Linus Torvalds
Browse files

mm, oom: rename zonelist locking functions 



try_set_zonelist_oom() and clear_zonelist_oom() are not named properly
to imply that they require locking semantics to avoid out_of_memory()
being reordered.

zone_scan_lock is required for both functions to ensure that there is
proper locking synchronization.

Rename try_set_zonelist_oom() to oom_zonelist_trylock() and rename
clear_zonelist_oom() to oom_zonelist_unlock() to imply there is proper
locking semantics.

At the same time, convert oom_zonelist_trylock() to return bool instead
of int since only success and failure are tested.

Signed-off-by: default avatarDavid Rientjes <rientjes@google.com>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 8d060bf4

include/linux/oom.h

+2 −2
Original line number Original line Diff line number Diff line
@@ -55,8 +55,8 @@ extern void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, 
			     struct mem_cgroup *memcg, nodemask_t *nodemask,

			     struct mem_cgroup *memcg, nodemask_t *nodemask,

			     const char *message);

			     const char *message);





extern int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);

extern bool oom_zonelist_trylock(struct zonelist *zonelist, gfp_t gfp_flags);

extern void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_flags);

extern void oom_zonelist_unlock(struct zonelist *zonelist, gfp_t gfp_flags);





extern void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,

extern void check_panic_on_oom(enum oom_constraint constraint, gfp_t gfp_mask,

			       int order, const nodemask_t *nodemask);

			       int order, const nodemask_t *nodemask);

mm/oom_kill.c

+13 −17
Original line number Original line Diff line number Diff line
@@ -559,28 +559,25 @@ EXPORT_SYMBOL_GPL(unregister_oom_notifier); 
 * if a parallel OOM killing is already taking place that includes a zone in

 * if a parallel OOM killing is already taking place that includes a zone in

 * the zonelist.  Otherwise, locks all zones in the zonelist and returns 1.

 * the zonelist.  Otherwise, locks all zones in the zonelist and returns 1.

 */

 */

int try_set_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask)

bool oom_zonelist_trylock(struct zonelist *zonelist, gfp_t gfp_mask)

{

{

	struct zoneref *z;

	struct zoneref *z;

	struct zone *zone;

	struct zone *zone;

	int ret = 1;

	bool ret = true;





	spin_lock(&zone_scan_lock);

	spin_lock(&zone_scan_lock);

	for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) {

	for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask))

		if (zone_is_oom_locked(zone)) {

		if (zone_is_oom_locked(zone)) {

			ret = 0;

			ret = false;

			goto out;

			goto out;

		}

		}

	}





	for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) {

	/*

	/*

		 * Lock each zone in the zonelist under zone_scan_lock so a

	 * Lock each zone in the zonelist under zone_scan_lock so a parallel

		 * parallel invocation of try_set_zonelist_oom() doesn't succeed

	 * call to oom_zonelist_trylock() doesn't succeed when it shouldn't.

		 * when it shouldn't.

	 */

	 */

	for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask))

		zone_set_flag(zone, ZONE_OOM_LOCKED);

		zone_set_flag(zone, ZONE_OOM_LOCKED);

	}





out:

out:

	spin_unlock(&zone_scan_lock);

	spin_unlock(&zone_scan_lock);
@@ -592,15 +589,14 @@ out: 
 * allocation attempts with zonelists containing them may now recall the OOM

 * allocation attempts with zonelists containing them may now recall the OOM

 * killer, if necessary.

 * killer, if necessary.

 */

 */

void clear_zonelist_oom(struct zonelist *zonelist, gfp_t gfp_mask)

void oom_zonelist_unlock(struct zonelist *zonelist, gfp_t gfp_mask)

{

{

	struct zoneref *z;

	struct zoneref *z;

	struct zone *zone;

	struct zone *zone;





	spin_lock(&zone_scan_lock);

	spin_lock(&zone_scan_lock);

	for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask)) {

	for_each_zone_zonelist(zone, z, zonelist, gfp_zone(gfp_mask))

		zone_clear_flag(zone, ZONE_OOM_LOCKED);

		zone_clear_flag(zone, ZONE_OOM_LOCKED);

	}

	spin_unlock(&zone_scan_lock);

	spin_unlock(&zone_scan_lock);

}

}
@@ -695,8 +691,8 @@ void pagefault_out_of_memory(void) 
		return;

		return;





	zonelist = node_zonelist(first_memory_node, GFP_KERNEL);

	zonelist = node_zonelist(first_memory_node, GFP_KERNEL);

	if (try_set_zonelist_oom(zonelist, GFP_KERNEL)) {

	if (oom_zonelist_trylock(zonelist, GFP_KERNEL)) {

		out_of_memory(NULL, 0, 0, NULL, false);

		out_of_memory(NULL, 0, 0, NULL, false);

		clear_zonelist_oom(zonelist, GFP_KERNEL);

		oom_zonelist_unlock(zonelist, GFP_KERNEL);

	}

	}

}
 
}

mm/page_alloc.c

+3 −3
Original line number Original line Diff line number Diff line
@@ -2246,8 +2246,8 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, 
{

{

	struct page *page;

	struct page *page;





	/* Acquire the OOM killer lock for the zones in zonelist */

	/* Acquire the per-zone oom lock for each zone */

	if (!try_set_zonelist_oom(zonelist, gfp_mask)) {

	if (!oom_zonelist_trylock(zonelist, gfp_mask)) {

		schedule_timeout_uninterruptible(1);

		schedule_timeout_uninterruptible(1);

		return NULL;

		return NULL;

	}

	}
@@ -2285,7 +2285,7 @@ __alloc_pages_may_oom(gfp_t gfp_mask, unsigned int order, 
	out_of_memory(zonelist, gfp_mask, order, nodemask, false);

	out_of_memory(zonelist, gfp_mask, order, nodemask, false);





out:

out:

	clear_zonelist_oom(zonelist, gfp_mask);

	oom_zonelist_unlock(zonelist, gfp_mask);

	return page;

	return page;

}

}

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