Commit 476b30a0 authored by Yang Shi's avatar Yang Shi Committed by Linus Torvalds
Browse files

mm: vmscan: don't need allocate shrinker->nr_deferred for memcg aware shrinkers 

Now nr_deferred is available on per memcg level for memcg aware
shrinkers, so don't need allocate shrinker->nr_deferred for such
shrinkers anymore.

The prealloc_memcg_shrinker() would return -ENOSYS if !CONFIG_MEMCG or
memcg is disabled by kernel command line, then shrinker's
SHRINKER_MEMCG_AWARE flag would be cleared.  This makes the
implementation of this patch simpler.

Link: https://lkml.kernel.org/r/20210311190845.9708-12-shy828301@gmail.com


Signed-off-by: default avatarYang Shi <shy828301@gmail.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Reviewed-by: default avatarKirill Tkhai <ktkhai@virtuozzo.com>
Acked-by: default avatarRoman Gushchin <guro@fb.com>
Reviewed-by: default avatarShakeel Butt <shakeelb@google.com>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 86750830

mm/vmscan.c

+16 −15
Original line number Diff line number Diff line
@@ -346,6 +346,9 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker) 
{

	int id, ret = -ENOMEM;



	if (mem_cgroup_disabled())

		return -ENOSYS;



	down_write(&shrinker_rwsem);

	/* This may call shrinker, so it must use down_read_trylock() */

	id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);
@@ -425,7 +428,7 @@ static bool writeback_throttling_sane(struct scan_control *sc) 
#else

static int prealloc_memcg_shrinker(struct shrinker *shrinker)

{

	return 0;

	return -ENOSYS;

}



static void unregister_memcg_shrinker(struct shrinker *shrinker)
@@ -537,8 +540,18 @@ static unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, 
 */

int prealloc_shrinker(struct shrinker *shrinker)

{

	unsigned int size = sizeof(*shrinker->nr_deferred);

	unsigned int size;

	int err;



	if (shrinker->flags & SHRINKER_MEMCG_AWARE) {

		err = prealloc_memcg_shrinker(shrinker);

		if (err != -ENOSYS)

			return err;



		shrinker->flags &= ~SHRINKER_MEMCG_AWARE;

	}



	size = sizeof(*shrinker->nr_deferred);

	if (shrinker->flags & SHRINKER_NUMA_AWARE)

		size *= nr_node_ids;
@@ -546,28 +559,16 @@ int prealloc_shrinker(struct shrinker *shrinker) 
	if (!shrinker->nr_deferred)

		return -ENOMEM;



	if (shrinker->flags & SHRINKER_MEMCG_AWARE) {

		if (prealloc_memcg_shrinker(shrinker))

			goto free_deferred;

	}



	return 0;



free_deferred:

	kfree(shrinker->nr_deferred);

	shrinker->nr_deferred = NULL;

	return -ENOMEM;

}



void free_prealloced_shrinker(struct shrinker *shrinker)

{

	if (!shrinker->nr_deferred)

		return;



	if (shrinker->flags & SHRINKER_MEMCG_AWARE) {

		down_write(&shrinker_rwsem);

		unregister_memcg_shrinker(shrinker);

		up_write(&shrinker_rwsem);

		return;

	}



	kfree(shrinker->nr_deferred);