Commit 20cd1892 authored by Qi Zheng's avatar Qi Zheng Committed by Andrew Morton
Browse files

mm: shrinkers: make count and scan in shrinker debugfs lockless 

Like global and memcg slab shrink, also use SRCU to make count and scan
operations in memory shrinker debugfs lockless.

Link: https://lkml.kernel.org/r/20230313112819.38938-6-zhengqi.arch@bytedance.com


Signed-off-by: default avatarQi Zheng <zhengqi.arch@bytedance.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarKirill Tkhai <tkhai@ya.ru>
Acked-by: default avatarRoman Gushchin <roman.gushchin@linux.dev>
Cc: Christian König <christian.koenig@amd.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Shakeel Butt <shakeelb@google.com>
Cc: Sultan Alsawaf <sultan@kerneltoast.com>
Cc: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Yang Shi <shy828301@gmail.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 475733dd

mm/shrinker_debug.c

+8 −17
Original line number Diff line number Diff line
@@ -5,10 +5,12 @@ 
#include <linux/seq_file.h>

#include <linux/shrinker.h>

#include <linux/memcontrol.h>

#include <linux/srcu.h>



/* defined in vmscan.c */

extern struct rw_semaphore shrinker_rwsem;

extern struct list_head shrinker_list;

extern struct srcu_struct shrinker_srcu;



static DEFINE_IDA(shrinker_debugfs_ida);

static struct dentry *shrinker_debugfs_root;
@@ -49,18 +51,13 @@ static int shrinker_debugfs_count_show(struct seq_file *m, void *v) 
	struct mem_cgroup *memcg;

	unsigned long total;

	bool memcg_aware;

	int ret, nid;

	int ret = 0, nid, srcu_idx;



	count_per_node = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL);

	if (!count_per_node)

		return -ENOMEM;



	ret = down_read_killable(&shrinker_rwsem);

	if (ret) {

		kfree(count_per_node);

		return ret;

	}

	rcu_read_lock();

	srcu_idx = srcu_read_lock(&shrinker_srcu);



	memcg_aware = shrinker->flags & SHRINKER_MEMCG_AWARE;
@@ -91,8 +88,7 @@ static int shrinker_debugfs_count_show(struct seq_file *m, void *v) 
		}

	} while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL);



	rcu_read_unlock();

	up_read(&shrinker_rwsem);

	srcu_read_unlock(&shrinker_srcu, srcu_idx);



	kfree(count_per_node);

	return ret;
@@ -115,9 +111,8 @@ static ssize_t shrinker_debugfs_scan_write(struct file *file, 
		.gfp_mask = GFP_KERNEL,

	};

	struct mem_cgroup *memcg = NULL;

	int nid;

	int nid, srcu_idx;

	char kbuf[72];

	ssize_t ret;



	read_len = size < (sizeof(kbuf) - 1) ? size : (sizeof(kbuf) - 1);

	if (copy_from_user(kbuf, buf, read_len))
@@ -146,11 +141,7 @@ static ssize_t shrinker_debugfs_scan_write(struct file *file, 
		return -EINVAL;

	}



	ret = down_read_killable(&shrinker_rwsem);

	if (ret) {

		mem_cgroup_put(memcg);

		return ret;

	}

	srcu_idx = srcu_read_lock(&shrinker_srcu);



	sc.nid = nid;

	sc.memcg = memcg;
@@ -159,7 +150,7 @@ static ssize_t shrinker_debugfs_scan_write(struct file *file, 


	shrinker->scan_objects(shrinker, &sc);



	up_read(&shrinker_rwsem);

	srcu_read_unlock(&shrinker_srcu, srcu_idx);

	mem_cgroup_put(memcg);



	return size;