Commit cf2e309e authored by Qi Zheng's avatar Qi Zheng Committed by Andrew Morton
Browse files

mm: shrinkers: convert shrinker_rwsem to mutex 

Now there are no readers of shrinker_rwsem, so we can simply replace it
with mutex lock.

Link: https://lkml.kernel.org/r/20230313112819.38938-9-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 1643db98

drivers/md/dm-cache-metadata.c

+1 −1
Original line number Diff line number Diff line
@@ -1828,7 +1828,7 @@ int dm_cache_metadata_abort(struct dm_cache_metadata *cmd) 
	 * Replacement block manager (new_bm) is created and old_bm destroyed outside of

	 * cmd root_lock to avoid ABBA deadlock that would result (due to life-cycle of

	 * shrinker associated with the block manager's bufio client vs cmd root_lock).

	 * - must take shrinker_rwsem without holding cmd->root_lock

	 * - must take shrinker_mutex without holding cmd->root_lock

	 */

	new_bm = dm_block_manager_create(cmd->bdev, DM_CACHE_METADATA_BLOCK_SIZE << SECTOR_SHIFT,

					 CACHE_MAX_CONCURRENT_LOCKS);

drivers/md/dm-thin-metadata.c

+1 −1
Original line number Diff line number Diff line
@@ -1887,7 +1887,7 @@ int dm_pool_abort_metadata(struct dm_pool_metadata *pmd) 
	 * Replacement block manager (new_bm) is created and old_bm destroyed outside of

	 * pmd root_lock to avoid ABBA deadlock that would result (due to life-cycle of

	 * shrinker associated with the block manager's bufio client vs pmd root_lock).

	 * - must take shrinker_rwsem without holding pmd->root_lock

	 * - must take shrinker_mutex without holding pmd->root_lock

	 */

	new_bm = dm_block_manager_create(pmd->bdev, THIN_METADATA_BLOCK_SIZE << SECTOR_SHIFT,

					 THIN_MAX_CONCURRENT_LOCKS);

fs/super.c

+1 −1
Original line number Diff line number Diff line
@@ -54,7 +54,7 @@ static char *sb_writers_name[SB_FREEZE_LEVELS] = { 
 * One thing we have to be careful of with a per-sb shrinker is that we don't

 * drop the last active reference to the superblock from within the shrinker.

 * If that happens we could trigger unregistering the shrinker from within the

 * shrinker path and that leads to deadlock on the shrinker_rwsem. Hence we

 * shrinker path and that leads to deadlock on the shrinker_mutex. Hence we

 * take a passive reference to the superblock to avoid this from occurring.

 */

static unsigned long super_cache_scan(struct shrinker *shrink,

mm/shrinker_debug.c

+7 −7
Original line number Diff line number Diff line
@@ -8,7 +8,7 @@ 
#include <linux/srcu.h>



/* defined in vmscan.c */

extern struct rw_semaphore shrinker_rwsem;

extern struct mutex shrinker_mutex;

extern struct list_head shrinker_list;

extern struct srcu_struct shrinker_srcu;
@@ -168,7 +168,7 @@ int shrinker_debugfs_add(struct shrinker *shrinker) 
	char buf[128];

	int id;



	lockdep_assert_held(&shrinker_rwsem);

	lockdep_assert_held(&shrinker_mutex);



	/* debugfs isn't initialized yet, add debugfs entries later. */

	if (!shrinker_debugfs_root)
@@ -211,7 +211,7 @@ int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...) 
	if (!new)

		return -ENOMEM;



	down_write(&shrinker_rwsem);

	mutex_lock(&shrinker_mutex);



	old = shrinker->name;

	shrinker->name = new;
@@ -229,7 +229,7 @@ int shrinker_debugfs_rename(struct shrinker *shrinker, const char *fmt, ...) 
			shrinker->debugfs_entry = entry;

	}



	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);



	kfree_const(old);
@@ -241,7 +241,7 @@ struct dentry *shrinker_debugfs_remove(struct shrinker *shrinker) 
{

	struct dentry *entry = shrinker->debugfs_entry;



	lockdep_assert_held(&shrinker_rwsem);

	lockdep_assert_held(&shrinker_mutex);



	kfree_const(shrinker->name);

	shrinker->name = NULL;
@@ -266,14 +266,14 @@ static int __init shrinker_debugfs_init(void) 
	shrinker_debugfs_root = dentry;



	/* Create debugfs entries for shrinkers registered at boot */

	down_write(&shrinker_rwsem);

	mutex_lock(&shrinker_mutex);

	list_for_each_entry(shrinker, &shrinker_list, list)

		if (!shrinker->debugfs_entry) {

			ret = shrinker_debugfs_add(shrinker);

			if (ret)

				break;

		}

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);



	return ret;

}

mm/vmscan.c

+17 −17
Original line number Diff line number Diff line
@@ -35,7 +35,7 @@ 
#include <linux/cpuset.h>

#include <linux/compaction.h>

#include <linux/notifier.h>

#include <linux/rwsem.h>

#include <linux/mutex.h>

#include <linux/delay.h>

#include <linux/kthread.h>

#include <linux/freezer.h>
@@ -202,7 +202,7 @@ static void set_task_reclaim_state(struct task_struct *task, 
}



LIST_HEAD(shrinker_list);

DECLARE_RWSEM(shrinker_rwsem);

DEFINE_MUTEX(shrinker_mutex);

DEFINE_SRCU(shrinker_srcu);

static atomic_t shrinker_srcu_generation = ATOMIC_INIT(0);
@@ -225,7 +225,7 @@ static struct shrinker_info *shrinker_info_protected(struct mem_cgroup *memcg, 
{

	return srcu_dereference_check(memcg->nodeinfo[nid]->shrinker_info,

				      &shrinker_srcu,

				      lockdep_is_held(&shrinker_rwsem));

				      lockdep_is_held(&shrinker_mutex));

}



static struct shrinker_info *shrinker_info_srcu(struct mem_cgroup *memcg,
@@ -304,7 +304,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) 
	int nid, size, ret = 0;

	int map_size, defer_size = 0;



	down_write(&shrinker_rwsem);

	mutex_lock(&shrinker_mutex);

	map_size = shrinker_map_size(shrinker_nr_max);

	defer_size = shrinker_defer_size(shrinker_nr_max);

	size = map_size + defer_size;
@@ -320,7 +320,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) 
		info->map_nr_max = shrinker_nr_max;

		rcu_assign_pointer(memcg->nodeinfo[nid]->shrinker_info, info);

	}

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);



	return ret;

}
@@ -336,7 +336,7 @@ static int expand_shrinker_info(int new_id) 
	if (!root_mem_cgroup)

		goto out;



	lockdep_assert_held(&shrinker_rwsem);

	lockdep_assert_held(&shrinker_mutex);



	map_size = shrinker_map_size(new_nr_max);

	defer_size = shrinker_defer_size(new_nr_max);
@@ -386,7 +386,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker) 
	if (mem_cgroup_disabled())

		return -ENOSYS;



	down_write(&shrinker_rwsem);

	mutex_lock(&shrinker_mutex);

	id = idr_alloc(&shrinker_idr, shrinker, 0, 0, GFP_KERNEL);

	if (id < 0)

		goto unlock;
@@ -400,7 +400,7 @@ static int prealloc_memcg_shrinker(struct shrinker *shrinker) 
	shrinker->id = id;

	ret = 0;

unlock:

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);

	return ret;

}
@@ -410,7 +410,7 @@ static void unregister_memcg_shrinker(struct shrinker *shrinker) 


	BUG_ON(id < 0);



	lockdep_assert_held(&shrinker_rwsem);

	lockdep_assert_held(&shrinker_mutex);



	idr_remove(&shrinker_idr, id);

}
@@ -445,7 +445,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) 
		parent = root_mem_cgroup;



	/* Prevent from concurrent shrinker_info expand */

	down_write(&shrinker_rwsem);

	mutex_lock(&shrinker_mutex);

	for_each_node(nid) {

		child_info = shrinker_info_protected(memcg, nid);

		parent_info = shrinker_info_protected(parent, nid);
@@ -454,7 +454,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) 
			atomic_long_add(nr, &parent_info->nr_deferred[i]);

		}

	}

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);

}



static bool cgroup_reclaim(struct scan_control *sc)
@@ -703,9 +703,9 @@ void free_prealloced_shrinker(struct shrinker *shrinker) 
	shrinker->name = NULL;

#endif

	if (shrinker->flags & SHRINKER_MEMCG_AWARE) {

		down_write(&shrinker_rwsem);

		mutex_lock(&shrinker_mutex);

		unregister_memcg_shrinker(shrinker);

		up_write(&shrinker_rwsem);

		mutex_unlock(&shrinker_mutex);

		return;

	}
@@ -715,11 +715,11 @@ void free_prealloced_shrinker(struct shrinker *shrinker) 


void register_shrinker_prepared(struct shrinker *shrinker)

{

	down_write(&shrinker_rwsem);

	mutex_lock(&shrinker_mutex);

	list_add_tail_rcu(&shrinker->list, &shrinker_list);

	shrinker->flags |= SHRINKER_REGISTERED;

	shrinker_debugfs_add(shrinker);

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);

}



static int __register_shrinker(struct shrinker *shrinker)
@@ -769,13 +769,13 @@ void unregister_shrinker(struct shrinker *shrinker) 
	if (!(shrinker->flags & SHRINKER_REGISTERED))

		return;



	down_write(&shrinker_rwsem);

	mutex_lock(&shrinker_mutex);

	list_del_rcu(&shrinker->list);

	shrinker->flags &= ~SHRINKER_REGISTERED;

	if (shrinker->flags & SHRINKER_MEMCG_AWARE)

		unregister_memcg_shrinker(shrinker);

	debugfs_entry = shrinker_debugfs_remove(shrinker);

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);



	atomic_inc(&shrinker_srcu_generation);

	synchronize_srcu(&shrinker_srcu);