Commit 8a0e8bb1 authored by Qi Zheng's avatar Qi Zheng Committed by Andrew Morton
Browse files

mm: shrinker: convert shrinker_rwsem to mutex 

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

[akpm@linux-foundation.org: update the fix to alloc_shrinker_info()]
Link: https://lkml.kernel.org/r/20230911094444.68966-46-zhengqi.arch@bytedance.com


Signed-off-by: default avatarQi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: default avatarMuchun Song <songmuchun@bytedance.com>
Cc: Abhinav Kumar <quic_abhinavk@quicinc.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: Andreas Gruenbacher <agruenba@redhat.com>
Cc: Anna Schumaker <anna@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Bob Peterson <rpeterso@redhat.com>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Carlos Llamas <cmllamas@google.com>
Cc: Chandan Babu R <chandan.babu@oracle.com>
Cc: Chao Yu <chao@kernel.org>
Cc: Chris Mason <clm@fb.com>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Christian Koenig <christian.koenig@amd.com>
Cc: Chuck Lever <cel@kernel.org>
Cc: Coly Li <colyli@suse.de>
Cc: Dai Ngo <Dai.Ngo@oracle.com>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Daniel Vetter <daniel.vetter@ffwll.ch>
Cc: "Darrick J. Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Dave Hansen <dave.hansen@linux.intel.com>
Cc: David Airlie <airlied@gmail.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: David Sterba <dsterba@suse.com>
Cc: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Cc: Gao Xiang <hsiangkao@linux.alibaba.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Huang Rui <ray.huang@amd.com>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Jaegeuk Kim <jaegeuk@kernel.org>
Cc: Jani Nikula <jani.nikula@linux.intel.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Jason Wang <jasowang@redhat.com>
Cc: Jeff Layton <jlayton@kernel.org>
Cc: Jeffle Xu <jefflexu@linux.alibaba.com>
Cc: Joel Fernandes (Google) <joel@joelfernandes.org>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Cc: Josef Bacik <josef@toxicpanda.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Kent Overstreet <kent.overstreet@gmail.com>
Cc: Kirill Tkhai <tkhai@ya.ru>
Cc: Marijn Suijten <marijn.suijten@somainline.org>
Cc: "Michael S. Tsirkin" <mst@redhat.com>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Nadav Amit <namit@vmware.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Oleksandr Tyshchenko <oleksandr_tyshchenko@epam.com>
Cc: Olga Kornievskaia <kolga@netapp.com>
Cc: Paul E. McKenney <paulmck@kernel.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rob Clark <robdclark@gmail.com>
Cc: Rob Herring <robh@kernel.org>
Cc: Rodrigo Vivi <rodrigo.vivi@intel.com>
Cc: Roman Gushchin <roman.gushchin@linux.dev>
Cc: Sean Paul <sean@poorly.run>
Cc: Sergey Senozhatsky <senozhatsky@chromium.org>
Cc: Song Liu <song@kernel.org>
Cc: Stefano Stabellini <sstabellini@kernel.org>
Cc: Steven Price <steven.price@arm.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tomeu Vizoso <tomeu.vizoso@collabora.com>
Cc: Tom Talpey <tom@talpey.com>
Cc: Trond Myklebust <trond.myklebust@hammerspace.com>
Cc: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Xuan Zhuo <xuanzhuo@linux.alibaba.com>
Cc: Yue Hu <huyue2@coolpad.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 604b8b65

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);

fs/super.c

+1 −1
Original line number Diff line number Diff line
@@ -178,7 +178,7 @@ static void super_wake(struct super_block *sb, unsigned int flag) 
 * 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.c

+15 −15
Original line number Diff line number Diff line
@@ -8,7 +8,7 @@ 
#include "internal.h"



LIST_HEAD(shrinker_list);

DECLARE_RWSEM(shrinker_rwsem);

DEFINE_MUTEX(shrinker_mutex);



#ifdef CONFIG_MEMCG

static int shrinker_nr_max;
@@ -80,7 +80,7 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) 
	int nid, ret = 0;

	int array_size = 0;



	down_write(&shrinker_rwsem);

	mutex_lock(&shrinker_mutex);

	array_size = shrinker_unit_size(shrinker_nr_max);

	for_each_node(nid) {

		info = kvzalloc_node(sizeof(*info) + array_size, GFP_KERNEL, nid);
@@ -91,12 +91,12 @@ int alloc_shrinker_info(struct mem_cgroup *memcg) 
			goto err;

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

	}

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);



	return ret;



err:

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);

	free_shrinker_info(memcg);

	return -ENOMEM;

}
@@ -105,7 +105,7 @@ static struct shrinker_info *shrinker_info_protected(struct mem_cgroup *memcg, 
						     int nid)

{

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

					 lockdep_is_held(&shrinker_rwsem));

					 lockdep_is_held(&shrinker_mutex));

}



static int expand_one_shrinker_info(struct mem_cgroup *memcg, int new_size,
@@ -155,7 +155,7 @@ static int expand_shrinker_info(int new_id) 
	if (!root_mem_cgroup)

		goto out;



	lockdep_assert_held(&shrinker_rwsem);

	lockdep_assert_held(&shrinker_mutex);



	new_size = shrinker_unit_size(new_nr_max);

	old_size = shrinker_unit_size(shrinker_nr_max);
@@ -218,7 +218,7 @@ static int shrinker_memcg_alloc(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;
@@ -232,7 +232,7 @@ static int shrinker_memcg_alloc(struct shrinker *shrinker) 
	shrinker->id = id;

	ret = 0;

unlock:

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);

	return ret;

}
@@ -242,7 +242,7 @@ static void shrinker_memcg_remove(struct shrinker *shrinker) 


	BUG_ON(id < 0);



	lockdep_assert_held(&shrinker_rwsem);

	lockdep_assert_held(&shrinker_mutex);



	idr_remove(&shrinker_idr, id);

}
@@ -293,7 +293,7 @@ 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);
@@ -306,7 +306,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) 
			}

		}

	}

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);

}

#else

static int shrinker_memcg_alloc(struct shrinker *shrinker)
@@ -740,11 +740,11 @@ void shrinker_register(struct shrinker *shrinker) 
		return;

	}



	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);



	init_completion(&shrinker->done);

	/*
@@ -784,7 +784,7 @@ void shrinker_free(struct shrinker *shrinker) 
		wait_for_completion(&shrinker->done);

	}



	down_write(&shrinker_rwsem);

	mutex_lock(&shrinker_mutex);

	if (shrinker->flags & SHRINKER_REGISTERED) {

		/*

		 * Now we can safely remove it from the shrinker_list and then
@@ -799,7 +799,7 @@ void shrinker_free(struct shrinker *shrinker) 


	if (shrinker->flags & SHRINKER_MEMCG_AWARE)

		shrinker_memcg_remove(shrinker);

	up_write(&shrinker_rwsem);

	mutex_unlock(&shrinker_mutex);



	if (debugfs_entry)

		shrinker_debugfs_remove(debugfs_entry, debugfs_id);

mm/shrinker_debug.c

+7 −7
Original line number Diff line number Diff line
@@ -9,7 +9,7 @@ 
#include "internal.h"



/* defined in vmscan.c */

extern struct rw_semaphore shrinker_rwsem;

extern struct mutex shrinker_mutex;

extern struct list_head shrinker_list;



static DEFINE_IDA(shrinker_debugfs_ida);
@@ -165,7 +165,7 @@ 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)
@@ -208,7 +208,7 @@ 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;
@@ -226,7 +226,7 @@ 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);
@@ -239,7 +239,7 @@ struct dentry *shrinker_debugfs_detach(struct shrinker *shrinker, 
{

	struct dentry *entry = shrinker->debugfs_entry;



	lockdep_assert_held(&shrinker_rwsem);

	lockdep_assert_held(&shrinker_mutex);



	*debugfs_id = entry ? shrinker->debugfs_id : -1;

	shrinker->debugfs_entry = NULL;
@@ -265,14 +265,14 @@ 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;

}