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: Qi Zheng <zhengqi.arch@bytedance.com>
Reviewed-by: Muchun 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: Andrew Morton <akpm@linux-foundation.org>

1 files changed, 15 insertions, 15 deletions

diff --git a/mm/shrinker.c b/mm/shrinker.c
index ef22f20a97cb..dd91eab43ed3 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -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);