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Message-Id: <20230824034304.37411-45-zhengqi.arch@bytedance.com>
Date: Thu, 24 Aug 2023 11:43:03 +0800
From: Qi Zheng <zhengqi.arch@...edance.com>
To: akpm@...ux-foundation.org, david@...morbit.com, tkhai@...ru,
vbabka@...e.cz, roman.gushchin@...ux.dev, djwong@...nel.org,
brauner@...nel.org, paulmck@...nel.org, tytso@....edu,
steven.price@....com, cel@...nel.org, senozhatsky@...omium.org,
yujie.liu@...el.com, gregkh@...uxfoundation.org,
muchun.song@...ux.dev
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org,
linux-fsdevel@...r.kernel.org,
Qi Zheng <zhengqi.arch@...edance.com>
Subject: [PATCH v5 44/45] mm: shrinker: hold write lock to reparent shrinker nr_deferred
For now, reparent_shrinker_deferred() is the only holder of read lock of
shrinker_rwsem. And it already holds the global cgroup_mutex, so it will
not be called in parallel.
Therefore, in order to convert shrinker_rwsem to shrinker_mutex later,
here we change to hold the write lock of shrinker_rwsem to reparent.
Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
---
mm/shrinker.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/shrinker.c b/mm/shrinker.c
index a66e2a30cc16..b8cb9d2f5dbf 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c
@@ -292,7 +292,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg)
parent = root_mem_cgroup;
/* Prevent from concurrent shrinker_info expand */
- down_read(&shrinker_rwsem);
+ down_write(&shrinker_rwsem);
for_each_node(nid) {
child_info = shrinker_info_protected(memcg, nid);
parent_info = shrinker_info_protected(parent, nid);
@@ -305,7 +305,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg)
}
}
}
- up_read(&shrinker_rwsem);
+ up_write(&shrinker_rwsem);
}
#else
static int shrinker_memcg_alloc(struct shrinker *shrinker)
--
2.30.2
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