[PATCH v4 47/48] mm: shrinker: hold write lock to reparent shrinker nr_deferred
From: Qi Zheng <hidden>
Date: 2023-08-07 11:24:12
Also in:
dm-devel, dri-devel, kvm, linux-arm-msm, linux-bcache, linux-btrfs, linux-ext4, linux-f2fs-devel, linux-fsdevel, linux-mm, linux-nfs, linux-raid, linux-xfs, lkml, rcu, xen-devel
Subsystem:
memory management, shrinker, the rest · Maintainers:
Andrew Morton, Dave Chinner, Linus Torvalds
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 <redacted> --- mm/shrinker.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/shrinker.c b/mm/shrinker.c
index fee6f62904fb..a12dede5d21f 100644
--- a/mm/shrinker.c
+++ b/mm/shrinker.c@@ -299,7 +299,7 @@ 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);
@@ -312,7 +312,7 @@ 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