[PATCH 27/29] mm: vmscan: hold write lock to reparent shrinker nr_deferred
From: Qi Zheng <hidden>
Date: 2023-06-22 09:06:12
Also in:
dm-devel, dri-devel, intel-gfx, linux-arm-msm, linux-bcache, linux-btrfs, linux-ext4, linux-fsdevel, linux-mm, linux-nfs, linux-xfs, lkml
Subsystem:
memory management, memory management - mglru (multi-gen lru), memory management - reclaim, the rest · Maintainers:
Andrew Morton, Johannes Weiner, 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/vmscan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 357a1f2ad690..0711b63e68d9 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c@@ -433,7 +433,7 @@ 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);
@@ -442,7 +442,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) atomic_long_add(nr, &parent_info->nr_deferred[i]); } } - up_read(&shrinker_rwsem); + up_write(&shrinker_rwsem); } static bool cgroup_reclaim(struct scan_control *sc)
--
2.30.2