From: Jiayuan Chen The legacy memory.limit_in_bytes and memory.memsw.limit_in_bytes writers retry page_counter_set_max() by reclaiming synchronously in the writer context. memory.force_empty similarly loops in synchronous reclaim until the cgroup is empty or reclaim stops making progress. These writes hold a kernfs active reference on the file. If cgroup removal starts in parallel, the remover sets CSS_DYING and then waits in kernfs_drain() under cgroup_mutex for the active reference to drain. Continuing reclaim after the memcg is dying can therefore delay cgroup removal and keep cgroup_mutex held for a long time. Stop the v1 reclaim loops once the memcg is dying. For limit resizing, keep the existing -EBUSY semantics when the new limit could not be installed. For memory.force_empty, keep the existing best-effort success semantics. Reported-by: Zhou Yingfu Cc: Jiayuan Chen Signed-off-by: Jiayuan Chen --- mm/memcontrol-v1.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/mm/memcontrol-v1.c b/mm/memcontrol-v1.c index 765069211567..ad23de985d9a 100644 --- a/mm/memcontrol-v1.c +++ b/mm/memcontrol-v1.c @@ -1513,6 +1513,9 @@ static int mem_cgroup_resize_max(struct mem_cgroup *memcg, if (!ret) break; + if (memcg_is_dying(memcg)) + break; + if (!drained) { drain_all_stock(memcg); drained = true; @@ -1551,6 +1554,9 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg) if (signal_pending(current)) return -EINTR; + if (memcg_is_dying(memcg)) + break; + if (!try_to_free_mem_cgroup_pages(memcg, 1, GFP_KERNEL, MEMCG_RECLAIM_MAY_SWAP, NULL)) nr_retries--; -- 2.43.0