The quilt patch titled Subject: mm/list_lru: code clean up for reparenting has been removed from the -mm tree. Its filename was mm-list_lru-code-clean-up-for-reparenting.patch This patch was dropped because it was merged into the mm-stable branch of git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm ------------------------------------------------------ From: Kairui Song <kasong@xxxxxxxxxxx> Subject: mm/list_lru: code clean up for reparenting Date: Tue, 5 Nov 2024 01:52:54 +0800 No feature change, just change of code structure and fix comment. The list lrus are not empty until memcg_reparent_list_lru_node() calls are all done, so the comments in memcg_offline_kmem were slightly inaccurate. Link: https://lkml.kernel.org/r/20241104175257.60853-4-ryncsn@xxxxxxxxx Signed-off-by: Kairui Song <kasong@xxxxxxxxxxx> Reviewed-by: Muchun Song <muchun.song@xxxxxxxxx> Acked-by: Shakeel Butt <shakeel.butt@xxxxxxxxx> Cc: Chengming Zhou <zhouchengming@xxxxxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Cc: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx> Cc: Michal Hocko <mhocko@xxxxxxxx> Cc: Qi Zheng <zhengqi.arch@xxxxxxxxxxxxx> Cc: Roman Gushchin <roman.gushchin@xxxxxxxxx> Cc: Waiman Long <longman@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/list_lru.c | 39 +++++++++++++++++---------------------- mm/memcontrol.c | 7 ------- 2 files changed, 17 insertions(+), 29 deletions(-) --- a/mm/list_lru.c~mm-list_lru-code-clean-up-for-reparenting +++ a/mm/list_lru.c @@ -421,35 +421,16 @@ out: spin_unlock_irq(&nlru->lock); } -static void memcg_reparent_list_lru(struct list_lru *lru, - int src_idx, struct mem_cgroup *dst_memcg) -{ - int i; - - for_each_node(i) - memcg_reparent_list_lru_node(lru, i, src_idx, dst_memcg); - - memcg_list_lru_free(lru, src_idx); -} - void memcg_reparent_list_lrus(struct mem_cgroup *memcg, struct mem_cgroup *parent) { struct cgroup_subsys_state *css; struct list_lru *lru; - int src_idx = memcg->kmemcg_id; + int src_idx = memcg->kmemcg_id, i; /* * Change kmemcg_id of this cgroup and all its descendants to the * parent's id, and then move all entries from this cgroup's list_lrus * to ones of the parent. - * - * After we have finished, all list_lrus corresponding to this cgroup - * are guaranteed to remain empty. So we can safely free this cgroup's - * list lrus in memcg_list_lru_free(). - * - * Changing ->kmemcg_id to the parent can prevent memcg_list_lru_alloc() - * from allocating list lrus for this cgroup after memcg_list_lru_free() - * call. */ rcu_read_lock(); css_for_each_descendant_pre(css, &memcg->css) { @@ -460,9 +441,23 @@ void memcg_reparent_list_lrus(struct mem } rcu_read_unlock(); + /* + * With kmemcg_id set to parent, holding the lock of each list_lru_node + * below can prevent list_lru_{add,del,isolate} from touching the lru, + * safe to reparent. + */ mutex_lock(&list_lrus_mutex); - list_for_each_entry(lru, &memcg_list_lrus, list) - memcg_reparent_list_lru(lru, src_idx, parent); + list_for_each_entry(lru, &memcg_list_lrus, list) { + for_each_node(i) + memcg_reparent_list_lru_node(lru, i, src_idx, parent); + + /* + * Here all list_lrus corresponding to the cgroup are guaranteed + * to remain empty, we can safely free this lru, any further + * memcg_list_lru_alloc() call will simply bail out. + */ + memcg_list_lru_free(lru, src_idx); + } mutex_unlock(&list_lrus_mutex); } --- a/mm/memcontrol.c~mm-list_lru-code-clean-up-for-reparenting +++ a/mm/memcontrol.c @@ -3111,13 +3111,6 @@ static void memcg_offline_kmem(struct me parent = root_mem_cgroup; memcg_reparent_objcgs(memcg, parent); - - /* - * After we have finished memcg_reparent_objcgs(), all list_lrus - * corresponding to this cgroup are guaranteed to remain empty. - * The ordering is imposed by list_lru_node->lock taken by - * memcg_reparent_list_lrus(). - */ memcg_reparent_list_lrus(memcg, parent); } _ Patches currently in -mm which might be from kasong@xxxxxxxxxxx are