From 1d5f6069f6212c51aa56b64922e60ec4eb3c0e3a Mon Sep 17 00:00:00 2001 From: ZhangPeng Date: Tue, 24 Dec 2024 16:47:53 +0800 Subject: [PATCH 17/23] Revert "cgroup: Make operations on the cgroup root_list RCU safe" hulk inclusion category: feature bugzilla: https://gitee.com/openeuler/kernel/issues/IBDFAV ---------------------------------------------------------------------- This reverts commit 486eff6ae48b78edc20a4e51596f332c20f2f75f. Signed-off-by: ZhangPeng --- include/linux/cgroup-defs.h | 1 - kernel/cgroup/cgroup-internal.h | 3 +-- kernel/cgroup/cgroup.c | 23 +++++++---------------- 3 files changed, 8 insertions(+), 19 deletions(-) diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 05ece896af7d..6e3227a688de 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -591,7 +591,6 @@ struct cgroup_root { /* A list running through the active hierarchies */ struct list_head root_list; - struct rcu_head rcu; /* Hierarchy-specific flags */ unsigned int flags; diff --git a/kernel/cgroup/cgroup-internal.h b/kernel/cgroup/cgroup-internal.h index f5fb12890645..96a9bd2c26f0 100644 --- a/kernel/cgroup/cgroup-internal.h +++ b/kernel/cgroup/cgroup-internal.h @@ -170,8 +170,7 @@ extern struct list_head cgroup_roots; /* iterate across the hierarchies */ #define for_each_root(root) \ - list_for_each_entry_rcu((root), &cgroup_roots, root_list, \ - lockdep_is_held(&cgroup_mutex)) + list_for_each_entry((root), &cgroup_roots, root_list) /** * for_each_subsys - iterate all enabled cgroup subsystems diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index c26a9b3a3576..52fe6ba2fefd 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -1315,7 +1315,7 @@ static void cgroup_exit_root_id(struct cgroup_root *root) void cgroup_free_root(struct cgroup_root *root) { - kfree_rcu(root, rcu); + kfree(root); } static void cgroup_destroy_root(struct cgroup_root *root) @@ -1348,7 +1348,7 @@ static void cgroup_destroy_root(struct cgroup_root *root) spin_unlock_irq(&css_set_lock); if (!list_empty(&root->root_list)) { - list_del_rcu(&root->root_list); + list_del(&root->root_list); cgroup_root_count--; } @@ -1388,15 +1388,7 @@ static inline struct cgroup *__cset_cgroup_from_root(struct css_set *cset, } } - /* - * If cgroup_mutex is not held, the cgrp_cset_link will be freed - * before we remove the cgroup root from the root_list. Consequently, - * when accessing a cgroup root, the cset_link may have already been - * freed, resulting in a NULL res_cgroup. However, by holding the - * cgroup_mutex, we ensure that res_cgroup can't be NULL. - * If we don't hold cgroup_mutex in the caller, we must do the NULL - * check. - */ + BUG_ON(!res_cgroup); return res_cgroup; } @@ -1455,6 +1447,7 @@ static struct cgroup *current_cgns_cgroup_dfl(void) static struct cgroup *cset_cgroup_from_root(struct css_set *cset, struct cgroup_root *root) { + lockdep_assert_held(&cgroup_mutex); lockdep_assert_held(&css_set_lock); return __cset_cgroup_from_root(cset, root); @@ -1462,9 +1455,7 @@ static struct cgroup *cset_cgroup_from_root(struct css_set *cset, /* * Return the cgroup for "task" from the given hierarchy. Must be - * called with css_set_lock held to prevent task's groups from being modified. - * Must be called with either cgroup_mutex or rcu read lock to prevent the - * cgroup root from being destroyed. + * called with cgroup_mutex and css_set_lock held. */ struct cgroup *task_cgroup_from_root(struct task_struct *task, struct cgroup_root *root) @@ -2039,7 +2030,7 @@ void init_cgroup_root(struct cgroup_fs_context *ctx) struct cgroup_root *root = ctx->root; struct cgroup *cgrp = &root->cgrp; - INIT_LIST_HEAD_RCU(&root->root_list); + INIT_LIST_HEAD(&root->root_list); atomic_set(&root->nr_cgrps, 1); cgrp->root = root; init_cgroup_housekeeping(cgrp); @@ -2123,7 +2114,7 @@ int cgroup_setup_root(struct cgroup_root *root, u16 ss_mask) * care of subsystems' refcounts, which are explicitly dropped in * the failure exit path. */ - list_add_rcu(&root->root_list, &cgroup_roots); + list_add(&root->root_list, &cgroup_roots); cgroup_root_count++; /* -- 2.25.1