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Date: Thu, 30 Jul 2020 15:00:24 +0300 From: Kirill Tkhai <ktkhai@...tuozzo.com> To: viro@...iv.linux.org.uk, adobriyan@...il.com, davem@...emloft.net, ebiederm@...ssion.com, akpm@...ux-foundation.org, christian.brauner@...ntu.com, areber@...hat.com, serge@...lyn.com, linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org, ktkhai@...tuozzo.com Subject: [PATCH 12/23] user: Free user_ns one RCU grace period after final counter put This is needed to link user_ns into ns_idr in next patch. Signed-off-by: Kirill Tkhai <ktkhai@...tuozzo.com> --- include/linux/user_namespace.h | 5 ++++- kernel/user_namespace.c | 9 ++++++++- 2 files changed, 12 insertions(+), 2 deletions(-) diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h index 64cf8ebdc4ec..58fede304201 100644 --- a/include/linux/user_namespace.h +++ b/include/linux/user_namespace.h @@ -79,7 +79,10 @@ struct user_namespace { #ifdef CONFIG_PERSISTENT_KEYRINGS struct key *persistent_keyring_register; #endif - struct work_struct work; + union { + struct work_struct work; + struct rcu_head rcu; + }; #ifdef CONFIG_SYSCTL struct ctl_table_set set; struct ctl_table_header *sysctls; diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c index 7c2bbe8f3e45..367a942bb484 100644 --- a/kernel/user_namespace.c +++ b/kernel/user_namespace.c @@ -171,6 +171,13 @@ int unshare_userns(unsigned long unshare_flags, struct cred **new_cred) return err; } +static void free_user_ns_rcu(struct rcu_head *head) +{ + struct user_namespace *ns = container_of(head, struct user_namespace, + rcu); + kmem_cache_free(user_ns_cachep, ns); +} + static void free_user_ns(struct work_struct *work) { struct user_namespace *parent, *ns = @@ -194,7 +201,7 @@ static void free_user_ns(struct work_struct *work) retire_userns_sysctls(ns); key_free_user_ns(ns); ns_free_inum(&ns->ns); - kmem_cache_free(user_ns_cachep, ns); + call_rcu(&ns->rcu, free_user_ns_rcu); dec_user_namespaces(ucounts); ns = parent; } while (refcount_dec_and_test(&parent->ns.count));
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