From 1adfcb03e31ba0d6be5fddf773da4357d0792cbb Mon Sep 17 00:00:00 2001 From: Al Viro Date: Thu, 3 Oct 2013 13:28:06 -0400 Subject: [PATCH] pid_namespace: make freeing struct pid_namespace rcu-delayed makes procfs ->premission() instances safety in RCU mode independent from vfsmount_lock. Signed-off-by: Al Viro --- include/linux/pid_namespace.h | 1 + kernel/pid_namespace.c | 8 +++++++- 2 files changed, 8 insertions(+), 1 deletion(-) diff --git a/include/linux/pid_namespace.h b/include/linux/pid_namespace.h index e2772666f004..7246ef3d4455 100644 --- a/include/linux/pid_namespace.h +++ b/include/linux/pid_namespace.h @@ -23,6 +23,7 @@ struct bsd_acct_struct; struct pid_namespace { struct kref kref; struct pidmap pidmap[PIDMAP_ENTRIES]; + struct rcu_head rcu; int last_pid; unsigned int nr_hashed; struct task_struct *child_reaper; diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c index 42086551a24a..06c62de9c711 100644 --- a/kernel/pid_namespace.c +++ b/kernel/pid_namespace.c @@ -132,6 +132,12 @@ static struct pid_namespace *create_pid_namespace(struct user_namespace *user_ns return ERR_PTR(err); } +static void delayed_free_pidns(struct rcu_head *p) +{ + kmem_cache_free(pid_ns_cachep, + container_of(p, struct pid_namespace, rcu)); +} + static void destroy_pid_namespace(struct pid_namespace *ns) { int i; @@ -140,7 +146,7 @@ static void destroy_pid_namespace(struct pid_namespace *ns) for (i = 0; i < PIDMAP_ENTRIES; i++) kfree(ns->pidmap[i].page); put_user_ns(ns->user_ns); - kmem_cache_free(pid_ns_cachep, ns); + call_rcu(&ns->rcu, delayed_free_pidns); } struct pid_namespace *copy_pid_ns(unsigned long flags, -- GitLab