path: root/kernel/fork.c
diff options
authorEric W. Biederman <>2012-08-01 17:33:47 (GMT)
committerEric W. Biederman <>2012-11-19 13:59:10 (GMT)
commit0a01f2cc390e10633a54f72c608cc3fe19a50c3d (patch)
treee713a1c45b5ce125a5d33b61d528cd45264d47a7 /kernel/fork.c
parent17cf22c33e1f1b5e435469c84e43872579497653 (diff)
pidns: Make the pidns proc mount/umount logic obvious.
Track the number of pids in the proc hash table. When the number of pids goes to 0 schedule work to unmount the kernel mount of proc. Move the mount of proc into alloc_pid when we allocate the pid for init. Remove the surprising calls of pid_ns_release proc in fork and proc_flush_task. Those code paths really shouldn't know about proc namespace implementation details and people have demonstrated several times that finding and understanding those code paths is difficult and non-obvious. Because of the call path detach pid is alwasy called with the rtnl_lock held free_pid is not allowed to sleep, so the work to unmounting proc is moved to a work queue. This has the side benefit of not blocking the entire world waiting for the unnecessary rcu_barrier in deactivate_locked_super. In the process of making the code clear and obvious this fixes a bug reported by Gao feng <> where we would leak a mount of proc during clone(CLONE_NEWPID|CLONE_NEWNET) if copy_pid_ns succeeded and copy_net_ns failed. Acked-by: "Serge E. Hallyn" <> Signed-off-by: "Eric W. Biederman" <>
Diffstat (limited to 'kernel/fork.c')
1 files changed, 0 insertions, 2 deletions
diff --git a/kernel/fork.c b/kernel/fork.c
index 7798c24..666dc8b 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -1476,8 +1476,6 @@ bad_fork_cleanup_io:
if (p->io_context)
- if (unlikely(clone_flags & CLONE_NEWPID))
- pid_ns_release_proc(p->nsproxy->pid_ns);
if (p->mm)