exit_notify() does exit_task_namespaces() after
forget_original_parent(). This was needed to ensure that ->nsproxy
can't be cleared prematurely, an exiting child we are going to
reparent can do do_notify_parent() and use the parent's (ours) pid_ns.
However, after 32084504 "pidns: use task_active_pid_ns in
do_notify_parent" ->nsproxy != NULL is no longer needed, we rely
on task_active_pid_ns().
Move exit_task_namespaces() from exit_notify() to do_exit(), after
exit_fs() and before exit_task_work().
This solves the problem reported by Andrey, free_ipc_ns()->shm_destroy()
does fput() which needs task_work_add().
Note: this particular problem can be fixed if we change fput(), and
that change makes sense anyway. But there is another reason to move
the callsite. The original reason for exit_task_namespaces() from
the middle of exit_notify() was subtle and it has already gone away,
now this looks confusing. And this allows us do simplify exit_notify(),
we can avoid unlock/lock(tasklist) and we can use ->exit_state instead
of PF_EXITING in forget_original_parent().
Reported-by: Andrey Vagin <ava...@openvz.org>
Signed-off-by: Oleg Nesterov <o...@redhat.com>
Acked-by: "Eric W. Biederman" <ebied...@xmission.com>
Acked-by: Andrey Vagin <ava...@openvz.org>
---
kernel/exit.c | 2 +-
1 files changed, 1 insertions(+), 1 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index 8fc3c8f..c623cd3 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -644,7 +644,6 @@ static void exit_notify(struct task_struct *tsk, int
group_dead)
* jobs, send them a SIGHUP and then a SIGCONT. (POSIX 3.2.2.2)
*/
forget_original_parent(tsk);
- exit_task_namespaces(tsk);
write_lock_irq(&tasklist_lock);
if (group_dead)
@@ -790,6 +789,7 @@ void do_exit(long code)
exit_shm(tsk);
exit_files(tsk);
exit_fs(tsk);
+ exit_task_namespaces(tsk);
exit_task_work(tsk);
check_stack_usage();
exit_thread();
--
1.5.5.1
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
