[merged] exit-call-disassociate_ctty-before-exit_task_namespaces.patch removed from -mm tree

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Subject: [merged] exit-call-disassociate_ctty-before-exit_task_namespaces.patch removed from -mm tree
To: oleg@xxxxxxxxxx,avagin@xxxxxxxxxx,ebiederm@xxxxxxxxxxxx,jdike@xxxxxxxxxxx,mingo@xxxxxxx,peter@xxxxxxxxxxxxxxxxxx,sreeharsha@xxxxxxxxxxx,stable@xxxxxxxxxxxxxxx,viro@xxxxxxxxxxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Tue, 08 Apr 2014 14:14:40 -0700


The patch titled
     Subject: exit: call disassociate_ctty() before exit_task_namespaces()
has been removed from the -mm tree.  Its filename was
     exit-call-disassociate_ctty-before-exit_task_namespaces.patch

This patch was dropped because it was merged into mainline or a subsystem tree

------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: exit: call disassociate_ctty() before exit_task_namespaces()

8aac62706ada ("move exit_task_namespaces() outside of exit_notify()")
breaks pppd and the exiting service crashes the kernel:

    BUG: unable to handle kernel NULL pointer dereference at 0000000000000028
    IP: [<ffffffffa06985a3>] ppp_register_channel+0x13/0x20 [ppp_generic]
    ...
    Call Trace:
     [<ffffffffa06ab2ab>] ? ppp_asynctty_open+0x12b/0x170 [ppp_async]
     [<ffffffff812ec907>] ? tty_ldisc_open.isra.2+0x27/0x60
     [<ffffffff812ed1d3>] ? tty_ldisc_hangup+0x1e3/0x220
     [<ffffffff812e4614>] ? __tty_hangup+0x2c4/0x440
     [<ffffffff812e56a1>] ? disassociate_ctty+0x61/0x270
     [<ffffffff810483c2>] ? do_exit+0x7f2/0xa50

ppp_register_channel() needs ->net_ns and current->nsproxy == NULL.

Move disassociate_ctty() before exit_task_namespaces(), it doesn't make
sense to delay it after perf_event_exit_task() or cgroup_exit().

This also allows to use task_work_add() inside the (nontrivial) code
paths in disassociate_ctty().

Investigated by Peter Hurley.

Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
Reported-by: Sree Harsha Totakura <sreeharsha@xxxxxxxxxxx>
Cc: Peter Hurley <peter@xxxxxxxxxxxxxxxxxx>
Cc: Sree Harsha Totakura <sreeharsha@xxxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Jeff Dike <jdike@xxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxx>
Cc: Andrey Vagin <avagin@xxxxxxxxxx>
Cc: Al Viro <viro@xxxxxxxxxxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>	[v3.10+]
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---

 kernel/exit.c |    6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff -puN kernel/exit.c~exit-call-disassociate_ctty-before-exit_task_namespaces kernel/exit.c
--- a/kernel/exit.c~exit-call-disassociate_ctty-before-exit_task_namespaces
+++ a/kernel/exit.c
@@ -784,6 +784,8 @@ void do_exit(long code)
 	exit_shm(tsk);
 	exit_files(tsk);
 	exit_fs(tsk);
+	if (group_dead)
+		disassociate_ctty(1);
 	exit_task_namespaces(tsk);
 	exit_task_work(tsk);
 	check_stack_usage();
@@ -799,13 +801,9 @@ void do_exit(long code)
 
 	cgroup_exit(tsk);
 
-	if (group_dead)
-		disassociate_ctty(1);
-
 	module_put(task_thread_info(tsk)->exec_domain->module);
 
 	proc_exit_connector(tsk);
-
 	/*
 	 * FIXME: do that only when needed, using sched_exit tracepoint
 	 */
_

Patches currently in -mm which might be from oleg@xxxxxxxxxx are

origin.patch

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