pidns: find_new_reaper() can no longer switch to init_pid_ns.child_reaper
authorOleg Nesterov <oleg@redhat.com>
Wed, 20 Jun 2012 19:53:04 +0000 (12:53 -0700)
committerLinus Torvalds <torvalds@linux-foundation.org>
Wed, 20 Jun 2012 21:39:36 +0000 (14:39 -0700)
commit50d75f8daead8a1f850c40a3b6c6575ab19b48cf
tree1917eec9deadded31869372207772d9a3d3ca11a
parent6347e90091041e34bea625370794c92f4ce71228
pidns: find_new_reaper() can no longer switch to init_pid_ns.child_reaper

find_new_reaper() changes pid_ns->child_reaper, see add0d4df ("pid_ns:
zap_pid_ns_processes: fix the ->child_reaper changing").

The original reason has gone away after the previous patch, ->children
list must be empty after zap_pid_ns_processes().

However now we can not switch to init_pid_ns.child_reaper.
__unhash_process() relies on the "->child_reaper == parent" check, but
this check does not work if the last exiting task is also the child
reaper.

As Eric sugested, we can change __unhash_process() to use the parent's
pid_ns and remove this code.

Also, with this change we can move detach_pid(PIDTYPE_PID) back, where it
was before the previous fix.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Louis Rilling <louis.rilling@kerlabs.com>
Cc: Mike Galbraith <efault@gmx.de>
Acked-by: Pavel Emelyanov <xemul@parallels.com>
Tested-by: Andrew Wagin <avagin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
kernel/exit.c