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author | Eric W. Biederman <ebiederm@xmission.com> | 2012-06-20 12:53:03 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-06-20 14:39:36 -0700 |
commit | 6347e90091041e34bea625370794c92f4ce71228 (patch) | |
tree | 20614d4eedd2993248be3c3562177c7e00f24b68 /.gitignore | |
parent | f39cdaebb89dc3e6dd4f3e75b6d4e87ef12190af (diff) | |
download | op-kernel-dev-6347e90091041e34bea625370794c92f4ce71228.zip op-kernel-dev-6347e90091041e34bea625370794c92f4ce71228.tar.gz |
pidns: guarantee that the pidns init will be the last pidns process reaped
Today we have a twofold bug. Sometimes release_task on pid == 1 in a pid
namespace can run before other processes in a pid namespace have had
release task called. With the result that pid_ns_release_proc can be
called before the last proc_flus_task() is done using upid->ns->proc_mnt,
resulting in the use of a stale pointer. This same set of circumstances
can lead to waitpid(...) returning for a processes started with
clone(CLONE_NEWPID) before the every process in the pid namespace has
actually exited.
To fix this modify zap_pid_ns_processess wait until all other processes in
the pid namespace have exited, even EXIT_DEAD zombies.
The delay_group_leader and related tests ensure that the thread gruop
leader will be the last thread of a process group to be reaped, or to
become EXIT_DEAD and self reap. With the change to zap_pid_ns_processes
we get the guarantee that pid == 1 in a pid namespace will be the last
task that release_task is called on.
With pid == 1 being the last task to pass through release_task
pid_ns_release_proc can no longer be called too early nor can wait return
before all of the EXIT_DEAD tasks in a pid namespace have exited.
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Oleg Nesterov <oleg@redhat.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>
Diffstat (limited to '.gitignore')
0 files changed, 0 insertions, 0 deletions