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    SubjectRe: [PATCH] namespaces: fix race at task exit
    On 01/25, Serge E. Hallyn wrote:
    >
    > In do_exit(), the exit_task_namespaces() was placed after
    > exit_notify() because exit_notify ends up using the pid
    > namespace both to access the reaper, and for detaching the
    > pid. However, this placement allows an nfs server to reap
    > the task before exit_task_namespaces() completes.
    >
    > This patch moves the exit_task_namespaces() into release_task,
    > below release_thread() which puts the pids(), and just above
    > the call_rcu(delayed_put_task_struct). I believe this should
    > solve both problems.
    >
    > Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
    >
    > ---
    >
    > kernel/exit.c | 2 +-
    > 1 files changed, 1 insertions(+), 1 deletions(-)
    >
    > 765277a4170d7bbd1c4613de661ec6ac64d5580a
    > diff --git a/kernel/exit.c b/kernel/exit.c
    > index 3540172..ab9ae30 100644
    > --- a/kernel/exit.c
    > +++ b/kernel/exit.c
    > @@ -174,6 +174,7 @@ repeat:
    > write_unlock_irq(&tasklist_lock);
    > proc_flush_task(p);
    > release_thread(p);
    > + exit_task_namespaces(p);
    > call_rcu(&p->rcu, delayed_put_task_struct);

    Probably I missed some other patches in this area, but I can't understand
    this fix.

    With this change we are doing __put_mnt_ns() when we surely don't have ->sighand,
    no? Could you please explain?

    Oleg.

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