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    SubjectRe: [PATCH 2/3] pidns: Guarantee that the pidns init will be the last pidns process reaped.
    Eric, sorry for the huge delay, I was on vacation when you sent this patch...

    On 05/06, Eric W. Biederman wrote:
    >
    > @@ -798,6 +815,12 @@ static void forget_original_parent(struct task_struct *father)
    > exit_ptrace(father);
    > reaper = find_new_reaper(father);
    >
    > + /* Return immediately if we aren't going to reparent anything */
    > + if (unlikely(reaper == father)) {
    > + write_unlock_irq(&tasklist_lock);
    > + return;
    > + }

    I was confused by the comment. Afaics, it is not that "we aren't
    going to reparent", we need this change because we can't "reparent"
    to the same thread, list_for_each_entry_safe() below can never stop.
    But this is off-topic...

    Hmm. I don't think the patch is 100% correct. Afaics, this needs more
    delay_pidns_leader() checks.

    For example. Suppose we have a CLONE_NEWPID zombie I, it has an
    EXIT_DEAD child D so delay_pidns_leader(I) == T.

    Now suppose that I->real_parent exits, lets denote this task as P.

    Suppose that P->real_parent ignores SIGCHLD.

    In this case P will do release_task(I) prematurely. And worse, when
    D finally does realease_task(D) it will do realease_task(I) again.

    Oleg.



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