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    SubjectRe: Signals to cinit
    On 11/12, Sukadev Bhattiprolu wrote:
    >
    > Oleg Nesterov [oleg@redhat.com] wrote:
    >
    > | On 11/10, sukadev@linux.vnet.ibm.com wrote:
    > | >
    > | > Also, what happens if a fatal signal is first received from a descendant
    > | > and while that is still pending, the same signal is received from ancestor
    > | > ns ? Won't the second one be ignored by legacy_queue() for the non-rt case ?
    >
    > On second thoughts, cinit is a normal process in its ancestor ns so it
    > might very well ignore the second instance of the signal (as long as it
    > does not ignore SIGKILL/SIGSTOP)
    >
    > |
    > | Please see my another email:
    > |
    > | We must also change sig_ignored() to drop SIGKILL/SIGSTOP early when
    > | it comes from the same ns. Otherwise, it can mask the next SIGKILL
    > | from the parent ns.
    >
    > Ok.
    >
    > |
    > | But this perhaps makes sense anyway, even without containers.
    > | Currently, when the global init has the pending SIGKILL, we can't
    > | trust __wait_event_killable/etc, and this is actually wrong.
    > |
    > | We can drop other SIG_DFL signals from the same namespace early as well.
    >
    > I think Eric's patchset did this and iirc, we ran into the problem of
    > blocked SIG_DFL signals ?

    Yes sure, I meant unblocked SIG_DFL signals. But SIGKILL can't be
    blocked fortunately.

    Again, the parent ns can't rely on, say, SIGTERM. It can be missed
    if cinit has a handler, we can do nothing in this case. And if it
    is blocked, most probably cinit already has a handler, or it will
    set it later, say, after exec. Or it can be just ignored.

    > | Or, we can just ignore this (imho) minor problem.
    >
    > I think so too.

    Great, so perhaps we can ignore the problem for now, and fix it
    later if the need arises.

    Oleg.



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