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    SubjectRe: Signals to cinit
    Oleg Nesterov [oleg@redhat.com] wrote:
    | (lkml cced because containers list's archive is not useable)
    |
    | On 11/10, Oleg Nesterov wrote:
    | >
    | > On 11/01, sukadev@linux.vnet.ibm.com wrote:
    | > >
    | > > Other approaches to try ?
    | >
    | > I think we should try to do something simple, even if not perfect. Because
    | > most users do not care about this problem since they do not use containers
    | > at all. It would be very sad to add intrusive changes to the code.
    | >
    | > I think we should fix another problem first. send_signal()->copy_siginfo()
    | > path must be changed anyway, when the signal comes from the parent ns we
    | > report the "wrong" si_code/si_pid, yes? So, somehow send_signal() must
    | > have "bool from_parent_ns" (or whatever) annyway.

    Yes, this was in both the patchsets we reviewed last year :-) I can send
    this fix out independently.

    | >
    | > Now, let's forget forget for a moment that send_signal()->__sigqueue_alloc()
    | > can fail.
    | >
    | > I think we should encode this "from_parent_ns" into "struct siginfo". I do
    | > not think it is good idea to extend this structure, I think we can introduce
    | > SI_FROM_PARENT_NS or we perhaps can use "SI_FROMUSER(info) && info->si_pid == 0".
    | > Or something. yes, sys_rt_sigqueueinfo() is problematic...

    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 ?

    Of course, this is a new scenario, specific to containers, and we may be
    able to define the policy without changing semantics.


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