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    SubjectRe: [PATCH 0/2] genirq/affinity: try to make sure online CPU is assgined to irq vector
    On Tue, 16 Jan 2018, Ming Lei wrote:

    > On Mon, Jan 15, 2018 at 09:40:36AM -0800, Christoph Hellwig wrote:
    > > On Tue, Jan 16, 2018 at 12:03:43AM +0800, Ming Lei wrote:
    > > > Hi,
    > > >
    > > > These two patches fixes IO hang issue reported by Laurence.
    > > >
    > > > 84676c1f21 ("genirq/affinity: assign vectors to all possible CPUs")
    > > > may cause one irq vector assigned to all offline CPUs, then this vector
    > > > can't handle irq any more.
    > >
    > > Well, that very much was the intention of managed interrupts. Why
    > > does the device raise an interrupt for a queue that has no online
    > > cpu assigned to it?
    >
    > It is because of irq_create_affinity_masks().

    That still does not answer the question. If the interrupt for a queue is
    assigned to an offline CPU, then the queue should not be used and never
    raise an interrupt. That's how managed interrupts have been designed.

    Thanks,

    tglx




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