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    SubjectRe: Regression causes a hang on boot with a Comtrol PCI card
    Hi Jesse,

    On Wed, Mar 13, 2019 at 11:50:07AM -0500, Jesse Hathaway wrote:
    > Two regressions cause Linux to hang on boot when a Comtrol PCI card
    > is present.
    >
    > If I revert the following two commits, I can boot again and the card
    > operates without issue:
    >
    > 1302fcf0d03e (refs/bisect/bad) PCI: Configure *all* devices, not just
    > hot-added ones
    > 1c3c5eab1715 sched/core: Enable might_sleep() and smp_processor_id()
    > checks early

    I'm very sorry about the regression, but thank you very much for
    narrowing it down and reporting it!

    How did you narrow it down to *two* commits, and do you have to revert
    both of them to avoid the hang? Usually a bisection identifies a
    single commit, and the two you mention aren't related.

    > ; lspci -vs 82:00.0
    > 82:00.0 Multiport serial controller: Comtrol Corporation Device 0061
    > Subsystem: Comtrol Corporation Device 0061
    > Flags: 66MHz, medium devsel, IRQ 35, NUMA node 1
    > Memory at c8004000 (32-bit, non-prefetchable) [size=4K]
    > Memory at c8000000 (32-bit, non-prefetchable) [size=16K]
    > Capabilities: [40] Hot-plug capable
    > Capabilities: [48] Power Management version 2
    > Kernel driver in use: rp2
    > Kernel modules: rp2
    >
    > Is it possible that the problem is that the card claims to support
    > Hot-plug, but does not?
    >
    > I would love to help fix this issue, please let me know what other
    > information would be helpful to provide.

    Can you collect a complete dmesg log (with a working kernel) and
    output of "sudo lspci -vvxxx"? You can open a bug report at
    https://bugzilla.kernel.org, attach the logs there, and respond here
    with the URL.

    Where does the hang happen? Is it when we configure the Comtrol card?

    Bjorn

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