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    SubjectRe: [PATCH v2] mm/page_isolation: fix a deadlock with printk()
    On (10/09/19 16:26), Michal Hocko wrote:
    > On Wed 09-10-19 15:56:32, Peter Oberparleiter wrote:
    > [...]
    > > A generic solution would be preferable from my point of view though,
    > > because otherwise each console driver owner would need to ensure that any
    > > lock taken in their console.write implementation is never held while
    > > memory is allocated/released.
    >
    > Considering that console.write is called from essentially arbitrary code
    > path IIUC then all the locks used in this path should be pretty much
    > tail locks or console internal ones without external dependencies.

    That's a good expectation, but I guess it's not always the case.

    One example might be NET console - net subsystem locks, net device
    drivers locks, maybe even some MM locks (skb allocations?).

    But even more "commonly used" consoles sometimes break that
    expectation. E.g. 8250

    serial8250_console_write()
    serial8250_modem_status()
    wake_up_interruptible()

    And so on.

    -ss

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