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    SubjectRe: possible circular locking dependency detected [was: linux-next: Tree for Aug 22]
    On Wed, Aug 23, 2017 at 09:03:04AM +0900, Byungchul Park wrote:
    > On Tue, Aug 22, 2017 at 09:43:56PM +0000, Bart Van Assche wrote:

    > The report is talking about the following lockup:
    >
    > A work in a worker A task work on exit to user
    > ------------------ ---------------------------
    > mutex_lock(&bdev->bd_mutex)
    > mutext_lock(&bdev->bd_mutex)
    > blk_execute_rq()
    > wait_for_completion_io_timeout(&A)
    > complete(&A)
    >
    > Is this impossible?
    >
    > To Peterz,
    >
    > Anyway I wanted to avoid lockdep reports in the case using a timeout
    > interface. Do you think it's still worth reporting the kind of lockup?

    Yes, people might not have expected to hit the timeout on this. They
    might think timeout means a dead device or something like that.

    I'd like to heard from the block folks if this was constructed thus on
    purpose though.

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