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Subject: Re: INFO: task hung in blk_queue_enter
From: Jens Axboe <axboe@kernel.dk>
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To: Ming Lei <ming.lei@redhat.com>
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> On Jun 1, 2018, at 10:54 PM, Ming Lei <ming.lei@redhat.com> wrote:
> 
>> On Fri, Jun 01, 2018 at 10:31:13PM -0600, Jens Axboe wrote:
>> On 6/1/18 8:36 PM, Ming Lei wrote:
>>>> clear the bit when we need to, potentially even adding a debug check to
>>>> blk_queue_enter_live() that complains if the ref was not already
>>>> elevated. Though that would be expensive, compared to the percpu inc
>>>> now. Not saying the bit is necessarily the best way forward, but I do
>>>> like it a LOT more than adding an argument to generic_make_request.
>>> 
>>> We may introduce generic_make_request_with_ref() for blk_queue_split(),
>>> what do you think of the following patch?
>> 
>> Functionally it'll work as well.
> 
> If you are fine with this one, I'm glad to prepare for a normal one,
> so that we can save one precious bio flag, and the total number is
> just 13.

We’ve never had much issue with bio specific flags, I prefer that approach to a wrapper around generic_make_request().