On 1/22/19 10:15 AM, Mike Snitzer wrote:
> On Tue, Jan 22 2019 at 3:20am -0500,
> Ming Lei <ming.lei@xxxxxxxxxx> wrote:
>
>> Except for blk_queue_split(), bio_split() is used for splitting bio too,
>> then the remained bio is often resubmit to queue via generic_make_request().
>> So the same queue enter recursion exits in this case too. Unfortunatley
>> commit cd4a4ae4683dc2 doesn't help this case.
>>
>> This patch covers the above case by setting BIO_QUEUE_ENTERED before calling
>> q->make_request_fn.
>>
>> In theory the per-bio flag is used to simulate one stack variable, it is
>> just fine to clear it after q->make_request_fn is returned. Especially
>> the same bio can't be submitted from another context.
>>
>> Fixes: cd4a4ae4683dc2 ("block: don't use blocking queue entered for recursive bio submits")
>> Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
>> Cc: Mike Snitzer <snitzer@xxxxxxxxxx>
>> Cc: NeilBrown <neilb@xxxxxxxx>
>> Signed-off-by: Ming Lei <ming.lei@xxxxxxxxxx>
>
> Looks good, I'll drop my DM patch that set/cleared BIO_QUEUE_ENTERED.
>
> Jens, you OK with picking this up for 5.0-rc?
>
> Reviewed-by: Mike Snitzer <snitzer@xxxxxxxxxx>
I am, thanks both of you for looking into this. I'm a bit behind on email
and patches from over the long weekend.
--
Jens Axboe
