On 11/21/2017 10:27 AM, Jens Axboe wrote:
> On 11/21/2017 03:14 AM, Christian Borntraeger wrote:
>> Bisect points to
>>
>> 1b5a7455d345b223d3a4658a9e5fce985b7998c1 is the first bad commit
>> commit 1b5a7455d345b223d3a4658a9e5fce985b7998c1
>> Author: Christoph Hellwig <[email protected]>
>> Date: Mon Jun 26 12:20:57 2017 +0200
>>
>> blk-mq: Create hctx for each present CPU
>>
>> commit 4b855ad37194f7bdbb200ce7a1c7051fecb56a08 upstream.
>>
>> Currently we only create hctx for online CPUs, which can lead to a lot
>> of churn due to frequent soft offline / online operations. Instead
>> allocate one for each present CPU to avoid this and dramatically simplify
>> the code.
>>
>> Signed-off-by: Christoph Hellwig <[email protected]>
>> Reviewed-by: Jens Axboe <[email protected]>
>> Cc: Keith Busch <[email protected]>
>> Cc: [email protected]
>> Cc: [email protected]
>> Link: http://lkml.kernel.org/r/[email protected]
>> Signed-off-by: Thomas Gleixner <[email protected]>
>> Cc: Oleksandr Natalenko <[email protected]>
>> Cc: Mike Galbraith <[email protected]>
>> Signed-off-by: Greg Kroah-Hartman <[email protected]>
>
> I wonder if we're simply not getting the masks updated correctly. I'll
> take a look.
Can't make it trigger here. We do init for each present CPU, which means
that if I offline a few CPUs here and register a queue, those still show
up as present (just offline) and get mapped accordingly.
>From the looks of it, your setup is different. If the CPU doesn't show
up as present and it gets hotplugged, then I can see how this condition
would trigger. What environment are you running this in? We might have
to re-introduce the cpu hotplug notifier, right now we just monitor
for a dead cpu and handle that.
--
Jens Axboe
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