On 1/26/22 6:32 PM, Guenter Roeck wrote:
> Hi,
>
> On Thu, Jan 13, 2022 at 10:55:36AM +0800, Laibin Qiu wrote:
>> In case of shared tags, there might be more than one hctx which
>> allocates from the same tags, and each hctx is limited to allocate at
>> most:
>> hctx_max_depth = max((bt->sb.depth + users - 1) / users, 4U);
>>
>> tag idle detection is lazy, and may be delayed for 30sec, so there
>> could be just one real active hctx(queue) but all others are actually
>> idle and still accounted as active because of the lazy idle detection.
>> Then if wake_batch is > hctx_max_depth, driver tag allocation may wait
>> forever on this real active hctx.
>>
>> Fix this by recalculating wake_batch when inc or dec active_queues.
>>
>> Fixes: 0d2602ca30e41 ("blk-mq: improve support for shared tags maps")
>> Suggested-by: Ming Lei <ming.lei@xxxxxxxxxx>
>> Suggested-by: John Garry <john.garry@xxxxxxxxxx>
>> Signed-off-by: Laibin Qiu <qiulaibin@xxxxxxxxxx>
>
> I understand this problem has been reported already, but still:
>
> This patch causes a hang in several of my qemu emulations when
> trying to boot from usb. Reverting it fixes the problem. Bisect log
> is attached.
>
> Boot logs are available at
> https://kerneltests.org/builders/qemu-arm-aspeed-master/builds/230/steps/qemubuildcommand/logs/stdio
> but don't really show much: the affected tests simply hang until they
> are aborted.
This one got reported a few days ago, can you check if applying:
https://git.kernel.dk/cgit/linux-block/commit/?h=block-5.17&id=10825410b956dc1ed8c5fbc8bbedaffdadde7f20
fixes it for you?
--
Jens Axboe
