Re: [PATCH] blk-mq: set RQF_USE_SCHED when the operation is known

[Hannes Reinecke <hare@suse.de>]

On 9/21/26 11:26 PM, Keith Busch wrote:
> From: Keith Busch <kbusch@kernel.org>
> 
> The cached requests are allocated for one operation but can be handed
> out for another. A passthrough command has RQF_USE_SCHED cleared, so
> using those flags for a subsequent read/write bio will insert it into
> the scheduler without ->prepare_request() and frees it without
> ->finish_request(). For kyber, this leaks the domain token acquired at
> dispatch and stalls the queue.
> 
> Don't set RQF_USE_SCHED based on the first operation the batch happened
> to be allocated for. Instead, set it after the request is claimed by an
> operation.
> 
> Fixes: 4b6a5d9cea91 ("block: enable batched allocation for blk_mq_alloc_request()")
> Cc: stable@vger.kernel.org
> Reported-by: Henry Hu <huhai@kylinos.cn>
> Signed-off-by: Keith Busch <kbusch@kernel.org>
> ---
>   block/blk-mq.c | 51 +++++++++++++++++++++++++++++---------------------
>   1 file changed, 30 insertions(+), 21 deletions(-)
> 
Reviewed-by: Hannes Reinecke <hare@kernel.org>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
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