On Sat, Aug 16, 2025 at 08:49:41AM +0800, Yu Kuai wrote: > Hi, > > 在 2025/8/15 22:47, Ming Lei 写道: > > On Fri, Aug 15, 2025 at 04:02:10PM +0800, Yu Kuai wrote: > > > From: Yu Kuai <yukuai3@xxxxxxxxxx> > > > > > > request_queue->nr_requests can be changed by: > > > > > > a) switching elevator by update nr_hw_queues > > > b) switching elevator by elevator sysfs attribute > > > c) configue queue sysfs attribute nr_requests > > ->elevator_lock is grabbed for updating ->nr_requests except for queue > > initialization, so what is the real problem you are trying to solve? > > > In order to fix the regression and prevent deadlock, we'll have to allocate > memory > > in the case bitmap tags grow before freezing the queue, also prevent > nr_requests > > to be updated by case a and b concurrently. Yeah, that is potential deadlock issue in updating nr_request. I feel the patch title is a bit confusing because q->nr_requests updating is already serialized. Thanks, Ming
