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 <hch@xxxxxx> >> 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 <hch@xxxxxx> >> Reviewed-by: Jens Axboe <axboe@xxxxxxxxx> >> Cc: Keith Busch <keith.busch@xxxxxxxxx> >> Cc: linux-block@xxxxxxxxxxxxxxx >> Cc: linux-nvme@xxxxxxxxxxxxxxxxxxx >> Link: http://lkml.kernel.org/r/20170626102058.10200-3-hch@xxxxxx >> Signed-off-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx> >> Cc: Oleksandr Natalenko <oleksandr@xxxxxxxxxxxxxx> >> Cc: Mike Galbraith <efault@xxxxxx> >> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > 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
