On 11/21/2017 07:09 PM, Jens Axboe wrote: > 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. I am not doing a hot unplug and the replug, I use KVM and add a previously not available CPU. in libvirt/virsh speak: <vcpu placement='static' current='1'>4</vcpu>
