On 01/11/2018 10:13 AM, Ming Lei wrote: > On Wed, Dec 20, 2017 at 04:47:21PM +0100, Christian Borntraeger wrote: >> On 12/18/2017 02:56 PM, Stefan Haberland wrote: >>> On 07.12.2017 00:29, Christoph Hellwig wrote: >>>> On Wed, Dec 06, 2017 at 01:25:11PM +0100, Christian Borntraeger wrote: >>>> t > commit 11b2025c3326f7096ceb588c3117c7883850c068 -> bad >>>>> blk-mq: create a blk_mq_ctx for each possible CPU >>>>> does not boot on DASD and >>>>> commit 9c6ae239e01ae9a9f8657f05c55c4372e9fc8bcc -> good >>>>> genirq/affinity: assign vectors to all possible CPUs >>>>> does boot with DASD disks. >>>>> >>>>> Also adding Stefan Haberland if he has an idea why this fails on DASD and adding Martin (for the >>>>> s390 irq handling code). >>>> That is interesting as it really isn't related to interrupts at all, >>>> it just ensures that possible CPUs are set in ->cpumask. >>>> >>>> I guess we'd really want: >>>> >>>> e005655c389e3d25bf3e43f71611ec12f3012de0 >>>> "blk-mq: only select online CPUs in blk_mq_hctx_next_cpu" >>>> >>>> before this commit, but it seems like the whole stack didn't work for >>>> your either. >>>> >>>> I wonder if there is some weird thing about nr_cpu_ids in s390? >>>> -- >>>> To unsubscribe from this list: send the line "unsubscribe linux-s390" in >>>> the body of a message to majordomo@xxxxxxxxxxxxxxx >>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> >>> >>> I tried this on my system and the blk-mq-hotplug-fix branch does not boot for me as well. >>> The disks get up and running and I/O works fine. At least the partition detection and EXT4-fs mount works. >>> >>> But at some point in time the disk do not get any requests. >>> >>> I currently have no clue why. >>> I took a dump and had a look at the disk states and they are fine. No error in the logs or in our debug entrys. Just empty DASD devices waiting to be called for I/O requests. >>> >>> Do you have anything I could have a look at? >> >> Jens, Christoph, so what do we do about this? >> To summarize: >> - commit 4b855ad37194f7 ("blk-mq: Create hctx for each present CPU") broke CPU hotplug. >> - Jens' quick revert did fix the issue and did not broke DASD support but has some issues >> with interrupt affinity. >> - Christoph patch set fixes the hotplug issue for virtio blk but causes I/O hangs on DASDs (even >> without hotplug). > > Hello, > > This one is a valid use case for VM, I think we need to fix that. > > Looks there is issue on the fouth patch("blk-mq: only select online > CPUs in blk_mq_hctx_next_cpu"), I fixed it in the following tree, and > the other 3 patches are same with Christoph's: > > https://github.com/ming1/linux.git v4.15-rc-block-for-next-cpuhot-fix > > gitweb: > https://github.com/ming1/linux/commits/v4.15-rc-block-for-next-cpuhot-fix > > Could you test it and provide the feedback? > > BTW, if it can't help this issue, could you boot from a normal disk first > and dump blk-mq debugfs of DASD later? That kernel seems to boot fine on my system with DASD disks.
