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). Christian
