Michael S. Tsirkin
2022-Sep-27 20:47 UTC
[PATCH v1] virtio_blk: should not use IRQD_AFFINITY_MANAGED in init_rq
On Sat, Sep 24, 2022 at 11:48:54AM +0800, Angus Chen wrote:> The background is that we use dpu in cloud computing,the arch is x86,80 > cores.We will have a lots of virtio devices,like 512 or more. > When we probe about 200 virtio_blk devices,it will fail and > the stack is print as follows: > > [25338.485128] virtio-pci 0000:b3:00.0: virtio_pci: leaving for legacy driver > [25338.496174] genirq: Flags mismatch irq 0. 00000080 (virtio418) vs. 00015a00 (timer) > [25338.503822] CPU: 20 PID: 5431 Comm: kworker/20:0 Kdump: loaded Tainted: G OE --------- - - 4.18.0-305.30.1.el8.x86_64 > [25338.516403] Hardware name: Inspur NF5280M5/YZMB-00882-10E, BIOS 4.1.21 08/25/2021 > [25338.523881] Workqueue: events work_for_cpu_fn > [25338.528235] Call Trace: > [25338.530687] dump_stack+0x5c/0x80 > [25338.534000] __setup_irq.cold.53+0x7c/0xd3 > [25338.538098] request_threaded_irq+0xf5/0x160 > [25338.542371] vp_find_vqs+0xc7/0x190 > [25338.545866] init_vq+0x17c/0x2e0 [virtio_blk] > [25338.550223] ? ncpus_cmp_func+0x10/0x10 > [25338.554061] virtblk_probe+0xe6/0x8a0 [virtio_blk] > [25338.558846] virtio_dev_probe+0x158/0x1f0 > [25338.562861] really_probe+0x255/0x4a0 > [25338.566524] ? __driver_attach_async_helper+0x90/0x90 > [25338.571567] driver_probe_device+0x49/0xc0 > [25338.575660] bus_for_each_drv+0x79/0xc0 > [25338.579499] __device_attach+0xdc/0x160 > [25338.583337] bus_probe_device+0x9d/0xb0 > [25338.587167] device_add+0x418/0x780 > [25338.590654] register_virtio_device+0x9e/0xe0 > [25338.595011] virtio_pci_probe+0xb3/0x140 > [25338.598941] local_pci_probe+0x41/0x90 > [25338.602689] work_for_cpu_fn+0x16/0x20 > [25338.606443] process_one_work+0x1a7/0x360 > [25338.610456] ? create_worker+0x1a0/0x1a0 > [25338.614381] worker_thread+0x1cf/0x390 > [25338.618132] ? create_worker+0x1a0/0x1a0 > [25338.622051] kthread+0x116/0x130 > [25338.625283] ? kthread_flush_work_fn+0x10/0x10 > [25338.629731] ret_from_fork+0x1f/0x40 > [25338.633395] virtio_blk: probe of virtio418 failed with error -16 > > After I did some work of this stack,took stap and crash to get more > information,I found that the auto irq_affinity affect this. > When "vp_find_vqs" call "vp_find_vqs_msix" failed,it will be go back > to call vp_find_vqs_msix again with ctx be false, and when it failed again, > we will call vp_find_vqs_intx,if the vp_dev->pci_dev->irq is zero, > we will get a backtrace like above. > > The log : > "genirq: Flags mismatch irq 0. 00000080 (virtio418) vs. 00015a00 (timer)" > was print because of the irq 0 is used by timer exclusive,and when > vp_find_vqs called vp_find_vqs_msix and return false twice,then it will > call vp_find_vqs_intx for the last try. > Because vp_dev->pci_dev->irq is zero,so it will be request irq 0 with > flag IRQF_SHARED.First this is a bug. We can fix that so it will fail more cleanly. We should check pci_dev->pin and if 0 do not try to use INT#x at all. It will still fail, just with a nicer backtrace.> without config CONFIG_GENERIC_IRQ_DEBUGFS, > I found that we called vp_find_vqs_msix failed twice because of > the irq resource was exhausted.I see. I don't know enough about how this work, but roughly I think the issue is at a high level - because of auto affinity, we try to reserve an interrupt on all CPUs - as there are 512 devices with a single vector per VQ we would have no issue as they would be spread between CPUs, but allocating on all CPUs fails. I don't think the issue should be fixed at blk level - it is not blk specifix - but yes this looks like a problem. Christoph, any idea?> crash> irq_domain.name,parent 0xffff9bff87d4dec0 > name = 0xffff9bff87c1fd60 "INTEL-IR-MSI-1-2" > parent = 0xffff9bff87400000 > crash> irq_domain.name,parent 0xffff9bff87400000 > name = 0xffff9bff87c24300 "INTEL-IR-1" > parent = 0xffff9bff87c6c900 > crash> irq_domain.name,parent 0xffff9bff87c6c900 > name = 0xffff9bff87c3ecd0 "VECTOR" > parent = 0x0----------------------the highest level > > and stap irq_matrix_alloc_managed get return value -ENOSPC. > > When no virtio_blk device probe,the vctor_matrix is: > crash> p *vector_matrix > $1 = { > matrix_bits = 256, > alloc_start = 32, > alloc_end = 236, > alloc_size = 204, > global_available = 15593, > global_reserved = 149, > systembits_inalloc = 3, > total_allocated = 409, > online_maps = 80, > maps = 0x2ff20, > scratch_map = {1161063342014463, 0, 1, 18446726481523507200, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, > system_map = {1125904739729407, 0, 1, 18446726481523507200, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} > } > > When the dump stack occur,the vector_matrix of system is exhausted. > crash> p *vector_matrix > $82 = { > matrix_bits = 256, > alloc_start = 32, > alloc_end = 236, > alloc_size = 204, > global_available = 0,//caq:irq left > global_reserved = 151, > systembits_inalloc = 3, > total_allocated = 1922,//caq:irq that allocated > online_maps = 80, > maps = 0x2ff20, > scratch_map = {18446744069952503807, 18446744073709551615, > 18446744073709551615, 18446735277616529407, 0, 0, 0, 0, 0, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}, > system_map = {1125904739729407, 0, 1, 18446726481523507200, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0} > } > > And we tested the virtio_blk device which request irq success, > we found that in a system with 80 cores and two numa ,one > virtio_blk device with just two data queues consume 81 irqs capacity, > Although it just only three irqs in /proc/interrupt,80 irqs capacity > is effected by function "irq_build_affinity_masks" with 2*40. > > before one virtio_blk device hotplug out: > crash> p *vector_matrix > $2 = { > matrix_bits = 256, > alloc_start = 32, > alloc_end = 236, > alloc_size = 204, > global_available = 15215, > global_reserved = 150, > systembits_inalloc = 3, > total_allocated = 553, > online_maps = 80, > maps = 0x2ff20, > scratch_map = {1179746449752063, 0, 1, 18446726481523507200, 0, 0, 0, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, > 0, 0, 0, 0, 0}, > system_map = {1125904739729407, 0, 1, 18446726481523507200, 0, 0, 0, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, > 0, 0, 0, 0, 0} > } > > after one virtio_blk device hotplug out: > crash> p *vector_matrix > $3 = { > matrix_bits = 256, > alloc_start = 32, > alloc_end = 236, > alloc_size = 204, > global_available = 15296,---it increase 81,include 1 config irq. > global_reserved = 150, > systembits_inalloc = 3, > total_allocated = 550,------it just decrease 3. > online_maps = 80, > maps = 0x2ff20, > scratch_map = {481036337152, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, > 0, 0, 0, 0}, > system_map = {1125904739729407, 0, 1, 18446726481523507200, 0, 0, 0, > 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, > 0, 0, 0, 0, 0} > } > > We test the new kernel also,it occur the same result. > [Fri Sep 23 04:51:42 2022] genirq: Flags mismatch irq 0. 00000080 (virtio608) vs. 00015a00 (timer) > [Fri Sep 23 04:51:42 2022] CPU: 0 PID: 5749 Comm: kworker/0:0 Kdump: loaded Tainted: G W OE 6.0.0-rc6+ #5 > [Fri Sep 23 04:51:42 2022] Hardware name: Inspur NF5280M5/YZMB-00882-10E, BIOS 4.1.19 06/16/2021 > [Fri Sep 23 04:51:42 2022] Workqueue: events work_for_cpu_fn > [Fri Sep 23 04:51:42 2022] Call Trace: > [Fri Sep 23 04:51:42 2022] <TASK> > [Fri Sep 23 04:51:42 2022] dump_stack_lvl+0x33/0x46 > [Fri Sep 23 04:51:42 2022] __setup_irq+0x705/0x770 > [Fri Sep 23 04:51:42 2022] request_threaded_irq+0x109/0x170 > [Fri Sep 23 04:51:42 2022] vp_find_vqs+0xc4/0x190 > [Fri Sep 23 04:51:42 2022] init_vqs+0x348/0x580 [virtio_net] > [Fri Sep 23 04:51:42 2022] virtnet_probe+0x54d/0xa80 [virtio_net] > [Fri Sep 23 04:51:42 2022] virtio_dev_probe+0x19c/0x240 > [Fri Sep 23 04:51:42 2022] really_probe+0x106/0x3e0 > [Fri Sep 23 04:51:42 2022] ? pm_runtime_barrier+0x4f/0xa0 > [Fri Sep 23 04:51:42 2022] __driver_probe_device+0x79/0x170 > [Fri Sep 23 04:51:42 2022] driver_probe_device+0x1f/0xa0 > [Fri Sep 23 04:51:42 2022] __device_attach_driver+0x85/0x110 > [Fri Sep 23 04:51:42 2022] ? driver_allows_async_probing+0x60/0x60 > [Fri Sep 23 04:51:42 2022] ? driver_allows_async_probing+0x60/0x60 > [Fri Sep 23 04:51:42 2022] bus_for_each_drv+0x67/0xb0 > [Fri Sep 23 04:51:42 2022] __device_attach+0xe9/0x1b0 > [Fri Sep 23 04:51:42 2022] bus_probe_device+0x87/0xa0 > [Fri Sep 23 04:51:42 2022] device_add+0x59f/0x950 > [Fri Sep 23 04:51:42 2022] ? dev_set_name+0x4e/0x70 > [Fri Sep 23 04:51:42 2022] register_virtio_device+0xac/0xf0 > [Fri Sep 23 04:51:42 2022] virtio_pci_probe+0x101/0x170 > [Fri Sep 23 04:51:42 2022] local_pci_probe+0x42/0xa0 > [Fri Sep 23 04:51:42 2022] work_for_cpu_fn+0x13/0x20 > [Fri Sep 23 04:51:42 2022] process_one_work+0x1c2/0x3d0 > [Fri Sep 23 04:51:42 2022] ? process_one_work+0x3d0/0x3d0 > [Fri Sep 23 04:51:42 2022] worker_thread+0x1b9/0x360 > [Fri Sep 23 04:51:42 2022] ? process_one_work+0x3d0/0x3d0 > [Fri Sep 23 04:51:42 2022] kthread+0xe6/0x110 > [Fri Sep 23 04:51:42 2022] ? kthread_complete_and_exit+0x20/0x20 > [Fri Sep 23 04:51:42 2022] ret_from_fork+0x1f/0x30 > [Fri Sep 23 04:51:42 2022] </TASK> > [Fri Sep 23 04:51:43 2022] virtio_net: probe of virtio608 failed with error -16 > > Fixes: ad71473d9c43 ("virtio_blk: use virtio IRQ affinity") > Signed-off-by: Angus Chen <angus.chen at jaguarmicro.com> > Tested-by: Liming Wu <liming.wu at jaguarmicro.com> > --- > drivers/block/virtio_blk.c | 3 +-- > 1 file changed, 1 insertion(+), 2 deletions(-) > > diff --git a/drivers/block/virtio_blk.c b/drivers/block/virtio_blk.c > index a8bcf3f664af..075de30a9bb4 100644 > --- a/drivers/block/virtio_blk.c > +++ b/drivers/block/virtio_blk.c > @@ -513,7 +513,6 @@ static int init_vq(struct virtio_blk *vblk) > struct virtqueue **vqs; > unsigned short num_vqs; > struct virtio_device *vdev = vblk->vdev; > - struct irq_affinity desc = { 0, }; > > err = virtio_cread_feature(vdev, VIRTIO_BLK_F_MQ, > struct virtio_blk_config, num_queues, > @@ -548,7 +547,7 @@ static int init_vq(struct virtio_blk *vblk) > } > > /* Discover virtqueues and write information to configuration. */ > - err = virtio_find_vqs(vdev, num_vqs, vqs, callbacks, names, &desc); > + err = virtio_find_vqs(vdev, num_vqs, vqs, callbacks, names, NULL); > if (err) > goto out; > > -- > 2.17.1
Christoph Hellwig
2022-Sep-28 09:45 UTC
[PATCH v1] virtio_blk: should not use IRQD_AFFINITY_MANAGED in init_rq
On Tue, Sep 27, 2022 at 04:47:20PM -0400, Michael S. Tsirkin wrote:> > The log : > > "genirq: Flags mismatch irq 0. 00000080 (virtio418) vs. 00015a00 (timer)" > > was print because of the irq 0 is used by timer exclusive,and when > > vp_find_vqs called vp_find_vqs_msix and return false twice,then it will > > call vp_find_vqs_intx for the last try. > > Because vp_dev->pci_dev->irq is zero,so it will be request irq 0 with > > flag IRQF_SHARED. > > First this is a bug. We can fix that so it will fail more cleanly. > > We should check pci_dev->pin and if 0 do not try to use INT#x > at all. > It will still fail, just with a nicer backtrace.How do we end up with a pci_dev without a valid PIN? Btw, that whole vp_find_* code looks extremely fucked up to me. The whole point of pci_alloc_irq_vectors* API is that it keeps drivers from poling into details of MSI-X v MSI vs INTX.> - because of auto affinity, we try to reserve an interrupt on all CPUs > - as there are 512 devices with a single vector per VQ we would > have no issue as they would be spread between CPUs, > but allocating on all CPUs fails. > > > I don't think the issue should be fixed at blk level - it is not > blk specifix - but yes this looks like a problem. > Christoph, any idea?I think this goes into the low-level interrupt vector allocator. I think Thomas is still the expert on it.