Message-Id: <20220924034854.323-1-angus.chen@jaguarmicro.com>
Date:   Sat, 24 Sep 2022 11:48:54 +0800
From:   Angus Chen <angus.chen@...uarmicro.com>
To:     jasowang@...hat.com, mst@...hat.com, pbonzini@...hat.com,
        axboe@...nel.dk
Cc:     virtualization@...ts.linux-foundation.org,
        linux-block@...r.kernel.org, linux-kernel@...r.kernel.org,
        Angus Chen <angus.chen@...uarmicro.com>,
        Liming Wu <liming.wu@...uarmicro.com>
Subject: [PATCH v1] virtio_blk: should not use IRQD_AFFINITY_MANAGED in init_rq

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.

without config CONFIG_GENERIC_IRQ_DEBUGFS,
I found that we called vp_find_vqs_msix failed twice because of
the irq resource was exhausted.

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@...uarmicro.com>
Tested-by: Liming Wu <liming.wu@...uarmicro.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

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