nvme-pci: use blk-mq mapping for unmanaged irqs [Linux 5.2]

nvme-pci: use blk-mq mapping for unmanaged irqs [Linux 5.2]

This Linux kernel change "nvme-pci: use blk-mq mapping for unmanaged irqs" is included in the Linux 5.2 release. This change is authored by Keith Busch <keith.busch [at] intel.com> on Tue May 21 10:56:43 2019 -0600. The commit for this change in Linux stable tree is cb9e0e5 (patch).

nvme-pci: use blk-mq mapping for unmanaged irqs

If a device is providing a single IRQ vector, the IO queue will share
that vector with the admin queue. This is an unmanaged vector, so does
not have a valid PCI IRQ affinity. Avoid trying to extract a managed
affinity in this case and let blk-mq set up the cpu:queue mapping instead.
Otherwise we'd hit the following warning when the device is using MSI:

 WARNING: CPU: 4 PID: 7 at drivers/pci/msi.c:1272 pci_irq_get_affinity+0x66/0x80
 Modules linked in: nvme nvme_core serio_raw
 CPU: 4 PID: 7 Comm: kworker/u16:0 Tainted: G        W         5.2.0-rc1+ #494
 Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
 Workqueue: nvme-reset-wq nvme_reset_work [nvme]
 RIP: 0010:pci_irq_get_affinity+0x66/0x80
 Code: 0b 31 c0 c3 83 e2 10 48 c7 c0 b0 83 35 91 74 2a 48 8b 87 d8 03 00 00 48 85 c0 74 0e 48 8b 50 30 48 85 d2 74 05 39 70 14 77 05 <0f> 0b 31 c0 c3 48 63 f6 48 8d 04 76 48 8d 04 c2 f3 c3 48 8b 40 30
 RSP: 0000:ffffb5abc01d3cc8 EFLAGS: 00010246
 RAX: ffff9536786a39c0 RBX: 0000000000000000 RCX: 0000000000000080
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff9536781ed000
 RBP: ffff95367346a008 R08: ffff95367d43f080 R09: ffff953678c07800
 R10: ffff953678164800 R11: 0000000000000000 R12: 0000000000000000
 R13: ffff9536781ed000 R14: 00000000ffffffff R15: ffff95367346a008
 FS:  0000000000000000(0000) GS:ffff95367d400000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: 00007fdf814a3ff0 CR3: 000000001a20f000 CR4: 00000000000006e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
 Call Trace:
  blk_mq_pci_map_queues+0x37/0xd0
  nvme_pci_map_queues+0x80/0xb0 [nvme]
  blk_mq_alloc_tag_set+0x133/0x2f0
  nvme_reset_work+0x105d/0x1590 [nvme]
  process_one_work+0x291/0x530
  worker_thread+0x218/0x3d0
  ? process_one_work+0x530/0x530
  kthread+0x111/0x130
  ? kthread_park+0x90/0x90
  ret_from_fork+0x1f/0x30
 ---[ end trace 74587339d93c83c0 ]---

Fixes: 22b5560195bd6 ("nvme-pci: Separate IO and admin queue IRQ vectors")
Reported-by: Iv├ín Chavero <[email protected]>
Reviewed-by: Ming Lei <[email protected]>
Signed-off-by: Keith Busch <[email protected]>

There are 2 lines of Linux source code added/deleted in this change. Code changes to Linux kernel are as follows.

 drivers/nvme/host/pci.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 599065e..f5621545 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -464,7 +464,7 @@ static int nvme_pci_map_queues(struct blk_mq_tag_set *set)
         * affinity), so use the regular blk-mq cpu mapping
         */
        map->queue_offset = qoff;
-       if (i != HCTX_TYPE_POLL)
+       if (i != HCTX_TYPE_POLL && offset)
            blk_mq_pci_map_queues(map, to_pci_dev(dev->dev), offset);
        else
            blk_mq_map_queues(map);

Leave a Reply

Your email address will not be published. Required fields are marked *