On Mon, Jul 31, 2017 at 04:48:29PM -0700, Stephen Hemminger wrote:
> The setup of MSI with Hyper-V host was sleeping with locks held.
> This error is reported when doing SR-IOV hotplug with kernel built with lockdep.
>
> BUG: sleeping function called from invalid context at kernel/sched/completion.c:93
> in_atomic(): 1, irqs_disabled(): 1, pid: 1405, name: ip
> 3 locks held by ip/1405:
> #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff976b10bb>] rtnetlink_rcv+0x1b/0x40
> #1: (&desc->request_mutex){+.+...}, at: [<ffffffff970ddd33>] __setup_irq+0xb3/0x720
> #2: (&irq_desc_lock_class){-.-...}, at: [<ffffffff970ddd65>] __setup_irq+0xe5/0x720
> irq event stamp: 3476
> hardirqs last enabled at (3475): [<ffffffff971b3005>] get_page_from_freelist+0x225/0xc90
> hardirqs last disabled at (3476): [<ffffffff978024e7>] _raw_spin_lock_irqsave+0x27/0x90
> softirqs last enabled at (2446): [<ffffffffc05ef0b0>] ixgbevf_configure+0x380/0x7c0 [ixgbevf]
> softirqs last disabled at (2444): [<ffffffffc05ef08d>] ixgbevf_configure+0x35d/0x7c0 [ixgbevf]
>
> The workaround is to poll for host response instead of blocking on
> completion.
>
> Signed-off-by: Stephen Hemminger <sthemmin@xxxxxxxxxxxxx>
Applied to pci/host-hv for v4.14, thanks!
> ---
> drivers/pci/host/pci-hyperv.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/pci/host/pci-hyperv.c b/drivers/pci/host/pci-hyperv.c
> index 415dcc69a502..334c9a7b8991 100644
> --- a/drivers/pci/host/pci-hyperv.c
> +++ b/drivers/pci/host/pci-hyperv.c
> @@ -50,6 +50,7 @@
> #include <linux/kernel.h>
> #include <linux/module.h>
> #include <linux/pci.h>
> +#include <linux/delay.h>
> #include <linux/semaphore.h>
> #include <linux/irqdomain.h>
> #include <asm/irqdomain.h>
> @@ -1159,7 +1160,12 @@ static void hv_compose_msi_msg(struct irq_data *data, struct msi_msg *msg)
> goto free_int_desc;
> }
>
> - wait_for_completion(&comp.comp_pkt.host_event);
> + /*
> + * Since this function is called with IRQ locks held, can't
> + * do normal wait for completion; instead poll.
> + */
> + while (!try_wait_for_completion(&comp.comp_pkt.host_event))
> + udelay(100);
>
> if (comp.comp_pkt.completion_status < 0) {
> dev_err(&hbus->hdev->device,
> --
> 2.11.0
>
