From: Lukas Wunner <lukas@wunner.de>
To: Steven Haigh <netwiz@crc.id.au>
Cc: linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org,
f.ebner@proxmox.com
Subject: Re: Qemu KVM thread spins at 100% CPU usage on scsi hot-unplug (kernel 6.6.8 guest)
Date: Thu, 28 Dec 2023 14:18:02 +0100 [thread overview]
Message-ID: <20231228131802.GA21994@wunner.de> (raw)
In-Reply-To: <3a7656ab-df4c-4d57-8866-661beffcddd7@crc.id.au>
On Thu, Dec 28, 2023 at 01:03:10PM +1100, Steven Haigh wrote:
> At some point in kernel 6.6.x, SCSI hotplug in qemu VMs broke. This was
> mostly fixed in the following commit to release 6.6.8:
> commit 5cc8d88a1b94b900fd74abda744c29ff5845430b
> Author: Bjorn Helgaas <bhelgaas@google.com>
> Date: Thu Dec 14 09:08:56 2023 -0600
> Revert "PCI: acpiphp: Reassign resources on bridge if necessary"
>
> After this commit, the SCSI block device is hotplugged correctly, and a device node as /dev/sdX appears within the qemu VM.
>
> New problem:
>
> When the same SCSI block device is hot-unplugged, the QEMU KVM process will
> spin at 100% CPU usage. The guest shows no CPU being used via top, but the
> host will continue to spin in the KVM thread until the VM is rebooted.
Find out the PID of the qemu process on the host, then cat /proc/$PID/stack
to see where the CPU time is spent.
next prev parent reply other threads:[~2023-12-28 13:18 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-12-28 2:03 Qemu KVM thread spins at 100% CPU usage on scsi hot-unplug (kernel 6.6.8 guest) Steven Haigh
2023-12-28 13:18 ` Lukas Wunner [this message]
2023-12-29 5:46 ` Steven Haigh
2024-01-03 9:46 ` Fiona Ebner
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