The 5.4.0-1075-azure and newer kernels are broken in that the VM can
easily panic when the Mellanox VF NIC is removed and added due to Azure
host servicing events or the below manual "unbind/bind" test (here the
GUID can be different in different VMs):
for i in `seq 1 1000`;
do
cd /sys/bus/vmbus/drivers/hv_pci;
echo abdc2107-402e-4704-8c88-c2b850696c3c > unbind;
echo abdc2107-402e-4704-8c88-c2b850696c3c > bind;
done
A sample panic call-trace is:
[ 107.359954] kernel BUG at
/build/linux-azure-5.4-4I3kFs/linux-azure-5.4-5.4.0/mm/slub.c:4020!
[ 107.363858] invalid opcode: 0000 [#1] SMP NOPTI
[ 107.365870] CPU: 0 PID: 334 Comm: kworker/0:2 Not tainted 5.4.0-1077-azure
#80~18.04.1-Ubuntu
[ 107.369589] Hardware name: Microsoft Corporation Virtual Machine/Virtual
Machine, BIOS 090008 12/07/2018
[ 107.373811] Workqueue: events vmbus_onmessage_work
[ 107.375909] RIP: 0010:kfree+0x1d2/0x240
…
[ 107.413789] Call Trace:
[ 107.414867] kobject_uevent_env+0x1b5/0x7e0
[ 107.416747] kobject_uevent+0xb/0x10
[ 107.418327] device_release_driver_internal+0x191/0x1c0
[ 107.420653] device_release_driver+0x12/0x20
[ 107.422523] bus_remove_device+0xe1/0x150
[ 107.424279] device_del+0x167/0x380
[ 107.425824] device_unregister+0x1a/0x60
[ 107.427536] vmbus_device_unregister+0x27/0x50
[ 107.429528] vmbus_onoffer_rescind+0x1d0/0x1f0
[ 107.431474] vmbus_onmessage+0x2c/0x70
[ 107.433104] vmbus_onmessage_work+0x22/0x30
[ 107.434919] process_one_work+0x209/0x400
[ 107.436661] worker_thread+0x34/0x40
It turns out there is a bug in https://git.launchpad.net/~canonical-
kernel/ubuntu/+source/linux-azure/+git/bionic/commit/?id=16a3c750a78d8,
which misses the second hunk of the upstream patch
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=877b911a5ba0.
Please apply the below patch to fix the issue:
--- a/drivers/pci/controller/pci-hyperv.c
+++ b/drivers/pci/controller/pci-hyperv.c
@@ -3653,7 +3653,7 @@ static int hv_pci_remove(struct hv_device *hdev)
hv_put_dom_num(hbus->bridge->domain_nr);
- free_page((unsigned long)hbus);
+ kfree(hbus);
return ret;
}
BTW, please apply this patch as well (Note: this patch is not really required
as it's only for error handling path, which is usually unlikely):
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=42c3d41832ef4fcf60aaa6f748de01ad99572adf
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https://bugs.launchpad.net/bugs/1965618
Title:
linux-azure: Focal 5.4 arm64 support
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