Re: [PATCH] iommu/vt-d: Remove unnecessary locking in intel_irq_remapping_alloc()

Nicolin Chen
2023-04-27T03:37:49Z

On Thu, Apr 27, 2023 at 11:20:40AM +0800, Baolu Lu wrote:

> > Attaching WARNINGs:
> > [ 19.680725] ------------[ cut here ]------------
> > [ 19.681083] WARNING: CPU: 0 PID: 561 at include/linux/mmap_lock.h:161 track_pfn_remap+0xf5/0x100

> > [ 19.684817] Call Trace:
> > [ 19.684893] <TASK>
> > [ 19.684967] remap_pfn_range+0x3e/0xa0
> > [ 19.685084] vfio_pci_mmap_fault+0x8a/0x160 [vfio_pci_core]

> I took a quick look. It seems that above warnings are irrelevant to this
> commit. Can you please simply revert this commit and check whether there
> are any changes?

I tried on top of the v6.3-rc5 tag. The warnings were triggered
constantly. And reverting the commit fixes it:
nicolinc@Asurada-Nvidia:~/work/mkt/images/nicolinc/src/kernel$ git log --oneline -2
cb3dc9b2417e (HEAD -> v6.3-rc5) Revert "iommu/vt-d: Remove unnecessary locking in intel_irq_remapping_alloc()"
7e364e56293b (tag: v6.3-rc5, jgg/linus) Linux 6.3-rc5

I don't think the commit is the causation yet there seems to be
a strong correlation here...

Thanks
Nic