From: Jason Gunthorpe <jgg@nvidia.com>
To: Alex Williamson <alex.williamson@redhat.com>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
peterx@redhat.com, prime.zeng@hisilicon.com, cohuck@redhat.com
Subject: Re: [PATCH v2] vfio/pci: Handle concurrent vma faults
Date: Mon, 28 Jun 2021 14:30:28 -0300 [thread overview]
Message-ID: <20210628173028.GF4459@nvidia.com> (raw)
In-Reply-To: <20210628104653.4ca65921.alex.williamson@redhat.com>
On Mon, Jun 28, 2021 at 10:46:53AM -0600, Alex Williamson wrote:
> On Wed, 10 Mar 2021 11:58:07 -0700
> Alex Williamson <alex.williamson@redhat.com> wrote:
>
> > vfio_pci_mmap_fault() incorrectly makes use of io_remap_pfn_range()
> > from within a vm_ops fault handler. This function will trigger a
> > BUG_ON if it encounters a populated pte within the remapped range,
> > where any fault is meant to populate the entire vma. Concurrent
> > inflight faults to the same vma will therefore hit this issue,
> > triggering traces such as:
If it is just about concurrancy can the vma_lock enclose
io_remap_pfn_range() ?
> IIRC, there were no blocking issues on this patch as an interim fix to
> resolve the concurrent fault issues with io_remap_pfn_range().
> Unfortunately it also got no Reviewed-by or Tested-by feedback. I'd
> like to put this in for v5.14 (should have gone in earlier). Any final
> comments? Thanks,
I assume there is a reason why vm_lock can't be used here, so I
wouldn't object, though I don't especially like the loss of tracking
either.
Jason
next prev parent reply other threads:[~2021-06-28 17:30 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 18:58 [PATCH v2] vfio/pci: Handle concurrent vma faults Alex Williamson
2021-06-28 16:46 ` Alex Williamson
2021-06-28 17:30 ` Jason Gunthorpe [this message]
2021-06-28 18:36 ` Alex Williamson
2021-06-28 18:52 ` Jason Gunthorpe
2021-06-28 19:30 ` Alex Williamson
2021-06-28 23:26 ` Jason Gunthorpe
2021-06-29 14:11 ` Alex Williamson
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