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] vfio/pci: Handle concurrent vma faults
Date: Fri, 12 Mar 2021 20:03:06 -0400 [thread overview]
Message-ID: <20210313000306.GI2356281@nvidia.com> (raw)
In-Reply-To: <20210312135844.5e97aac7@omen.home.shazbot.org>
On Fri, Mar 12, 2021 at 01:58:44PM -0700, Alex Williamson wrote:
> Yeah, we can indeed use memalloc_nofs_save/restore(). It seems we're
> trying to allocate something for pfnmap tracking and that enables lots
> of lockdep specific tests. Is it valid to wrap io_remap_pfn_range()
> around clearing this flag or am I just masking a bug? Thanks,
Yes, I think it is fine. Those functions are ment to be used in a
no-fs kind of region exactly like this.
no-fs is telling the allocator not to do reclaim which is forbidden
under the locks here (as reclaim will also attempt to get these locks)
I would defer to Michal Hocko though, maybe cc him on the final patch
series version.
Jason
prev parent reply other threads:[~2021-03-13 0:03 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-10 17:53 [PATCH] vfio/pci: Handle concurrent vma faults Alex Williamson
2021-03-10 18:14 ` Jason Gunthorpe
2021-03-10 18:34 ` Alex Williamson
2021-03-10 18:40 ` Jason Gunthorpe
2021-03-10 20:06 ` Peter Xu
2021-03-11 11:35 ` Christoph Hellwig
2021-03-11 16:35 ` Peter Xu
2021-03-12 19:16 ` Alex Williamson
2021-03-12 19:41 ` Jason Gunthorpe
2021-03-12 20:09 ` Alex Williamson
2021-03-12 20:58 ` Alex Williamson
2021-03-13 0:03 ` Jason Gunthorpe [this message]
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