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Date:   Tue, 9 Mar 2021 08:46:09 -0400
From:   Jason Gunthorpe <jgg@nvidia.com>
To:     "Zengtao (B)" <prime.zeng@hisilicon.com>
Cc:     Peter Xu <peterx@redhat.com>,
        Alex Williamson <alex.williamson@redhat.com>,
        Cornelia Huck <cohuck@redhat.com>,
        Kevin Tian <kevin.tian@intel.com>,
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        Jann Horn <jannh@google.com>,
        Max Gurtovoy <mgurtovoy@nvidia.com>,
        "kvm@vger.kernel.org" <kvm@vger.kernel.org>,
        "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
        Linuxarm <linuxarm@huawei.com>
Subject: Re: =?utf-8?B?562U5aSN?= =?utf-8?Q?=3A?= [PATCH] vfio/pci: make the
 vfio_pci_mmap_fault reentrant
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On Tue, Mar 09, 2021 at 03:49:09AM +0000, Zengtao (B) wrote:
> Hi guys:
> 
> Thanks for the helpful comments, after rethinking the issue, I have proposed
>  the following change: 
> 1. follow_pte instead of follow_pfn.

Still no on follow_pfn, you don't need it once you use vmf_insert_pfn

> 2. vmf_insert_pfn loops instead of io_remap_pfn_range
> 3. proper undos when some call fails.
> 4. keep the bigger lock range to avoid unessary pte install. 

Why do we need locks at all here?

Jason