From: Peter Xu <peterx@redhat.com>
To: Jason Gunthorpe <jgg@ziepe.ca>
Cc: dan.j.williams@intel.com, Paolo Bonzini <pbonzini@redhat.com>,
linux-kernel@vger.kernel.org, kvm@vger.kernel.org,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [PATCH 0/2] KVM: do not assume PTE is writable after follow_pfn
Date: Mon, 8 Feb 2021 17:02:59 -0500 [thread overview]
Message-ID: <20210208220259.GA71523@xz-x1> (raw)
In-Reply-To: <20210208185133.GW4718@ziepe.ca>
On Mon, Feb 08, 2021 at 02:51:33PM -0400, Jason Gunthorpe wrote:
> On Fri, Feb 05, 2021 at 01:14:11PM -0500, Peter Xu wrote:
>
> > But I do have a question on why dax as the only user needs to pass in the
> > notifier to follow_pte() for initialization.
>
> Not sure either, why does DAX opencode something very much like
> page_mkclean() with dax_entry_mkclean()?
>
> Also it looks like DAX uses the wrong notifier, it calls
> MMU_NOTIFY_CLEAR but page_mkclean_one() uses
> MMU_NOTIFY_PROTECTION_PAGE for the same PTE modification sequence??
>
> page_mkclean() has some technique to make the notifier have the right
> size without becoming entangled in the PTL locks..
Right. I guess it's because dax doesn't have "struct page*" on the back, so it
can't directly use page_mkclean(). However the whole logic does look very
similar, so maybe they can be merged in some way.
Thanks,
--
Peter Xu
next prev parent reply other threads:[~2021-02-08 22:03 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-05 10:32 [PATCH 0/2] KVM: do not assume PTE is writable after follow_pfn Paolo Bonzini
2021-02-05 10:32 ` [PATCH 1/2] mm: provide a sane PTE walking API for modules Paolo Bonzini
2021-02-05 13:49 ` Jason Gunthorpe
2021-02-08 17:39 ` Christoph Hellwig
2021-02-08 18:18 ` Paolo Bonzini
2021-02-09 8:14 ` Christoph Hellwig
2021-02-09 9:19 ` Paolo Bonzini
2021-02-05 10:32 ` [PATCH 2/2] KVM: do not assume PTE is writable after follow_pfn Paolo Bonzini
2021-02-05 15:43 ` kernel test robot
2021-02-05 17:41 ` kernel test robot
2021-02-05 18:14 ` [PATCH 0/2] " Peter Xu
2021-02-08 18:51 ` Jason Gunthorpe
2021-02-08 22:02 ` Peter Xu [this message]
2021-02-08 23:26 ` Jason Gunthorpe
2021-02-09 0:23 ` Peter Xu
2021-02-09 8:19 ` Christoph Hellwig
2021-02-09 10:02 ` Joao Martins
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