linux-kernel - Re: [PATCH v6 4/8] mm: Add write-protect and clean utilities for address space ranges

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Message-Id: <20191105195114.f75be5e76763da5546121b41@linux-foundation.org>
Date:   Tue, 5 Nov 2019 19:51:14 -0800
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Thomas Hellström (VMware) 
        <thomas_os@...pmail.org>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        torvalds@...ux-foundation.org,
        Thomas Hellstrom <thellstrom@...are.com>,
        Matthew Wilcox <willy@...radead.org>,
        Will Deacon <will.deacon@....com>,
        Peter Zijlstra <peterz@...radead.org>,
        Rik van Riel <riel@...riel.com>,
        Minchan Kim <minchan@...nel.org>,
        Michal Hocko <mhocko@...e.com>,
        Huang Ying <ying.huang@...el.com>,
        Jérôme Glisse <jglisse@...hat.com>,
        "Kirill A . Shutemov" <kirill@...temov.name>
Subject: Re: [PATCH v6 4/8] mm: Add write-protect and clean utilities for
 address space ranges

On Mon, 14 Oct 2019 15:22:00 +0200 Thomas Hellström (VMware) <thomas_os@...pmail.org> wrote:

> Add two utilities to 1) write-protect and 2) clean all ptes pointing into
> a range of an address space.
> The utilities are intended to aid in tracking dirty pages (either
> driver-allocated system memory or pci device memory).
> The write-protect utility should be used in conjunction with
> page_mkwrite() and pfn_mkwrite() to trigger write page-faults on page
> accesses. Typically one would want to use this on sparse accesses into
> large memory regions. The clean utility should be used to utilize
> hardware dirtying functionality and avoid the overhead of page-faults,
> typically on large accesses into small memory regions.

Not fully comfortable reviewing this one.

> --- a/mm/Kconfig
> +++ b/mm/Kconfig
> @@ -736,4 +736,7 @@ config ARCH_HAS_PTE_SPECIAL
>  config ARCH_HAS_HUGEPD
>  	bool
>  
> +config MAPPING_DIRTY_HELPERS
> +        bool
> +

But given this, it's your problem ;)  So

Acked-by: Andrew Morton <akpm@...ux-foundation.org>

Yes, please proceed with merging [1-4] via a drm tree.