[PATCH 1/7] mm: Add write-protect and clean utilities for address space ranges
Kirill A. Shutemov
kirill at shutemov.name
Wed Sep 18 14:41:02 UTC 2019
On Wed, Sep 18, 2019 at 02:59:08PM +0200, Thomas Hellström (VMware) wrote:
> From: Thomas Hellstrom <thellstrom at vmware.com>
>
> Add two utilities to a) write-protect and b) 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.
>
> The added file "as_dirty_helpers.c" is initially listed as maintained by
> VMware under our DRM driver. If somebody would like it elsewhere,
> that's of course no problem.
After quick glance, it looks a lot as rmap code duplication. Why not
extend rmap_walk() interface instead to cover range of pages?
>
> Cc: Andrew Morton <akpm at linux-foundation.org>
> Cc: Matthew Wilcox <willy at infradead.org>
> Cc: Will Deacon <will.deacon at arm.com>
> Cc: Peter Zijlstra <peterz at infradead.org>
> Cc: Rik van Riel <riel at surriel.com>
> Cc: Minchan Kim <minchan at kernel.org>
> Cc: Michal Hocko <mhocko at suse.com>
> Cc: Huang Ying <ying.huang at intel.com>
> Cc: Souptick Joarder <jrdr.linux at gmail.com>
> Cc: "Jérôme Glisse" <jglisse at redhat.com>
> Cc: linux-mm at kvack.org
> Cc: linux-kernel at vger.kernel.org
>
> Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
> Reviewed-by: Ralph Campbell <rcampbell at nvidia.com> #v1
> ---
> MAINTAINERS | 1 +
> include/linux/mm.h | 13 +-
> mm/Kconfig | 3 +
> mm/Makefile | 1 +
> mm/as_dirty_helpers.c | 392 ++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 409 insertions(+), 1 deletion(-)
> create mode 100644 mm/as_dirty_helpers.c
>
> diff --git a/MAINTAINERS b/MAINTAINERS
> index c2d975da561f..b596c7cf4a85 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -5287,6 +5287,7 @@ T: git git://people.freedesktop.org/~thomash/linux
> S: Supported
> F: drivers/gpu/drm/vmwgfx/
> F: include/uapi/drm/vmwgfx_drm.h
> +F: mm/as_dirty_helpers.c
Emm.. No. Core MM functinality cannot belong to random driver.
--
Kirill A. Shutemov
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