On 08/20/13 08:31, Cyrill Gorcunov wrote:
> Signed-off-by: Cyrill Gorcunov <gorcunov@xxxxxxxxxx>
> Cc: Pavel Emelyanov <xemul@xxxxxxxxxxxxx>
> Cc: Andy Lutomirski <luto@xxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Matt Mackall <mpm@xxxxxxxxxxx>
> Cc: Xiao Guangrong <xiaoguangrong@xxxxxxxxxxxxxxxxxx>
> Cc: Marcelo Tosatti <mtosatti@xxxxxxxxxx>
> Cc: KOSAKI Motohiro <kosaki.motohiro@xxxxxxxxx>
> Cc: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx>
> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> ---
> Documentation/vm/soft-dirty.txt | 7 +++++++
> 1 file changed, 7 insertions(+)
>
> Index: linux-2.6.git/Documentation/vm/soft-dirty.txt
> ===================================================================
> --- linux-2.6.git.orig/Documentation/vm/soft-dirty.txt
> +++ linux-2.6.git/Documentation/vm/soft-dirty.txt
> @@ -28,6 +28,13 @@ This is so, since the pages are still ma
> the kernel does is finds this fact out and puts both writable and soft-dirty
> bits on the PTE.
>
> + While in most cases tracking memory changes by #PF-s is more than enough
enough,
> +there is still a scenario when we can loose soft dirty bit -- a task does
lose soft dirty bits -- a task
> +unmap previously mapped memory region and then maps new one exactly at the
unmaps a previously mapped memory region and then maps a new one at exactly the
> +same place. When unmap called the kernel internally clears PTEs values
When unmap is called, the kernel internally clears PTE values
> +including soft dirty bit. To notify user space application about such
bits.
> +memory region renewal the kernel always mark new memory regions (and
marks
> +expanded regions) as soft dirtified.
or: as soft dirty.
>
> This feature is actively used by the checkpoint-restore project. You
> can find more details about it on http://criu.org
> --
--
~Randy
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