Signed-off-by: Cyrill Gorcunov <[email protected]> Cc: Pavel Emelyanov <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Matt Mackall <[email protected]> Cc: Xiao Guangrong <[email protected]> Cc: Marcelo Tosatti <[email protected]> Cc: KOSAKI Motohiro <[email protected]> Cc: Stephen Rothwell <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: "Aneesh Kumar K.V" <[email protected]> --- 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 +there is still a scenario when we can loose soft dirty bit -- a task does +unmap previously mapped memory region and then maps new one exactly at the +same place. When unmap called the kernel internally clears PTEs values +including soft dirty bit. To notify user space application about such +memory region renewal the kernel always mark new memory regions (and +expanded regions) as soft dirtified. This feature is actively used by the checkpoint-restore project. You can find more details about it on http://criu.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
