Here is updated one, thanks again. --- From: Cyrill Gorcunov <gorcu...@gmail.com> Subject: [PATCH] docs: Document soft dirty behaviour for freshly created memory regions
Signed-off-by: Cyrill Gorcunov <gorcu...@openvz.org> Cc: Pavel Emelyanov <xe...@parallels.com> Cc: Andy Lutomirski <l...@amacapital.net> Cc: Andrew Morton <a...@linux-foundation.org> Cc: Matt Mackall <m...@selenic.com> Cc: Xiao Guangrong <xiaoguangr...@linux.vnet.ibm.com> Cc: Marcelo Tosatti <mtosa...@redhat.com> Cc: KOSAKI Motohiro <kosaki.motoh...@gmail.com> Cc: Stephen Rothwell <s...@canb.auug.org.au> Cc: Peter Zijlstra <pet...@infradead.org> Cc: "Aneesh Kumar K.V" <aneesh.ku...@linux.vnet.ibm.com> Cc: Randy Dunlap <rdun...@infradead.org> --- 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 lose soft dirty bits -- a task +unmaps a previously mapped memory region and then maps a new one at exactly +the same place. When unmap is called, the kernel internally clears PTE values +including soft dirty bits. To notify user space application about such +memory region renewal the kernel always marks new memory regions (and +expanded regions) as soft dirty. 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 majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
