Subject: + mm-track-vma-changes-with-vm_softdirty-bit-fix.patch added to -mm tree To: gorcunov@xxxxxxxxx,akpm@xxxxxxxxxxxxxxxxxxxx,aneesh.kumar@xxxxxxxxxxxxxxxxxx,gorcunov@xxxxxxxxxx,kosaki.motohiro@xxxxxxxxx,luto@xxxxxxxxxxxxxx,mpm@xxxxxxxxxxx,mtosatti@xxxxxxxxxx,peterz@xxxxxxxxxxxxx,rdunlap@xxxxxxxxxxxxx,rob@xxxxxxxxxxx,sfr@xxxxxxxxxxxxxxxx,xemul@xxxxxxxxxxxxx,xiaoguangrong@xxxxxxxxxxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Tue, 20 Aug 2013 15:28:34 -0700 The patch titled Subject: docs: Document soft dirty behaviour for freshly created memory regions, v2 has been added to the -mm tree. Its filename is mm-track-vma-changes-with-vm_softdirty-bit-fix.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/mm-track-vma-changes-with-vm_softdirty-bit-fix.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/mm-track-vma-changes-with-vm_softdirty-bit-fix.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Cyrill Gorcunov <gorcunov@xxxxxxxxx> Subject: docs: Document soft dirty behaviour for freshly created memory regions, v2 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> Cc: Randy Dunlap <rdunlap@xxxxxxxxxxxxx> Cc: Rob Landley <rob@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/vm/soft-dirty.txt | 7 +++++++ 1 file changed, 7 insertions(+) diff -puN Documentation/vm/soft-dirty.txt~mm-track-vma-changes-with-vm_softdirty-bit-fix Documentation/vm/soft-dirty.txt --- a/Documentation/vm/soft-dirty.txt~mm-track-vma-changes-with-vm_softdirty-bit-fix +++ a/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 _ Patches currently in -mm which might be from gorcunov@xxxxxxxxx are arch-x86-include-asm-pgtable-2levelh-clean-up-pte_to_pgoff-and-pgoff_to_pte-helpers.patch mm-track-vma-changes-with-vm_softdirty-bit.patch mm-track-vma-changes-with-vm_softdirty-bit-fix.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html