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* [PATCH -mm] docs: Document soft dirty behaviour for freshly created memory regions
@ 2013-08-20 15:31 Cyrill Gorcunov
  2013-08-20 16:57 ` Randy Dunlap
  2013-08-20 21:15 ` [PATCH -mm] docs: Document soft dirty behaviour for freshly created memory regions Rob Landley
  0 siblings, 2 replies; 8+ messages in thread
From: Cyrill Gorcunov @ 2013-08-20 15:31 UTC (permalink / raw)
  To: Andrew Morton
  Cc: linux-mm, linux-kernel, Andy Lutomirski, Pavel Emelyanov,
	Matt Mackall, Xiao Guangrong, Marcelo Tosatti, KOSAKI Motohiro,
	Stephen Rothwell, Peter Zijlstra, Aneesh Kumar K.V

Signed-off-by: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: Pavel Emelyanov <xemul@parallels.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@gmail.com>
Cc: Stephen Rothwell <sfr@canb.auug.org.au>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@linux.vnet.ibm.com>
---
 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

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^ permalink raw reply	[flat|nested] 8+ messages in thread
end of thread, other threads:[~2013-08-20 21:43 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2013-08-20 15:31 [PATCH -mm] docs: Document soft dirty behaviour for freshly created memory regions Cyrill Gorcunov
2013-08-20 16:57 ` Randy Dunlap
2013-08-20 17:01   ` Cyrill Gorcunov
2013-08-20 17:25     ` Randy Dunlap
2013-08-20 18:13       ` [PATCH -mm] docs: Document soft dirty behaviour for freshly created memory regions, v3 Cyrill Gorcunov
2013-08-20 17:06   ` [PATCH -mm] docs: Document soft dirty behaviour for freshly created memory regions, v2 Cyrill Gorcunov
2013-08-20 21:15 ` [PATCH -mm] docs: Document soft dirty behaviour for freshly created memory regions Rob Landley
2013-08-20 21:43   ` Cyrill Gorcunov

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