Why a locked page must be copied in COW?

Mulyadi Santosa mulyadi.santosa at gmail.com
Sat Sep 15 11:24:00 EDT 2012

Hi Permenides...

On Sat, Sep 15, 2012 at 9:51 PM, Parmenides <mobile.parmenides at gmail.com> wrote:
> In conclusion, if old_page is locked or it is not locked and two or
> more  processes own old_page, we should copy it. I don't understand
> why a locked page must be copied regardless of how many processes own
> it. Why do we give a locked page a special consideration?

this is really new stuff.... okay, wp should be "write protect", right?

if that so, I have a mild good guess that copying the page is actually
a way to not add another pressure to the locked page.

By doing that, write protect could be done right away and write
operations follow that. Not sure if we need to do synchronization
between the new page and the old locked page.


Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

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