Re: [PATCH] x86: fix ref-counting bug in change_page_attr()

From: Ingo Molnar
Date: Mon Dec 17 2007 - 08:28:59 EST



* Jan Beulich <jbeulich@xxxxxxxxxx> wrote:

> When either calling change_page_attr() with the default attributes
> pages in the direct mapping have and a page's attributes already were
> set to the default or when changing the attributes from one
> non-default value to another, the reference counting broke, leading to
> either premature restoration of a large page or missing the
> opportunity to do so.
>
> At the same time, make __PHYSICAL_MASK_SHIFT on 64-bits the value it
> architecturally ought to have.

hm, does this patch fix any real bug seen live? (if yes then do you have
links to it, etc?) It would be a v2.6.24 fix in theory but it looks too
dangerous for that. So i've queued it up for v2.6.25, for the time
being.

Ingo
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