lkml.org 
[lkml]   [2007]   [Oct]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: race with page_referenced_one->ptep_test_and_clear_young and pagetable setup/pulldown
On Thu, 04 Oct 2007 18:43:32 -0700
Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> It seems to me that there are a few ways to fix this:
>
> 1. Use asm-generic/pgtable.h when CONFIG_PARAVIRT is enabled. This
> will clearly work, but is pretty blunt.
> 2. Make test_and_clear_pte_flags a new paravirt-op, which can be
> implemented in Xen as a hypercall, and as a raw
> test_and_clear_bit for everyone else. The downside is adding yet
> another pv-op.

Either of these two would work. Another alternative could be to
let test_and_clear_pte_flags have an exception table entry, where
we jump right to the next instruction if the instruction clearing
the flag fails.

That is the essentially variant you need for Xen, except the fast
path is still exactly the same it is as when running on native
hardware.

--
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/

\
 
 \ /
  Last update: 2007-10-05 03:55    [W:0.103 / U:1.864 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site