Re: [Xen-devel] Re: [PATCH] Fix performance problems with mprotect()

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

The BUG_ON() is valid until the per-domain biglock is removed.

 -- Keir

On 7/1/08 16:16, "Bruce Rogers" <BROGERS@xxxxxxxxxx> wrote:

> I'm not sure how this BUG_ON would get triggered with current x86 paging
> semantics, and probably isn't needed I think.
> Am I missing something?
> The code is almost exactly the same as the existing update_intpte, which has
> the same BUG_ON, and so I just left it in.
> (BTW:I considered merging the new functions into the non "sync" versions but
> opted not to.)
> 
> - Bruce
> 
>>>> On 1/7/2008 at 8:18 AM, in message <p73d4sdsly4.fsf@xxxxxxxxxxxxxx>, Andi
>>>> Kleen
> <andi@xxxxxxxxxxxxxx> wrote:
>> "Bruce Rogers" <brogers@xxxxxxxxxx> writes:
>>> +
>>> +        /* Allowed to change in Accessed/Dirty flags only. */
>>> +        BUG_ON((t ^ old) & ~(intpte_t)(_PAGE_ACCESSED|_PAGE_DIRTY));
>> 
>> 
>> Are you sure that BUG_ON can't be triggered from the hypercall?
>> It should error out in this case I think.
>> 
>> -Andi
> 
> 
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