On Wed, Sep 03, 2008 at 12:01:19AM +0100, Graham Cobb wrote:
> The bisection is complete. It took longer than I expected as many of the
> versions git-bisect wanted to test would not build UML without tracking down
> some additional patches.
>
> The bug seems to have been introduced with git commit
> 3963333fe6767f15141ab2dc3b933721c636c212 (uml: cover stubs with a VMA).
Excellent, the backtrace now makes a bit of sense. It looks like the
VMAs at the top of the address space are being overmapped by a call to
mmap. The question is why does it look like there's a big enough hole
there, when it ends up unmapping the stubs in order to make room for
the mmap.
> With hindsight I suppose I could have guessed that would be the commit: the
> crash seemed to be when unmapping a VMA. If my reading of the page flags is
> correct the problem is that the page has the PG_reserved flag set, so what is
> it doing in the VMA which is being unmapped?
A page of kernel code is mapped into the process. This page (and all
other pages containing kernel text) is marked reserved during boot.
> Let me know if you want me to run some more tests, for example if you want to
> add some printk's in the code to understand more about what is going on.
I'm going to need some more information. I'll get back to you with a
patch...
Jeff
--
Work email - jdike at linux dot intel dot com
--
To UNSUBSCRIBE, email to [EMAIL PROTECTED]
with a subject of "unsubscribe". Trouble? Contact [EMAIL PROTECTED]
