| |
|
 |
|
 |
|
|
|
| |
|
|
xen-devel
Re: [Xen-devel] Kernel bug from 3.0 (was phy disks and vifs timing out i
On Thu, Sep 01, 2011 at 04:43:05PM +0100, Ian Campbell wrote:
> On Thu, 2011-09-01 at 16:37 +0100, Konrad Rzeszutek Wilk wrote:
> > > >> vmalloc: remove vmalloc_sync_all() from alloc_vm_area()
> > > >>
> > > >> There's no need for it: it will get faulted into the current
> > > >> pagetable
> > > >> as needed.
> > > >>
> > > >> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
> > > >>
> > > >> The flaw in the reasoning here is that you cannot take a kernel fault
> > > >> while processing a hypercall, so hypercall arguments must have been
> > > >> faulted in beforehand and that is what the sync_all was for.
> > > >>
> > > >> It's probably fair to say that the Xen specific caller should take care
> > > >> of that Xen-specific requirement rather than pushing it into common
> > > >> code. On the other hand Xen is the only user and creating a Xen
> > > >> specific
> > > >> helper/wrapper seems a bit pointless.
> > > >
> > > > Perhaps then doing the vmalloc_sync_all() (or are more precise one:
> > > > vmalloc_sync_one) should be employed in the netback code then?
> > > >
> > > > And obviously guarded by the CONFIG_HIGHMEM case?
> > >
> > > Perhaps. But I think the correct thing to do initially is revert the
> > > change and then look at possible improvements. Particularly as the fix
> > > needs to be a backported to stable.
> >
> > I disagree. Ian pointed out properly that this a Xen requirment - and there
> > is no reason for us to slow down non-Xen runs with vmalloc_sync_all plucked
> > in
> > a generic path.
>
> There is literally no other caller of alloc_vm_area than xen so you
> won't be slowing anyone else down.
Duh! I totally missed that. Sounds plausible then - let me ping Andrew Morton
on re-adding the vmalloc back.
>
> Maybe we should add alloc_vm_area_sync and use that everywhere?
That is an option too.
>
> Ian.
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-devel
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-devel
|
|
|
| |
|
Home