On Wed, Aug 10, 2011 at 12:01:04PM +0300, Avi Kivity wrote: > On 08/10/2011 08:10 AM, David Gibson wrote: > >On Mon, Aug 08, 2011 at 11:24:09AM +0300, Avi Kivity wrote: > >> On 08/08/2011 09:03 AM, David Gibson wrote: [snip] > >This would seem to be a genuine bug in the hugepage code, which has > >just been hidden by SYNC_MMU. It should be quite easy to fix - the > >mapping is only stored in the struct page to get to the hugetlbfs > >superblock, so we could just store a direct superblock pointer > >instead, and bump it's refcount when we put that in the page private > >pointer. > > > >But then I'm not sure how qemu would detect that it's on a kernel > >where the bug is fixed and allow -mem-path to be used again. Any > >ideas? > > If it's just a kernel bug, the fix belongs in the kernel, not in qemu. Obviously. > We used to have KVM_CAPs to declare this sort of thing > (KVM_CAP_HUGETLBFS_WORKS_EVEN_WITHOUT_SYNC_MMU) but I don't think it > was a good idea. I tend to agree - especially since there's nothing actually kvm specific about this bug. AFAICT a driver which did gup on hugepages could trigger the bug equally well. -- David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_ | _way_ _around_! http://www.ozlabs.org/~dgibson -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
