Hi James.
On Sun, 11 May 2025 at 09:03, David Hildenbrand <david@xxxxxxxxxx> wrote:
>
> On 09.05.25 22:54, James Houghton wrote:
> > On Wed, Apr 30, 2025 at 9:57 AM Fuad Tabba <tabba@xxxxxxxxxx> wrote:
> >> +static int kvm_gmem_mmap(struct file *file, struct vm_area_struct *vma)
> >> +{
> >> + struct kvm_gmem *gmem = file->private_data;
> >> +
> >> + if (!kvm_arch_gmem_supports_shared_mem(gmem->kvm))
> >> + return -ENODEV;
> >> +
> >> + if ((vma->vm_flags & (VM_SHARED | VM_MAYSHARE)) !=
> >> + (VM_SHARED | VM_MAYSHARE)) {
> >> + return -EINVAL;
> >> + }
> >> +
> >> + vm_flags_set(vma, VM_DONTDUMP);
> >
> > Hi Fuad,
> >
> > Sorry if I missed this, but why exactly do we set VM_DONTDUMP here?
> > Could you leave a small comment? (I see that it seems to have
> > originally come from Patrick? [1]) I get that guest memory VMAs
> > generally should have VM_DONTDUMP; is there a bigger reason?
>
> (David replying)
>
> I assume because we might have inaccessible parts in there that SIGBUS
> on access.
That was my thinking.
> get_dump_page() does ignore any errors, though (returning NULL), so
> likely we don't need VM_DONTDUMP.
In which case I'll remove this from the next respin.
Thanks,
/fuad
> --
> Cheers,
>
> David / dhildenb
>
