Messages in this thread | | | Date | Tue, 23 Nov 2021 09:06:39 +0800 | From | Chao Peng <> | Subject | Re: [RFC v2 PATCH 13/13] KVM: Enable memfd based page invalidation/fallocate |
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On Mon, Nov 22, 2021 at 05:16:47PM +0300, Kirill A. Shutemov wrote: > On Fri, Nov 19, 2021 at 09:47:39PM +0800, Chao Peng wrote: > > Since the memory backing store does not get notified when VM is > > destroyed so need check if VM is still live in these callbacks. > > > > Signed-off-by: Yu Zhang <yu.c.zhang@linux.intel.com> > > Signed-off-by: Chao Peng <chao.p.peng@linux.intel.com> > > --- > > virt/kvm/memfd.c | 22 ++++++++++++++++++++++ > > 1 file changed, 22 insertions(+) > > > > diff --git a/virt/kvm/memfd.c b/virt/kvm/memfd.c > > index bd930dcb455f..bcfdc685ce22 100644 > > --- a/virt/kvm/memfd.c > > +++ b/virt/kvm/memfd.c > > @@ -12,16 +12,38 @@ > > #include <linux/memfd.h> > > const static struct guest_mem_ops *memfd_ops; > > > > +static bool vm_is_dead(struct kvm *vm) > > +{ > > + struct kvm *kvm; > > + > > + list_for_each_entry(kvm, &vm_list, vm_list) { > > + if (kvm == vm) > > + return false; > > + } > > I don't think this is enough. The struct kvm can be freed and re-allocated > from the slab and this function will give false-negetive.
Right.
> > Maybe the kvm has to be tagged with a sequential id that incremented every > allocation. This id can be checked here.
Sounds like a sequential id will be needed, no existing fields in struct kvm can work for this.
> > > + > > + return true; > > +} > > -- > Kirill A. Shutemov
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