On 03/09/21 18:18, Sean Christopherson wrote:
Before moving forward with a fix, I'd like to get Paolo's input on dropping track_srcu in favor of kvm->srcu and avoiding this altogheter. Note, Paolo is on vacation at the moment, so this won't get attention for a week or more.
The reason for track_srcu's existence is to avoid complications in kvm_arch_flush_shadow_memslot, which is called from the _write_ side of kvm->srcu but is on the _read_ side of track_srcu.
I think this should be fixed easily by taking slots_lock in kvm_page_track_register_notifier and kvm_page_track_unregister_notifier, however it's a bit more complicated from the point of view of the lock hierarchy and possible deadlocks.
So I'm open to patches that drop track_srcu, but for now I applied this patch.
Paolo
