On Thu, 27 May 2021 13:51:28 +0100, Quentin Perret <qperret@xxxxxxxxxx> wrote: > > The hyp_page refcount helpers currently rely on the hyp_pool lock for > serialization. However, this means the refcounts can't be changed from > the buddy allocator core as it already holds the lock, which means pages > have to go through odd transient states. > > For example, when a page is freed, its refcount is set to 0, and the > lock is transiently released before the page can be attached to a free > list in the buddy tree. This is currently harmless as the allocator > checks the list node of each page to see if it is available for > allocation or not, but it means the page refcount can't be trusted to > represent the state of the page even if the pool lock is held. > > In order to fix this, remove the pool locking from the refcount helpers, > and move all the logic to the buddy allocator. This will simplify the > removal of the list node from struct hyp_page in a later patch. Is there any chance some documentation could be added so that we have a record of what the locking boundaries are? Something along the line of what we have in arch/arm64/kvm/vgic/vgic.c, for example. Thanks, M. -- Without deviation from the norm, progress is not possible. _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
