David Hildenbrand <da...@redhat.com> wrote: > On 17.01.23 12:22, David Hildenbrand wrote: >> While playing with migration of virtio-mem with an ordinary file backing, >> I realized that migration and prealloc doesn't currently work as expected >> for virtio-mem. Further, Jing Qi reported that setup issues (insufficient >> huge pages on the destination) result in QEMU getting killed with SIGBUS >> instead of failing gracefully. >> In contrast to ordinary memory backend preallocation, virtio-mem >> preallocates memory before plugging blocks to the guest. Consequently, >> when migrating we are not actually preallocating on the destination but >> "only" migrate pages. Fix that be migrating the bitmap early, before any >> RAM content, and use that information to preallocate memory early, before >> migrating any RAM. >> Postcopy needs some extra care, and I realized that >> prealloc+postcopy is >> shaky in general. Let's at least try to mimic what ordinary >> prealloc+postcopy does: temporarily allocate the memory, discard it, and >> cross fingers that we'll still have sufficient memory when postcopy >> actually tries placing pages. >> Cc: Dr. David Alan Gilbert <dgilb...@redhat.com> >> Cc: Juan Quintela <quint...@redhat.com> >> Cc: Peter Xu <pet...@redhat.com> >> Cc: Michael S. Tsirkin <m...@redhat.com> >> Cc: Michal Privoznik <mpriv...@redhat.com> > > @Juan, David: I can similarly take this via my tree as well.
Reviewing it. I can get it through migration tree, thanks. Later, Juan.
