On Sat, Jan 13, 2024 at 05:44:33PM +0800, Nanyong Sun wrote: > HVO was previously disabled on arm64 [1] due to the lack of necessary > BBM(break-before-make) logic when changing page tables. > This set of patches fix this by adding necessary BBM sequence when > changing page table, and supporting vmemmap page fault handling to > fixup kernel address translation fault if vmemmap is concurrently accessed. I'm not keen on this approach. I'm not even sure it's safe. In the second patch, you take the init_mm.page_table_lock on the fault path but are we sure this is unlocked when the fault was taken? Basically you can get a fault anywhere something accesses a struct page. How often is this code path called? I wonder whether a stop_machine() approach would be simpler. Andrew, I'd suggest we drop these patches from the mm tree for the time being. They haven't received much review from the arm64 folk. Thanks. -- Catalin
