On Fri, Oct 12, 2018 at 06:31:57PM -0700, Joel Fernandes (Google) wrote: > This series speeds up mremap(2) syscall by copying page tables at the > PMD level even for non-THP systems. There is concern that the extra > 'address' argument that mremap passes to pte_alloc may do something > subtle architecture related in the future that may make the scheme not > work. Also we find that there is no point in passing the 'address' to > pte_alloc since its unused. So this patch therefore removes this > argument tree-wide resulting in a nice negative diff as well. Also > ensuring along the way that the enabled architectures do not do anything > funky with 'address' argument that goes unnoticed by the optimization. Did you happen to look at the history of where that address argument came from? -- just being curious here. ISTR something vague about architectures having different paging structure for different memory ranges.