On Wed, Oct 24, 2018 at 07:21:19PM -0700, Joel Fernandes wrote: > On Wed, Oct 24, 2018 at 10:37:16AM +0200, Peter Zijlstra wrote: > > 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. > > I didn't happen to do that analysis but from code analysis, no architecutre > is using it. Since its unused in the kernel, may be such architectures don't > exist or were removed, so we don't need to bother? Could you share more about > your concern with the removal of this argument? No concerns at all with removing it; I was purely curious as to the origin of the unused argument. Kirill provided that answer.
