On Tue, Feb 02, 2021 at 12:31:27PM -0800, Axel Rasmussen wrote: > For background, mm/userfaultfd.c provides a general mcopy_atomic > implementation. But some types of memory (e.g., hugetlb and shmem) need > a slightly different implementation, so they provide their own helpers > for this. In other words, userfaultfd is the only caller of this > function. > > This patch achieves two things: > > 1. Don't spend time compiling code which will end up never being > referenced anyway (a small build time optimization). > > 2. In future patches (e.g. [1]), we plan to extend the signature of > these helpers with UFFD-specific state (e.g., enums or structs defined > conditionally in userfaultfd_k.h). Once this happens, this patch will be > needed to avoid build errors (or, we'd need to define more UFFD-only > stuff unconditionally, which seems messier to me). > > Peter Xu suggested this be sent as a standalone patch, in the mailing > list discussion for [1]. > > [1] https://patchwork.kernel.org/project/linux-mm/list/?series=424091 > > Signed-off-by: Axel Rasmussen <axelrasmussen@xxxxxxxxxx> I meant a standalone patch along with the next version of your series would be good enough... :) If Mike is fine I won't complain if you'd squashed it into that patch either. The patch itself looks correct to me. Reviewed-by: Peter Xu <peterx@xxxxxxxxxx> Thanks, -- Peter Xu
