On Tue, Apr 12, 2022 at 04:22:21PM -0700, Andrew Morton wrote: > On Fri, 8 Apr 2022 23:08:29 -0700 (PDT) Hugh Dickins <hughd@xxxxxxxxxx> wrote: > > > > > > > Either way I'd rather do this optimization in iov_iter_zero rather > > > than hiding it in tmpfs. > > > > Let's see what others say. I think we would all prefer clear_user() to be > > enhanced, and hack around it neither here in tmpfs nor in iov_iter_zero(). > > But that careful work won't get done by magic, nor by me. > > > > And iov_iter_zero() has to deal with a wider range of possibilities, > > when pulling in cache lines of ZERO_PAGE(0) will be less advantageous, > > than in tmpfs doing a large dd - the case I'm aiming not to regress here > > (tmpfs has been copying ZERO_PAGE(0) like this for years). > > We do need something to get 5.18 fixed. Christoph, do you think we > should proceed with this patch for 5.18? Well, let's queue it up then.
