On Wed, Jan 03, 2024 at 05:33:56PM -0800, Darrick J. Wong wrote: > Sort of both. For xfbtrees (or anything mapping a xfs_buftarg atop an > xfile) we can't use the cheap(er) kmap_local_page and have to use kmap, > which ... is expensive, isn't it? A little, but not really enough to explain the numbers you quoted.. > Granted, forbidding highmem like you posted today makes all of this > /much/ simpler so I think it's probably worth the increased chances of > ENOMEM on i386. > > That said, why not avoid a trip through shmem_get_folio_gfp aka > filemap_get_entry if we can? Even if we can use page_address directly > now? Sure, I just suspect the commit message is wrong and it's not about mapping the page into the kernel address space but something else.
