On 23.05.22 08:38, Mike Rapoport wrote: > On Thu, May 12, 2022 at 09:54:59PM +0100, Matthew Wilcox wrote: >> The LWN writeup [1] on merging the MGLRU reminded me that I need to send >> out a plan for removing page flags that we can do without. >> >> 4. I think I can also consolidate PG_slab and PG_reserved into a "single >> bit" (not really, but change the encoding so that effectively they only >> take a single bit). > > PG_reserved could be a PageType, AFAIR no reserved pages are ever mapped to > userspace include/linux/page-flags.h documents for PG_reserved: "Pages part of the kernel image (including vDSO)" Further, vm_normal_page() contains a comment "NOTE! We still have PageReserved() pages in the page tables. eg. VDSO mappings can cause them to exist." -- Thanks, David / dhildenb
