[v1,0/9] mm: PG_reserved cleanups and documentation

Message

David Hildenbrand Dec. 14, 2018, 11:10 a.m. UTC

I was recently going over all users of PG_reserved. Short story: it is
difficult and sometimes not really clear if setting/checking for
PG_reserved is only a relict from the past. Easy to break things. I
guess I know have a pretty good idea wh things are like that
nowadays and how they evolved.

I had way more cleanups in this series inititally,
but some architectures take PG_reserved as a way to apply a different
caching strategy (for MMIO pages). So I decided to only include the most
obvious changes (that are less likely to break something). So the big
chunk of manual SetPageReserved users are MMIO/DMA related things on
device buffers.

Most notably, for device memory we will hopefully soon stop setting
PG_reserved. The the documentation has to be updated.

RFC -> V1:
- Add more details to "mm: better document PG_reserved"
- Add "arm64: kdump: No need to mark crashkernel pages manually
       PG_reserved"
- Add "ia64: perfmon: Don't mark buffer pages as PG_reserved"
- Added ACKs

David Hildenbrand (9):
  agp: efficeon: no need to set PG_reserved on GATT tables
  s390/vdso: don't clear PG_reserved
  powerpc/vdso: don't clear PG_reserved
  riscv/vdso: don't clear PG_reserved
  m68k/mm: use __ClearPageReserved()
  arm64: kexec: no need to ClearPageReserved()
  arm64: kdump: No need to mark crashkernel pages manually PG_reserved
  ia64: perfmon: Don't mark buffer pages as PG_reserved
  mm: better document PG_reserved

 arch/arm64/kernel/machine_kexec.c |  3 +-
 arch/arm64/mm/init.c              | 27 --------------
 arch/ia64/kernel/perfmon.c        | 59 +++----------------------------
 arch/m68k/mm/memory.c             |  2 +-
 arch/powerpc/kernel/vdso.c        |  2 --
 arch/riscv/kernel/vdso.c          |  1 -
 arch/s390/kernel/vdso.c           |  2 --
 drivers/char/agp/efficeon-agp.c   |  2 --
 include/linux/page-flags.h        | 33 +++++++++++++++--
 9 files changed, 37 insertions(+), 94 deletions(-)