[PATCH 0/3] filemap_add_folio_nocharge()

[Boris Burkov <boris@bur.io>]

I would like to revisit Qu's proposal to not charge btrfs extent_buffer
allocations to the user's cgroup.

https://lore.kernel.org/linux-mm/b5fef5372ae454a7b6da4f2f75c427aeab6a07d6.1727498749.git.wqu@suse.com/

I believe it is detrimental to randomly account these global pages to
the cgroup using them, basically at random. A bit more justification
and explanation in the patches themselves.

Three meta-considerations/questions:
1. Which tree should this go through, assuming it is acceptable?
   For now, I have based it off btrfs/for-next as that is what I am
   used to doing, but I am happy to re-send it based off the appropriate mm
   branch.
2. Christoph wrote the first patch as-is in his suggestion to Qu. I am happy
   to replace it with his authorship/s-o-b, I just didn't want to do that
   without asking. For now, I put his "Suggested-by".
3. The previous suggestion also requested "proper" documentation. I don't
   know what that entails in this case, and was unable to find corresponding
   documentation for filemap_add_folio() in the code or in Documentation/.
   Please let me know what I should be doing there, as well.

Boris Burkov (3):
  mm/filemap: add filemap_add_folio_nocharge()
  btrfs: use filemap_add_folio_nocharge() for extent_buffers
  mm: add vmstat for cgroup uncharged pages

 fs/btrfs/extent_io.c    |  4 ++--
 include/linux/mmzone.h  |  3 +++
 include/linux/pagemap.h |  2 ++
 mm/filemap.c            | 41 +++++++++++++++++++++++++++++++++++------
 mm/vmstat.c             |  3 +++
 5 files changed, 45 insertions(+), 8 deletions(-)

-- 
2.50.1