Re: [PATCH v4 0/3] introduce kernel file mapped folios

[Shakeel Butt <shakeel.butt@linux.dev>]

Hi Andrew, can you please pick this series up (replacing the "introduce
uncharged file mapped folios" series)? I think it is ready for wider
testing.

thanks,
Shakeel


On Thu, Aug 21, 2025 at 02:55:34PM -0700, Boris Burkov wrote:
> 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 account these global pages to the cgroup
> using them, basically at random. A bit more justification and explanation
> in the patches themselves.
> 
> ---
> Changelog:
> v4:
> - change the concept from "uncharged" to "kernel_file"
> - no longer violates the invariant that each mapped folio has a memcg
>   when CONFIG_MEMCG=y
> - no longer really tied to memcg conceptually, so simplify build/helpers
> v3:
> - use mod_node_page_state since we will never count cgroup stats
> - include Shakeel's patch that removes a WARNING triggered by this series
> v2:
> - switch from filemap_add_folio_nocharge() to AS_UNCHARGED on the
>   address_space.
> - fix an interrupt safety bug in the vmstat patch.
> - fix some foolish build errors for CONFIG_MEMCG=n
> 
> 
> 
> Boris Burkov (3):
>   mm/filemap: add AS_KERNEL_FILE
>   mm: add vmstat for kernel_file pages
>   btrfs: set AS_KERNEL_FILE on the btree_inode
> 
>  fs/btrfs/disk-io.c      |  1 +
>  include/linux/mmzone.h  |  1 +
>  include/linux/pagemap.h |  2 ++
>  mm/filemap.c            | 13 +++++++++++++
>  mm/vmstat.c             |  1 +
>  5 files changed, 18 insertions(+)
> 
> -- 
> 2.50.1
>