Re: [RFC PATCH 2/8] mm: Add PG_atomic

Matthew Wilcox
2025-11-12T15:56:27Z

On Wed, Nov 12, 2025 at 04:36:05PM +0530, Ojaswin Mujoo wrote:
> From: John Garry <john.g.garry@oracle.com>
>
> Add page flag PG_atomic, meaning that a folio needs to be written back
> atomically. This will be used by for handling RWF_ATOMIC buffered IO
> in upcoming patches.

Page flags are a precious resource. I'm not thrilled about allocating one
to this rather niche usecase. Wouldn't this be more aptly a flag on the
address_space rather than the folio? ie if we're doing this kind of write
to a file, aren't most/all of the writes to the file going to be atomic?