Re: [PATCH 3/5] mm: Do not try to write pinned folio during memory cleaning writeback

[Jan Kara <jack@suse.cz>]

On Thu 09-02-23 18:10:23, John Hubbard wrote:
> On 2/9/23 17:54, John Hubbard wrote:
> > On 2/9/23 04:31, Jan Kara wrote:
> > > When a folio is pinned, there is no point in trying to write it during
> > > memory cleaning writeback. We cannot reclaim the folio until it is
> > > unpinned anyway and we cannot even be sure the folio is really clean.
> > > On top of that writeback of such folio may be problematic as the data
> > > can change while the writeback is running thus causing checksum or
> > > DIF/DIX failures. So just don't bother doing memory cleaning writeback
> > > for pinned folios.
> > > 
> > > Signed-off-by: Jan Kara <jack@suse.cz>
> > > ---
> > >   fs/9p/vfs_addr.c            |  2 +-
> > >   fs/afs/file.c               |  2 +-
> > >   fs/afs/write.c              |  6 +++---
> > >   fs/btrfs/extent_io.c        | 14 +++++++-------
> > >   fs/btrfs/free-space-cache.c |  2 +-
> > >   fs/btrfs/inode.c            |  2 +-
> > >   fs/btrfs/subpage.c          |  2 +-
> > 
> 
> Oh, and one more fix, below, is required in order to build with my local
> test config. Assuming that it is reasonable to deal with pinned pages
> here, which I think it is:
> 
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> index 9c759df700ca..c3279fb0edc8 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_shmem.c
> @@ -313,7 +313,7 @@ void __shmem_writeback(size_t size, struct address_space *mapping)
>  		if (!page)
>  			continue;
> -		if (!page_mapped(page) && clear_page_dirty_for_io(page)) {
> +		if (!page_mapped(page) && clear_page_dirty_for_io(&wbc, page)) {
>  			int ret;
>  			SetPageReclaim(page);
> 

Thanks, fixed up. It didn't occur to me to grep drivers/ for these
functions :).

								Honza
-- 
Jan Kara <jack@suse.com>
SUSE Labs, CR