Re: [PATCH 3/6] shmem: move reclaim check early on writepages()

[Luis Chamberlain]

On Mon, Mar 06, 2023 at 03:01:52PM +0100, David Hildenbrand wrote:
> On 03.03.23 00:27, Luis Chamberlain wrote:
> > @@ -1340,6 +1340,18 @@ static int shmem_writepage(struct page *page, struct writeback_control *wbc)
> >   	swp_entry_t swap;
> >   	pgoff_t index;
> > +	/*
> > +	 * Our capabilities prevent regular writeback or sync from ever calling
> > +	 * shmem_writepage; but a stacking filesystem might use ->writepage of
> > +	 * its underlying filesystem, in which case tmpfs should write out to
> > +	 * swap only in response to memory pressure, and not for the writeback
> > +	 * threads or sync.
> > +	 */
> > +	if (!wbc->for_reclaim) {
> 
> if (WARN_ON_ONCE(!wbc->for_reclaim))
> 
> > +		WARN_ON_ONCE(1);	/* Still happens? Tell us about it! */
> 
> And drop the comment :) That's what WARN_ON_ONCE is all about.

Good call, will add that to v2.

> Acked-by: David Hildenbrand <david@xxxxxxxxxx>

Great thanks,

  Luis