Re: [PATCH v2 1/5] mm,hugetlb: Change mechanism to detect a COW on private mapping

[David Hildenbrand]

On 25.06.25 09:49, Oscar Salvador wrote:
> On Mon, Jun 23, 2025 at 04:09:51PM +0200, David Hildenbrand wrote:
> > > -	/*
> > > -	 * hugetlb_wp() requires page locks of pte_page(vmf.orig_pte) and
> > > -	 * pagecache_folio, so here we need take the former one
> > > -	 * when folio != pagecache_folio or !pagecache_folio.
> > > -	 */
> > > +	/* hugetlb_wp() requires page locks of pte_page(vmf.orig_pte) */
> > >    	folio = page_folio(pte_page(vmf.orig_pte));
> > > -	if (folio != pagecache_folio)
> > > -		if (!folio_trylock(folio)) {
> > > -			need_wait_lock = 1;
> > > -			goto out_ptl;
> > > -		}
> > > -
> > > +	folio_lock(folio);
> > >    	folio_get(folio);
> >
> > Just realized that this won't work for this patch here, as we are holding
> > the PTL.
> >
> > In patch #2 you do the right thing.
>
> Yap, missed that.
> I might have to do the lock-unlock-dance here, and then in patch#2 move
> it to hugetlb_wp.
> Sounds reasonable?

Yes

--
Cheers,

David / dhildenb