Re: [PATCH mm-unstable v2 1/3] mm/contig_alloc: support __GFP_COMP

[Andrew Morton]

On Thu, 22 Aug 2024 16:21:27 +0800 Yu Liao <liaoyu15@xxxxxxxxxx> wrote:

> > +#ifdef CONFIG_CONTIG_ALLOC
> > +static inline struct folio *folio_alloc_gigantic_noprof(int order, gfp_t gfp,
> > +							int nid, nodemask_t *node)
> > +{
> > +	struct page *page;
> > +
> > +	if (WARN_ON(!order || !(gfp | __GFP_COMP)))
> 
> It doesn't seem right, it should be !(gfp & __GFP_COMP).

Yup.  Although I'm wondering why we're checking __GFP_COMP at all? 
It's a gigantic page - we know it's compound, so why require that the
caller tell us something we already know?

--- a/include/linux/gfp.h~mm-contig_alloc-support-__gfp_comp-fix
+++ a/include/linux/gfp.h
@@ -452,7 +452,7 @@ static inline struct folio *folio_alloc_
 {
 	struct page *page;
 
-	if (WARN_ON(!order || !(gfp | __GFP_COMP)))
+	if (WARN_ON(!order || !(gfp & __GFP_COMP)))
 		return NULL;
 
 	page = alloc_contig_pages_noprof(1 << order, gfp, nid, node);
_