Re: [PATCH v6 03/16] dma-debug: refactor to use physical addresses for page mapping

Leon Romanovsky
2025-09-10T05:26:23Z

On Tue, Sep 09, 2025 at 10:37:48PM +0300, Leon Romanovsky wrote:
> On Tue, Sep 09, 2025 at 04:27:31PM +0300, Leon Romanovsky wrote:
> > From: Leon Romanovsky <leonro@nvidia.com>
>
> <...>
>
> > include/linux/page-flags.h | 1 +
>
> <...>
>
> > --- a/include/linux/page-flags.h
> > +++ b/include/linux/page-flags.h
> > @@ -614,6 +614,7 @@ FOLIO_FLAG(dropbehind, FOLIO_HEAD_PAGE)
> > * available at this point.
> > */
> > #define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
> > +#define PhysHighMem(__p) (PageHighMem(phys_to_page(__p)))
>
> This was a not so great idea to add PhysHighMem() because of "else"
> below which unfolds to maze of macros and automatically generated
> functions with "static inline int Page##uname ..." signature.
>
> > #define folio_test_highmem(__f) is_highmem_idx(folio_zonenum(__f))
> > #else
> > PAGEFLAG_FALSE(HighMem, highmem)

After sleeping over it, the following hunk will help:

diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index dfbc4ba86bba2..2a1f346178024 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -614,11 +614,11 @@ FOLIO_FLAG(dropbehind, FOLIO_HEAD_PAGE)
* available at this point.
*/
#define PageHighMem(__p) is_highmem_idx(page_zonenum(__p))
-#define PhysHighMem(__p) (PageHighMem(phys_to_page(__p)))
#define folio_test_highmem(__f) is_highmem_idx(folio_zonenum(__f))
#else
PAGEFLAG_FALSE(HighMem, highmem)
#endif
+#define PhysHighMem(__p) (PageHighMem(phys_to_page(__p)))

/* Does kmap_local_folio() only allow access to one page of the folio? */
#ifdef CONFIG_DEBUG_KMAP_LOCAL_FORCE_MAP

>
> Thanks
>