[PATCH] mm: clean up obsolete check on space in page->flags

[PATCH] mm: clean up obsolete check on space in page->flags

[Yu Zhao]

The check in linux/mm.h was intended to make sure we don't overrun
page flags. But it's obsolete because it doesn't include
LAST_CPUPID_WIDTH nor KASAN_TAG_WIDTH.

Just remove check since we already have it covered in
linux/page-flags-layout.h (near the end of the file).

Signed-off-by: Yu Zhao <yuzhao@google.com>
---
 include/linux/mm.h | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index c97ea3b694e6..2e7596cce9d8 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -921,10 +921,6 @@ vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf);
 
 #define ZONEID_PGSHIFT		(ZONEID_PGOFF * (ZONEID_SHIFT != 0))
 
-#if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
-#error SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
-#endif
-
 #define ZONES_MASK		((1UL << ZONES_WIDTH) - 1)
 #define NODES_MASK		((1UL << NODES_WIDTH) - 1)
 #define SECTIONS_MASK		((1UL << SECTIONS_WIDTH) - 1)
-- 
2.24.0.393.g34dc348eaf-goog

Re: [PATCH] mm: clean up obsolete check on space in page->flags

[David Hildenbrand]

On 08.12.19 19:35, Yu Zhao wrote:
> The check in linux/mm.h was intended to make sure we don't overrun
> page flags. But it's obsolete because it doesn't include
> LAST_CPUPID_WIDTH nor KASAN_TAG_WIDTH.
> 
> Just remove check since we already have it covered in
> linux/page-flags-layout.h (near the end of the file).
> 
> Signed-off-by: Yu Zhao <yuzhao@google.com>
> ---
>  include/linux/mm.h | 4 ----
>  1 file changed, 4 deletions(-)
> 
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index c97ea3b694e6..2e7596cce9d8 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -921,10 +921,6 @@ vm_fault_t finish_mkwrite_fault(struct vm_fault *vmf);
>  
>  #define ZONEID_PGSHIFT		(ZONEID_PGOFF * (ZONEID_SHIFT != 0))
>  
> -#if SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
> -#error SECTIONS_WIDTH+NODES_WIDTH+ZONES_WIDTH > BITS_PER_LONG - NR_PAGEFLAGS
> -#endif
> -
>  #define ZONES_MASK		((1UL << ZONES_WIDTH) - 1)
>  #define NODES_MASK		((1UL << NODES_WIDTH) - 1)
>  #define SECTIONS_MASK		((1UL << SECTIONS_WIDTH) - 1)
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb