Re: + mm-replace-20-page_shift-with-common-macros-for-pages-mb-conversion-fix.patch added to mm-unstable branch

[Andrew Morton <akpm@linux-foundation.org>]

On Fri, 22 Aug 2025 18:37:45 -0400 Zi Yan <ziy@nvidia.com> wrote:

> > +#define PAGES_TO_KB(pages) ((pages) >> (10 - PAGE_SHIFT))
> > +#define KB_TO_PAGES(kb)    ((kb) << (10 - PAGE_SHIFT))
> 
> Left shift and right shift with a negative value. Aren't they undefined
> behaviors?

Actually I just misread the bug report.  I'll redo:

From: Andrew Morton <akpm@linux-foundation.org>
Subject: mm-replace-20-page_shift-with-common-macros-for-pages-mb-conversion-fix
Date: Fri Aug 22 02:54:15 PM PDT 2025

remove arc's private PAGES_TO_MB, remove its unused PAGES_TO_KB

Reported-by: kernel test robot <lkp@intel.com>
Closes: https://lkml.kernel.org/r/202508230539.pnO97SIj-lkp@intel.com
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Ye Liu <liuye@kylinos.cn>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: David Hildenbrand <david@redhat.com>
Cc: Chris Li <chrisl@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

 arch/arc/include/asm/arcregs.h |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/arch/arc/include/asm/arcregs.h~mm-replace-20-page_shift-with-common-macros-for-pages-mb-conversion-fix
+++ a/arch/arc/include/asm/arcregs.h
@@ -146,14 +146,13 @@
 
 #ifndef __ASSEMBLER__
 
+#include <linux/mm.h>
+
 #include <soc/arc/arc_aux.h>
 
 /* Helpers */
 #define TO_KB(bytes)		((bytes) >> 10)
 #define TO_MB(bytes)		(TO_KB(bytes) >> 10)
-#define PAGES_TO_KB(n_pages)	((n_pages) << (PAGE_SHIFT - 10))
-#define PAGES_TO_MB(n_pages)	(PAGES_TO_KB(n_pages) >> 10)
-
 
 /*
  ***************************************************************
_