Subject: linux-next: build failure after merge of the mm tree

From: Stephen Rothwell <[email-masked]>
Date: Tue, 13 Jun 2023 16:21:19 +1000

Hi all,

After merging the mm tree, today's linux-next build (powerpc
ppc44x_defconfig) failed like this:

In file included from arch/powerpc/include/asm/page.h:247,
                 from arch/powerpc/include/asm/thread_info.h:13,
                 from include/linux/thread_info.h:60,
                 from include/asm-generic/preempt.h:5,
                 from ./arch/powerpc/include/generated/asm/preempt.h:1,
                 from include/linux/preempt.h:78,
                 from include/linux/spinlock.h:56,
                 from include/linux/ipc.h:5,
                 from include/uapi/linux/sem.h:5,
                 from include/linux/sem.h:5,
                 from include/linux/compat.h:14,
                 from arch/powerpc/kernel/asm-offsets.c:12:
arch/powerpc/include/asm/page_32.h:16: warning: "ARCH_DMA_MINALIGN" redefined
   16 | #define ARCH_DMA_MINALIGN       L1_CACHE_BYTES
      | 
In file included from include/linux/time.h:5,
                 from include/linux/compat.h:10:
include/linux/cache.h:104: note: this is the location of the previous definition
  104 | #define ARCH_DMA_MINALIGN __alignof__(unsigned long long)
      | 

(lots of theses)

Caused by commit

  cc7335787e73 ("mm/slab: decouple ARCH_KMALLOC_MINALIGN from ARCH_DMA_MINALIGN")

I have applied the following hack for today - we need something better.

From: Stephen Rothwell <[email-masked]>
Date: Tue, 13 Jun 2023 16:07:16 +1000
Subject: [PATCH] fix up for "mm/slab: decouple ARCH_KMALLOC_MINALIGN from ARCH_DMA_MINALIGN"

Signed-off-by: Stephen Rothwell <[email-masked]>
---
 arch/powerpc/include/asm/cache.h | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/arch/powerpc/include/asm/cache.h b/arch/powerpc/include/asm/cache.h
index ae0a68a838e8..e9be1396dfd1 100644
--- a/arch/powerpc/include/asm/cache.h
+++ b/arch/powerpc/include/asm/cache.h
@@ -142,5 +142,14 @@ static inline void iccci(void *addr)
 }
 
 #endif /* !__ASSEMBLY__ */
+
+#ifndef __powerpc64__
+#ifdef CONFIG_NOT_COHERENT_CACHE
+#ifndef ARCH_DMA_MINALIGN
+#define ARCH_DMA_MINALIGN	L1_CACHE_BYTES
+#endif
+#endif
+#endif
+
 #endif /* __KERNEL__ */
 #endif /* _ASM_POWERPC_CACHE_H */
-- 
2.39.2

-- 
Cheers,
Stephen Rothwell