linux-next: build warning after merge of the mm tree

Stephen Rothwell
2022-07-21T09:55:20Z

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Hi all,

After merging the mm tree, today's linux-next build (powerpc
ppc64_defconfig) produced this warning:

In file included from arch/powerpc/include/asm/book3s/64/mmu-hash.h:20,
from arch/powerpc/include/asm/book3s/64/mmu.h:32,
from arch/powerpc/include/asm/mmu.h:393,
from arch/powerpc/include/asm/lppaca.h:46,
from arch/powerpc/include/asm/paca.h:18,
from arch/powerpc/include/asm/current.h:13,
from include/linux/thread_info.h:23,
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:55,
from include/linux/mmzone.h:8,
from include/linux/gfp.h:7,
from include/linux/mm.h:7,
from mm/khugepaged.c:4:
arch/powerpc/include/asm/book3s/64/pgtable.h:190:25: warning: "__pte_index_size" is not defined, evaluates to 0 [-Wundef]
190 | #define PTE_INDEX_SIZE __pte_index_size
| ^~~~~~~~~~~~~~~~
arch/powerpc/include/asm/book3s/64/pgtable.h:241:39: note: in expansion of macro 'PTE_INDEX_SIZE'
241 | #define PMD_SHIFT (PAGE_SHIFT + PTE_INDEX_SIZE)
| ^~~~~~~~~~~~~~
include/linux/huge_mm.h:109:25: note: in expansion of macro 'PMD_SHIFT'
109 | #define HPAGE_PMD_SHIFT PMD_SHIFT
| ^~~~~~~~~
include/linux/huge_mm.h:105:26: note: in expansion of macro 'HPAGE_PMD_SHIFT'
105 | #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
| ^~~~~~~~~~~~~~~
mm/khugepaged.c:95:5: note: in expansion of macro 'HPAGE_PMD_ORDER'
95 | #if HPAGE_PMD_ORDER < 16
| ^~~~~~~~~~~~~~~

Introduced by commit

adcc4e193b6b ("mm/khugepaged: use minimal bits to store num page < HPAGE_PMD_NR")

So HPAGE_PMD_ORDER is not a constant on ppc64 ...

I applied this hack for today (which makes it build without warning and
puts things more or less back as they were for ppo64).

From: Stephen Rothwell <sfr@canb.auug.org.au>
Date: Thu, 21 Jul 2022 19:49:40 +1000
Subject: [PATCH] fix up for "mm/khugepaged: use minimal bits to store num page < HPAGE_PMD_NR"

Signed-off-by: Stephen Rothwell <sfr@canb.auug.org.au>
---
mm/khugepaged.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 28cb8429dad4..d8e388106322 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -92,7 +92,9 @@ struct collapse_control {
bool is_khugepaged;

/* Num pages scanned per node */
-#if HPAGE_PMD_ORDER < 16
+#if defined(CONFIG_PPC64)
+ u32 node_load[MAX_NUMNODES];
+#elif HPAGE_PMD_ORDER < 16
u16 node_load[MAX_NUMNODES];
#else
u32 node_load[MAX_NUMNODES];
--
2.35.1