linux-kernel - [PATCH 1/2] fixup! mm: make HPAGE_PXD

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Date: Fri, 22 Mar 2024 23:33:09 -0400
From: peterx@...hat.com
To: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	SeongJae Park <sj@...nel.org>,
	peterx@...hat.com
Subject: [PATCH 1/2] fixup! mm: make HPAGE_PXD_* macros even if !THP

From: Peter Xu <peterx@...hat.com>

[To be squashed into the corresponding patch]

I initially wanted to simply cover all macros to be under
PGTABLE_HAS_HUGE_LEAVES, but I found that it won't work, we must define
HPAGE_PMD_SHIFT even if PMD_SHIFT is not defined (!MMU case)..

The only solution is use the old trick of "({ BUILD_BUG(); 0; })".

Signed-off-by: Peter Xu <peterx@...hat.com>
---
 include/linux/huge_mm.h | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index f451f0bdab97..d210c849ab7a 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -84,17 +84,23 @@ extern struct kobj_attribute shmem_enabled_attr;
 #define thp_vma_allowable_order(vma, vm_flags, smaps, in_pf, enforce_sysfs, order) \
 	(!!thp_vma_allowable_orders(vma, vm_flags, smaps, in_pf, enforce_sysfs, BIT(order)))
 
+#ifdef CONFIG_PGTABLE_HAS_HUGE_LEAVES
 #define HPAGE_PMD_SHIFT PMD_SHIFT
-#define HPAGE_PMD_SIZE	((1UL) << HPAGE_PMD_SHIFT)
-#define HPAGE_PMD_MASK	(~(HPAGE_PMD_SIZE - 1))
+#define HPAGE_PUD_SHIFT PUD_SHIFT
+#else
+#define HPAGE_PMD_SHIFT ({ BUILD_BUG(); 0; })
+#define HPAGE_PUD_SHIFT ({ BUILD_BUG(); 0; })
+#endif
+
 #define HPAGE_PMD_ORDER (HPAGE_PMD_SHIFT-PAGE_SHIFT)
 #define HPAGE_PMD_NR (1<<HPAGE_PMD_ORDER)
+#define HPAGE_PMD_MASK	(~(HPAGE_PMD_SIZE - 1))
+#define HPAGE_PMD_SIZE	((1UL) << HPAGE_PMD_SHIFT)
 
-#define HPAGE_PUD_SHIFT PUD_SHIFT
-#define HPAGE_PUD_SIZE	((1UL) << HPAGE_PUD_SHIFT)
-#define HPAGE_PUD_MASK	(~(HPAGE_PUD_SIZE - 1))
 #define HPAGE_PUD_ORDER (HPAGE_PUD_SHIFT-PAGE_SHIFT)
 #define HPAGE_PUD_NR (1<<HPAGE_PUD_ORDER)
+#define HPAGE_PUD_MASK	(~(HPAGE_PUD_SIZE - 1))
+#define HPAGE_PUD_SIZE	((1UL) << HPAGE_PUD_SHIFT)
 
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
 
-- 
2.44.0