linux-kernel - [PATCH v4 2/7] mm: Implement for_each_valid_pfn() for CONFIG

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Message-ID: <20250423133821.789413-3-dwmw2@infradead.org>
Date: Wed, 23 Apr 2025 14:33:38 +0100
From: David Woodhouse <dwmw2@...radead.org>
To: Mike Rapoport <rppt@...nel.org>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
	"Sauerwein, David" <dssauerw@...zon.de>,
	Anshuman Khandual <anshuman.khandual@....com>,
	Ard Biesheuvel <ardb@...nel.org>,
	Catalin Marinas <catalin.marinas@....com>,
	David Hildenbrand <david@...hat.com>,
	Marc Zyngier <maz@...nel.org>,
	Mark Rutland <mark.rutland@....com>,
	Mike Rapoport <rppt@...ux.ibm.com>,
	Will Deacon <will@...nel.org>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	Ruihan Li <lrh2000@....edu.cn>
Subject: [PATCH v4 2/7] mm: Implement for_each_valid_pfn() for CONFIG_FLATMEM

From: David Woodhouse <dwmw@...zon.co.uk>

In the FLATMEM case, the default pfn_valid() just checks that the PFN is
within the range [ ARCH_PFN_OFFSET .. ARCH_PFN_OFFSET + max_mapnr ).

The for_each_valid_pfn() function can therefore be a simple for() loop
using those as min/max respectively.

Signed-off-by: David Woodhouse <dwmw@...zon.co.uk>
Reviewed-by: Mike Rapoport (Microsoft) <rppt@...nel.org>
---
 include/asm-generic/memory_model.h | 10 +++++++++-
 1 file changed, 9 insertions(+), 1 deletion(-)

diff --git a/include/asm-generic/memory_model.h b/include/asm-generic/memory_model.h
index a3b5029aebbd..74d0077cc5fa 100644
--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -30,7 +30,15 @@ static inline int pfn_valid(unsigned long pfn)
 	return pfn >= pfn_offset && (pfn - pfn_offset) < max_mapnr;
 }
 #define pfn_valid pfn_valid
-#endif
+
+#ifndef for_each_valid_pfn
+#define for_each_valid_pfn(pfn, start_pfn, end_pfn)			 \
+	for ((pfn) = max_t(unsigned long, (start_pfn), ARCH_PFN_OFFSET); \
+	     (pfn) < min_t(unsigned long, (end_pfn),			 \
+			   ARCH_PFN_OFFSET + max_mapnr);		 \
+	     (pfn)++)
+#endif /* for_each_valid_pfn */
+#endif /* valid_pfn */
 
 #elif defined(CONFIG_SPARSEMEM_VMEMMAP)
 
-- 
2.49.0