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From: peterx@redhat.com
To: linux-mm@kvack.org,
	linux-kernel@vger.kernel.org
Cc: Huacai Chen <chenhuacai@kernel.org>,
	peterx@redhat.com,
	David Hildenbrand <david@redhat.com>,
	Jason Gunthorpe <jgg@nvidia.com>,
	Nathan Chancellor <nathan@kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Matthew Wilcox <willy@infradead.org>,
	WANG Xuerui <kernel@xen0n.name>,
	Ryan Roberts <ryan.roberts@arm.com>,
	loongarch@lists.linux.dev
Subject: [PATCH 3/3] fixup! mm/arch: provide pud_pfn() fallback
Date: Tue,  2 Apr 2024 21:32:49 -0400
Message-ID: <20240403013249.1418299-4-peterx@redhat.com>
In-Reply-To: <20240403013249.1418299-1-peterx@redhat.com>
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From: Peter Xu <peterx@redhat.com>

Signed-off-by: Peter Xu <peterx@redhat.com>
---
 include/linux/pgtable.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/pgtable.h b/include/linux/pgtable.h
index fa8f92f6e2d7..0f4b2faa1d71 100644
--- a/include/linux/pgtable.h
+++ b/include/linux/pgtable.h
@@ -1882,9 +1882,13 @@ typedef unsigned int pgtbl_mod_mask;
  * code.  Now it happens too for pud_pfn (and can happen for larger
  * mappings too in the future; we're not there yet).  Instead of defining
  * it for all archs (like pmd_pfn), provide a fallback.
+ *
+ * Note that returning 0 here means any arch that didn't define this can
+ * get severely wrong when it hits a real pud leaf.  It's arch's
+ * responsibility to properly define it when a huge pud is possible.
  */
 #ifndef pud_pfn
-#define pud_pfn(x) ({ BUILD_BUG(); 0; })
+#define pud_pfn(x) 0
 #endif
 
 /*
-- 
2.44.0