linux-kernel - [PATCH 5/7] mm/x86: Make pud_leaf() only cares about PSE bit

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Date: Fri, 21 Jun 2024 10:25:02 -0400
From: Peter Xu <peterx@...hat.com>
To: linux-kernel@...r.kernel.org,
	linux-mm@...ck.org
Cc: x86@...nel.org,
	Borislav Petkov <bp@...en8.de>,
	Dave Jiang <dave.jiang@...el.com>,
	"Kirill A . Shutemov" <kirill@...temov.name>,
	Ingo Molnar <mingo@...hat.com>,
	Oscar Salvador <osalvador@...e.de>,
	peterx@...hat.com,
	Matthew Wilcox <willy@...radead.org>,
	Vlastimil Babka <vbabka@...e.cz>,
	Dan Williams <dan.j.williams@...el.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Hugh Dickins <hughd@...gle.com>,
	Michael Ellerman <mpe@...erman.id.au>,
	Dave Hansen <dave.hansen@...ux.intel.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	linuxppc-dev@...ts.ozlabs.org,
	Christophe Leroy <christophe.leroy@...roup.eu>,
	Rik van Riel <riel@...riel.com>,
	Mel Gorman <mgorman@...hsingularity.net>,
	"Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
	Nicholas Piggin <npiggin@...il.com>,
	Huang Ying <ying.huang@...el.com>
Subject: [PATCH 5/7] mm/x86: Make pud_leaf() only cares about PSE bit

An entry should be reported as PUD leaf even if it's PROT_NONE, in which
case PRESENT bit isn't there. I hit bad pud without this when testing dax
1G on zapping a PROT_NONE PUD.

Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: Ingo Molnar <mingo@...hat.com>
Cc: Borislav Petkov <bp@...en8.de>
Cc: Dave Hansen <dave.hansen@...ux.intel.com>
Cc: x86@...nel.org
Signed-off-by: Peter Xu <peterx@...hat.com>
---
 arch/x86/include/asm/pgtable.h | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/pgtable.h b/arch/x86/include/asm/pgtable.h
index 65b8e5bb902c..25fc6d809572 100644
--- a/arch/x86/include/asm/pgtable.h
+++ b/arch/x86/include/asm/pgtable.h
@@ -1073,8 +1073,7 @@ static inline pmd_t *pud_pgtable(pud_t pud)
 #define pud_leaf pud_leaf
 static inline bool pud_leaf(pud_t pud)
 {
-	return (pud_val(pud) & (_PAGE_PSE | _PAGE_PRESENT)) ==
-		(_PAGE_PSE | _PAGE_PRESENT);
+	return pud_val(pud) & _PAGE_PSE;
 }
 
 static inline int pud_bad(pud_t pud)
-- 
2.45.0