The patch titled
Subject: mm/x86: make pud_leaf() only care about PSE bit
has been added to the -mm mm-unstable branch. Its filename is
mm-x86-make-pud_leaf-only-care-about-pse-bit.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-x86-make-pud_leaf-only-care-about-pse-bit.patch
This patch will later appear in the mm-unstable branch at
git://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm
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------------------------------------------------------
From: Peter Xu <peterx@xxxxxxxxxx>
Subject: mm/x86: make pud_leaf() only care about PSE bit
Date: Mon, 12 Aug 2024 14:12:22 -0400
When working on mprotect() on 1G dax entries, I hit an zap bad pud error
when zapping a huge pud that is with PROT_NONE permission.
Here the problem is x86's pud_leaf() requires both PRESENT and PSE bits
set to report a pud entry as a leaf, but that doesn't look right, as it's
not following the pXd_leaf() definition that we stick with so far, where
PROT_NONE entries should be reported as leaves.
To fix it, change x86's pud_leaf() implementation to only check against
PSE bit to report a leaf, irrelevant of whether PRESENT bit is set.
Link: https://lkml.kernel.org/r/20240812181225.1360970-5-peterx@xxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Acked-by: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Reviewed-by: David Hildenbrand <david@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Dave Jiang <dave.jiang@xxxxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: "Edgecombe, Rick P" <rick.p.edgecombe@xxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill@xxxxxxxxxxxxx>
Cc: Matthew Wilcox <willy@xxxxxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Oscar Salvador <osalvador@xxxxxxx>
Cc: Paolo Bonzini <pbonzini@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxxx>
Cc: Sean Christopherson <seanjc@xxxxxxxxxx>
Cc: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/x86/include/asm/pgtable.h | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/arch/x86/include/asm/pgtable.h~mm-x86-make-pud_leaf-only-care-about-pse-bit
+++ a/arch/x86/include/asm/pgtable.h
@@ -1078,8 +1078,7 @@ static inline pmd_t *pud_pgtable(pud_t p
#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)
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
mm-dax-dump-start-address-in-fault-handler.patch
mm-mprotect-push-mmu-notifier-to-puds.patch
mm-powerpc-add-missing-pud-helpers.patch
mm-x86-make-pud_leaf-only-care-about-pse-bit.patch
mm-x86-implement-arch_check_zapped_pud.patch
mm-x86-add-missing-pud-helpers.patch
mm-mprotect-fix-dax-pud-handlings.patch
