The patch titled
Subject: mm/powerpc: redefine pXd_huge() with pXd_leaf()
has been added to the -mm mm-unstable branch. Its filename is
mm-powerpc-redefine-pxd_huge-with-pxd_leaf.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-powerpc-redefine-pxd_huge-with-pxd_leaf.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/powerpc: redefine pXd_huge() with pXd_leaf()
Date: Mon, 18 Mar 2024 16:03:59 -0400
PowerPC book3s 4K mostly has the same definition on both, except
pXd_huge() constantly returns 0 for hash MMUs. As Michael Ellerman
pointed out [1], it is safe to check _PAGE_PTE on hash MMUs, as the bit
will never be set so it will keep returning false.
As a reference, __p[mu]d_mkhuge() will trigger a BUG_ON trying to create
such huge mappings for 4K hash MMUs. Meanwhile, the major powerpc hugetlb
pgtable walker __find_linux_pte() already used pXd_leaf() to check leaf
hugetlb mappings.
The goal should be that we will have one API pXd_leaf() to detect all
kinds of huge mappings (hugepd is still special in this case, though).
AFAICT we need to use the pXd_leaf() impl (rather than pXd_huge()'s) to
make sure ie. THPs on hash MMU will also return true.
This helps to simplify a follow up patch to drop pXd_huge() treewide.
NOTE: *_leaf() definition need to be moved before the inclusion of
asm/book3s/64/pgtable-4k.h, which defines pXd_huge() with it.
[1] https://lore.kernel.org/r/87v85zo6w7.fsf@mail.lhotse
Link: https://lkml.kernel.org/r/20240318200404.448346-10-peterx@xxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Cc: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxx>
Cc: "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Andreas Larsson <andreas@xxxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Bjorn Andersson <andersson@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Fabio Estevam <festevam@xxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Konrad Dybcio <konrad.dybcio@xxxxxxxxxx>
Cc: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
Cc: Lucas Stach <l.stach@xxxxxxxxxxxxxx>
Cc: Mark Salter <msalter@xxxxxxxxxx>
Cc: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: Russell King <linux@xxxxxxxxxxxxxxx>
Cc: Shawn Guo <shawnguo@xxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Will Deacon <will@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
arch/powerpc/include/asm/book3s/64/pgtable-4k.h | 14 +------
arch/powerpc/include/asm/book3s/64/pgtable.h | 27 ++++++--------
2 files changed, 14 insertions(+), 27 deletions(-)
--- a/arch/powerpc/include/asm/book3s/64/pgtable-4k.h~mm-powerpc-redefine-pxd_huge-with-pxd_leaf
+++ a/arch/powerpc/include/asm/book3s/64/pgtable-4k.h
@@ -8,22 +8,12 @@
#ifdef CONFIG_HUGETLB_PAGE
static inline int pmd_huge(pmd_t pmd)
{
- /*
- * leaf pte for huge page
- */
- if (radix_enabled())
- return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
- return 0;
+ return pmd_leaf(pmd);
}
static inline int pud_huge(pud_t pud)
{
- /*
- * leaf pte for huge page
- */
- if (radix_enabled())
- return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
- return 0;
+ return pud_leaf(pud);
}
/*
--- a/arch/powerpc/include/asm/book3s/64/pgtable.h~mm-powerpc-redefine-pxd_huge-with-pxd_leaf
+++ a/arch/powerpc/include/asm/book3s/64/pgtable.h
@@ -262,6 +262,18 @@ extern unsigned long __kernel_io_end;
extern struct page *vmemmap;
extern unsigned long pci_io_base;
+
+#define pmd_leaf pmd_leaf
+static inline bool pmd_leaf(pmd_t pmd)
+{
+ return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
+}
+
+#define pud_leaf pud_leaf
+static inline bool pud_leaf(pud_t pud)
+{
+ return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
+}
#endif /* __ASSEMBLY__ */
#include <asm/book3s/64/hash.h>
@@ -1426,20 +1438,5 @@ static inline bool is_pte_rw_upgrade(uns
return false;
}
-/*
- * Like pmd_huge(), but works regardless of config options
- */
-#define pmd_leaf pmd_leaf
-static inline bool pmd_leaf(pmd_t pmd)
-{
- return !!(pmd_raw(pmd) & cpu_to_be64(_PAGE_PTE));
-}
-
-#define pud_leaf pud_leaf
-static inline bool pud_leaf(pud_t pud)
-{
- return !!(pud_raw(pud) & cpu_to_be64(_PAGE_PTE));
-}
-
#endif /* __ASSEMBLY__ */
#endif /* _ASM_POWERPC_BOOK3S_64_PGTABLE_H_ */
_
Patches currently in -mm which might be from peterx@xxxxxxxxxx are
mm-memory-fix-missing-pte-marker-for-page-on-pte-zaps.patch
mm-hmm-process-pud-swap-entry-without-pud_huge.patch
mm-gup-cache-p4d-in-follow_p4d_mask.patch
mm-gup-check-p4d-presence-before-going-on.patch
mm-x86-change-pxd_huge-behavior-to-exclude-swap-entries.patch
mm-sparc-change-pxd_huge-behavior-to-exclude-swap-entries.patch
mm-arm-use-macros-to-define-pmd-pud-helpers.patch
mm-arm-redefine-pmd_huge-with-pmd_leaf.patch
mm-arm64-merge-pxd_huge-and-pxd_leaf-definitions.patch
mm-powerpc-redefine-pxd_huge-with-pxd_leaf.patch
mm-gup-merge-pxd-huge-mapping-checks.patch
mm-treewide-replace-pxd_huge-with-pxd_leaf.patch
mm-treewide-remove-pxd_huge.patch
mm-arm-remove-pmd_thp_or_huge.patch
mm-document-pxd_leaf-api.patch
