The patch titled
Subject: mm/hmm: process pud swap entry without pud_huge()
has been added to the -mm mm-unstable branch. Its filename is
mm-hmm-process-pud-swap-entry-without-pud_huge.patch
This patch will shortly appear at
https://git.kernel.org/pub/scm/linux/kernel/git/akpm/25-new.git/tree/patches/mm-hmm-process-pud-swap-entry-without-pud_huge.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/hmm: process pud swap entry without pud_huge()
Date: Mon, 18 Mar 2024 16:03:51 -0400
Swap pud entries do not always return true for pud_huge() for all archs.
x86 and sparc (so far) allow it, but all the rest do not accept a swap
entry to be reported as pud_huge(). So it's not safe to check swap
entries within pud_huge(). Check swap entries before pud_huge(), so it
should be always safe.
This is the only place in the kernel that (IMHO, wrongly) relies on
pud_huge() to return true on pud swap entries. The plan is to cleanup
pXd_huge() to only report non-swap mappings for all archs.
Link: https://lkml.kernel.org/r/20240318200404.448346-2-peterx@xxxxxxxxxx
Signed-off-by: Peter Xu <peterx@xxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Cc: Alistair Popple <apopple@xxxxxxxxxx>
Cc: Andreas Larsson <andreas@xxxxxxxxxxx>
Cc: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxx>
Cc: Arnd Bergmann <arnd@xxxxxxxx>
Cc: Bjorn Andersson <andersson@xxxxxxxxxx>
Cc: Borislav Petkov <bp@xxxxxxxxx>
Cc: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Christophe Leroy <christophe.leroy@xxxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxxxxxxxx>
Cc: David S. Miller <davem@xxxxxxxxxxxxx>
Cc: Fabio Estevam <festevam@xxxxxxx>
Cc: Ingo Molnar <mingo@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: Michael Ellerman <mpe@xxxxxxxxxxxxxx>
Cc: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
Cc: Muchun Song <muchun.song@xxxxxxxxx>
Cc: Naoya Horiguchi <naoya.horiguchi@xxxxxxx>
Cc: "Naveen N. Rao" <naveen.n.rao@xxxxxxxxxxxxx>
Cc: Nicholas Piggin <npiggin@xxxxxxxxx>
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>
---
mm/hmm.c | 7 +------
1 file changed, 1 insertion(+), 6 deletions(-)
--- a/mm/hmm.c~mm-hmm-process-pud-swap-entry-without-pud_huge
+++ a/mm/hmm.c
@@ -424,7 +424,7 @@ static int hmm_vma_walk_pud(pud_t *pudp,
walk->action = ACTION_CONTINUE;
pud = READ_ONCE(*pudp);
- if (pud_none(pud)) {
+ if (!pud_present(pud)) {
spin_unlock(ptl);
return hmm_vma_walk_hole(start, end, -1, walk);
}
@@ -435,11 +435,6 @@ static int hmm_vma_walk_pud(pud_t *pudp,
unsigned long *hmm_pfns;
unsigned long cpu_flags;
- if (!pud_present(pud)) {
- spin_unlock(ptl);
- return hmm_vma_walk_hole(start, end, -1, walk);
- }
-
i = (addr - range->start) >> PAGE_SHIFT;
npages = (end - addr) >> PAGE_SHIFT;
hmm_pfns = &range->hmm_pfns[i];
_
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
