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| author | Linus Torvalds <torvalds@linux-foundation.org> | 2025-10-23 09:26:47 -1000 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2025-10-23 09:26:47 -1000 |
| commit | 266ee584e55eed108583ab4f45b5de734522502d (patch) | |
| tree | efa2221863e7edb02b2fad69818c0f3b86577f53 | |
| parent | ab431bc39741e9d9bd3102688439e1864c857a74 (diff) | |
| parent | b98c94eed4a975e0c80b7e90a649a46967376f58 (diff) | |
| download | tip-266ee584e55eed108583ab4f45b5de734522502d.tar.gz | |
Merge tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux
Pull arm64 fixes from Catalin Marinas:
- Do not make a clean PTE dirty in pte_mkwrite()
The Arm architecture, for backwards compatibility reasons (ARMv8.0
before in-hardware dirty bit management - DBM), uses the PTE_RDONLY
bit to mean !dirty while the PTE_WRITE bit means DBM enabled. The
arm64 pte_mkwrite() simply clears the PTE_RDONLY bit and this
inadvertently makes the PTE pte_hw_dirty(). Most places making a PTE
writable also invoke pte_mkdirty() but do_swap_page() does not and we
end up with dirty, freshly swapped in, writeable pages.
- Do not warn if the destination page is already MTE-tagged in
copy_highpage()
In the majority of the cases, a destination page copied into is
freshly allocated without the PG_mte_tagged flag set. However, the
folio migration may be restarted if __folio_migrate_mapping() failed,
triggering the benign WARN_ON_ONCE().
* tag 'arm64-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/arm64/linux:
arm64: mte: Do not warn if the page is already tagged in copy_highpage()
arm64, mm: avoid always making PTE dirty in pte_mkwrite()
| -rw-r--r-- | arch/arm64/include/asm/pgtable.h | 3 | ||||
| -rw-r--r-- | arch/arm64/mm/copypage.c | 11 |
2 files changed, 10 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/pgtable.h b/arch/arm64/include/asm/pgtable.h index aa89c2e67ebc84..0944e296dd4a4c 100644 --- a/arch/arm64/include/asm/pgtable.h +++ b/arch/arm64/include/asm/pgtable.h @@ -293,7 +293,8 @@ static inline pmd_t set_pmd_bit(pmd_t pmd, pgprot_t prot) static inline pte_t pte_mkwrite_novma(pte_t pte) { pte = set_pte_bit(pte, __pgprot(PTE_WRITE)); - pte = clear_pte_bit(pte, __pgprot(PTE_RDONLY)); + if (pte_sw_dirty(pte)) + pte = clear_pte_bit(pte, __pgprot(PTE_RDONLY)); return pte; } diff --git a/arch/arm64/mm/copypage.c b/arch/arm64/mm/copypage.c index a86c897017df08..cd5912ba617b70 100644 --- a/arch/arm64/mm/copypage.c +++ b/arch/arm64/mm/copypage.c @@ -35,7 +35,7 @@ void copy_highpage(struct page *to, struct page *from) from != folio_page(src, 0)) return; - WARN_ON_ONCE(!folio_try_hugetlb_mte_tagging(dst)); + folio_try_hugetlb_mte_tagging(dst); /* * Populate tags for all subpages. @@ -51,8 +51,13 @@ void copy_highpage(struct page *to, struct page *from) } folio_set_hugetlb_mte_tagged(dst); } else if (page_mte_tagged(from)) { - /* It's a new page, shouldn't have been tagged yet */ - WARN_ON_ONCE(!try_page_mte_tagging(to)); + /* + * Most of the time it's a new page that shouldn't have been + * tagged yet. However, folio migration can end up reusing the + * same page without untagging it. Ignore the warning if the + * page is already tagged. + */ + try_page_mte_tagging(to); mte_copy_page_tags(kto, kfrom); set_page_mte_tagged(to); |