[PW_SID:1099714] [RESEND] riscv: mm: exclude invalid THP PMDs from page table check#2001
[PW_SID:1099714] [RESEND] riscv: mm: exclude invalid THP PMDs from page table check#2001linux-riscv-bot wants to merge 1 commit into
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RISC-V THP splitting uses a temporary invalid PMD state where pmd_mkinvalid() clears _PAGE_PRESENT and _PAGE_PROT_NONE but leaves _PAGE_LEAF set so the MM code can still recognize the PMD as a THP split in-progress entry. That temporary state no longer describes a user-accessible mapping, but page_table_check currently treats it as one because the RISC-V PMD user-accessibility test only checks whether the PMD is a leaf and has user permissions. As a result, when a PMD-sized anonymous THP is split during a COW fault, page_table_check can account the invalid intermediate PMD as a live PMD mapping, and then account the replacement PTE mappings again when the split installs the PTE table. This leaves stale PMD accounting behind and later triggers page_table_check failures such as a non-zero anon_map_count when the folio is freed. Fix this by tightening pmd_user_accessible_page() so PMD page-table-check accounting only considers leaf PMDs that still carry either _PAGE_PRESENT or _PAGE_PROT_NONE. This preserves the THP split semantics required by the MM code while preventing page_table_check from treating invalid split PMDs as live user mappings. With CONFIG_PAGE_TABLE_CHECK=y and CONFIG_PAGE_TABLE_CHECK_ENFORCED=y, tools/testing/selftests/mm/cow completes successfully on RISC-V after this change. Fixes: 3fee229 ("riscv/mm: enable ARCH_SUPPORTS_PAGE_TABLE_CHECK") Cc: stable@vger.kernel.org Signed-off-by: Yunhui Cui <cuiyunhui@bytedance.com> Signed-off-by: Linux RISC-V bot <linux.riscv.bot@gmail.com>
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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Patch 1: "[RESEND] riscv: mm: exclude invalid THP PMDs from page table check" |
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PR for series 1099714 applied to workflow__riscv__fixes
Name: [RESEND] riscv: mm: exclude invalid THP PMDs from page table check
URL: https://patchwork.kernel.org/project/linux-riscv/list/?series=1099714
Version: 1