Commit 8b1cb4a2e819 ("mm/pagewalk: fix EFI_PGT_DUMP of
espfix area") made no-VMA page table walks use
pte_offset_kernel() for any address above TASK_SIZE. This avoided
pte_offset_map() validation on EFI page table dumps, where efi_mm
could walk x86 espfix PMDs that intentionally look bad to pmd_bad().efi_mm is now marked with MMF_KERNEL, and no-VMA walks use mm_is_kernel() to select pte_offset_kernel() for kernel mm's. As a result we no longer need to handle the EFI_PGT_DUMP case explicitly.The address check is therefore redundant for EFI_PGT_DUMP and makes the condition harder to reason about. Remove the address check and associated comment; mm_is_kernel() should be sufficient on its own. Tested by booting x86 QEMU with CONFIG_EFI_PGT_DUMP=y and reading /sys/kernel/debug/page_tables/efi. Assisted-by: Codex:GPT-5.5 Signed-off-by: Kevin Brodsky <[email protected]> --- mm/pagewalk.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) diff --git a/mm/pagewalk.c b/mm/pagewalk.c index a3f47d1de3c5..0dd9d4ad9b68 100644 --- a/mm/pagewalk.c +++ b/mm/pagewalk.c @@ -68,17 +68,14 @@ static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end, if (walk->no_vma) { /* * pte_offset_map() might apply user-specific validation. - * Indeed, on x86_64 the pmd entries set up by init_espfix_ap() - * fit its pmd_bad() check (_PAGE_NX set and _PAGE_RW clear), - * and CONFIG_EFI_PGT_DUMP efi_mm goes so far as to walk them. */ - if (mm_is_kernel(walk->mm) || addr >= TASK_SIZE) + if (mm_is_kernel(walk->mm)) pte = pte_offset_kernel(pmd, addr); else pte = pte_offset_map(pmd, addr); if (pte) { err = walk_pte_range_inner(pte, addr, end, walk); - if (!mm_is_kernel(walk->mm) && addr < TASK_SIZE) + if (!mm_is_kernel(walk->mm)) pte_unmap(pte); } } else { -- 2.51.2
