test_and_clear_young_ptes(9)

💅 test_and_clear_young_ptes(9) — a Kernel API Manual moment 🎀

okay so bestie, we're in the Kernel API Manual today and the star of the show is test_and_clear_young_ptes(9). yes the name is a mouthful, no we're not skipping it, it's literally iconic. sit down, hydrate, let's go ✨

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🌸 NAME 🌸

test_and_clear_young_ptes — marks PTEs that map consecutive pages of the same folio as old. that's the whole vibe. it's giving "aging out" but for page table entries 🫶

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✨ SYNOPSIS ✨

bool test_and_clear_young_ptes (struct vm_area_struct *vma , unsigned
long addr , pte_t *ptep , unsigned int nr );

note the return type: bool. note the four args. no cap, that's it 🔥

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🦋 ARGUMENTS 🦋

• vma — the virtual memory area the pages are mapped into. like, the neighborhood bestie 🏡
• addr — the address the first page is mapped at. page one, main character energy ⭐
• ptep — page table pointer for the first entry. your lil entry point 💅
• nr — number of entries to clear the access bit on. yes it's a count, yes it matters 👑

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💜 DESCRIPTION 💜

so this one may be overridden by the architecture. iykyk. if the arch doesn't have its own fancy version, it's implemented as a simple loop over ptep_test_and_clear_young. simple loop, simple slay 🌈

⚠️ also psa: the PTE bits in the PTE range besides the PFN can differ. for example, some PTEs might be write-protected. so don't go assuming they're all twins, because they are not 🙈

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🧚 CONTEXT 🧚

the caller holds the page table lock 🔒. the PTEs map consecutive pages that belong to the same folio. and the PTEs are all in the same PMD. that's the whole situation, no notes 💀

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👑 RETURN 👑

whether any PTE was young. that's it. a bool. literally yes or no 🍓

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🌸 SEE ALSO 🌸

kernel file ./include/linux/pgtable.h — and the whole friend group:

• lazy_mmu_mode_enable(9)
• lazy_mmu_mode_disable(9)
• __task_lazy_mmu_mode_pause(9)
• lazy_mmu_mode_pause(9)
• __task_lazy_mmu_mode_resume(9)
• lazy_mmu_mode_resume(9)
• pte_batch_hint(9)
• set_ptes(9)
• clear_young_dirty_ptes(9)
• get_and_clear_full_ptes(9)
• get_and_clear_ptes(9)
• clear_full_ptes(9)
• clear_ptes(9)
• clear_nonpresent_ptes(9)
• ptep_try_set(9)
• flush_tlb_before_set(9)
• wrprotect_ptes(9)
• clear_flush_young_ptes(9)
• modify_prot_start_ptes(9)
• modify_prot_commit_ptes(9)
• pfnmap_setup_cachemode(9)
• pfnmap_track(9)
• pfnmap_untrack(9)
• pfnmap_setup_cachemode_pfn(9)

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and that's the page bb 🫶 sourced from ./include/linux, dated October 2026, living under the Kernel API Manual banner — test_and_clear_young_ptes(9), periodt. go clear some access bits responsibly 💖✨