ptep_try_set(9)

💅 ptep_try_set(9) — the Kernel API Manual tea 🫶

okay bestie, buckle up, because we're diving into ptep_try_set(9) from the Kernel API Manual and honestly? it's giving ✨atomic vibes✨

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🎀 NAME 🎀

ptep_try_set — atomically set an empty kernel PTE, no cap 💅

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🌸 SYNOPSIS 🌸

bool ptep_try_set (pte_t *ptep , pte_t new_pte );

literally that's the whole signature, slay 🦋

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✨ ARGUMENTS ✨

• ptep — the page table entry, bestie. the slot we're eyeing 👀
• new_pte — the value we wanna install in there 💖

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🔥 DESCRIPTION 🔥

okay so here's the whole vibe: ptep_try_set atomically sets *ptep to new_pte iff *ptep is pte_none. it returns true on success — and returns false if the slot was already populated or if the arch has no implementation. it's giving "you had one shot" energy 💅

⚠️ this is for special kernel page tables only — never user page tables. not me being dramatic, that's just the rule 🙈

the caller must prevent concurrent teardown of ptep and must accept that other writers may race. yes, bestie, accept it — other writers are gonna race, that's just the situation 🫶

and listen: concurrent clearers must use ptep_get_and_clear so that racing accesses agree on the outcome. teamwork makes the dream work, fr fr 🌈

architectures opt in by providing a cmpxchg-based override and defining ptep_try_set as an identity macro — iconic behavior, honestly 👑

the generic stub returns false, which is correct for callers that fall through to oops on failure. yes that's on purpose. no that's not a bug. it's correct 😭💀

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🦋 SEE ALSO 🦋

Kernel file ./include/linux/pgtable.h and also this whole squad of legends:

• 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)
• flush_tlb_before_set(9)
• wrprotect_ptes(9)
• clear_flush_young_ptes(9)
• test_and_clear_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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that's the whole page, bestie, go forth and set those PTEs atomically 💜

mwah 💋 — this little number lives in ./include/linux, dated October 2026, and that's the tea 🍓