clear_pfnblock_bit(9)

💅 clear_pfnblock_bit(9) — the kernel API manual, bestie edition

Okay so this is clear_pfnblock_bit(9) from the Kernel API Manual — literally the page where we learn how to clear one (1) standalone bit of a pageblock. Lowkey iconic, highkey niche. Let's get into it 🫶

---

✨ NAME ✨

clear_pfnblock_bit — clear a standalone bit of a pageblock 🌸

---

🦋 SYNOPSIS 🦋

void clear_pfnblock_bit (const struct page *page , unsigned long pfn ,
       enum pageblock_bits pb_bit );

That's the whole vibe: returns void, takes three args, done. No cap. ✨

---

🎀 ARGUMENTS 🎀

• page — the page within the block of interest 💖 (it's a const struct page *, so like… hands off, we're just reading)
• pfn — the target page frame number (unsigned long, she's got range)
• pb_bit — the pageblock bit to clear, typed as enum pageblock_bits, iykyk

---

👑 SEE ALSO 👑

Kernel file ./mm/page_alloc.c — and honestly the whole friend group is here, so lemme introduce the squad 💅:

• __get_pfnblock_flags_mask(9)
• get_pfnblock_bit(9)
• get_pfnblock_migratetype(9)
• __set_pfnblock_flags_mask(9)
• set_pfnblock_bit(9)
• set_pageblock_migratetype(9)
• __move_freepages_block_isolate(9)
• __putback_isolated_page(9)
• __free_pages(9)
• free_pages(9)
• alloc_pages_exact(9)
• alloc_pages_exact_nid(9)
• free_pages_exact(9)
• nr_free_zone_pages(9)
• nr_free_buffer_pages(9)
• find_next_best_node(9)
• free_reserved_pages(9)
• setup_per_zone_wmarks(9)
• __free_contig_range(9)
• alloc_contig_frozen_range(9)
• alloc_contig_range(9)
• alloc_contig_frozen_pages(9)
• alloc_contig_pages(9)
• free_contig_frozen_range(9)
• free_contig_range(9)
• alloc_pages_nolock(9)

Like, that's the entire contact list bestie 😭 go read them too, they ate 🔥

---

Fr fr, this is a void function — it clears the bit and dips, no return value energy at all 🙈

---

okay that's the page!! 💜 sourced from ./mm, dated October 2026, and honestly? clear_pfnblock_bit(9) stays the main character. periodt. 🦋✨🎀