__filemap_get_folio_mpol(9)

💅 __filemap_get_folio_mpol(9) 💅

okay bestie, welcome to the Kernel API Manual side of the group chat ✨ this is the page for __filemap_get_folio_mpol(9), and it is literally about finding a folio and getting a reference to it. very kernel-internals main character energy, no cap 🎀

✨ NAME ✨

__filemap_get_folio_mpol — Find and get a reference to a folio. That’s the whole vibe: find the folio, get the reference. 💅

🦋 SYNOPSIS 🦋

struct folio * __filemap_get_folio_mpol (struct address_space *mapping ,
pgoff_t index , fgf_t fgp_flags , gfp_t gfp , struct mempolicy *policy
);

🌸 ARGUMENTS 🌸

• mapping — the address_space to search. 🔍
• index — the page index. 📑
• fgp_flags — FGP flags modify how the folio is returned. 🎀
• gfp — memory allocation flags to use if FGP_CREAT is specified. 🧠
• policy — NUMA memory allocation policy to follow. 🌈

💖 DESCRIPTION 💖

okay so this function looks up the page cache entry at mapping & index. That’s the lookup. 🔎

If FGP_LOCK or FGP_CREAT are specified, then the function may sleep — even if the GFP flags specified for FGP_CREAT are atomic. Yes, even then. Like, it can literally nap on you. 😴

If this function returns a folio, it is returned with an increased refcount. So if it hands you a folio, the refcount has been bumped — you got a ref, bestie. 🫶

⭐ RETURN ⭐

The found folio, or an ERR_PTR otherwise. That’s the tea. ⭐

🔥 SEE ALSO 🔥

go read these too, bestie — the whole filemap cinematic universe is right here:

• Kernel file ./mm/filemap.c
• filemap_remove_folio(9)
• filemap_fdatawrite_range(9)
• filemap_flush_range(9)
• filemap_flush(9)
• filemap_range_has_page(9)
• filemap_fdatawait_range(9)
• filemap_fdatawait_range_keep_errors(9)
• file_fdatawait_range(9)
• filemap_fdatawait_keep_errors(9)
• filemap_write_and_wait_range(9)
• file_check_and_advance_wb_err(9)
• file_write_and_wait_range(9)
• replace_page_cache_folio(9)
• softleaf_entry_wait_on_locked(9)
• folio_put_wait_locked(9)
• folio_unlock(9)
• folio_end_read(9)
• folio_end_private_2(9)
• folio_wait_private_2(9)
• folio_wait_private_2_killable(9)
• folio_end_writeback_no_dropbehind(9)
• folio_end_writeback(9)
• __folio_lock(9)
• page_cache_next_miss(9)
• page_cache_prev_miss(9)
• find_get_entries(9)
• find_lock_entries(9)
• filemap_get_folios(9)
• filemap_get_folios_contig(9)
• filemap_get_folios_tag(9)
• filemap_get_folios_dirty(9)
• filemap_read(9)
• generic_file_read_iter(9)
• filemap_splice_read(9)
• mapping_seek_hole_data(9)
• filemap_fault(9)
• read_cache_folio(9)
• mapping_read_folio_gfp(9)
• read_cache_page_gfp(9)
• __generic_file_write_iter(9)
• generic_file_write_iter(9)
• filemap_release_folio(9)
• filemap_invalidate_inode(9)
• filemap_cachestat(9)

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cute little sign-off moment: this one is from source/version ./mm, dated October 2026, and it’s the __filemap_get_folio_mpol(9) page. bye bestie, go handle those references responsibly 💖✨