read_cache_page_gfp(9)

💅 read_cache_page_gfp — kernel API manual, but make it make sense 💅

okay so bestie, you're reading the page for read_cache_page_gfp, and honestly? it's giving "small function, big responsibilities." let's get into it 🫶

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✨ SYNOPSIS ✨

struct page * read_cache_page_gfp (struct address_space *mapping ,
pgoff_t index , gfp_t gfp );

three args, one struct page * coming back at you. no cap. 🌸

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🎀 ARGUMENTS 🎀

• mapping — the page's address_space. like, which address space are we even doing this in, bestie? this one.
• index — the page index. yes, the index. go find your page. 🔍
• gfp — the page allocator flags to use if allocating. these are your flags, you picked them, you own them. 💅

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💖 DESCRIPTION 💖

so this is literally the same as "read_mapping_page(mapping, index, NULL)", except any new page allocations get done using the allocation flags you specify. same vibe, your flags. ✨

if the page does not get brought uptodate, it returns -EIO. not great, not terrible, but definitely not the slay outcome. 😭

also — important, bestie — the function expects mapping->invalidate_lock to be already held when you call it. like, it's not gonna grab it for you. you gotta walk in with it. 🙈

fr fr, hold the lock before you call this. the function is not doing the lock chores for you, that's not its job.

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🦋 RETURN 🦋

• up to date page on success — iconic, we love a win 👑
• ERR_PTR on failure — not the moment, but okay 💀

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🔥 SEE ALSO 🔥

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)
• __filemap_get_folio_mpol(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)
• __generic_file_write_iter(9)
• generic_file_write_iter(9)
• filemap_release_folio(9)
• filemap_invalidate_inode(9)
• filemap_cachestat(9)

like, that's a whole friend group. mwah. 🧚

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and that's the page, bestie 💜 this one came out of ./mm and it's dated October 2026 — so go forth, pass your gfp flags, hold your invalidate_lock, and slay. 🌈⭐