tag_pages_for_writeback(9)

🌸 tag_pages_for_writeback(9) 🌸

okay so bestie, welcome to the Kernel API Manual — section 9, yes we are in our kernel era — and today’s main character is tag_pages_for_writeback, the function that tags pages so writeback knows what’s up. 💅✨

💖 NAME 💖

tag_pages_for_writeback — tag pages to be written by writeback 🎀

🎀 SYNOPSIS 🎀

void tag_pages_for_writeback (struct address_space *mapping , pgoff_t
start , pgoff_t end );

🦋 ARGUMENTS 🦋

• mapping — address space structure to write
• start — starting page index
• end — ending page index (inclusive)

✨ DESCRIPTION ✨

So this function scans the page range from start to end (inclusive) and tags all pages that have the DIRTY tag set with a special TOWRITE tag. That’s the whole glow-up: DIRTY pages get the TOWRITE stamp. 🫶

Then the caller can use the TOWRITE tag to identify pages eligible for writeback. It’s giving “handy little eligibility list.” 😌

This mechanism is used to avoid livelocking of writeback by a process steadily creating new dirty pages in the file. And because of that, it is important for this function to be quick — so that it can tag pages faster than a dirtying process can create them. no cap, the speed is literally the point. 🔥

🌈 SEE ALSO 🌈

Kernel file: ./mm/page-writeback.c — go say hi to the neighbors: 🦋

• node_dirtyable_memory(9)
• global_dirtyable_memory(9)
• domain_dirty_limits(9)
• global_dirty_limits(9)
• node_dirty_limit(9)
• node_dirty_ok(9)
• __wb_calc_thresh(9)
• balance_dirty_pages_ratelimited_flags(9)
• balance_dirty_pages_ratelimited(9)
• wb_over_bg_thresh(9)
• writeback_iter(9)
• filemap_dirty_folio(9)
• folio_redirty_for_writepage(9)
• folio_mark_dirty(9)
• folio_wait_writeback(9)
• folio_wait_writeback_killable(9)
• folio_wait_stable(9)

source/version: ./mm · date: October 2026 · page: tag_pages_for_writeback(9) — bye bestie, go tag some pages responsibly! 🫶💖🎀