isolate_migratepages_block(9)

💅 isolate_migratepages_block(9) — from the Kernel API Manual

okay so bestie, picture this: you're deep in mm/compaction.c and you need to pull out every page in a little chunk of memory that's actually down to move. that's this function. it's giving "surgical page extraction" and honestly? iconic. ✨

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🌸 SYNOPSIS

int isolate_migratepages_block (struct compact_control *cc , unsigned long low_pfn , unsigned long end_pfn , isolate_mode_t mode );

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🎀 ARGUMENTS

• cc — the compaction control structure, aka the main character. it holds all the state for the whole operation 🫶
• low_pfn — the very first PFN you wanna isolate. the starting line 📍
• end_pfn — the one-past-the-last PFN to isolate, and no cap, it has to be within the same pageblock 🚧
• mode — the isolation mode to be used. pick your vibe 🌈

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💖 DESCRIPTION

so what it does is isolate all the pages that can be migrated from the range [low_pfn, end_pfn). and when we say range, we mean it — that bad boy is expected to live inside the same pageblock, fr fr.

it returns an errno, like:

• -EAGAIN or -EINTR — in case e.g. a signal is pending or there's congestion 😭
• -ENOMEM — in case we could not allocate a page 💀
• 0 — the good ending ✨

also important, don't skip this: cc->migrate_pfn will contain the next pfn to scan. so you always know where to pick back up 👑

the pages get isolated onto the cc->migratepages list — and lowkey note this — that list is not required to be empty, so don't come for it. and cc->nr_migratepages gets updated accordingly, because numbers gotta stay honest 🧮

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🦋 SEE ALSO

• Kernel file ./mm/compaction.c
• isolate_freepages_range(9)
• skip_isolation_on_order(9)
• isolate_migratepages_range(9)
• try_to_compact_pages(9)

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bestie reminder: the range being inside the same pageblock isn't a suggestion, it's the whole assignment. treat it with respect 🙈

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kisses from the ./mm directory, version dated October 2026 — isolate_migratepages_block(9), you will always be famous 💜🎀