for_each_free_mem_range(9)

✨ for_each_free_mem_range ✨

okay so real talk: this is a page straight out of the Kernel API Manual, and it's about walking through the free areas of memblock. bestie, it's giving "low-level memory lore" and honestly? obsessed. let's get into it 💅

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🌸 NAME 🌸

for_each_free_mem_range — iterate through free memblock areas

like, you loop over the free chunks. that's the whole vibe. periodt.

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🦋 SYNOPSIS 🦋

for_each_free_mem_range (i , nid , flags , p_start , p_end , p_nid );

copy that exactly, no cap — the spacing is part of the aesthetic 🎀

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💖 ARGUMENTS 💖

six whole parameters, and yes, every single one matters:

• i — a u64 used as the loop variable. it's your counter girlie, she's doing the walking 🚶‍♀️
• nid — the node selector. pass NUMA_NO_NODE if you want all the nodes, no picking favorites 🌈
• flags — you pick which blocks you want based on memory attributes. choose wisely ✨
• p_start — a ptr to a phys_addr_t for the start address of the range. it can be NULL, she's flexible 🫶
• p_end — a ptr to a phys_addr_t for the end address of the range. also can be NULL, no pressure 💜
• p_nid — a ptr to an int for the nid of the range. and yep, can be NULL too. the whole trio is optional and i love that for them 😭

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🔥 DESCRIPTION 🔥

so what does it actually do? it walks over the free (memory && !reserved) areas of memblock. literally that's it, that's the job 💀

and the iconic part: it's available as soon as memblock is initialized. no waiting around, she's ready immediately. main character energy from the jump 👑

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👑 SEE ALSO 👑

the whole friend group, fr fr — go read these too:

• Kernel file ./include/linux/memblock.h
• enum memblock_flags(9)
• struct memblock_region(9)
• struct memblock_type(9)
• struct memblock(9)
• for_each_physmem_range(9)
• __for_each_mem_range(9)
• __for_each_mem_range_rev(9)
• for_each_mem_range(9)
• for_each_mem_range_rev(9)
• for_each_reserved_mem_range(9)
• for_each_mem_pfn_range(9)
• for_each_free_mem_range_reverse(9)
• memblock_set_current_limit(9)
• memblock_region_memory_base_pfn(9)
• memblock_region_memory_end_pfn(9)
• memblock_region_reserved_base_pfn(9)
• memblock_region_reserved_end_pfn(9)
• for_each_mem_region(9)
• for_each_reserved_mem_region(9)

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and that's the page, bestie 🧚💫 sourced from ./include/linux, dated October 2026, and the manual entry is for_each_free_mem_range(9) in case you forgot already 💖 mwah, go loop some memblock 🍓