check_realloc_usable_mem(9)

✨ check_realloc_usable_mem(9) — the kernel API manual glow-up ✨

okay so this is a page from the Kernel API Manual, bestie, and it's about one tiny but lowkey iconic function: check_realloc_usable_mem. sit down, grab a strawberry drink 🍓, and let's get into it.

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🌸 NAME 🌸

check_realloc_usable_mem — reallocate the buffer if it literally cannot accommodate the entries 💅

like, it's giving "make room or make an exit." periodt.

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🎀 SYNOPSIS 🎀

__be64 * check_realloc_usable_mem (struct umem_info *um_info , int cnt );

yes the spacing is exactly like that, don't come for me, I copy things character for character around here 🫶

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🦋 ARGUMENTS 🦋

• um_info — the usable memory buffer and all the ranges info. it's the whole vibe package, both the buffer and the range deets live here ✨
• cnt — the number of entries we need to accommodate. as in, how many entries gotta fit. no cap.

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💖 DESCRIPTION 💖

so here's the tea: this function frees up the old buffer if the memory reallocation fails. that's the whole safety net, and honestly? iconic behaviour. 🔥

and it returns the buffer on success, or NULL on error. that's it, that's the contract. if you see NULL come back, something went wrong, bestie — handle it. 😭

lowkey important: a failing realloc means the old buffer gets freed, so like… don't go using stale pointers after that. that's not me adding lore, that's just what "frees up the old buffer if memory reallocation fails" means. 🙈

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🌈 SEE ALSO 🌈

the whole friend group, fr fr — all of these live in the kernel file ./arch/powerpc/kexec/file_load_64.c:

• add_usable_mem(9)
• kdump_setup_usable_lmb(9)
• add_usable_mem_property(9)
• update_usable_mem_fdt(9)
• load_backup_segment(9)
• load_elfcorehdr_segment(9)
• load_crashdump_segments_ppc64(9)
• setup_purgatory_ppc64(9)
• cpu_node_size(9)
• kexec_extra_fdt_size_ppc64(9)
• setup_new_fdt_ppc64(9)
• arch_kexec_kernel_image_probe(9)
• arch_kimage_file_post_load_cleanup(9)

go read them, they're all main character energy in their own way 👑

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okay and finally, the sign-off 🎀 — this page comes to you from ./arch/powerpc/kexec, dated October 2026, and it's the check_realloc_usable_mem(9) page, one last time for the people in the back. slay, bye! 💜✨