kstrndup(9)

kstrndup(9) 💅

okay so bestie, welcome to the Kernel API Manual page for kstrndup(9) — manual name folded in near the top like a little name tag, we're not doing the copy-paste header thing ✨

🎀 NAME 🎀

kstrndup — allocate space for and copy an existing string. That's the whole vibe: it grabs memory and duplicates a string for you. periodt.

🌸 SYNOPSIS 🌸

char * kstrndup (const char *s , size_t max , gfp_t gfp );

✨ ARGUMENTS ✨

• s — the string to duplicate. Like, the original string bestie, the one you want a copy of.
• max — read at most max chars from s. There is literally a cap, and the cap is max.
• gfp — the GFP mask used in the kmalloc call when allocating memory. That's the allocation vibe check for this function.

🫶 NOTE 🫶

Use kmemdup_nul instead if the size is known exactly. Not me telling you what to do, just the manpage telling you what to do 💅

🔥 RETURN 🔥

newly allocated copy of s or NULL in case of error. So you either get the duplicate or a NULL situation, and that's the whole return story.

🦋 SEE ALSO 🦋

Kernel file ./mm/util.c and all these besties:

• kfree_const(9)
• __kmemdup_nul(9)
• kstrdup(9)
• kstrdup_const(9)
• kmemdup(9)
• kmemdup_array(9)
• kvmemdup(9)
• kmemdup_nul(9)
• memdup_user(9)
• vmemdup_user(9)
• strndup_user(9)
• memdup_user_nul(9)
• randomize_page(9)
• __account_locked_vm(9)
• account_locked_vm(9)
• __vmalloc_array(9)
• vmalloc_array(9)
• __vcalloc(9)
• vcalloc(9)
• folio_mapping(9)
• folio_copy(9)
• get_cmdline(9)
• mem_dump_obj(9)
• compat_set_desc_from_vma(9)
• __compat_vma_mmap(9)
• compat_vma_mmap(9)
• snapshot_page(9)
• mmap_action_prepare(9)
• mmap_action_complete(9)
• folio_pte_batch(9)
• page_range_contiguous(9)

mwah 💋 this one lives under ./mm, dated October 2026, and yes it's all about kstrndup(9) — bye bestie 🫶