copy_from_user_nofault(9)

🌸 NAME 🌸

okay so bestie, this page is literally all about copy_from_user_nofault(9) from the Kernel API Manual — its whole thing is safely attempt to read from a user-space location. 💖✨

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✨ SYNOPSIS ✨

here's the exact signature, character for character, no cap:

long copy_from_user_nofault (void *dst , const void __user *src , size_t size );

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🎀 ARGUMENTS 🎀

• dst — pointer to the buffer that shall take the data. 🫶
• src — address to read from. This must be a user address. 👀
• size — size of the data chunk. 📏

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💅 DESCRIPTION 💅

Safely read from user address src to the buffer at dst. If a kernel fault happens, handle that and return -EFAULT. 😭🔥

bestie caveat: that -EFAULT is the return when the kernel fault gets handled — it's literally the fallback, not a vibe. 💀

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🦋 SEE ALSO 🦋

the kernel file is ./mm/maccess.c, and these related icons are absolutely worth a peek:

• copy_to_user_nofault(9)
• strncpy_from_user_nofault(9)
• strnlen_user_nofault(9)

iykyk 💅

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mwah 💋 footer tea: source/version ./mm, date October 2026 — bye bestie! 🫶✨