__copy_to_user_inatomic(9)

📦 version 7.3.1, in nixpkgs unstable

💅 __copy_to_user_inatomic ✨

okay bestie, welcome to the Kernel API Manual 🎀 — today's main character is __copy_to_user_inatomic, and honestly? she's iconic, but she comes with ✨rules✨ so let's get into it 🫶

🌸 NAME 🌸

__copy_to_user_inatomic — copy a block of data into user space, with less checking 💫

like yes, she copies, but she does not do the whole security-check routine for you. you're on your own for that part, bestie 😭

🦋 SYNOPSIS 🦋

unsigned long __copy_to_user_inatomic (void __user *to , const void *from , unsigned long n );

that's the whole vibe. three args, one unsigned long coming back at you 💜

🍓 ARGUMENTS 🍓

  • to — the destination address, and it lives in user space. that's where the data's going, periodt 💅
  • from — the source address, and this one's in kernel space. that's where the data's coming from 🌈
  • n — number of bytes to copy. literally just how much you're moving, no cap 🔥

🧚 CONTEXT 🧚

User context only. 🚨

that's it. that's the whole rule. do not try this anywhere else, i'm begging 🙈

⭐ DESCRIPTION ⭐

so basically: you're copying data from kernel space to user space 💖

but here's the thing — the caller must check the specified block with access_ok before calling this function. like, that's not optional, that's the whole assignment, bestie 📝

the caller should also make sure he pins the user space address, so that we don't result in page fault and sleep 😴💀 — like, we are literally not trying to fall asleep mid-copy in an atomic context, that would be a whole mess 🫠

🔮 SEE ALSO 🔮

go check out the kernel file ./include/linux/uaccess.h for the lore 📖 plus all these other icons:

and that's the tea 🍵 this little page lives in ./include/linux and it's dated October 2026 — so yeah, she's from the future, slay 👑✨ mwah, study up and stay safe out there 💖🎀🦋

📦 where this page comes from