rdma_umap_priv_init(9)

🌟 rdma_umap_priv_init(9) 🌟

okay so welcome to this lil page from the Kernel API Manual, bestie 💖. it's all about rdma_umap_priv_init, and it's literally giving “initialize the private data of a vma” energy 💅✨.

🌸 NAME 🌸

rdma_umap_priv_init — Initialize the private data of a vma 🎀

🌈 SYNOPSIS 🌈

void rdma_umap_priv_init (struct rdma_umap_priv *priv , struct
       vm_area_struct *vma , struct rdma_user_mmap_entry *entry );

💖 ARGUMENTS 💖

• priv — The already allocated private data 🫶. like it's already yours, no cap.
• vma — The vm area struct that needs private data 🦋.
• entry — entry into the mmap_xa that needs to be linked with this vma 🔗.

🦋 DESCRIPTION 🦋

Each time we map IO memory into user space this keeps track of the mapping 👀. When the device is hot-unplugged we 'zap' the mmaps in user space to point to the zero page and allow the hot unplug to proceed 💀.

This is necessary for cases like PCI physical hot unplug as the actual BAR memory may vanish after this and access to it from userspace could MCE 😭. that's the serious part, bestie — not cute at all.

RDMA drivers supporting disassociation must have their user space designed to cope in some way with their IO pages going to the zero page 🫶. so yeah, user space gotta be ready for that plot twist.

👀 SEE ALSO 👀

Kernel file ./drivers/infiniband/core/ib_core_uverbs.c

• rdma_user_mmap_io(9)
• rdma_user_mmap_entry_get_pgoff(9)
• rdma_user_mmap_entry_get(9)
• rdma_user_mmap_entry_put(9)
• rdma_user_mmap_entry_remove(9)
• rdma_user_mmap_entry_insert_range(9)
• rdma_user_mmap_entry_insert(9)
• rdma_udata_to_dev(9)
• _uverbs_alloc(9)
• uverbs_get_buffer_desc(9)

mwah 💋 this lil sign-off is from source/version ./drivers/infiniband/core, dated October 2026, and yes bestie, it's still the rdma_umap_priv_init(9) manual — periodt 🌈👑.