size_of is part of std::prelude as of Rust 1.80 (with size_of_val,
align_of, align_of_val), and the workspace MSRV is 1.89, so qualifying
it (mem::size_of, std::mem::size_of, core::mem::size_of) is unnecessary.
Convert every qualified size_of call-site to the bare prelude form and
drop the now-redundant `use std::mem::size_of;` imports, keeping
`use std::mem;` where it still serves non-prelude items (transmute,
swap, replace, take, zeroed, MaybeUninit, offset_of). size_of is the
only one of the four currently used in the tree.
Pure refactor, no behavioural change. Follow-up to the
clippy::absolute_paths cleanup (#7670), as discussed in #8444.
Signed-off-by: Henry Hrvoje Tonkovac <htonkovac@gmail.com>
Assisted-by: Claude:Opus-4.8
Plumb the SocketUffdMemorySource into the receiving side of live
migration. When memory_mode=postcopy is requested, the destination
brings up a dedicated fault connection, registers userfaultfd on the
restored memory regions, and serves guest pages on demand over that
connection while the VM resumes early.
Signed-off-by: Sebastien Boeuf <sboeuf@meta.com>
Assisted-by: Claude:claude-opus-4-7
Add the socket-backed UffdMemorySource that resolves each fault by
sending a Command::PageFault request to the peer over a dedicated fault
connection.
Signed-off-by: Sebastien Boeuf <sboeuf@meta.com>
Assisted-by: Claude:claude-opus-4-7
Extract the page content provider out of the userfaultfd handler so it
can be plugged with different backends in followup commits.
No functional change intended.
Signed-off-by: Sebastien Boeuf <sboeuf@meta.com>
Assisted-by: Claude:claude-opus-4-7
Prefer /dev/userfaultfd (Linux 6.1+) over the userfaultfd(2) syscall
for obtaining userfaultfd file descriptors. The device path bypasses
the capable(CAP_SYS_PTRACE) and vm.unprivileged_userfaultfd sysctl
checks that block the syscall in user-namespaced containers, using
file permissions instead.
Falls back to the syscall on older kernels or when the device node
does not exist.
Signed-off-by: Roberto Campesato <render@metalabs.org>
Assisted-by: Claude:claude-opus-4-6
Import common std types used by the userfaultfd wrapper instead of
spelling the full paths at every use site.
Signed-off-by: Keith Adler <kadler@cloudflare.com>
Add safe Rust wrappers around the raw userfaultfd ioctls: create
(syscall + API handshake), register (missing-page mode), copy
(resolve fault), and wake (unblock threads after EEXIST race).
These are used by the demand-paged snapshot restore handler in a
subsequent commit.
Signed-off-by: Shayon Mukherjee <shayonj@gmail.com>
