Work

Everything below is in checkpoint-restore/criu, the Linux checkpoint/restore tool. Links go to the merged commits or the pull request.

Google Summer of Code 2026

Checkpoint/restore support for the identity data the kernel attaches to Unix socket messages. Mentored by Alexander Mikhalitsyn. Written up in the article.

Earlier upstream work

• Per-thread timer_slack_ns checkpoint/restore

  Collected from each thread through PR_GET_TIMERSLACK inside the parasite and restored per thread, so a process that tuned its own timer slack keeps it. Image format change, plus a test.

• Pipe ownership on restore

  A pipe restored by a root CRIU stayed owned by root, so a non-root process got EACCES reopening its own pipe through /proc/self/fd. Fixes issue #2984.

• Partial write handling in bwritev()

  Unbuffered writes went straight to writev(), which can return short. A short write there leaves a checkpoint image quietly incomplete.

• Dangling pointers in the Unix socket icon hash

  A failed allocation partway through could leave half-inserted entries in a global hash. Everything is now allocated before anything is published.

• Memory leaks and a truncation check in the socket queue

  Several leaks along error paths, a packet that could be left on a list with its data already freed, a missing MSG_CTRUNC check, and a control buffer too small for the file descriptors SCM_RIGHTS can carry.

• Double-open of the userns image in stream mode

  The image streamer rejects duplicate file requests, so the entry is now read once and shared. Plus assorted CI and coverage fixes.