Changes

Linux v6.12 add more balloon stat: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/diff/include/uapi/linux/virtio_balloon.h?id=v6.12&id2=v6.11

related commit: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?h=74c025c5d7e4ac7c7ad269c1ee64da4bdfe4770c

I supported it, when kernel >= v6.12, stat:

# curl --unix-socket firecracker.sock http://localhost/balloon/statistics
{"target_pages":1835008,"actual_pages":1835008,"target_mib":7168,"actual_mib":7168,"swap_in":0,"swap_out":0,"major_faults":1360,"minor_faults":126031,"free_memory":142065664,"total_memory":8351473664,"available_memory":437428224,"disk_caches":470376448,"hugetlb_allocations":0,"hugetlb_failures":0,"oom_kill":0,"alloc_stall":0,"async_scan":524492800,"direct_scan":0,"async_reclaim":413532160,"direct_reclaim":0}

otherwise:

# curl --unix-socket firecracker.sock http://localhost/balloon/statistics
{"target_pages":1806336,"actual_pages":1806336,"target_mib":7056,"actual_mib":7056,"swap_in":0,"swap_out":0,"major_faults":1777,"minor_faults":788590,"free_memory":131616768,"total_memory":8352452608,"available_memory":536666112,"disk_caches":577331200,"hugetlb_allocations":0,"hugetlb_failures":0}

Reason

I run firecrack with vmlinux v6.12, and balloon stat crashed:

stat api show no memory stat.

# curl --unix-socket firecracker.sock http://localhost/balloon/statistics
{"target_pages":1806336,"actual_pages":1806336,"target_mib":7056,"actual_mib":7056}

License Acceptance

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CONTRIBUTING.md.

PR Checklist

• I have read and understand CONTRIBUTING.md.
• I have run tools/devtool checkbuild --all to verify that the PR passes
  build checks on all supported architectures.
• I have run tools/devtool checkstyle to verify that the PR passes the
  automated style checks.
• I have described what is done in these changes, why they are needed, and
  how they are solving the problem in a clear and encompassing way.
• I have updated any relevant documentation (both in code and in the docs)
  in the PR.
• I have mentioned all user-facing changes in CHANGELOG.md.
• If a specific issue led to this PR, this PR closes the issue.
• When making API changes, I have followed the
  Runbook for Firecracker API changes.
• I have tested all new and changed functionalities in unit tests and/or
  integration tests.
• I have linked an issue to every new TODO.

• This functionality cannot be added in rust-vmm.