mountinfo: linux: use /proc/thread-self/mountinfo #128
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I guess this was not backported in the RHEL 3.10 kernels? I think RHEL 7 reaches EOL June next year, so ... it's getting closer. |
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(For future reference, this was motivated by opencontainers/runc#3985.) |
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Wdyt @kolyshkin? |
kolyshkin
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Oct 26, 2023
In a Go program with many threads, which goroutine is running on the thread-group leader thread is not something programs can controls. Thus, even if you use runtime.LockOSThread() for threads that have different mount namespaces, it's possible that /proc/self will refer to the "wrong" thread. The solution is to simply use /proc/thread-self, which will always provide the correct result for the calling thread. For pre-3.17 kernels we use /proc/self/task/<tid> as a fallback. The usage of /proc/self/mountinfo caused isuses for a patch to runc which creates a thread to create id-mapped mounts (which requires joining the container mount namespace). Signed-off-by: Aleksa Sarai <[email protected]>
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@thaJeztah ptal |
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Merging as this doesn't seem like a breaking change, and we need it in runc (#3985). |
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Ah, it seems that we need the |
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In a Go program with many threads, which goroutine is running on the thread-group leader thread is not something programs can controls. Thus, even if you use runtime.LockOSThread() for threads that have different mount namespaces, it's possible that /proc/self will refer to the "wrong" thread.
The solution is to simply use /proc/thread-self, which will always provide the correct result for the calling thread.
The usage of /proc/self/mountinfo caused isuses for a patch to runc which creates a thread to create id-mapped mounts (which requires joining the container mount namespace).
Signed-off-by: Aleksa Sarai [email protected]