Use raw syscalls to avoid sporadic hangs#2425
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utam0k merged 1 commit intoyouki-dev:mainfrom Oct 12, 2023
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Additional details and impacted files@@ Coverage Diff @@
## main #2425 +/- ##
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- Coverage 66.01% 65.93% -0.08%
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Files 133 133
Lines 16832 16851 +19
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Hits 11111 11111
- Misses 5721 5740 +19 |
Signed-off-by: Jorge Prendes <jorge.prendes@gmail.com>
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Member
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@jprendes I appreciate your investigation and PR. Have you checked if this patch worked fine for runwasi? |
Contributor
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@utam0k it seems to work. It is difficult to say as the original issue is sporadic. |
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The
setgroups/setresgid/setresuidfunctions innix/libcare not safe to call afterclone/clone3.These function use a blocking mechanism that synchronises across all threads in the process.
To do this
libc(glibc/musl) needs to do some bookkeeping, which breaks on the new process afterclone.See the discussion in containerd/runwasi#347 for more details.
This PR worksaround that issue by using raw syscalls for
setgroups/setresgid/setresuid.This is generally not safe, as the raw syscalls only affect the calling thread and not the whole process.
It is safe to do so in this case because at the point when they are called in libcontainer the init process only has one thread.