Fix ESRCH in sched_setaffinity due to glibc TID caching with clone3#264
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kiyoungkim-gg wants to merge 1 commit intogoogle:masterfrom
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Fix ESRCH in sched_setaffinity due to glibc TID caching with clone3#264kiyoungkim-gg wants to merge 1 commit intogoogle:masterfrom
kiyoungkim-gg wants to merge 1 commit intogoogle:masterfrom
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When nsjail creates a new process in a new PID namespace (CLONE_NEWPID) using the direct kernel syscall clone/clone3 (introduced in d1f332b), glibc's internal PID/TID cache is not updated for the child process. As a result, calling the glibc wrapper `sched_setaffinity(0, ...)` inside the child process causes glibc to inadvertently pass the cached parent's TID to the kernel instead of 0 (current thread). Since the parent's TID does not exist within the new PID namespace, the kernel returns ESRCH (No such process). This commit fixes the issue by bypassing the glibc wrapper and invoking the `sched_setaffinity` syscall directly via `util::syscall`. This ensures that `0` is passed accurately to the kernel, referring to the current thread.
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This issue was originally found when # of max_cpus is less than actual # of CPUs. The original error message was something like
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@robertswiecki Can you help me to get this reviewed if possible? Thanks! |
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When nsjail creates a new process in a new PID namespace (CLONE_NEWPID) using the direct kernel syscall clone/clone3 (introduced in d1f332b), glibc's internal PID/TID cache is not updated for the child process.
As a result, calling the glibc wrapper
sched_setaffinity(0, ...)inside the child process causes glibc to inadvertently pass the cached parent's TID to the kernel instead of 0 (current thread). Since the parent's TID does not exist within the new PID namespace, the kernel returns ESRCH (No such process).This commit fixes the issue by bypassing the glibc wrapper and invoking the
sched_setaffinitysyscall directly viautil::syscall. This ensures that0is passed accurately to the kernel, referring to the current thread.