By the spec, fork() copies only the thread which executes it.
So it may happen, what while one thread is doing a fork,
another thread is holding `clone_lock` mutex
(e.g. doing a `fork()` or `exit()`).
So the child process is born with the mutex being held,
and there are nobody to release it.
As the thread executing do_syscall() is not considered running,
start_exclusive() does not protect us from the case.
Resolves: https://gitlab.com/qemu-project/qemu/-/issues/3226
Signed-off-by: Aleksandr Sergeev <sergeev0xef@gmail.com>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20260126151612.2176451-1-sergeev0xef@gmail.com>
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