Messages in this thread | | | Date | Tue, 20 Oct 2015 15:31:55 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH 1/2] wait/ptrace: always assume __WALL if the child is traced |
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On Tue, 20 Oct 2015 19:17:54 +0200 Oleg Nesterov <oleg@redhat.com> wrote:
> The following program (simplified version of generated by syzkaller) > > #include <pthread.h> > #include <unistd.h> > #include <sys/ptrace.h> > #include <stdio.h> > #include <signal.h> > > void *thread_func(void *arg) > { > ptrace(PTRACE_TRACEME, 0,0,0); > return 0; > } > > int main(void) > { > pthread_t thread; > > if (fork()) > return 0; > > while (getppid() != 1) > ; > > pthread_create(&thread, NULL, thread_func, NULL); > pthread_join(thread, NULL); > return 0; > } > > creates the unreapable zombie if /sbin/init doesn't use __WALL. > > This is not a kernel bug, at least in a sense that everything works as > expected: debugger should reap a traced sub-thread before it can reap > the leader, but without __WALL/__WCLONE do_wait() ignores sub-threads. > > Unfortunately, it seems that /sbin/init in most (all?) distributions > doesn't use it and we have to change the kernel to avoid the problem.
Well, to fix this a distro needs to roll out a new kernel. Or a new init(8). Is there any reason to believe that distributing/deploying a new kernel is significantly easier for everyone? Because fixing init sounds like a much preferable solution to this problem.
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