start the global /sbin/init with 0,0 special pids
As Eric pointed out, there is no problem with init starting with sid == pgid == 0, and this was historical linux behavior changed in 2.6.18. Remove kernel_init()->__set_special_pids(), this is unneeded and complicates the rules for sys_setsid(). This change and the previous change in daemonize() mean that /sbin/init does not need the special "session != 1" hack in sys_setsid() any longer. We can't remove this check yet, we should cleanup copy_process(CLONE_NEWPID) first, so update the comment only. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Pavel Emelyanov <xemul@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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@ -833,7 +833,6 @@ static int __init kernel_init(void * unused)
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*/
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init_pid_ns.child_reaper = current;
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__set_special_pids(task_pid(current));
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cad_pid = task_pid(current);
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smp_prepare_cpus(setup_max_cpus);
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@ -1054,12 +1054,11 @@ asmlinkage long sys_setsid(void)
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if (group_leader->signal->leader)
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goto out;
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/* Fail if a process group id already exists that equals the proposed
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* session id.
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/* Fail if a process group id already exists that equals the
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* proposed session id.
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*
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* Don't check if session == 1 because kernel threads and CLONE_NEWPID
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* tasks use this session id and so the check will always fail and make
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* it so init cannot successfully call setsid.
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* Don't check if session == 1, clone(CLONE_NEWPID) creates
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* this group/session beforehand.
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*/
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if (session != 1 && pid_task(sid, PIDTYPE_PGID))
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goto out;
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