Global init can have sub-threads, so ->pid check is not reliable enough for is_global_init(), we need to check tgid instead. This has been spotted by Oleg and a fix was proposed by Richard a long time ago (see the link below). Oleg wrote: :Because is_global_init() is only true for the main thread of /sbin/init. : :Just look at oom_unkillable_task(). It tries to not kill init. But, say, :select_bad_process() can happily find a sub-thread of is_global_init() :and still kill it. I recently hit the problem in question; re-sending the patch (to the best of my knowledge it has never been submitted) with updated function comment. Credit goes to Oleg and Richard. Link: https://www.redhat.com/archives/linux-audit/2013-December/msg00086.html Reported-by: Oleg Nesterov <oleg@xxxxxxxxxx> Suggested-by: Richard Guy Briggs <rgb@xxxxxxxxxx> Acked-by: Serge Hallyn <serge.hallyn@xxxxxxxxxxxxx> Cc: <stable@xxxxxxxxxxxxxxx> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@xxxxxxxxx> --- include/linux/sched.h | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/include/linux/sched.h b/include/linux/sched.h index daf600e..d33de52 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2013,7 +2013,8 @@ static inline int pid_alive(const struct task_struct *p) } /** - * is_global_init - check if a task structure is init + * is_global_init - check if a task structure is init. Since init + * is free to have sub-threads we need to check tgid. * @tsk: Task structure to be checked. * * Check if a task structure is the first user space task the kernel created. @@ -2022,7 +2023,7 @@ static inline int pid_alive(const struct task_struct *p) */ static inline int is_global_init(struct task_struct *tsk) { - return tsk->pid == 1; + return task_tgid_nr(tsk) == 1; } extern struct pid *cad_pid; -- 2.7.0.rc0.20.g4b9ab0e -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html