• Oleg Nesterov's avatar
    [PATCH] pidhash: don't count idle threads · 73b9ebfe
    Oleg Nesterov authored
    fork_idle() does unhash_process() just after copy_process().  Contrary,
    boot_cpu's idle thread explicitely registers itself for each pid_type with nr
    = 0.
    
    copy_process() already checks p->pid != 0 before process_counts++, I think we
    can just skip attach_pid() calls and job control inits for idle threads and
    kill unhash_process().  We don't need to cleanup ->proc_dentry in fork_idle()
    because with this patch idle threads are never hashed in
    kernel/pid.c:pid_hash[].
    
    We don't need to hash pid == 0 in pidmap_init().  free_pidmap() is never
    called with pid == 0 arg, so it will never be reused.  So it is still possible
    to use pid == 0 in any PIDTYPE_xxx namespace from kernel/pid.c's POV.
    
    However with this patch we don't hash pid == 0 for PIDTYPE_PID case.  We still
    have have PIDTYPE_PGID/PIDTYPE_SID entries with pid == 0: /sbin/init and
    kernel threads which don't call daemonize().
    Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
    Cc: "Eric W. Biederman" <ebiederm@xmission.com>
    Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
    Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
    73b9ebfe
pid.c 6.49 KB