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authorOleg Nesterov <oleg@redhat.com>2013-07-04 00:08:31 +0200
committerLinus Torvalds <torvalds@linux-foundation.org>2013-07-04 01:08:03 +0200
commit8190773985141f063e1d6dc10200527c655abfb5 (patch)
tree5c148834f047748dfa2ce3500236b89656976567 /kernel/user.c
parentkernel/fork.c:copy_process(): unify CLONE_THREAD-or-thread_group_leader code (diff)
downloadlinux-8190773985141f063e1d6dc10200527c655abfb5.tar.xz
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kernel/fork.c:copy_process(): don't add the uninitialized child to thread/task/pid lists
copy_process() adds the new child to thread_group/init_task.tasks list and then does attach_pid(child, PIDTYPE_PID). This means that the lockless next_thread() or next_task() can see this thread with the wrong pid. Say, "ls /proc/pid/task" can list the same inode twice. We could move attach_pid(child, PIDTYPE_PID) up, but in this case find_task_by_vpid() can find the new thread before it was fully initialized. And this is already true for PIDTYPE_PGID/PIDTYPE_SID, With this patch copy_process() initializes child->pids[*].pid first, then calls attach_pid() to insert the task into the pid->tasks list. attach_pid() no longer need the "struct pid*" argument, it is always called after pid_link->pid was already set. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Cc: "Eric W. Biederman" <ebiederm@xmission.com> Cc: Michal Hocko <mhocko@suse.cz> Cc: Pavel Emelyanov <xemul@parallels.com> Cc: Sergey Dyasly <dserrg@gmail.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'kernel/user.c')
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