Messages in this thread Patch in this message |  | | | Date | Fri, 25 May 2012 18:00:08 +0200 | | From | Oleg Nesterov <> | | Subject | [PATCH -mm 1/1] pidns: find_new_reaper() can no longer switch to init_pid_ns.child_reaper |
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find_new_reaper() changes pid_ns->child_reaper, see add0d4df "pid_ns: zap_pid_ns_processes: fix the ->child_reaper changing".
The original reason has gone away after the previous patch, ->children list must be empty after zap_pid_ns_processes(). However, "can't clear ->child_reaper or leave it alone" is still true, and now we can not use init_pid_ns.child_reaper.
__unhash_process() relies on the "->child_reaper == parent" check, but this check does not work if the last exiting task is also the child reaper.
Change find_new_reaper() to use pid_ns->parent->child_reaper.
Signed-off-by: Oleg Nesterov <oleg@redhat.com> --- kernel/exit.c | 8 ++++---- 1 files changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/exit.c b/kernel/exit.c index b3e6e0e..9f9af91 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -733,11 +733,11 @@ static struct task_struct *find_new_reaper(struct task_struct *father) zap_pid_ns_processes(pid_ns); write_lock_irq(&tasklist_lock); /* - * We can not clear ->child_reaper or leave it alone. - * There may by stealth EXIT_DEAD tasks on ->children, - * forget_original_parent() must move them somewhere. + * Our parent can be ->child_reaper as well, make sure + * we don't break the "child_reaper == parent" logic in + * __unhash_process(). */ - pid_ns->child_reaper = init_pid_ns.child_reaper; + pid_ns->child_reaper = pid_ns->parent->child_reaper; } else if (father->signal->has_child_subreaper) { struct task_struct *reaper; -- 1.5.5.1
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