Messages in this thread | | | Date | Tue, 10 Oct 2017 13:50:35 +0200 | From | Oleg Nesterov <> | Subject | Re: [PATCH v4 1/2] pid: Replace pid bitmap implementation with IDR API |
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On 10/09, Andrew Morton wrote: > > > @@ -240,17 +230,11 @@ void zap_pid_ns_processes(struct pid_namespace *pid_ns) > > * > > */ > > read_lock(&tasklist_lock); > > - nr = next_pidmap(pid_ns, 1); > > - while (nr > 0) { > > - rcu_read_lock(); > > - > > - task = pid_task(find_vpid(nr), PIDTYPE_PID); > > + nr = 2; > > + idr_for_each_entry_continue(&pid_ns->idr, pid, nr) { > > + task = pid_task(pid, PIDTYPE_PID); > > if (task && !__fatal_signal_pending(task)) > > send_sig_info(SIGKILL, SEND_SIG_FORCED, task); > > - > > - rcu_read_unlock(); > > - > > - nr = next_pidmap(pid_ns, nr); > > } > > read_unlock(&tasklist_lock); > > Especially here. I don't think pidmap_lock is held. Is that IDR > iteration safe?
Yes, this doesn't look right, we need rcu_read_lock() or pidmap_lock.
And, we also need rcu_read_lock() for another reason, to protect "struct pid".
Gargi, I suggested to use idr_for_each_entry_continue(), but now I am wondering if we should use idr_for_each() instead. IIUC this would be a bit faster? Not that I think this is really important...
Oleg.
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