Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752528AbdI0PHC (ORCPT ); Wed, 27 Sep 2017 11:07:02 -0400 Received: from mail-oi0-f67.google.com ([209.85.218.67]:33306 "EHLO mail-oi0-f67.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751985AbdI0PHB (ORCPT ); Wed, 27 Sep 2017 11:07:01 -0400 X-Google-Smtp-Source: AOwi7QBvkkzxLxDcQz7l0nOa/pwLJ23Q2HwzFjgFIQNwryoodw22rFluO/y/MgqDAY2GNYA77O2w2wdd/CMnkeqM1C4= MIME-Version: 1.0 In-Reply-To: <20170927140658.GA28133@redhat.com> References: <1506517794.21121.93.camel@surriel.com> <20170927140658.GA28133@redhat.com> From: Gargi Sharma Date: Wed, 27 Sep 2017 20:36:30 +0530 Message-ID: Subject: Re: [PATCH v2 1/2] pid: Replace pid bitmap implementation with IDR API To: Oleg Nesterov Cc: Rik van Riel , linux-kernel@vger.kernel.org, Julia Lawall , akpm@linux-foundation.org, mingo@kernel.org, pasha.tatashin@oracle.com, ktkhai@virtuozzo.com Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1803 Lines: 56 On Wed, Sep 27, 2017 at 7:36 PM, Oleg Nesterov wrote: > On 09/27, Rik van Riel wrote: >> >> > @@ -240,17 +230,18 @@ 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(); >> > + pid = idr_get_next(&pid_ns->idr, &nr); >> > + while (pid) { >> > >> > - task = pid_task(find_vpid(nr), PIDTYPE_PID); >> > - if (task && !__fatal_signal_pending(task)) >> > - send_sig_info(SIGKILL, SEND_SIG_FORCED, >> > task); >> > + rcu_read_lock(); >> > >> > + 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); >> > >> >> I believe we should be fine with just the idr_for_each_entry_continue() >> surrounding the loop, > > Yes, and please move "nr = 2" close to idr_for_each_entry_continue() to > make it clear why do we use _continue (to skip nr == 1). > >> and not need the while (pid) around that. >> >> That should still iterate over all the pids in the namespace, and >> simplify the code even more. > > And make this patch correct ;) > > because currently it is wrong, zap_pid_ns_processes() won't kill the pid > returned by the first idr_get_next(). Yes, I missed this. I can simply remove the idr_get_next() before the idr_for_each_continue and that will take care of it. Thanks! Gargi > > Oleg. >