Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1031075Ab1EWWVO (ORCPT ); Mon, 23 May 2011 18:21:14 -0400 Received: from smtp-out.google.com ([216.239.44.51]:19276 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932197Ab1EWWVL (ORCPT ); Mon, 23 May 2011 18:21:11 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=date:from:x-x-sender:to:cc:subject:in-reply-to:message-id :references:user-agent:mime-version:content-type; b=c4Iq2xByisEnqWiRnSc6jizdGSCb1TvvUGD0yhA2hC0/p1qFDOwDQZrPJM7s3OqpQN TR1nqHdkUpX4GViuxiXw== Date: Mon, 23 May 2011 15:20:54 -0700 (PDT) From: David Rientjes X-X-Sender: rientjes@chino.kir.corp.google.com To: KOSAKI Motohiro cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, caiqian@redhat.com, hughd@google.com, kamezawa.hiroyu@jp.fujitsu.com, minchan.kim@gmail.com, oleg@redhat.com Subject: Re: [PATCH 2/5] oom: kill younger process first In-Reply-To: <4DD62007.6020600@jp.fujitsu.com> Message-ID: References: <4DD61F80.1020505@jp.fujitsu.com> <4DD62007.6020600@jp.fujitsu.com> User-Agent: Alpine 2.00 (DEB 1167 2008-08-23) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2215 Lines: 66 On Fri, 20 May 2011, KOSAKI Motohiro wrote: > diff --git a/include/linux/sched.h b/include/linux/sched.h > index 013314a..3698379 100644 > --- a/include/linux/sched.h > +++ b/include/linux/sched.h > @@ -2194,6 +2194,9 @@ static inline unsigned long wait_task_inactive(struct task_struct *p, > #define next_task(p) \ > list_entry_rcu((p)->tasks.next, struct task_struct, tasks) > > +#define prev_task(p) \ > + list_entry((p)->tasks.prev, struct task_struct, tasks) > + > #define for_each_process(p) \ > for (p = &init_task ; (p = next_task(p)) != &init_task ; ) > > @@ -2206,6 +2209,14 @@ extern bool current_is_single_threaded(void); > #define do_each_thread(g, t) \ > for (g = t = &init_task ; (g = t = next_task(g)) != &init_task ; ) do > > +/* > + * Similar to do_each_thread(). but two difference are there. > + * - traverse tasks reverse order (i.e. younger to older) > + * - caller must hold tasklist_lock. rcu_read_lock isn't enough > +*/ > +#define do_each_thread_reverse(g, t) \ > + for (g = t = &init_task ; (g = t = prev_task(g)) != &init_task ; ) do > + > #define while_each_thread(g, t) \ > while ((t = next_thread(t)) != g) > > diff --git a/mm/oom_kill.c b/mm/oom_kill.c > index 43d32ae..e6a6c6f 100644 > --- a/mm/oom_kill.c > +++ b/mm/oom_kill.c > @@ -282,7 +282,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, > struct task_struct *chosen = NULL; > *ppoints = 0; > > - do_each_thread(g, p) { > + do_each_thread_reverse(g, p) { > unsigned int points; > > if (!p->mm) Same response as when you initially proposed this patch: the comment needs to explicitly state that it is not break-safe just like do_each_thread(). See http://marc.info/?l=linux-mm&m=130507027312785 A comment such as /* * Reverse of do_each_thread(); still not break-safe. * Must hold tasklist_lock. */ would suffice. There are no "callers" to a macro. After that: Acked-by: David Rientjes -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/