From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932481Ab3LDNDx (ORCPT ); Wed, 4 Dec 2013 08:03:53 -0500 Received: from mx1.redhat.com ([209.132.183.28]:37457 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932385Ab3LDNDP (ORCPT ); Wed, 4 Dec 2013 08:03:15 -0500 Date: Wed, 4 Dec 2013 14:04:12 +0100 From: Oleg Nesterov To: Andrew Morton Cc: David Rientjes , "Eric W. Biederman" , Frederic Weisbecker , Mandeep Singh Baines , "Ma, Xindong" , Michal Hocko , Sameer Nanda , Sergey Dyasly , "Tu, Xiaobing" , linux-kernel@vger.kernel.org Subject: [PATCH v2 2/4] oom_kill: change oom_kill.c to use for_each_thread() Message-ID: <20131204130412.GA6005@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131204130351.GA5984@redhat.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Change oom_kill.c to use for_each_thread() rather than the racy while_each_thread() which can loop forever if we race with exit. Note also that most users were buggy even if while_each_thread() was fine, the task can exit even _before_ rcu_read_lock(). Fortunately the new for_each_thread() only requires the stable task_struct, so this change fixes both problems. Signed-off-by: Oleg Nesterov Reviewed-and-Tested-by: Sergey Dyasly Reviewed-by: Sameer Nanda --- mm/oom_kill.c | 20 ++++++++++---------- 1 files changed, 10 insertions(+), 10 deletions(-) diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 1e4a600..96d7945 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -59,7 +59,7 @@ static bool has_intersects_mems_allowed(struct task_struct *tsk, { struct task_struct *start = tsk; - do { + for_each_thread(start, tsk) { if (mask) { /* * If this is a mempolicy constrained oom, tsk's @@ -77,7 +77,7 @@ static bool has_intersects_mems_allowed(struct task_struct *tsk, if (cpuset_mems_allowed_intersects(current, tsk)) return true; } - } while_each_thread(start, tsk); + } return false; } @@ -97,14 +97,14 @@ static bool has_intersects_mems_allowed(struct task_struct *tsk, */ struct task_struct *find_lock_task_mm(struct task_struct *p) { - struct task_struct *t = p; + struct task_struct *t; - do { + for_each_thread(p, t) { task_lock(t); if (likely(t->mm)) return t; task_unlock(t); - } while_each_thread(p, t); + } return NULL; } @@ -301,7 +301,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, unsigned long chosen_points = 0; rcu_read_lock(); - do_each_thread(g, p) { + for_each_process_thread(g, p) { unsigned int points; switch (oom_scan_process_thread(p, totalpages, nodemask, @@ -323,7 +323,7 @@ static struct task_struct *select_bad_process(unsigned int *ppoints, chosen = p; chosen_points = points; } - } while_each_thread(g, p); + } if (chosen) get_task_struct(chosen); rcu_read_unlock(); @@ -406,7 +406,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, { struct task_struct *victim = p; struct task_struct *child; - struct task_struct *t = p; + struct task_struct *t; struct mm_struct *mm; unsigned int victim_points = 0; static DEFINE_RATELIMIT_STATE(oom_rs, DEFAULT_RATELIMIT_INTERVAL, @@ -437,7 +437,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, * still freeing memory. */ read_lock(&tasklist_lock); - do { + for_each_thread(p, t) { list_for_each_entry(child, &t->children, sibling) { unsigned int child_points; @@ -455,7 +455,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order, get_task_struct(victim); } } - } while_each_thread(p, t); + } read_unlock(&tasklist_lock); rcu_read_lock(); -- 1.5.5.1