From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.linuxfoundation.org ([140.211.169.12]:37244 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751746AbdEWKjY (ORCPT ); Tue, 23 May 2017 06:39:24 -0400 Subject: Patch "sched/fair: Do not announce throttled next buddy in dequeue_task_fair()" has been added to the 4.4-stable tree To: khlebnikov@yandex-team.ru, benjamin.pineau@mirakl.com, bsegall@google.com, gregkh@linuxfoundation.org, mingo@kernel.org, peterz@infradead.org, tglx@linutronix.de, torvalds@linux-foundation.org Cc: , From: Date: Tue, 23 May 2017 12:39:12 +0200 Message-ID: <1495535952133224@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org List-ID: This is a note to let you know that I've just added the patch titled sched/fair: Do not announce throttled next buddy in dequeue_task_fair() to the 4.4-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: sched-fair-do-not-announce-throttled-next-buddy-in-dequeue_task_fair.patch and it can be found in the queue-4.4 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let know about it. >>From 754bd598be9bbc953bc709a9e8ed7f3188bfb9d7 Mon Sep 17 00:00:00 2001 From: Konstantin Khlebnikov Date: Thu, 16 Jun 2016 15:57:15 +0300 Subject: sched/fair: Do not announce throttled next buddy in dequeue_task_fair() From: Konstantin Khlebnikov commit 754bd598be9bbc953bc709a9e8ed7f3188bfb9d7 upstream. Hierarchy could be already throttled at this point. Throttled next buddy could trigger a NULL pointer dereference in pick_next_task_fair(). Signed-off-by: Konstantin Khlebnikov Signed-off-by: Peter Zijlstra (Intel) Reviewed-by: Ben Segall Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/146608183552.21905.15924473394414832071.stgit@buzz Signed-off-by: Ingo Molnar Cc: Ben Pineau Signed-off-by: Greg Kroah-Hartman --- kernel/sched/fair.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -4233,15 +4233,14 @@ static void dequeue_task_fair(struct rq /* Don't dequeue parent if it has other entities besides us */ if (cfs_rq->load.weight) { + /* Avoid re-evaluating load for this entity: */ + se = parent_entity(se); /* * Bias pick_next to pick a task from this cfs_rq, as * p is sleeping when it is within its sched_slice. */ - if (task_sleep && parent_entity(se)) - set_next_buddy(parent_entity(se)); - - /* avoid re-evaluating load for this entity */ - se = parent_entity(se); + if (task_sleep && se && !throttled_hierarchy(cfs_rq)) + set_next_buddy(se); break; } flags |= DEQUEUE_SLEEP; Patches currently in stable-queue which might be from khlebnikov@yandex-team.ru are queue-4.4/sched-fair-do-not-announce-throttled-next-buddy-in-dequeue_task_fair.patch queue-4.4/sched-fair-initialize-throttle_count-for-new-task-groups-lazily.patch