From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 6DF45C3A59F for ; Thu, 29 Aug 2019 18:29:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 46D322339E for ; Thu, 29 Aug 2019 18:29:33 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567103373; bh=Sjz+ob3tjn27OF37DZBGEmsnfNuVRsOjYEddGEdbDeM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=l7DvNrcstGURXWS1Ny45GUWv0WJE61Y9U8gkKT4YWM5vtteawR+U8YHEASpYnr5J7 T0Lsvzx/3NntVAxc6kxnuBRnGbIyHf/j7J1KXlu9HJPBvnqfEPB0mrtMsomMh2Kqqe 4EJykfkkG3j7qMKzliyxD4DeG0Jwo4am3ycxcXzc= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729078AbfH2SO5 (ORCPT ); Thu, 29 Aug 2019 14:14:57 -0400 Received: from mail.kernel.org ([198.145.29.99]:56476 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729031AbfH2SOw (ORCPT ); Thu, 29 Aug 2019 14:14:52 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id A532C23404; Thu, 29 Aug 2019 18:14:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567102491; bh=Sjz+ob3tjn27OF37DZBGEmsnfNuVRsOjYEddGEdbDeM=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Nm/W27LvX5q6jIutVpNBx4y9VV45hJGKvwDYLv2D9OPRfC8mUhw3H49VTEC9BbUSb V/efdCElcEh30PXIAD1svT6WraFeTy2/GLL26XHSLDzjfpPv1AYYtoVzXl6PNtWZKe WePXPeZF2R4MBdqiYgaFw1vdMg+XV343dN9stSa4= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Sebastian Andrzej Siewior , Linus Torvalds , Peter Zijlstra , Thomas Gleixner , Ingo Molnar , Sasha Levin Subject: [PATCH AUTOSEL 5.2 47/76] sched/core: Schedule new worker even if PI-blocked Date: Thu, 29 Aug 2019 14:12:42 -0400 Message-Id: <20190829181311.7562-47-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190829181311.7562-1-sashal@kernel.org> References: <20190829181311.7562-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Sebastian Andrzej Siewior [ Upstream commit b0fdc01354f45d43f082025636ef808968a27b36 ] If a task is PI-blocked (blocking on sleeping spinlock) then we don't want to schedule a new kworker if we schedule out due to lock contention because !RT does not do that as well. A spinning spinlock disables preemption and a worker does not schedule out on lock contention (but spin). On RT the RW-semaphore implementation uses an rtmutex so tsk_is_pi_blocked() will return true if a task blocks on it. In this case we will now start a new worker which may deadlock if one worker is waiting on progress from another worker. Since a RW-semaphore starts a new worker on !RT, we should do the same on RT. XFS is able to trigger this deadlock. Allow to schedule new worker if the current worker is PI-blocked. Signed-off-by: Sebastian Andrzej Siewior Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20190816160626.12742-1-bigeasy@linutronix.de Signed-off-by: Ingo Molnar Signed-off-by: Sasha Levin --- kernel/sched/core.c | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 4d5962232a553..42bc2986520d7 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -3469,7 +3469,7 @@ void __noreturn do_task_dead(void) static inline void sched_submit_work(struct task_struct *tsk) { - if (!tsk->state || tsk_is_pi_blocked(tsk)) + if (!tsk->state) return; /* @@ -3485,6 +3485,9 @@ static inline void sched_submit_work(struct task_struct *tsk) preempt_enable_no_resched(); } + if (tsk_is_pi_blocked(tsk)) + return; + /* * If we are going to sleep and we have plugged IO queued, * make sure to submit it to avoid deadlocks. -- 2.20.1