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=unavailable 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 EA9F1C433DF for ; Fri, 5 Jun 2020 12:30:47 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C88AD2070B for ; Fri, 5 Jun 2020 12:30:47 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591360247; bh=jHd1X1zusmajFRLzbO/kks6/nt/Ek1Ar51xZCouIZN0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=etUoAGAafR5GdreYPxxGfYFVwaauwlCo8cw2n/mGHNTvDjqbmxbbFNDe8Ou8lGS/p hP1cGKfIJLqKEyYkX819j0Q2PkjKQwVfOmwp47yIdxVs/XAVMPpNC4oF3AcC2+GxKz 50QXW6movuHa5kscC9XGJRKzNni9ox7EYfDKhleg= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726802AbgFEMZf (ORCPT ); Fri, 5 Jun 2020 08:25:35 -0400 Received: from mail.kernel.org ([198.145.29.99]:56604 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726656AbgFEMZX (ORCPT ); Fri, 5 Jun 2020 08:25:23 -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 EEF262075B; Fri, 5 Jun 2020 12:25:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1591359922; bh=jHd1X1zusmajFRLzbO/kks6/nt/Ek1Ar51xZCouIZN0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=eFnIrvpF9zrOGlz/uzEgdA3BISZYtqh3mhEqaLeYoxOXR61ytOOoDt96VWaDsmE/p 2jd58XAVagftYeZY7kShgZhKuw8pAEoi6iGnK32FydcrKQIGwZJNNw1eIrIlB56OE1 pKZUr+K9H9rDLvlFhSuLhcpajfTpBmPdqkaDtThU= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Jens Axboe , Stefano Garzarella , Ingo Molnar , Peter Zijlstra , Sasha Levin Subject: [PATCH AUTOSEL 5.6 04/17] sched/fair: Don't NUMA balance for kthreads Date: Fri, 5 Jun 2020 08:25:03 -0400 Message-Id: <20200605122517.2882338-4-sashal@kernel.org> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20200605122517.2882338-1-sashal@kernel.org> References: <20200605122517.2882338-1-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: Jens Axboe [ Upstream commit 18f855e574d9799a0e7489f8ae6fd8447d0dd74a ] Stefano reported a crash with using SQPOLL with io_uring: BUG: kernel NULL pointer dereference, address: 00000000000003b0 CPU: 2 PID: 1307 Comm: io_uring-sq Not tainted 5.7.0-rc7 #11 RIP: 0010:task_numa_work+0x4f/0x2c0 Call Trace: task_work_run+0x68/0xa0 io_sq_thread+0x252/0x3d0 kthread+0xf9/0x130 ret_from_fork+0x35/0x40 which is task_numa_work() oopsing on current->mm being NULL. The task work is queued by task_tick_numa(), which checks if current->mm is NULL at the time of the call. But this state isn't necessarily persistent, if the kthread is using use_mm() to temporarily adopt the mm of a task. Change the task_tick_numa() check to exclude kernel threads in general, as it doesn't make sense to attempt ot balance for kthreads anyway. Reported-by: Stefano Garzarella Signed-off-by: Jens Axboe Signed-off-by: Ingo Molnar Acked-by: Peter Zijlstra Link: https://lore.kernel.org/r/865de121-8190-5d30-ece5-3b097dc74431@kernel.dk Signed-off-by: Sasha Levin --- kernel/sched/fair.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c index 603d3d3cbf77..efb15f0f464b 100644 --- a/kernel/sched/fair.c +++ b/kernel/sched/fair.c @@ -2682,7 +2682,7 @@ static void task_tick_numa(struct rq *rq, struct task_struct *curr) /* * We don't care about NUMA placement if we don't have memory. */ - if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work) + if ((curr->flags & (PF_EXITING | PF_KTHREAD)) || work->next != work) return; /* -- 2.25.1