From patchwork Wed Apr 6 11:59:50 2016 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Anton Blanchard X-Patchwork-Id: 606957 Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3qg48t3vmbz9t3t for ; Wed, 6 Apr 2016 22:02:22 +1000 (AEST) Authentication-Results: ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=lists.ozlabs.org header.i=@lists.ozlabs.org header.b=NkBtILjD; dkim=fail reason="signature verification failed" (1024-bit key; secure) header.d=samba.org header.i=@samba.org header.b=uWwSX4cl; dkim-atps=neutral Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 3qg48t2tnTzDqBZ for ; Wed, 6 Apr 2016 22:02:22 +1000 (AEST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=lists.ozlabs.org; s=201601; t=1459944142; bh=rKR3RvAKRpqMFAfvbv5wvKQomsAR2CO1J2UMtVum1Fs=; h=Date:To:Subject:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To:Cc: From; b=NkBtILjDJnSEVuxdbpxKlqnV9kekOvYQWNANQCrdsgqK3fjVY/DsYzJqSiZ4UZCQG Io8PVjiU3O2FCWdddlpnMhqmA/s7cuKeQWVWZp8C5mzvOBGtA/ixCUT94K2PgLuMlN Fo1qL63Zc7IftlC5bpejBfjlD+2JovG/HWQtnBCE= X-Original-To: linuxppc-dev@lists.ozlabs.org Delivered-To: linuxppc-dev@lists.ozlabs.org Received: from hr2.samba.org (hr2.samba.org [IPv6:2a01:4f8:192:486::147:1]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3qg47905zxzDq6S for ; Wed, 6 Apr 2016 22:00:53 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; secure) header.d=samba.org header.i=@samba.org header.b=uWwSX4cl; dkim-atps=neutral DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=samba.org; s=42627210; h=Message-ID:Cc:To:From:Date; bh=5bHui+GYcb/XGmslB4HW91MWYT3SINY/X+souF2C920=; b=uWwSX4clmR0CbWbBkxzuWaLAavZhYeNONWY0h3FLYJbpVW9pnY8IJ00xLchKxYamFcmUzwzRXghKHfNpD3Hdelt/kgDQcJjYiYRHp8vT6YiqoVYv4GaHBTsGFHFro40S+EftVVMDQsS7TUJu/VIewfIUdUit9bihBmbzqHYnU8Y=; Received: from [127.0.0.2] (localhost [127.0.0.1]) by hr2.samba.org with esmtpsa (TLS1.2:ECDHE_RSA_AES_128_GCM_SHA256:128) (Exim) id 1anm8H-0007Kv-AY; Wed, 06 Apr 2016 12:00:25 +0000 Date: Wed, 6 Apr 2016 21:59:50 +1000 To: Peter Zijlstra Subject: [PATCH] sched/cpuacct: Check for NULL when using task_pt_regs() Message-ID: <20160406215950.04bc3f0b@kryten> In-Reply-To: <20160406110803.GI2906@worktop> References: <20160404140312.GA28495@linux.vnet.ibm.com> <20160406065436.GB3078@gmail.com> <20160406203219.788ae7cf@kryten> <20160406110803.GI2906@worktop> X-Mailer: Claws Mail 3.12.0 (GTK+ 2.24.28; x86_64-pc-linux-gnu) MIME-Version: 1.0 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-Patchwork-Original-From: Anton Blanchard via Linuxppc-dev From: Anton Blanchard Reply-To: Anton Blanchard Cc: Stephen Rothwell , htejun@gmail.com, Srikar Dronamraju , efault@gmx.de, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, zhaolei@cn.fujitsu.com, yangds.fnst@cn.fujitsu.com, hpa@zytor.com, tj@kernel.org, tglx@linutronix.de, torvalds@linux-foundation.org, Ingo Molnar Errors-To: linuxppc-dev-bounces+patchwork-incoming=ozlabs.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Peter, > Ah, so sometihng like: > > struct pt_regs *regs = task_pt_regs(); > int index = CPUACCT_USAGE_SYSTEM; > > if (regs && user_mode(regs)) > index = CPUACCT_USAGE_USER; > > should work, right? Looks good, and the patch below does fix the oops for me. Anton --- task_pt_regs() can return NULL for kernel threads, so add a check. This fixes an oops at boot on ppc64. Signed-off-by: Anton Blanchard --- diff --git a/kernel/sched/cpuacct.c b/kernel/sched/cpuacct.c index df947e0..41f85c4 100644 --- a/kernel/sched/cpuacct.c +++ b/kernel/sched/cpuacct.c @@ -316,12 +316,11 @@ static struct cftype files[] = { void cpuacct_charge(struct task_struct *tsk, u64 cputime) { struct cpuacct *ca; - int index; + int index = CPUACCT_USAGE_SYSTEM; + struct pt_regs *regs = task_pt_regs(tsk); - if (user_mode(task_pt_regs(tsk))) + if (regs && user_mode(regs)) index = CPUACCT_USAGE_USER; - else - index = CPUACCT_USAGE_SYSTEM; rcu_read_lock();