From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) (using TLSv1.2 with cipher ADH-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3yjHCK0jBTzDrM5 for ; Thu, 23 Nov 2017 22:29:01 +1100 (AEDT) Received: from ozlabs.org (ozlabs.org [IPv6:2401:3900:2:1::2]) by bilbo.ozlabs.org (Postfix) with ESMTP id 3yjHCJ6qVfz8tCD for ; Thu, 23 Nov 2017 22:29:00 +1100 (AEDT) Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 3yjHCJ3Sxhz9s3w for ; Thu, 23 Nov 2017 22:28:59 +1100 (AEDT) Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.21/8.16.0.21) with SMTP id vANBSsZp068201 for ; Thu, 23 Nov 2017 06:28:58 -0500 Received: from e06smtp11.uk.ibm.com (e06smtp11.uk.ibm.com [195.75.94.107]) by mx0a-001b2d01.pphosted.com with ESMTP id 2educ81rxg-1 (version=TLSv1.2 cipher=AES256-SHA bits=256 verify=NOT) for ; Thu, 23 Nov 2017 06:28:57 -0500 Received: from localhost by e06smtp11.uk.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Thu, 23 Nov 2017 11:18:35 -0000 Subject: Re: [PATCH] powernv: Avoid calling trace tlbie in kexec path. To: Balbir Singh Cc: linuxppc-dev , Michael Ellerman , "Aneesh Kumar K.V" References: <151137178794.14123.18003389448303728066.stgit@jupiter.in.ibm.com> From: Mahesh Jagannath Salgaonkar Date: Thu, 23 Nov 2017 16:48:31 +0530 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Message-Id: List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On 11/23/2017 04:26 AM, Balbir Singh wrote: > On Thu, Nov 23, 2017 at 4:32 AM, Mahesh J Salgaonkar > wrote: >> From: Mahesh Salgaonkar >> >> Rebooting into a new kernel with kexec fails in trace_tlbie() which is >> called from native_hpte_clear(). This happens if the running kernel has >> CONFIG_LOCKDEP enabled. With lockdep enabled, the tracepoints always >> execute few RCU checks regardless of whether tracing is on or off. >> We are already in the last phase of kexec sequence in real mode with >> HILE_BE set. At this point the RCU check ends up in RCU_LOCKDEP_WARN and >> causes kexec to fail. >> > > Effectively we can't enter the trace point code after we've set > HILE_BE. Do we need > a fixes tag? Or is this a side-effect of a new generic change? Yup. I missed it. Will resend the patch with fixes tag Fixes: 0428491cba92 ("powerpc/mm: Trace tlbie(l) instructions") > > I think the right thing in the longer run might be to do a TRACE_EVENT_CONDITION > and have the condition do the right thing, but what you have for now is good. > > Balbir Singh. >