From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ob0-x236.google.com (mail-ob0-x236.google.com [IPv6:2607:f8b0:4003:c01::236]) (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 3qxM9J6yRDzDqB4 for ; Sat, 30 Apr 2016 04:07:16 +1000 (AEST) Received: by mail-ob0-x236.google.com with SMTP id x1so36349266obt.0 for ; Fri, 29 Apr 2016 11:07:16 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: From: Andy Lutomirski Date: Fri, 29 Apr 2016 11:06:53 -0700 Message-ID: Subject: Re: [RFC PATCH v2 05/18] sched: add task flag for preempt IRQ tracking To: Josh Poimboeuf Cc: Jessica Yu , Jiri Kosina , Miroslav Benes , Ingo Molnar , Peter Zijlstra , Michael Ellerman , Heiko Carstens , live-patching@vger.kernel.org, "linux-kernel@vger.kernel.org" , X86 ML , linuxppc-dev@lists.ozlabs.org, "linux-s390@vger.kernel.org" , Vojtech Pavlik , Jiri Slaby , Petr Mladek , Chris J Arges , Andy Lutomirski Content-Type: text/plain; charset=UTF-8 List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Thu, Apr 28, 2016 at 1:44 PM, Josh Poimboeuf wrote: > A preempted function might not have had a chance to save the frame > pointer to the stack yet, which can result in its caller getting skipped > on a stack trace. > > Add a flag to indicate when the task has been preempted so that stack > dump code can determine whether the stack trace is reliable. I think I like this, but how do you handle the rather similar case in which a task goes to sleep because it's waiting on IO that happened in response to get_user, put_user, copy_from_user, etc? --Andy