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=-0.6 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no 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 E7A53C2D0CE for ; Fri, 24 Jan 2020 05:02:31 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A22522072C for ; Fri, 24 Jan 2020 05:02:31 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="MwrTy9e7" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A22522072C Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2ABB76B02A7; Fri, 24 Jan 2020 00:02:31 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 25B9C6B02A8; Fri, 24 Jan 2020 00:02:31 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 170EE6B02A9; Fri, 24 Jan 2020 00:02:31 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0044.hostedemail.com [216.40.44.44]) by kanga.kvack.org (Postfix) with ESMTP id 02C156B02A7 for ; Fri, 24 Jan 2020 00:02:30 -0500 (EST) Received: from smtpin04.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with SMTP id A0D34180AD806 for ; Fri, 24 Jan 2020 05:02:30 +0000 (UTC) X-FDA: 76411332060.04.start13_15ddf83e9fa61 X-HE-Tag: start13_15ddf83e9fa61 X-Filterd-Recvd-Size: 3293 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) by imf08.hostedemail.com (Postfix) with ESMTP for ; Fri, 24 Jan 2020 05:02:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20170209; h=In-Reply-To:Content-Transfer-Encoding :Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=ov31A6tYKcczbAgX5V+K/86bJ5Mzf/GVps9NpBV92oA=; b=MwrTy9e7zWFtY+ARjOGY0FjNXH XHKtTGNYClFWFRLZh1KzO2E6mrNLhwzW80c/Pm15BcjbBYcBYBQpvKWdL26Y4F9pvsSsj/mXHLwvD DNuDftcC/mCDNRo4klh7c8mt1ywyIaBLlhraNWuDfJ8DWnpiKXG8o5satL11AZWjbocO0XmeqvWUe xIQKvRapY1sPTLkj549d6W+gciGXO+lYVOo0tFIHGZN9XFiMTwuSKVxI1hfdYSelKPjjgtruuxYLC f6OUy/Mm6Lb6QNOCpl+PiOrlMkjI9O0xTijyh9icTzEAxZ/lK/oeH+kjwI+kvKZVLY++oTDHoCiv4 oCbLVLhg==; Received: from willy by bombadil.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1iur6Y-0004ub-AN; Fri, 24 Jan 2020 05:02:02 +0000 Date: Thu, 23 Jan 2020 21:02:02 -0800 From: Matthew Wilcox To: Qian Cai Cc: Peter Zijlstra , mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, paulmck@kernel.org, tglx@linutronix.de, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, Matt Turner , linux-parisc@vger.kernel.org, Helge Deller Subject: Re: [PATCH v2] sched/core: fix illegal RCU from offline CPUs Message-ID: <20200124050202.GJ4675@bombadil.infradead.org> References: <20200121103506.GH14914@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, Jan 23, 2020 at 11:21:35PM -0500, Qian Cai wrote: > > On Jan 21, 2020, at 5:35 AM, Peter Zijlstra wr= ote: > >=20 > > Something like this; except you'll need to go audit archs to make sur= e > > they all call idle_task_exit() and/or put in comments on why they don= 't > > have to (perhaps their bringup switches them to &init_mm unconditiona= lly > > and the switch_mm() is not required). >=20 > Damn, I am having a hard time to motivate myself to learn all about tho= se two =E2=80=9Cdead=E2=80=9C arches from scratch. I suppose the first st= ep we could put a dummy finish_cpu() for alpha and parisc if they don=E2=80= =99t call idle_task_exit() in the first place anyway, so if it is a bug t= here it is another issue that could be dealt with in a separate patch lat= er? Or you could consult the maintainers of those architectures? There are r= egular pull requests for parisc still, and alpha still gets odd fixes. It would have helped had you not trimmed the context so aggressively. For those seeing this thread for the first time, try: https://lore.kernel.org/linux-mm/A72A7F42-A166-4403-B12C-32B2D7A662C4@lca= .pw/T/#t