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=-3.6 required=3.0 tests=BAYES_00,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 2ED9CC433E0 for ; Tue, 5 Jan 2021 14:26:57 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A759A2065C for ; Tue, 5 Jan 2021 14:26:56 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A759A2065C 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 238B68D0080; Tue, 5 Jan 2021 09:26:56 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1C0718D006E; Tue, 5 Jan 2021 09:26:56 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 039AB8D0080; Tue, 5 Jan 2021 09:26:55 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0168.hostedemail.com [216.40.44.168]) by kanga.kvack.org (Postfix) with ESMTP id DC9458D006E for ; Tue, 5 Jan 2021 09:26:55 -0500 (EST) Received: from smtpin23.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id A3C641EF3 for ; Tue, 5 Jan 2021 14:26:55 +0000 (UTC) X-FDA: 77671947990.23.view17_4c1722b274d9 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin23.hostedemail.com (Postfix) with ESMTP id 818C137606 for ; Tue, 5 Jan 2021 14:26:55 +0000 (UTC) X-HE-Tag: view17_4c1722b274d9 X-Filterd-Recvd-Size: 3456 Received: from merlin.infradead.org (merlin.infradead.org [205.233.59.134]) by imf48.hostedemail.com (Postfix) with ESMTP for ; Tue, 5 Jan 2021 14:26:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=WPt4GbgvCJj/QsPuZwFr/Sd2QDQgrOU3f9zQkLRLZCE=; b=VshOaC0GH4R/GHWLsOrEaR8b2K f1iVB2FdwmZspXhWCtXhYE0GQ+yD/lw0u3Gu3dCbCNz13IM4rb22OcMQwgeEUHxl59jRWfCCWdTLf SG8aDNnaltBNlBEXR/znh11f4cffx+/uqrDDigCA60AwXTif2IMu9dTSIxq/oUf1nXwXXoUI5N0zU WdXCQt6Z4Bl4Z8tlEQutzgQtBVXUgAUjNEPmQoXV3NO0bmwTyDvSS6l4ynZk1xvwrkVkdKU/bK5mg 6vqcdVrvcdmg+ulkaE5YZq7M5aACoMBNmaz0qBh27/+cI/0oEu5UOwR8sW0yodinZPb3sqVCFQLcC WtDxcDsA==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kwnIR-0000DE-BP; Tue, 05 Jan 2021 14:26:51 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id B3A4730377D; Tue, 5 Jan 2021 15:26:48 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 9EE9621210122; Tue, 5 Jan 2021 15:26:48 +0100 (CET) Date: Tue, 5 Jan 2021 15:26:48 +0100 From: Peter Zijlstra To: Nadav Amit Cc: Andrea Arcangeli , linux-mm , lkml , Yu Zhao , Andy Lutomirski , Peter Xu , Pavel Emelyanov , Mike Kravetz , Mike Rapoport , Minchan Kim , Will Deacon , Mel Gorman Subject: Re: [RFC PATCH v2 1/2] mm/userfaultfd: fix memory corruption due to writeprotect Message-ID: <20210105142648.GJ3040@hirez.programming.kicks-ass.net> References: <20201225092529.3228466-1-namit@vmware.com> <20201225092529.3228466-2-namit@vmware.com> <20210104122227.GL3021@hirez.programming.kicks-ass.net> <20210105081325.GD3040@hirez.programming.kicks-ass.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: 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 Tue, Jan 05, 2021 at 12:52:48AM -0800, Nadav Amit wrote: > > On Jan 5, 2021, at 12:13 AM, Peter Zijlstra wrote: > > > > On Mon, Jan 04, 2021 at 02:24:38PM -0500, Andrea Arcangeli wrote: > >> The problematic one not pictured is the one of the wrprotect that has > >> to be running in another CPU which is also isn't picture above. More > >> accurate traces are posted later in the thread. > > > > What thread? I don't seem to have discovered it yet, and the cover > > letter from Nadav doesn't seem to have a msgid linking it either. > > Sorry for that: > > https://lore.kernel.org/lkml/X+K7JMrTEC9SpVIB@google.com/T/ Much reading later.. OK, go with the write-lock for now.