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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,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 4594BC433E0 for ; Tue, 5 Jan 2021 14:27:46 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0C5102065C for ; Tue, 5 Jan 2021 14:27:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727379AbhAEO1p (ORCPT ); Tue, 5 Jan 2021 09:27:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56428 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727005AbhAEO1o (ORCPT ); Tue, 5 Jan 2021 09:27:44 -0500 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 55FC5C061795 for ; Tue, 5 Jan 2021 06:27:04 -0800 (PST) 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: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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.