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=-5.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_MUTT autolearn=ham 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 959E1C43387 for ; Fri, 11 Jan 2019 23:17:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 508B321783 for ; Fri, 11 Jan 2019 23:17:03 +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="PNKxCRqE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726282AbfAKXRC (ORCPT ); Fri, 11 Jan 2019 18:17:02 -0500 Received: from bombadil.infradead.org ([198.137.202.133]:36426 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725794AbfAKXRC (ORCPT ); Fri, 11 Jan 2019 18:17:02 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.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: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=CqUrK5dNQEzXqROC1W6wTAlH6VB8x27DzSSJz0NWLaA=; b=PNKxCRqE8uKre6yZ5mT4/I1c1 bvKOeLTqnmOUbxaqEWvawGxK3QjgzVohm/VDasY1WtbMMgLj3/Nvd6lSlAymxjGrEIalUj6zuWea4 fpETwvZWV9x+Dtyj0Ke8EOjKofcI3Z8BeJxiNSexYAZ36xpVw8glRbxLm4N1zlfmSP0cVDARTb0jz aHVp3rV0GbRSXLBULKV0xXJWAb5cDfKYODa/eVJRYZd+PcR7F0QrlXgiWbdliZx8qUthYIBXLArB6 yqlB6yIRZZwiXZawAe8Yj99xfqn0xnu+tN6go4xBdxBZZs12NfsXPdATPOIb4jg2HHnxk/RzsY2WV TziJUY5dA==; Received: from willy by bombadil.infradead.org with local (Exim 4.90_1 #2 (Red Hat Linux)) id 1gi62m-000375-Cm; Fri, 11 Jan 2019 23:16:52 +0000 Date: Fri, 11 Jan 2019 15:16:52 -0800 From: Matthew Wilcox To: Qian Cai Cc: akpm@linux-foundation.org, esploit@protonmail.ch, jejb@linux.ibm.com, dgilbert@interlog.com, martin.petersen@oracle.com, joeypabalinas@gmail.com, walken@google.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] rbtree: fix the red root Message-ID: <20190111231652.GN6310@bombadil.infradead.org> References: <20190111181600.GJ6310@bombadil.infradead.org> <20190111205843.25761-1-cai@lca.pw> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190111205843.25761-1-cai@lca.pw> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 11, 2019 at 03:58:43PM -0500, Qian Cai wrote: > diff --git a/lib/rbtree_test.c b/lib/rbtree_test.c > index b7055b2a07d3..afad0213a117 100644 > --- a/lib/rbtree_test.c > +++ b/lib/rbtree_test.c > @@ -345,6 +345,17 @@ static int __init rbtree_test_init(void) > check(0); > } > > + /* > + * a little regression test to catch a bug may be introduced by > + * 6d58452dc06 (rbtree: adjust root color in rb_insert_color() only when > + * necessary) > + */ > + insert(nodes, &root); > + nodes->rb.__rb_parent_color = RB_RED; > + insert(nodes + 1, &root); > + erase(nodes + 1, &root); > + erase(nodes, &root); That's not a fair test! You're poking around in the data structure to create the situation. This test would have failed before 6d58452dc06 too. How do we create a tree that has a red parent at root, only using insert() and erase()?