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=-8.1 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=unavailable 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 E7648ECDE46 for ; Fri, 26 Oct 2018 09:32:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AE51B2082D for ; Fri, 26 Oct 2018 09:32:01 +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="JBVbhtkX" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AE51B2082D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727250AbeJZSIU (ORCPT ); Fri, 26 Oct 2018 14:08:20 -0400 Received: from merlin.infradead.org ([205.233.59.134]:60898 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726128AbeJZSIU (ORCPT ); Fri, 26 Oct 2018 14:08:20 -0400 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: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=Flwloc/RXwyekTLnRQWtL8hKTHk4sO/+tf4eemj4N/8=; b=JBVbhtkXD4liY1/FC72eP/K8Y qdxheF3aUiRM/BaZiS+pD2ZCLuoxiAPhUjDBK7qBE/JgnmBwt/pQqctpanIF7qVcarV9AMmCoGpHt 0zGcsg/o6Lwf8SwQTfyphP6dkSTgdXEO/+GAZigeCB1VLK91Lb8XglxkA8RrmNTraU9scmO6rUSuM 0YXHimbrxH+OGxkUWVo933P4Ph+FAxk6uCmI0cK9mKeoolEkWYidrvEJiD3Up0GFFWyVxrtL0/UYG cuiLMCAfVEQ5DyXZ5m9wRmpC5TpEUTxuwBsesjJzj9wYaaft4itIvI/zM6jixa25fuK49XnEyLphW OJxb6+UYw==; Received: from [167.98.65.38] (helo=worktop) by merlin.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gFySm-00017Q-IQ; Fri, 26 Oct 2018 09:31:28 +0000 Received: by worktop (Postfix, from userid 1000) id A334F6E07BE; Fri, 26 Oct 2018 11:31:26 +0200 (CEST) Date: Fri, 26 Oct 2018 11:31:26 +0200 From: Peter Zijlstra To: Igor Stoppa Cc: Mimi Zohar , Kees Cook , Matthew Wilcox , Dave Chinner , James Morris , Michal Hocko , kernel-hardening@lists.openwall.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, igor.stoppa@huawei.com, Dave Hansen , Jonathan Corbet , Laura Abbott , Greg Kroah-Hartman , Andrew Morton , Masahiro Yamada , Alexey Dobriyan , Pekka Enberg , "Paul E. McKenney" , Lihao Liang , linux-kernel@vger.kernel.org Subject: Re: [PATCH 12/17] prmem: linked list: set alignment Message-ID: <20181026093126.GC3159@worktop.c.hoisthospitality.com> References: <20181023213504.28905-1-igor.stoppa@huawei.com> <20181023213504.28905-13-igor.stoppa@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181023213504.28905-13-igor.stoppa@huawei.com> User-Agent: Mutt/1.5.22.1 (2013-10-16) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Oct 24, 2018 at 12:34:59AM +0300, Igor Stoppa wrote: > As preparation to using write rare on the nodes of various types of > lists, specify that the fields in the basic data structures must be > aligned to sizeof(void *) > > It is meant to ensure that any static allocation will not cross a page > boundary, to allow pointers to be updated in one step. > > Signed-off-by: Igor Stoppa > CC: Greg Kroah-Hartman > CC: Andrew Morton > CC: Masahiro Yamada > CC: Alexey Dobriyan > CC: Pekka Enberg > CC: "Paul E. McKenney" > CC: Lihao Liang > CC: linux-kernel@vger.kernel.org > --- > include/linux/types.h | 20 ++++++++++++++++---- > 1 file changed, 16 insertions(+), 4 deletions(-) > > diff --git a/include/linux/types.h b/include/linux/types.h > index 9834e90aa010..53609bbdcf0f 100644 > --- a/include/linux/types.h > +++ b/include/linux/types.h > @@ -183,17 +183,29 @@ typedef struct { > } atomic64_t; > #endif > > +#ifdef CONFIG_PRMEM > struct list_head { > - struct list_head *next, *prev; > -}; > + struct list_head *next __aligned(sizeof(void *)); > + struct list_head *prev __aligned(sizeof(void *)); > +} __aligned(sizeof(void *)); > > -struct hlist_head { > - struct hlist_node *first; > +struct hlist_node { > + struct hlist_node *next __aligned(sizeof(void *)); > + struct hlist_node **pprev __aligned(sizeof(void *)); > +} __aligned(sizeof(void *)); Argh.. are we really supporting platforms that do not naturally align this? If so, which and can't we fix those? Also, if you force alignment on a member, the structure as a whole inherits the largest member alignment. Also, you made something that was simple an unreadable mess without proper justification (ie. you fail to show need).