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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 73413C4332F for ; Thu, 29 Sep 2022 11:53:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235459AbiI2Lx2 convert rfc822-to-8bit (ORCPT ); Thu, 29 Sep 2022 07:53:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41610 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235036AbiI2LxZ (ORCPT ); Thu, 29 Sep 2022 07:53:25 -0400 Received: from eu-smtp-delivery-151.mimecast.com (eu-smtp-delivery-151.mimecast.com [185.58.85.151]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BC3A7151B10 for ; Thu, 29 Sep 2022 04:53:23 -0700 (PDT) Received: from AcuMS.aculab.com (156.67.243.121 [156.67.243.121]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_CBC_SHA384) id uk-mta-322-FG1UcietOBqlK6YUwDSrzw-1; Thu, 29 Sep 2022 12:53:20 +0100 X-MC-Unique: FG1UcietOBqlK6YUwDSrzw-1 Received: from AcuMS.Aculab.com (10.202.163.4) by AcuMS.aculab.com (10.202.163.4) with Microsoft SMTP Server (TLS) id 15.0.1497.38; Thu, 29 Sep 2022 12:53:17 +0100 Received: from AcuMS.Aculab.com ([::1]) by AcuMS.aculab.com ([::1]) with mapi id 15.00.1497.040; Thu, 29 Sep 2022 12:53:17 +0100 From: David Laight To: 'Hugh Dickins' , Vlastimil Babka CC: Joel Fernandes , Hyeonggon Yoo <42.hyeyoo@gmail.com>, Matthew Wilcox , Andrew Morton , "linux-kernel@vger.kernel.org" , "linux-mm@kvack.org" Subject: RE: amusing SLUB compaction bug when CC_OPTIMIZE_FOR_SIZE Thread-Topic: amusing SLUB compaction bug when CC_OPTIMIZE_FOR_SIZE Thread-Index: AQHY02LHNvo5HN+EEECxPXiP8YKQXa32TN+Q Date: Thu, 29 Sep 2022 11:53:17 +0000 Message-ID: <9368c760191448bba0e062709cc7c799@AcuMS.aculab.com> References: <35502bdd-1a78-dea1-6ac3-6ff1bcc073fa@suse.cz> In-Reply-To: Accept-Language: en-GB, en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: x-ms-exchange-transport-fromentityheader: Hosted x-originating-ip: [10.202.205.107] MIME-Version: 1.0 X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: aculab.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > -static void rcu_free_slab(struct rcu_head *h) > +/* > + * rcu_free_slab() must be __aligned(4) because its address is saved > + * in the rcu_head field, which coincides with page->mapping, which > + * causes trouble if compaction mistakes it for PAGE_MAPPING_MOVABLE. > + */ > +__aligned(4) static void rcu_free_slab(struct rcu_head *h) > { > struct slab *slab = container_of(h, struct slab, rcu_head); > Isn't that going to cause grief with options that align functions on 16/32byte boundaries when adding space for 'other stuff'? David - Registered Address Lakeside, Bramley Road, Mount Farm, Milton Keynes, MK1 1PT, UK Registration No: 1397386 (Wales)