Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762514Ab3JQTNk (ORCPT ); Thu, 17 Oct 2013 15:13:40 -0400 Received: from a9-42.smtp-out.amazonses.com ([54.240.9.42]:55627 "EHLO a9-42.smtp-out.amazonses.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1762224Ab3JQTNj (ORCPT ); Thu, 17 Oct 2013 15:13:39 -0400 Date: Thu, 17 Oct 2013 19:13:38 +0000 From: Christoph Lameter X-X-Sender: cl@gentwo.org To: Joonsoo Kim cc: Pekka Enberg , Andrew Morton , Joonsoo Kim , David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Wanpeng Li Subject: Re: [PATCH v2 13/15] slab: use struct page for slab management In-Reply-To: <1381913052-23875-14-git-send-email-iamjoonsoo.kim@lge.com> Message-ID: <00000141c7d66282-aa92b1f2-2a69-424b-9498-8e5367304d32-000000@email.amazonses.com> References: <1381913052-23875-1-git-send-email-iamjoonsoo.kim@lge.com> <1381913052-23875-14-git-send-email-iamjoonsoo.kim@lge.com> User-Agent: Alpine 2.02 (DEB 1266 2009-07-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII X-SES-Outgoing: 2013.10.17-54.240.9.42 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 920 Lines: 25 On Wed, 16 Oct 2013, Joonsoo Kim wrote: > - * see PAGE_MAPPING_ANON below. > - */ > + union { > + struct address_space *mapping; /* If low bit clear, points to > + * inode address_space, or NULL. > + * If page mapped as anonymous > + * memory, low bit is set, and > + * it points to anon_vma object: > + * see PAGE_MAPPING_ANON below. > + */ > + void *s_mem; /* slab first object */ > + }; The overloading of mapping has caused problems in the past since slab pages are (or are they no longer?) used for DMA to disk. At that point the I/O subsystem may be expecting a mapping in the page struct if this field is not NULL. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/