From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f176.google.com (mail-pd0-f176.google.com [209.85.192.176]) by kanga.kvack.org (Postfix) with ESMTP id 7F05B6B00BC for ; Thu, 17 Oct 2013 15:13:41 -0400 (EDT) Received: by mail-pd0-f176.google.com with SMTP id g10so2609379pdj.35 for ; Thu, 17 Oct 2013 12:13:41 -0700 (PDT) Date: Thu, 17 Oct 2013 19:13:38 +0000 From: Christoph Lameter 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> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Joonsoo Kim Cc: Pekka Enberg , Andrew Morton , Joonsoo Kim , David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Wanpeng Li 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, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org