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=-8.6 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 089F9C433ED for ; Fri, 14 May 2021 01:01:34 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 605F560D07 for ; Fri, 14 May 2021 01:01:33 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 605F560D07 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 9F38C6B0036; Thu, 13 May 2021 21:01:32 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9A3B76B006E; Thu, 13 May 2021 21:01:32 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7F6456B0070; Thu, 13 May 2021 21:01:32 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0087.hostedemail.com [216.40.44.87]) by kanga.kvack.org (Postfix) with ESMTP id 4D4466B0036 for ; Thu, 13 May 2021 21:01:32 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id E3C52181D861F for ; Fri, 14 May 2021 01:01:31 +0000 (UTC) X-FDA: 78138033582.21.E8BAE23 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf11.hostedemail.com (Postfix) with ESMTP id 074602000248 for ; Fri, 14 May 2021 01:01:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.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; bh=AewoeCdKzupjrAmmf0ZaCNC8yUlU7sjr3AelIO0F/XM=; b=aeMzHZzq2PEe+UoOqIrdKwzBHp SpD13pChgGsdAlUV5up3rlgtz61ceBqKB4YVlPxrnpfIlr7qixm35r1pzxJdKP5QLSEv8lpn96D0y XzkuZ5dWtc2OwZ5MLmRA63ZiRfVsiuzDjvNofa4ETRslxO8M2Jiy0ABimf/OQBBIBKNe6+XoAKHKm jnu6IBehlAN86e5u5i1YiDGMdh6HbEFpXvmqZfg0uWWZ0RgIYELAbrImjCvmT3Mj3MNXddpgvVD4Q wk2S0O02ZQlAvoJJaMqZAfsaJd5UMN1xmGhYemsBXOmYPilm+wJEFjNiGZw6xjlSivEfoga3pOTMt bF+rEfzQ==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lhMBp-009wQq-20; Fri, 14 May 2021 01:00:50 +0000 Date: Fri, 14 May 2021 02:00:29 +0100 From: Matthew Wilcox To: Matteo Croce Cc: netdev@vger.kernel.org, linux-mm@kvack.org, Ayush Sawal , Vinay Kumar Yadav , Rohit Maheshwari , "David S. Miller" , Jakub Kicinski , Thomas Petazzoni , Marcin Wojtas , Russell King , Mirko Lindner , Stephen Hemminger , Tariq Toukan , Jesper Dangaard Brouer , Ilias Apalodimas , Alexei Starovoitov , Daniel Borkmann , John Fastabend , Boris Pismenny , Arnd Bergmann , Andrew Morton , "Peter Zijlstra (Intel)" , Vlastimil Babka , Yu Zhao , Will Deacon , Fenghua Yu , Roman Gushchin , Hugh Dickins , Peter Xu , Jason Gunthorpe , Jonathan Lemon , Alexander Lobakin , Cong Wang , wenxu , Kevin Hao , Jakub Sitnicki , Marco Elver , Willem de Bruijn , Miaohe Lin , Yunsheng Lin , Guillaume Nault , linux-kernel@vger.kernel.org, linux-rdma@vger.kernel.org, bpf@vger.kernel.org, Eric Dumazet , David Ahern , Lorenzo Bianconi , Saeed Mahameed , Andrew Lunn , Paolo Abeni , Sven Auhagen Subject: Re: [PATCH net-next v5 1/5] mm: add a signature in struct page Message-ID: References: <20210513165846.23722-1-mcroce@linux.microsoft.com> <20210513165846.23722-2-mcroce@linux.microsoft.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210513165846.23722-2-mcroce@linux.microsoft.com> X-Rspamd-Queue-Id: 074602000248 Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=infradead.org header.s=casper.20170209 header.b=aeMzHZzq; dmarc=none; spf=none (imf11.hostedemail.com: domain of willy@infradead.org has no SPF policy when checking 90.155.50.34) smtp.mailfrom=willy@infradead.org X-Rspamd-Server: rspam03 X-Stat-Signature: pu6hrxh969fhp1kizqrszy3qyy8p9wjs X-HE-Tag: 1620954089-432318 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, May 13, 2021 at 06:58:42PM +0200, Matteo Croce wrote: > struct { /* page_pool used by netstack */ > + /** > + * @pp_magic: magic value to avoid recycling non > + * page_pool allocated pages. > + * It aliases with page->lru.next I'm not really keen on documenting what aliases with what. pp_magic also aliases with compound_head, 'next' (for slab), and dev_pagemap. This is an O(n^2) documentation problem ... I feel like I want to document the pfmemalloc bit in mm_types.h, but I don't have a concrete suggestion yet. > +++ b/include/net/page_pool.h > @@ -63,6 +63,8 @@ > */ > #define PP_ALLOC_CACHE_SIZE 128 > #define PP_ALLOC_CACHE_REFILL 64 > +#define PP_SIGNATURE (POISON_POINTER_DELTA + 0x40) I wonder if this wouldn't be better in linux/poison.h?