From patchwork Fri Apr 16 23:07:24 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 12209275 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=-16.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 05885C433B4 for ; Fri, 16 Apr 2021 23:08:28 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 8F58A610E7 for ; Fri, 16 Apr 2021 23:08:27 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 8F58A610E7 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 DEC9C6B0070; Fri, 16 Apr 2021 19:08:26 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DC2AB6B0071; Fri, 16 Apr 2021 19:08:26 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id C8ADD6B0072; Fri, 16 Apr 2021 19:08:26 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0119.hostedemail.com [216.40.44.119]) by kanga.kvack.org (Postfix) with ESMTP id AE1326B0070 for ; Fri, 16 Apr 2021 19:08:26 -0400 (EDT) Received: from smtpin10.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay03.hostedemail.com (Postfix) with ESMTP id 62BAE824805A for ; Fri, 16 Apr 2021 23:08:26 +0000 (UTC) X-FDA: 78039771012.10.C7F3FC9 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf11.hostedemail.com (Postfix) with ESMTP id 47D142000254 for ; Fri, 16 Apr 2021 23:08:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:MIME-Version: References:In-Reply-To:Message-Id:Date:Subject:Cc:To:From:Sender:Reply-To: Content-Type:Content-ID:Content-Description; bh=7RQQOKlZfptY8lQfv4l5MN8bW99nIhpZAUjYQWKjbHY=; b=YmfVnEk3XiuEP8jmPep/KMKTCm FCer4kctEbk/+GNHuBZ8YFNrdKU44xlcl41J+bNFEc53pi74cE5/BLRbsjHC4f8PKiEVIVwlUAR7t Z55+HNT/99N2xVNKwp+BxJDdxbFavbZStT6ml+LiqeSScnyJEGjUY1qv3vZy9XpWik8pDr0R3u9mr YZpRlXaZY6zK/e2aevHlOS8hCwxYF9T5hfqXwKOxLAXe4vi1AER+8AHlbktawk4qufHp5LqztQe62 fJGCts2hlsjYoXQcLvgSA+p/Z2uMF0IYb8xmYDmqAjunEiQdpXqkeM7qmy56jDoYHdcHnWv1GagYl bqoyQWlQ==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lXXYn-00AZOP-Kg; Fri, 16 Apr 2021 23:07:43 +0000 From: "Matthew Wilcox (Oracle)" To: brouer@redhat.com Cc: "Matthew Wilcox (Oracle)" , linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-arm-kernel@lists.infradead.org, linux-mips@vger.kernel.org, ilias.apalodimas@linaro.org, mcroce@linux.microsoft.com, grygorii.strashko@ti.com, arnd@kernel.org, hch@lst.de, linux-snps-arc@lists.infradead.org, mhocko@kernel.org, mgorman@suse.de Subject: [PATCH 2/2] mm: Indicate pfmemalloc pages in compound_head Date: Sat, 17 Apr 2021 00:07:24 +0100 Message-Id: <20210416230724.2519198-3-willy@infradead.org> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20210416230724.2519198-1-willy@infradead.org> References: <20210416230724.2519198-1-willy@infradead.org> MIME-Version: 1.0 X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 47D142000254 X-Stat-Signature: pm4xt86jyka3xn336443wej5pz8sfyr4 Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf11; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1618614495-953705 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: The net page_pool wants to use a magic value to identify page pool pages. The best place to put it is in the first word where it can be clearly a non-pointer value. That means shifting dma_addr up to alias with ->index, which means we need to find another way to indicate page_is_pfmemalloc(). Since page_pool doesn't want to set its magic value on pages which are pfmemalloc, we can use bit 1 of compound_head to indicate that the page came from the memory reserves. Signed-off-by: Matthew Wilcox (Oracle) --- include/linux/mm.h | 12 +++++++----- include/linux/mm_types.h | 7 +++---- 2 files changed, 10 insertions(+), 9 deletions(-) diff --git a/include/linux/mm.h b/include/linux/mm.h index 8ba434287387..44eab3f6d5ae 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -1629,10 +1629,12 @@ struct address_space *page_mapping_file(struct page *page); static inline bool page_is_pfmemalloc(const struct page *page) { /* - * Page index cannot be this large so this must be - * a pfmemalloc page. + * This is not a tail page; compound_head of a head page is unused + * at return from the page allocator, and will be overwritten + * by callers who do not care whether the page came from the + * reserves. */ - return page->index == -1UL; + return page->compound_head & 2; } /* @@ -1641,12 +1643,12 @@ static inline bool page_is_pfmemalloc(const struct page *page) */ static inline void set_page_pfmemalloc(struct page *page) { - page->index = -1UL; + page->compound_head = 2; } static inline void clear_page_pfmemalloc(struct page *page) { - page->index = 0; + page->compound_head = 0; } /* diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 5aacc1c10a45..39f7163dcace 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -96,10 +96,9 @@ struct page { unsigned long private; }; struct { /* page_pool used by netstack */ - /** - * @dma_addr: might require a 64-bit value on - * 32-bit architectures. - */ + unsigned long pp_magic; + unsigned long xmi; + unsigned long _pp_mapping_pad; unsigned long dma_addr[2]; }; struct { /* slab, slob and slub */