From patchwork Fri Apr 16 23:07:23 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthew Wilcox X-Patchwork-Id: 12209279 X-Patchwork-Delegate: kuba@kernel.org 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=-18.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED, USER_AGENT_GIT autolearn=unavailable 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 D1123C43470 for ; Fri, 16 Apr 2021 23:07:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AB1346137D for ; Fri, 16 Apr 2021 23:07:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234712AbhDPXIT (ORCPT ); Fri, 16 Apr 2021 19:08:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45750 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234856AbhDPXIR (ORCPT ); Fri, 16 Apr 2021 19:08:17 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1ED92C061574; Fri, 16 Apr 2021 16:07:52 -0700 (PDT) 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=tfA9/CMMjzVJbfa5k3nU3g5wOaQhTGv4Y2DdGMdqE7Q=; b=sTOSCTMeSHNrr2R6hLTjOnMirn /l111sXXa+hkgheaR3XHlrEYp9dRyu1Hx8aLdl7v/0IpOQHkQIeiAwc7DnALGgsfq1OfrOHRpSTWO SYlZOacvnN9dQNE9YhagejFjJKq3xQKyWtSOPbovu7laaFnuJSs6yA3l8k88k+5LfIDyBsGCKy7um vF5omj4LN2RyRJXB6KRFFzh/OdYT/oj1ZLEfFu9KqMqY1JcBqzP8ZhrETltLNmZvDtTz/WlHs3SMZ 6KuL/e0wM16OjO/w9S7tttTFE1ATb7HFLwJ8ZeoYI0HagCJy/8znvaOXSqeZQgTAoUqdG6HDHOzRs 28cEctHw==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lXXYg-00AZOD-UA; Fri, 16 Apr 2021 23:07:32 +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 1/2] mm: Fix struct page layout on 32-bit systems Date: Sat, 17 Apr 2021 00:07:23 +0100 Message-Id: <20210416230724.2519198-2-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 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org X-Patchwork-Delegate: kuba@kernel.org 32-bit architectures which expect 8-byte alignment for 8-byte integers and need 64-bit DMA addresses (arc, arm, mips, ppc) had their struct page inadvertently expanded in 2019. When the dma_addr_t was added, it forced the alignment of the union to 8 bytes, which inserted a 4 byte gap between 'flags' and the union. Fix this by storing the dma_addr_t in one or two adjacent unsigned longs. This restores the alignment to that of an unsigned long, and also fixes a potential problem where (on a big endian platform), the bit used to denote PageTail could inadvertently get set, and a racing get_user_pages_fast() could dereference a bogus compound_head(). Fixes: c25fff7171be ("mm: add dma_addr_t to struct page") Signed-off-by: Matthew Wilcox (Oracle) Reported-by: kernel test robot Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Jesper Dangaard Brouer Acked-by: Ilias Apalodimas --- include/linux/mm_types.h | 4 ++-- include/net/page_pool.h | 12 +++++++++++- net/core/page_pool.c | 12 +++++++----- 3 files changed, 20 insertions(+), 8 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 6613b26a8894..5aacc1c10a45 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -97,10 +97,10 @@ struct page { }; struct { /* page_pool used by netstack */ /** - * @dma_addr: might require a 64-bit value even on + * @dma_addr: might require a 64-bit value on * 32-bit architectures. */ - dma_addr_t dma_addr; + unsigned long dma_addr[2]; }; struct { /* slab, slob and slub */ union { diff --git a/include/net/page_pool.h b/include/net/page_pool.h index b5b195305346..db7c7020746a 100644 --- a/include/net/page_pool.h +++ b/include/net/page_pool.h @@ -198,7 +198,17 @@ static inline void page_pool_recycle_direct(struct page_pool *pool, static inline dma_addr_t page_pool_get_dma_addr(struct page *page) { - return page->dma_addr; + dma_addr_t ret = page->dma_addr[0]; + if (sizeof(dma_addr_t) > sizeof(unsigned long)) + ret |= (dma_addr_t)page->dma_addr[1] << 32; + return ret; +} + +static inline void page_pool_set_dma_addr(struct page *page, dma_addr_t addr) +{ + page->dma_addr[0] = addr; + if (sizeof(dma_addr_t) > sizeof(unsigned long)) + page->dma_addr[1] = addr >> 32; } static inline bool is_page_pool_compiled_in(void) diff --git a/net/core/page_pool.c b/net/core/page_pool.c index ad8b0707af04..f014fd8c19a6 100644 --- a/net/core/page_pool.c +++ b/net/core/page_pool.c @@ -174,8 +174,10 @@ static void page_pool_dma_sync_for_device(struct page_pool *pool, struct page *page, unsigned int dma_sync_size) { + dma_addr_t dma_addr = page_pool_get_dma_addr(page); + dma_sync_size = min(dma_sync_size, pool->p.max_len); - dma_sync_single_range_for_device(pool->p.dev, page->dma_addr, + dma_sync_single_range_for_device(pool->p.dev, dma_addr, pool->p.offset, dma_sync_size, pool->p.dma_dir); } @@ -226,7 +228,7 @@ static struct page *__page_pool_alloc_pages_slow(struct page_pool *pool, put_page(page); return NULL; } - page->dma_addr = dma; + page_pool_set_dma_addr(page, dma); if (pool->p.flags & PP_FLAG_DMA_SYNC_DEV) page_pool_dma_sync_for_device(pool, page, pool->p.max_len); @@ -294,13 +296,13 @@ void page_pool_release_page(struct page_pool *pool, struct page *page) */ goto skip_dma_unmap; - dma = page->dma_addr; + dma = page_pool_get_dma_addr(page); - /* When page is unmapped, it cannot be returned our pool */ + /* When page is unmapped, it cannot be returned to our pool */ dma_unmap_page_attrs(pool->p.dev, dma, PAGE_SIZE << pool->p.order, pool->p.dma_dir, DMA_ATTR_SKIP_CPU_SYNC); - page->dma_addr = 0; + page_pool_set_dma_addr(page, 0); skip_dma_unmap: /* This may be the last page returned, releasing the pool, so * it is not safe to reference pool afterwards. 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: 12209281 X-Patchwork-Delegate: kuba@kernel.org 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=-18.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 E0833C433B4 for ; Fri, 16 Apr 2021 23:08:30 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C2664610CC for ; Fri, 16 Apr 2021 23:08:30 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229719AbhDPXIz (ORCPT ); Fri, 16 Apr 2021 19:08:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45892 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233979AbhDPXIw (ORCPT ); Fri, 16 Apr 2021 19:08:52 -0400 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 28BE1C061574; Fri, 16 Apr 2021 16:08:26 -0700 (PDT) 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 Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org 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 */