From patchwork Tue May 11 01:03:15 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Andrew Morton X-Patchwork-Id: 434827 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=-15.8 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, URIBL_BLOCKED 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 A0015C433ED for ; Tue, 11 May 2021 01:03:18 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 717AE6161C for ; Tue, 11 May 2021 01:03:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229920AbhEKBEW (ORCPT ); Mon, 10 May 2021 21:04:22 -0400 Received: from mail.kernel.org ([198.145.29.99]:37934 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229628AbhEKBEW (ORCPT ); Mon, 10 May 2021 21:04:22 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id DF03E61613; Tue, 11 May 2021 01:03:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1620694996; bh=6xyZ0PXSGA7w0A/O8UPA3RjDuRJjvBCSsAsCqruje1c=; h=Date:From:To:Subject:From; b=Nea1O16jfKK9ZVSP7qnZTIg8LB8oD/QOOFnKhckHGd2RJTxlY1+uVU2HLGc/UjUTn f5yr+ErnJNHM2J49V/CfkGZKtGUDeusFIMM5Sa3VgsGagVxryHSquDzrKS+r4/88ZR jsSPkJTMl1gyAD80LPzP3BQjt8/tQrLDCbAXg4wg= Date: Mon, 10 May 2021 18:03:15 -0700 From: akpm@linux-foundation.org To: brouer@redhat.com, ilias.apalodimas@linaro.org, mcroce@linux.microsoft.com, mm-commits@vger.kernel.org, stable@vger.kernel.org, vbabka@suse.cz, willy@infradead.org Subject: + mm-fix-struct-page-layout-on-32-bit-systems.patch added to -mm tree Message-ID: <20210511010315.6rVNNKQr3%akpm@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch titled Subject: mm: fix struct page layout on 32-bit systems has been added to the -mm tree. Its filename is mm-fix-struct-page-layout-on-32-bit-systems.patch This patch should soon appear at https://ozlabs.org/~akpm/mmots/broken-out/mm-fix-struct-page-layout-on-32-bit-systems.patch and later at https://ozlabs.org/~akpm/mmotm/broken-out/mm-fix-struct-page-layout-on-32-bit-systems.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/process/submit-checklist.rst when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: "Matthew Wilcox (Oracle)" Subject: mm: fix struct page layout on 32-bit systems 32-bit architectures which expect 8-byte alignment for 8-byte integers and need 64-bit DMA addresses (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. We always store the low bits in the first word to prevent the PageTail bit from being inadvertently set on a big endian platform. If that happened, get_user_pages_fast() racing against a page which was freed and reallocated to the page_pool could dereference a bogus compound_head(), which would be hard to trace back to this cause. Link: https://lkml.kernel.org/r/20210510153211.1504886-1-willy@infradead.org Fixes: c25fff7171be ("mm: add dma_addr_t to struct page") Signed-off-by: Matthew Wilcox (Oracle) Acked-by: Ilias Apalodimas Acked-by: Jesper Dangaard Brouer Acked-by: Vlastimil Babka Tested-by: Matteo Croce Cc: Signed-off-by: Andrew Morton --- 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(-) --- a/include/linux/mm_types.h~mm-fix-struct-page-layout-on-32-bit-systems +++ a/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 { --- a/include/net/page_pool.h~mm-fix-struct-page-layout-on-32-bit-systems +++ a/include/net/page_pool.h @@ -198,7 +198,17 @@ static inline void page_pool_recycle_dir 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] << 16 << 16; + 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] = upper_32_bits(addr); } static inline bool is_page_pool_compiled_in(void) --- a/net/core/page_pool.c~mm-fix-struct-page-layout-on-32-bit-systems +++ a/net/core/page_pool.c @@ -174,8 +174,10 @@ static void page_pool_dma_sync_for_devic 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); } @@ -195,7 +197,7 @@ static bool page_pool_dma_map(struct pag if (dma_mapping_error(pool->p.dev, dma)) return false; - 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); @@ -331,13 +333,13 @@ void page_pool_release_page(struct 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.