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Tue, 04 Dec 2018 21:48:46 -0800 (PST) Received: from drinkcat2.tpe.corp.google.com ([2401:fa00:1:b:f659:7f17:ea11:4e8e]) by smtp.gmail.com with ESMTPSA id 4sm30806513pfq.10.2018.12.04.21.48.42 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 04 Dec 2018 21:48:45 -0800 (PST) From: Nicolas Boichat To: Will Deacon Subject: [PATCH v4 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables Date: Wed, 5 Dec 2018 13:48:25 +0800 Message-Id: <20181205054828.183476-1-drinkcat@chromium.org> X-Mailer: git-send-email 2.20.0.rc1.387.gf8505762e3-goog MIME-Version: 1.0 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20181204_214857_047216_2E0DBFF6 X-CRM114-Status: GOOD ( 13.43 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Michal Hocko , Levin Alexander , linux-mm@kvack.org, Christoph Lameter , Huaisheng Ye , Joerg Roedel , Matthew Wilcox , hch@infradead.org, linux-arm-kernel@lists.infradead.org, David Rientjes , yingjoe.chen@mediatek.com, Vlastimil Babka , Tomasz Figa , Mike Rapoport , Matthias Brugger , Joonsoo Kim , Yong Wu , Robin Murphy , linux-kernel@vger.kernel.org, Pekka Enberg , iommu@lists.linux-foundation.org, Andrew Morton , Mel Gorman Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+patchwork-linux-arm=patchwork.kernel.org@lists.infradead.org X-Virus-Scanned: ClamAV using ClamSMTP This is a follow-up to the discussion in [1], [2]. IOMMUs using ARMv7 short-descriptor format require page tables (level 1 and 2) to be allocated within the first 4GB of RAM, even on 64-bit systems. For L1 tables that are bigger than a page, we can just use __get_free_pages with GFP_DMA32 (on arm64 systems only, arm would still use GFP_DMA). For L2 tables that only take 1KB, it would be a waste to allocate a full page, so we considered 3 approaches: 1. This series, adding support for GFP_DMA32 slab caches. 2. genalloc, which requires pre-allocating the maximum number of L2 page tables (4096, so 4MB of memory). 3. page_frag, which is not very memory-efficient as it is unable to reuse freed fragments until the whole page is freed. [3] This series is the most memory-efficient approach. [1] https://lists.linuxfoundation.org/pipermail/iommu/2018-November/030876.html [2] https://lists.linuxfoundation.org/pipermail/iommu/2018-December/031696.html [3] https://patchwork.codeaurora.org/patch/671639/ Changes since v1: - Add support for SLAB_CACHE_DMA32 in slab and slub (patches 1/2) - iommu/io-pgtable-arm-v7s (patch 3): - Changed approach to use SLAB_CACHE_DMA32 added by the previous commit. - Use DMA or DMA32 depending on the architecture (DMA for arm, DMA32 for arm64). Changes since v2: - Reworded and expanded commit messages - Added cache_dma32 documentation in PATCH 2/3. v3 used the page_frag approach, see [3]. Nicolas Boichat (3): mm: slab/slub: Add check_slab_flags function to check for valid flags mm: Add support for kmem caches in DMA32 zone iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging Documentation/ABI/testing/sysfs-kernel-slab | 9 ++++++++ drivers/iommu/io-pgtable-arm-v7s.c | 20 +++++++++++++---- include/linux/slab.h | 2 ++ mm/internal.h | 22 +++++++++++++++++-- mm/slab.c | 10 +++------ mm/slab.h | 3 ++- mm/slab_common.c | 2 +- mm/slub.c | 24 +++++++++++++++------ 8 files changed, 70 insertions(+), 22 deletions(-)