From: Nicolas Boichat <drinkcat@chromium.org>
To: Will Deacon <will.deacon@arm.com>
Cc: Michal Hocko <mhocko@suse.com>,
Levin Alexander <Alexander.Levin@microsoft.com>,
linux-mm@kvack.org, Christoph Lameter <cl@linux.com>,
Huaisheng Ye <yehs1@lenovo.com>, Joerg Roedel <joro@8bytes.org>,
Matthew Wilcox <willy@infradead.org>,
hch@infradead.org, linux-arm-kernel@lists.infradead.org,
David Rientjes <rientjes@google.com>,
yingjoe.chen@mediatek.com, Vlastimil Babka <vbabka@suse.cz>,
Tomasz Figa <tfiga@google.com>,
Mike Rapoport <rppt@linux.vnet.ibm.com>,
hsinyi@chromium.org, Matthias Brugger <matthias.bgg@gmail.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Yong Wu <yong.wu@mediatek.com>,
Robin Murphy <robin.murphy@arm.com>,
linux-kernel@vger.kernel.org, stable@vger.kernel.org,
Pekka Enberg <penberg@kernel.org>,
iommu@lists.linux-foundation.org,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@techsingularity.net>
Subject: [PATCH v6 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables
Date: Mon, 10 Dec 2018 09:15:01 +0800 [thread overview]
Message-ID: <20181210011504.122604-1-drinkcat@chromium.org> (raw)
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.
stable@ note:
We confirmed that this is a regression, and IOMMU errors happen on 4.19
and linux-next/master on MT8173 (elm, Acer Chromebook R13). The issue
most likely starts from commit ad67f5a6545f ("arm64: replace ZONE_DMA
with ZONE_DMA32"), i.e. 4.15, and presumably breaks a number of Mediatek
platforms (and maybe others?).
[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].
Changes since v4:
- Dropped change that removed GFP_DMA32 from GFP_SLAB_BUG_MASK:
instead we can just call kmem_cache_*alloc without GFP_DMA32
parameter. This also means that we can drop PATCH v4 1/3, as we
do not make any changes in GFP flag verification.
- Dropped hunks that added cache_dma32 sysfs file, and moved
the hunks to PATCH v5 3/3, so that maintainer can decide whether
to pick the change independently.
Changes since v5:
- Rename ARM_V7S_TABLE_SLAB_CACHE to ARM_V7S_TABLE_SLAB_FLAGS.
- Add stable@ to cc.
Nicolas Boichat (3):
mm: Add support for kmem caches in DMA32 zone
iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging
mm: Add /sys/kernel/slab/cache/cache_dma32
Documentation/ABI/testing/sysfs-kernel-slab | 9 +++++++++
drivers/iommu/io-pgtable-arm-v7s.c | 19 +++++++++++++++----
include/linux/slab.h | 2 ++
mm/slab.c | 2 ++
mm/slab.h | 3 ++-
mm/slab_common.c | 2 +-
mm/slub.c | 16 ++++++++++++++++
tools/vm/slabinfo.c | 7 ++++++-
8 files changed, 53 insertions(+), 7 deletions(-)
--
2.20.0.rc2.403.gdbc3b29805-goog
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next reply other threads:[~2018-12-10 1:15 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-10 1:15 Nicolas Boichat [this message]
2018-12-10 1:15 ` [PATCH v6 1/3] mm: Add support for kmem caches in DMA32 zone Nicolas Boichat
2018-12-10 1:15 ` [PATCH v6 2/3] iommu/io-pgtable-arm-v7s: Request DMA32 memory, and improve debugging Nicolas Boichat
2018-12-10 15:35 ` Will Deacon
2019-01-19 23:57 ` Will Deacon
2018-12-10 1:15 ` [PATCH v6 3/3] mm: Add /sys/kernel/slab/cache/cache_dma32 Nicolas Boichat
[not found] ` <CANMq1KAmFKpcxi49wJyfP4N01A80B2d-2RGY2Wrwg0BvaFxAxg@mail.gmail.com>
2019-01-11 10:21 ` [PATCH v6 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables Joerg Roedel
2019-01-22 22:51 ` Nicolas Boichat
2019-02-13 17:12 ` Vlastimil Babka
2019-02-25 0:23 ` Nicolas Boichat
2019-03-19 7:41 ` Nicolas Boichat
2019-03-19 17:56 ` Andrew Morton
2019-03-20 0:20 ` Nicolas Boichat
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