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 1/3] mm: Add support for kmem caches in DMA32 zone
Date: Mon, 10 Dec 2018 09:15:02 +0800 [thread overview]
Message-ID: <20181210011504.122604-2-drinkcat@chromium.org> (raw)
In-Reply-To: <20181210011504.122604-1-drinkcat@chromium.org>
IOMMUs using ARMv7 short-descriptor format require page tables
to be allocated within the first 4GB of RAM, even on 64-bit systems.
On arm64, this is done by passing GFP_DMA32 flag to memory allocation
functions.
For IOMMU L2 tables that only take 1KB, it would be a waste to allocate
a full page using get_free_pages, so we considered 3 approaches:
1. This patch, 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.
This change makes it possible to create a custom cache in DMA32 zone
using kmem_cache_create, then allocate memory using kmem_cache_alloc.
We do not create a DMA32 kmalloc cache array, as there are currently
no users of kmalloc(..., GFP_DMA32). These calls will continue to
trigger a warning, as we keep GFP_DMA32 in GFP_SLAB_BUG_MASK.
This implies that calls to kmem_cache_*alloc on a SLAB_CACHE_DMA32
kmem_cache must _not_ use GFP_DMA32 (it is anyway redundant and
unnecessary).
Cc: stable@vger.kernel.org
Signed-off-by: Nicolas Boichat <drinkcat@chromium.org>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
---
Changes since v2:
- Clarified commit message
- Add entry in sysfs-kernel-slab to document the new sysfs file
(v3 used the page_frag approach)
Changes since v4:
- Added details to commit message
- 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 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 3/3, so that maintainer can decide whether
to pick the change independently.
(no change since v5)
include/linux/slab.h | 2 ++
mm/slab.c | 2 ++
mm/slab.h | 3 ++-
mm/slab_common.c | 2 +-
mm/slub.c | 5 +++++
5 files changed, 12 insertions(+), 2 deletions(-)
diff --git a/include/linux/slab.h b/include/linux/slab.h
index 11b45f7ae4057c..9449b19c5f107a 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -32,6 +32,8 @@
#define SLAB_HWCACHE_ALIGN ((slab_flags_t __force)0x00002000U)
/* Use GFP_DMA memory */
#define SLAB_CACHE_DMA ((slab_flags_t __force)0x00004000U)
+/* Use GFP_DMA32 memory */
+#define SLAB_CACHE_DMA32 ((slab_flags_t __force)0x00008000U)
/* DEBUG: Store the last owner for bug hunting */
#define SLAB_STORE_USER ((slab_flags_t __force)0x00010000U)
/* Panic if kmem_cache_create() fails */
diff --git a/mm/slab.c b/mm/slab.c
index 73fe23e649c91a..124f8c556d27fb 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2109,6 +2109,8 @@ int __kmem_cache_create(struct kmem_cache *cachep, slab_flags_t flags)
cachep->allocflags = __GFP_COMP;
if (flags & SLAB_CACHE_DMA)
cachep->allocflags |= GFP_DMA;
+ if (flags & SLAB_CACHE_DMA32)
+ cachep->allocflags |= GFP_DMA32;
if (flags & SLAB_RECLAIM_ACCOUNT)
cachep->allocflags |= __GFP_RECLAIMABLE;
cachep->size = size;
diff --git a/mm/slab.h b/mm/slab.h
index 4190c24ef0e9df..fcf717e12f0a86 100644
--- a/mm/slab.h
+++ b/mm/slab.h
@@ -127,7 +127,8 @@ static inline slab_flags_t kmem_cache_flags(unsigned int object_size,
/* Legal flag mask for kmem_cache_create(), for various configurations */
-#define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | SLAB_PANIC | \
+#define SLAB_CORE_FLAGS (SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA | \
+ SLAB_CACHE_DMA32 | SLAB_PANIC | \
SLAB_TYPESAFE_BY_RCU | SLAB_DEBUG_OBJECTS )
#if defined(CONFIG_DEBUG_SLAB)
diff --git a/mm/slab_common.c b/mm/slab_common.c
index 70b0cc85db67f8..18b7b809c8d064 100644
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -53,7 +53,7 @@ static DECLARE_WORK(slab_caches_to_rcu_destroy_work,
SLAB_FAILSLAB | SLAB_KASAN)
#define SLAB_MERGE_SAME (SLAB_RECLAIM_ACCOUNT | SLAB_CACHE_DMA | \
- SLAB_ACCOUNT)
+ SLAB_CACHE_DMA32 | SLAB_ACCOUNT)
/*
* Merge control. If this is set then no merging of slab caches will occur.
diff --git a/mm/slub.c b/mm/slub.c
index c229a9b7dd5448..4caadb926838ef 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -3583,6 +3583,9 @@ static int calculate_sizes(struct kmem_cache *s, int forced_order)
if (s->flags & SLAB_CACHE_DMA)
s->allocflags |= GFP_DMA;
+ if (s->flags & SLAB_CACHE_DMA32)
+ s->allocflags |= GFP_DMA32;
+
if (s->flags & SLAB_RECLAIM_ACCOUNT)
s->allocflags |= __GFP_RECLAIMABLE;
@@ -5671,6 +5674,8 @@ static char *create_unique_id(struct kmem_cache *s)
*/
if (s->flags & SLAB_CACHE_DMA)
*p++ = 'd';
+ if (s->flags & SLAB_CACHE_DMA32)
+ *p++ = 'D';
if (s->flags & SLAB_RECLAIM_ACCOUNT)
*p++ = 'a';
if (s->flags & SLAB_CONSISTENCY_CHECKS)
--
2.20.0.rc2.403.gdbc3b29805-goog
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next prev parent reply other threads:[~2018-12-10 1:16 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-12-10 1:15 [PATCH v6 0/3] iommu/io-pgtable-arm-v7s: Use DMA32 zone for page tables Nicolas Boichat
2018-12-10 1:15 ` Nicolas Boichat [this message]
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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