[PATCH v4 2/3] mm: Add support for kmem caches in DMA32 zone
From: Nicolas Boichat <hidden>
Date: 2018-12-05 05:48:57
Also in:
linux-iommu, linux-mm, lkml
Subsystem:
memory management, memory management - core, slab allocator, the rest · Maintainers:
Andrew Morton, David Hildenbrand, Vlastimil Babka, Harry Yoo, Linus Torvalds
In some cases (e.g. IOMMU ARMv7s page allocator), we need to allocate
data structures smaller than a page with GFP_DMA32 flag.
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). The new test in check_slab_flags
ensures that such calls still fail (as they do before this change).
Fixes: ad67f5a6545f ("arm64: replace ZONE_DMA with ZONE_DMA32")
Signed-off-by: Nicolas Boichat <redacted>
---
Changes since v2:
- Clarified commit message
- Add entry in sysfs-kernel-slab to document the new sysfs file
(v3 used the page_frag approach)
Documentation/ABI/testing/sysfs-kernel-slab | 9 +++++++++
include/linux/slab.h | 2 ++
mm/internal.h | 8 ++++++--
mm/slab.c | 4 +++-
mm/slab.h | 3 ++-
mm/slab_common.c | 2 +-
mm/slub.c | 18 +++++++++++++++++-
7 files changed, 40 insertions(+), 6 deletions(-)
diff --git a/Documentation/ABI/testing/sysfs-kernel-slab b/Documentation/ABI/testing/sysfs-kernel-slab
index 29601d93a1c2ea..d742c6cfdffbe9 100644
--- a/Documentation/ABI/testing/sysfs-kernel-slab
+++ b/Documentation/ABI/testing/sysfs-kernel-slab@@ -106,6 +106,15 @@ Description: are from ZONE_DMA. Available when CONFIG_ZONE_DMA is enabled. +What: /sys/kernel/slab/cache/cache_dma32 +Date: December 2018 +KernelVersion: 4.21 +Contact: Nicolas Boichat <drinkcat@chromium.org> +Description: + The cache_dma32 file is read-only and specifies whether objects + are from ZONE_DMA32. + Available when CONFIG_ZONE_DMA32 is enabled. + What: /sys/kernel/slab/cache/cpu_slabs Date: May 2007 KernelVersion: 2.6.22
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/internal.h b/mm/internal.h
index a2ee82a0cd44ae..fd244ad716eaf8 100644
--- a/mm/internal.h
+++ b/mm/internal.h@@ -14,6 +14,7 @@ #include <linux/fs.h> #include <linux/mm.h> #include <linux/pagemap.h> +#include <linux/slab.h> #include <linux/tracepoint-defs.h> /*
@@ -34,9 +35,12 @@ #define GFP_CONSTRAINT_MASK (__GFP_HARDWALL|__GFP_THISNODE) /* Check for flags that must not be used with a slab allocator */ -static inline gfp_t check_slab_flags(gfp_t flags) +static inline gfp_t check_slab_flags(gfp_t flags, slab_flags_t slab_flags) { - gfp_t bug_mask = __GFP_DMA32 | __GFP_HIGHMEM | ~__GFP_BITS_MASK; + gfp_t bug_mask = __GFP_HIGHMEM | ~__GFP_BITS_MASK; + + if (!IS_ENABLED(CONFIG_ZONE_DMA32) || !(slab_flags & SLAB_CACHE_DMA32)) + bug_mask |= __GFP_DMA32; if (unlikely(flags & bug_mask)) { gfp_t invalid_mask = flags & bug_mask;
diff --git a/mm/slab.c b/mm/slab.c
index 65a774f05e7836..2fd3b9a996cbe6 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;
@@ -2643,7 +2645,7 @@ static struct page *cache_grow_begin(struct kmem_cache *cachep, * Be lazy and only check for valid flags here, keeping it out of the * critical path in kmem_cache_alloc(). */ - flags = check_slab_flags(flags); + flags = check_slab_flags(flags, cachep->flags); WARN_ON_ONCE(cachep->ctor && (flags & __GFP_ZERO)); local_flags = flags & (GFP_CONSTRAINT_MASK|GFP_RECLAIM_MASK);
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 21a3f6866da472..6d47765a82d150 100644
--- a/mm/slub.c
+++ b/mm/slub.c@@ -1685,7 +1685,7 @@ static struct page *allocate_slab(struct kmem_cache *s, gfp_t flags, int node) static struct page *new_slab(struct kmem_cache *s, gfp_t flags, int node) { - flags = check_slab_flags(flags); + flags = check_slab_flags(flags, s->flags); return allocate_slab(s, flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
@@ -3577,6 +3577,9 @@ 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;
@@ -5095,6 +5098,14 @@ static ssize_t cache_dma_show(struct kmem_cache *s, char *buf) SLAB_ATTR_RO(cache_dma); #endif +#ifdef CONFIG_ZONE_DMA32 +static ssize_t cache_dma32_show(struct kmem_cache *s, char *buf) +{ + return sprintf(buf, "%d\n", !!(s->flags & SLAB_CACHE_DMA32)); +} +SLAB_ATTR_RO(cache_dma32); +#endif + static ssize_t usersize_show(struct kmem_cache *s, char *buf) { return sprintf(buf, "%u\n", s->usersize);
@@ -5435,6 +5446,9 @@ static struct attribute *slab_attrs[] = { #ifdef CONFIG_ZONE_DMA &cache_dma_attr.attr, #endif +#ifdef CONFIG_ZONE_DMA32 + &cache_dma32_attr.attr, +#endif #ifdef CONFIG_NUMA &remote_node_defrag_ratio_attr.attr, #endif
@@ -5665,6 +5679,8 @@ 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.rc1.387.gf8505762e3-goog
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