Re: [PATCH v2 2/3] mm: Add support for SLAB_CACHE_DMA32

2018-11-21 Thread Nicolas Boichat 
On Thu, Nov 22, 2018 at 2:32 AM Christopher Lameter  wrote:
>
> On Sun, 11 Nov 2018, Nicolas Boichat wrote:
>
> > SLAB_CACHE_DMA32 is only available after explicit kmem_cache_create calls,
> > no default cache is created for kmalloc. Add a test in check_slab_flags
> > for this.
>
> This does not define the dma32 kmalloc array. Is that intentional?

Yes that's intentional, AFAICT there is no user, so there is no point
creating the cache.

 (okay, I could find one, but it's probably broken:
git grep GFP_DMA32 | grep k[a-z]*alloc
drivers/media/platform/vivid/vivid-osd.c: dev->video_vbase =
kzalloc(dev->video_buffer_size, GFP_KERNEL | GFP_DMA32);
).

> In that
> case you need to fail any request for GFP_DMA32 coming in via kmalloc.

Well, we do check for these in check_slab_flags (aka GFP_SLAB_BUG_MASK
before patch 1/3 of this series), so, with or without this patch,
calls with GFP_DMA32 will end up failing in check_slab_flags.
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Re: [PATCH v2 2/3] mm: Add support for SLAB_CACHE_DMA32

2018-11-21 Thread Christopher Lameter 
On Sun, 11 Nov 2018, Nicolas Boichat wrote:

> SLAB_CACHE_DMA32 is only available after explicit kmem_cache_create calls,
> no default cache is created for kmalloc. Add a test in check_slab_flags
> for this.

This does not define the dma32 kmalloc array. Is that intentional? In that
case you need to fail any request for GFP_DMA32 coming in via kmalloc.
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[PATCH v2 2/3] mm: Add support for SLAB_CACHE_DMA32

2018-11-11 Thread Nicolas Boichat 
SLAB_CACHE_DMA32 is only available after explicit kmem_cache_create calls,
no default cache is created for kmalloc. Add a test in check_slab_flags
for this.

Fixes: ad67f5a6545f ("arm64: replace ZONE_DMA with ZONE_DMA32")
Signed-off-by: Nicolas Boichat 
---
 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 +-
 6 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/include/linux/slab.h b/include/linux/slab.h
index 918f374e7156f4..afc51ee1dae5d4 100644
--- a/include/linux/slab.h
+++ b/include/linux/slab.h
@@ -32,6 +32,8 @@
 #define SLAB_HWCACHE_ALIGN ((slab_flags_t __force)0x2000U)
 /* Use GFP_DMA memory */
 #define SLAB_CACHE_DMA ((slab_flags_t __force)0x4000U)
+/* Use GFP_DMA32 memory */
+#define SLAB_CACHE_DMA32   ((slab_flags_t __force)0x8000U)
 /* DEBUG: Store the last owner for bug hunting */
 #define SLAB_STORE_USER((slab_flags_t __force)0x0001U)
 /* Panic if kmem_cache_create() fails */
diff --git a/mm/internal.h b/mm/internal.h
index 7a500b232e4a43..2aa9c8491d2ca2 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -14,6 +14,7 @@
 #include 
 #include 
 #include 
+#include 
 #include 
 
 /*
@@ -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 251e09a5a3ef5c..6efcaad6a02b70 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -2122,6 +2122,8 @@ 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;
@@ -2656,7 +2658,7 @@ 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 58c6c1c2a78ee3..9632772e14beb2 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 7eb8dc136c1cb8..f204385553bbac 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 1cca562bebdc8d..c639bd008e8c11 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1681,7 +1681,7 @@ 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);
@@ -3571,6 +3571,9 @@ 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;
 
@@ -5090,6 +5093,14 @@ static ssize_t cache_dma_show(struct kmem_cache *s, char 
*buf)