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 <drink...@chromium.org>
---
 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)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 7a500b232e4a43..2aa9c8491d2ca2 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 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)
 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);
@@ -5430,6 +5441,9 @@ 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
@@ -5660,6 +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)
-- 
2.19.1.930.g4563a0d9d0-goog

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