mm/slab: limit kmalloc() minimum alignment to dma_get_cache_alignment()

Do not create kmalloc() caches which are not aligned to
dma_get_cache_alignment().  There is no functional change since for
current architectures defining ARCH_DMA_MINALIGN, ARCH_KMALLOC_MINALIGN
equals ARCH_DMA_MINALIGN (and dma_get_cache_alignment()).  On
architectures without a specific ARCH_DMA_MINALIGN,
dma_get_cache_alignment() is 1, so no change to the kmalloc() caches.

Link: https://lkml.kernel.org/r/20230612153201.554742-5-catalin.marinas@arm.com
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Vlastimil Babka <vbabka@suse.cz>
Tested-by: Isaac J. Manjarres <isaacmanjarres@google.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Alasdair Kergon <agk@redhat.com>
Cc: Ard Biesheuvel <ardb@kernel.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: Jerry Snitselaar <jsnitsel@redhat.com>
Cc: Joerg Roedel <joro@8bytes.org>
Cc: Jonathan Cameron <jic23@kernel.org>
Cc: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Cc: Lars-Peter Clausen <lars@metafoo.de>
Cc: Logan Gunthorpe <logang@deltatee.com>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Mark Brown <broonie@kernel.org>
Cc: Mike Snitzer <snitzer@kernel.org>
Cc: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: Saravana Kannan <saravanak@google.com>
Cc: Will Deacon <will@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/slab_common.c b/mm/slab_common.c
index 7f069159aee2ccab1a6f765db80d14dcb83647f0..7c6475847fdf3a2fde9027f2d0272df9d39806dc 100644 (file)
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -17,6 +17,7 @@
 #include <linux/cpu.h>
 #include <linux/uaccess.h>
 #include <linux/seq_file.h>
+#include <linux/dma-mapping.h>
 #include <linux/proc_fs.h>
 #include <linux/debugfs.h>
 #include <linux/kasan.h>
@@ -862,9 +863,18 @@ void __init setup_kmalloc_cache_index_table(void)
        }
 }
 
+static unsigned int __kmalloc_minalign(void)
+{
+       return dma_get_cache_alignment();
+}
+
 void __init
 new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
 {
+       unsigned int minalign = __kmalloc_minalign();
+       unsigned int aligned_size = kmalloc_info[idx].size;
+       int aligned_idx = idx;
+
        if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) {
                flags |= SLAB_RECLAIM_ACCOUNT;
        } else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) {
@@ -877,9 +887,17 @@ new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
                flags |= SLAB_CACHE_DMA;
        }
 
-       kmalloc_caches[type][idx] = create_kmalloc_cache(
-                                       kmalloc_info[idx].name[type],
-                                       kmalloc_info[idx].size, flags);
+       if (minalign > ARCH_KMALLOC_MINALIGN) {
+               aligned_size = ALIGN(aligned_size, minalign);
+               aligned_idx = __kmalloc_index(aligned_size, false);
+       }
+
+       if (!kmalloc_caches[type][aligned_idx])
+               kmalloc_caches[type][aligned_idx] = create_kmalloc_cache(
+                                       kmalloc_info[aligned_idx].name[type],
+                                       aligned_size, flags);
+       if (idx != aligned_idx)
+               kmalloc_caches[type][idx] = kmalloc_caches[type][aligned_idx];
 
        /*
         * If CONFIG_MEMCG_KMEM is enabled, disable cache merging for