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| author | Catalin Marinas <catalin.marinas@arm.com> | 2023-10-06 18:39:34 +0200 |
|---|---|---|
| committer | Vlastimil Babka <vbabka@suse.cz> | 2023-10-11 15:24:49 +0200 |
| commit | c15cdea517414e0b29a11e0a0e2443d127c9109b (patch) | |
| tree | ccfdf44f1a0bac74de6d8b6a6f77e22d5449c820 /mm | |
| parent | Linux 6.6-rc5 (diff) | |
| download | linux-c15cdea517414e0b29a11e0a0e2443d127c9109b.tar.xz linux-c15cdea517414e0b29a11e0a0e2443d127c9109b.zip | |
mm: slab: Do not create kmalloc caches smaller than arch_slab_minalign()
Commit b035f5a6d852 ("mm: slab: reduce the kmalloc() minimum alignment
if DMA bouncing possible") allows architectures with non-coherent DMA to
define a small ARCH_KMALLOC_MINALIGN (e.g. sizeof(unsigned long long))
and this has been enabled on arm64. With KASAN_HW_TAGS enabled, however,
ARCH_SLAB_MINALIGN becomes 16 on arm64 (arch_slab_minalign() dynamically
selects it since commit d949a8155d13 ("mm: make minimum slab alignment a
runtime property")). This can lead to a situation where kmalloc-8 caches
are attempted to be created with a kmem_caches.size aligned to 16. When
the cache is mergeable, it can lead to kernel warnings like:
sysfs: cannot create duplicate filename '/kernel/slab/:d-0000016'
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 6.6.0-rc1-00001-gda98843cd306-dirty #5
Hardware name: QEMU QEMU Virtual Machine, BIOS 0.0.0 02/06/2015
Call trace:
dump_backtrace+0x90/0xe8
show_stack+0x18/0x24
dump_stack_lvl+0x48/0x60
dump_stack+0x18/0x24
sysfs_warn_dup+0x64/0x80
sysfs_create_dir_ns+0xe8/0x108
kobject_add_internal+0x98/0x264
kobject_init_and_add+0x8c/0xd8
sysfs_slab_add+0x12c/0x248
slab_sysfs_init+0x98/0x14c
do_one_initcall+0x6c/0x1b0
kernel_init_freeable+0x1c0/0x288
kernel_init+0x24/0x1e0
ret_from_fork+0x10/0x20
kobject: kobject_add_internal failed for :d-0000016 with -EEXIST, don't try to register things with the same name in the same directory.
SLUB: Unable to add boot slab dma-kmalloc-8 to sysfs
Limit the __kmalloc_minalign() return value (used to create the
kmalloc-* caches) to arch_slab_minalign() so that kmalloc-8 caches are
skipped when KASAN_HW_TAGS is enabled (both config and runtime).
Reported-by: Mark Rutland <mark.rutland@arm.com>
Fixes: b035f5a6d852 ("mm: slab: reduce the kmalloc() minimum alignment if DMA bouncing possible")
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Cc: Peter Collingbourne <pcc@google.com>
Cc: stable@vger.kernel.org # 6.5.x
Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Diffstat (limited to 'mm')
| -rw-r--r-- | mm/slab_common.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/mm/slab_common.c b/mm/slab_common.c index 8fda308e400d..9bbffe82d65a 100644 --- a/mm/slab_common.c +++ b/mm/slab_common.c @@ -895,10 +895,13 @@ void __init setup_kmalloc_cache_index_table(void) static unsigned int __kmalloc_minalign(void) { + unsigned int minalign = dma_get_cache_alignment(); + if (IS_ENABLED(CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC) && is_swiotlb_allocated()) - return ARCH_KMALLOC_MINALIGN; - return dma_get_cache_alignment(); + minalign = ARCH_KMALLOC_MINALIGN; + + return max(minalign, arch_slab_minalign()); } void __init |