6.5-stable review patch. If anyone has any objections, please let me know.
------------------
From: Catalin Marinas <catalin.marinas@xxxxxxx>
commit c15cdea517414e0b29a11e0a0e2443d127c9109b upstream.
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@xxxxxxx>
Fixes: b035f5a6d852 ("mm: slab: reduce the kmalloc() minimum alignment if DMA bouncing possible")
Signed-off-by: Catalin Marinas <catalin.marinas@xxxxxxx>
Cc: Peter Collingbourne <pcc@xxxxxxxxxx>
Cc: stable@xxxxxxxxxxxxxxx # 6.5.x
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/slab_common.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
--- a/mm/slab_common.c
+++ b/mm/slab_common.c
@@ -864,11 +864,13 @@ void __init setup_kmalloc_cache_index_ta
static unsigned int __kmalloc_minalign(void)
{
+ unsigned int minalign = dma_get_cache_alignment();
+
#ifdef CONFIG_DMA_BOUNCE_UNALIGNED_KMALLOC
if (io_tlb_default_mem.nslabs)
- return ARCH_KMALLOC_MINALIGN;
+ minalign = ARCH_KMALLOC_MINALIGN;
#endif
- return dma_get_cache_alignment();
+ return max(minalign, arch_slab_minalign());
}
void __init
