6.5-stable review patch. If anyone has any objections, please let me know.
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From: Catalin Marinas catalin.marinas@arm.com
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@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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- 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