| Message ID | 20231006163934.3273940-1-catalin.marinas@arm.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | [RESEND] mm: slab: Do not create kmalloc caches smaller than arch_slab_minalign() | expand |
On 10/6/23 18:39, Catalin Marinas wrote: > 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). > > Fixes: b035f5a6d852 ("mm: slab: reduce the kmalloc() minimum alignment if DMA bouncing possible") > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > Reported-by: Mark Rutland <mark.rutland@arm.com> > Cc: Andrew Morton <akpm@linux-foundation.org> > Cc: Vlastimil Babka <vbabka@suse.cz> > Cc: Peter Collingbourne <pcc@google.com> > Cc: <stable@vger.kernel.org> # 6.5.x > --- > > The previous post was messed up by my git send-email configuration, so > sending it again. Also cc'ing Vlastimil since he reviewed the previous > slab changes for ARCH_KMALLOC_MINALIGN. Thanks. It also touches only slab files so I can take it via slab tree. > mm/slab_common.c | 7 +++++-- > 1 file changed, 5 insertions(+), 2 deletions(-) > > diff --git a/mm/slab_common.c b/mm/slab_common.c > index cd71f9581e67..8b45922ed295 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 ALIGN(minalign, arch_slab_minalign()); Could it be max() instead of ALIGN()? It would be more obvious, at least to me :) > } > > void __init
On Mon, Oct 09, 2023 at 10:22:52AM +0200, Vlastimil Babka wrote: > On 10/6/23 18:39, Catalin Marinas wrote: > > 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). > > > > Fixes: b035f5a6d852 ("mm: slab: reduce the kmalloc() minimum alignment if DMA bouncing possible") > > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> > > Reported-by: Mark Rutland <mark.rutland@arm.com> > > Cc: Andrew Morton <akpm@linux-foundation.org> > > Cc: Vlastimil Babka <vbabka@suse.cz> > > Cc: Peter Collingbourne <pcc@google.com> > > Cc: <stable@vger.kernel.org> # 6.5.x > > --- > > > > The previous post was messed up by my git send-email configuration, so > > sending it again. Also cc'ing Vlastimil since he reviewed the previous > > slab changes for ARCH_KMALLOC_MINALIGN. Thanks. > > It also touches only slab files so I can take it via slab tree. Thanks. > > mm/slab_common.c | 7 +++++-- > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > diff --git a/mm/slab_common.c b/mm/slab_common.c > > index cd71f9581e67..8b45922ed295 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 ALIGN(minalign, arch_slab_minalign()); > > Could it be max() instead of ALIGN()? It would be more obvious, at least to > me :) Yeah, max() would do since they are all a power of two. Do you want me to repost?
On 10/9/23 13:20, Catalin Marinas wrote: >> > mm/slab_common.c | 7 +++++-- >> > 1 file changed, 5 insertions(+), 2 deletions(-) >> > >> > diff --git a/mm/slab_common.c b/mm/slab_common.c >> > index cd71f9581e67..8b45922ed295 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 ALIGN(minalign, arch_slab_minalign()); >> >> Could it be max() instead of ALIGN()? It would be more obvious, at least to >> me :) > > Yeah, max() would do since they are all a power of two. Do you want me > to repost? No need, picked up and changed locally. Thanks!
diff --git a/mm/slab_common.c b/mm/slab_common.c index cd71f9581e67..8b45922ed295 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 ALIGN(minalign, arch_slab_minalign()); } void __init
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). Fixes: b035f5a6d852 ("mm: slab: reduce the kmalloc() minimum alignment if DMA bouncing possible") Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> Reported-by: Mark Rutland <mark.rutland@arm.com> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Peter Collingbourne <pcc@google.com> Cc: <stable@vger.kernel.org> # 6.5.x --- The previous post was messed up by my git send-email configuration, so sending it again. Also cc'ing Vlastimil since he reviewed the previous slab changes for ARCH_KMALLOC_MINALIGN. Thanks. mm/slab_common.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-)