slab: Handle ARCH_DMA_MINALIGN correctly (c601fd69) · Commits · 戴 / test

James Hogan hit boot problems in next-20130204 on Meta: META213-Thread0 DSP [LogF] kobject (4fc03980): tried to init an initialized object, something is seriously wrong. META213-Thread0 DSP [LogF] META213-Thread0 DSP [LogF] Call trace: META213-Thread0 DSP [LogF] [<4000888c>] _show_stack+0x68/0x7c META213-Thread0 DSP [LogF] [<400088b4>] _dump_stack+0x14/0x28 META213-Thread0 DSP [LogF] [<40103794>] _kobject_init+0x58/0x9c META213-Thread0 DSP [LogF] [<40103810>] _kobject_create+0x38/0x64 META213-Thread0 DSP [LogF] [<40103eac>] _kobject_create_and_add+0x14/0x8c META213-Thread0 DSP [LogF] [<40190ac4>] _mnt_init+0xd8/0x220 META213-Thread0 DSP [LogF] [<40190508>] _vfs_caches_init+0xb0/0x160 META213-Thread0 DSP [LogF] [<401851f4>] _start_kernel+0x274/0x340 META213-Thread0 DSP [LogF] [<40188424>] _metag_start_kernel+0x58/0x6c META213-Thread0 DSP [LogF] [<40000044>] __start+0x44/0x48 META213-Thread0 DSP [LogF] META213-Thread0 DSP [LogF] devtmpfs: initialized META213-Thread0 DSP [LogF] L2 Cache: Not present META213-Thread0 DSP [LogF] BUG: failure at fs/sysfs/dir.c:736/sysfs_read_ns_type()! META213-Thread0 DSP [LogF] Kernel panic - not syncing: BUG! META213-Thread0 DSP [Thread Exit] Thread has exited - return code = 4294967295 And bisected the problem to commit ("slab: Common constants for kmalloc boundaries"). As it turns out, a fixed KMALLOC_SHIFT_LOW does not work for arches with higher alignment requirements. Determine KMALLOC_SHIFT_LOW from ARCH_DMA_MINALIGN instead. Reported-and-tested-by:

James Hogan <james.hogan@imgtec.com> Signed-off-by:

Christoph Lameter <cl@linux.com> Signed-off-by:

Pekka Enberg <penberg@kernel.org>

include/linux/slab.h

+18 −14

Original line number	Diff line number	Diff line
		@@ -133,6 +133,19 @@ void kfree(const void *);
		void kzfree(const void *);
		size_t ksize(const void *);

		/*
		* Some archs want to perform DMA into kmalloc caches and need a guaranteed
		* alignment larger than the alignment of a 64-bit integer.
		* Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
		*/
		#if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
		#define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
		#define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
		#define KMALLOC_SHIFT_LOW ilog2(ARCH_DMA_MINALIGN)
		#else
		#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
		#endif

		#ifdef CONFIG_SLOB
		/*
		* Common fields provided in kmem_cache by all slab allocators
		@@ -179,7 +192,9 @@ struct kmem_cache {
		#define KMALLOC_SHIFT_HIGH ((MAX_ORDER + PAGE_SHIFT - 1) <= 25 ? \
		(MAX_ORDER + PAGE_SHIFT - 1) : 25)
		#define KMALLOC_SHIFT_MAX KMALLOC_SHIFT_HIGH
		#ifndef KMALLOC_SHIFT_LOW
		#define KMALLOC_SHIFT_LOW 5
		#endif
		#else
		/*
		* SLUB allocates up to order 2 pages directly and otherwise
		@@ -187,8 +202,10 @@ struct kmem_cache {
		*/
		#define KMALLOC_SHIFT_HIGH (PAGE_SHIFT + 1)
		#define KMALLOC_SHIFT_MAX (MAX_ORDER + PAGE_SHIFT)
		#ifndef KMALLOC_SHIFT_LOW
		#define KMALLOC_SHIFT_LOW 3
		#endif
		#endif

		/* Maximum allocatable size */
		#define KMALLOC_MAX_SIZE (1UL << KMALLOC_SHIFT_MAX)
		@@ -200,9 +217,7 @@ struct kmem_cache {
		/*
		* Kmalloc subsystem.
		*/
		#if defined(ARCH_DMA_MINALIGN) && ARCH_DMA_MINALIGN > 8
		#define KMALLOC_MIN_SIZE ARCH_DMA_MINALIGN
		#else
		#ifndef KMALLOC_MIN_SIZE
		#define KMALLOC_MIN_SIZE (1 << KMALLOC_SHIFT_LOW)
		#endif

		@@ -289,17 +304,6 @@ static __always_inline int kmalloc_size(int n)
		}
		#endif /* !CONFIG_SLOB */

		/*
		* Some archs want to perform DMA into kmalloc caches and need a guaranteed
		* alignment larger than the alignment of a 64-bit integer.
		* Setting ARCH_KMALLOC_MINALIGN in arch headers allows that.
		*/
		#ifdef ARCH_DMA_MINALIGN
		#define ARCH_KMALLOC_MINALIGN ARCH_DMA_MINALIGN
		#else
		#define ARCH_KMALLOC_MINALIGN __alignof__(unsigned long long)
		#endif

		/*
		* Setting ARCH_SLAB_MINALIGN in arch headers allows a different alignment.
		* Intended for arches that get misalignment faults even for 64 bit integer

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