diff options
| author | Catalin Marinas <catalin.marinas@arm.com> | 2015-11-05 18:45:54 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2015-11-05 19:34:48 -0800 |
| commit | d4322d88f5fdf92729dd40f923013414fbb2184d (patch) | |
| tree | 29fc526e9b18457f593e19617295f25ea8ee7ff0 | |
| parent | 9f835703ea67633617ca82bc150f6ee70831b40a (diff) | |
mm: slab: only move management objects off-slab for sizes larger than KMALLOC_MIN_SIZE
On systems with a KMALLOC_MIN_SIZE of 128 (arm64, some mips and powerpc
configurations defining ARCH_DMA_MINALIGN to 128), the first
kmalloc_caches[] entry to be initialised after slab_early_init = 0 is
"kmalloc-128" with index 7. Depending on the debug kernel configuration,
sizeof(struct kmem_cache) can be larger than 128 resulting in an
INDEX_NODE of 8.
Commit 8fc9cf420b36 ("slab: make more slab management structure off the
slab") enables off-slab management objects for sizes starting with
PAGE_SIZE >> 5 (128 bytes for a 4KB page configuration) and the creation
of the "kmalloc-128" cache would try to place the management objects
off-slab. However, since KMALLOC_MIN_SIZE is already 128 and
freelist_size == 32 in __kmem_cache_create(), kmalloc_slab(freelist_size)
returns NULL (kmalloc_caches[7] not populated yet). This triggers the
following bug on arm64:
kernel BUG at /work/Linux/linux-2.6-aarch64/mm/slab.c:2283!
Internal error: Oops - BUG: 0 [#1] SMP
Modules linked in:
CPU: 0 PID: 0 Comm: swapper Not tainted 4.3.0-rc4+ #540
Hardware name: Juno (DT)
PC is at __kmem_cache_create+0x21c/0x280
LR is at __kmem_cache_create+0x210/0x280
[...]
Call trace:
__kmem_cache_create+0x21c/0x280
create_boot_cache+0x48/0x80
create_kmalloc_cache+0x50/0x88
create_kmalloc_caches+0x4c/0xf4
kmem_cache_init+0x100/0x118
start_kernel+0x214/0x33c
This patch introduces an OFF_SLAB_MIN_SIZE definition to avoid off-slab
management objects for sizes equal to or smaller than KMALLOC_MIN_SIZE.
Fixes: 8fc9cf420b36 ("slab: make more slab management structure off the slab")
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: <stable@vger.kernel.org> [3.15+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | mm/slab.c | 5 |
1 files changed, 3 insertions, 2 deletions
diff --git a/mm/slab.c b/mm/slab.c index 4fcc5dd8d5a6..461935bab9ef 100644 --- a/mm/slab.c +++ b/mm/slab.c @@ -282,6 +282,7 @@ static void kmem_cache_node_init(struct kmem_cache_node *parent) #define CFLGS_OFF_SLAB (0x80000000UL) #define OFF_SLAB(x) ((x)->flags & CFLGS_OFF_SLAB) +#define OFF_SLAB_MIN_SIZE (max_t(size_t, PAGE_SIZE >> 5, KMALLOC_MIN_SIZE + 1)) #define BATCHREFILL_LIMIT 16 /* @@ -2212,7 +2213,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags) * it too early on. Always use on-slab management when * SLAB_NOLEAKTRACE to avoid recursive calls into kmemleak) */ - if ((size >= (PAGE_SIZE >> 5)) && !slab_early_init && + if (size >= OFF_SLAB_MIN_SIZE && !slab_early_init && !(flags & SLAB_NOLEAKTRACE)) /* * Size is large, assume best to place the slab management obj @@ -2276,7 +2277,7 @@ __kmem_cache_create (struct kmem_cache *cachep, unsigned long flags) /* * This is a possibility for one of the kmalloc_{dma,}_caches. * But since we go off slab only for object size greater than - * PAGE_SIZE/8, and kmalloc_{dma,}_caches get created + * OFF_SLAB_MIN_SIZE, and kmalloc_{dma,}_caches get created * in ascending order,this should not happen at all. * But leave a BUG_ON for some lucky dude. */ |