Re: BUG: enable_cpucache failed for radix_tree_node, error 12 (was: Re: [PATCH v3 9/9] slab: remove BAD_ALIEN_MAGIC)

[Joonsoo Kim <js1304@gmail.com>]

2014-08-07 20:52 GMT+09:00 Geert Uytterhoeven <geert@linux-m68k.org>:
> Hi Joonsoo,
>
> On Tue, Jul 1, 2014 at 10:27 AM, Joonsoo Kim <iamjoonsoo.kim@lge.com> wrote:
>> BAD_ALIEN_MAGIC value isn't used anymore. So remove it.
>>
>> Acked-by: Christoph Lameter <cl@linux.com>
>> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>> ---
>>  mm/slab.c |    4 +---
>>  1 file changed, 1 insertion(+), 3 deletions(-)
>>
>> diff --git a/mm/slab.c b/mm/slab.c
>> index 7820a45..60c9e11 100644
>> --- a/mm/slab.c
>> +++ b/mm/slab.c
>> @@ -470,8 +470,6 @@ static struct kmem_cache kmem_cache_boot = {
>>         .name = "kmem_cache",
>>  };
>>
>> -#define BAD_ALIEN_MAGIC 0x01020304ul
>> -
>>  static DEFINE_PER_CPU(struct delayed_work, slab_reap_work);
>>
>>  static inline struct array_cache *cpu_cache_get(struct kmem_cache *cachep)
>> @@ -838,7 +836,7 @@ static int transfer_objects(struct array_cache *to,
>>  static inline struct alien_cache **alloc_alien_cache(int node,
>>                                                 int limit, gfp_t gfp)
>>  {
>> -       return (struct alien_cache **)BAD_ALIEN_MAGIC;
>> +       return NULL;
>>  }
>
> With latest mainline, I'm getting a crash during bootup on m68k/ARAnyM:
>
> enable_cpucache failed for radix_tree_node, error 12.
> kernel BUG at /scratch/geert/linux/linux-m68k/mm/slab.c:1522!
> *** TRAP #7 ***   FORMAT=0
> Current process id is 0
> BAD KERNEL TRAP: 00000000
> Modules linked in:
> PC: [<0039c92c>] kmem_cache_init_late+0x70/0x8c
> SR: 2200  SP: 00345f90  a2: 0034c2e8
> d0: 0000003d    d1: 00000000    d2: 00000000    d3: 003ac942
> d4: 00000000    d5: 00000000    a0: 0034f686    a1: 0034f682
> Process swapper (pid: 0, task=0034c2e8)
> Frame format=0
> Stack from 00345fc4:
>         002f69ef 002ff7e5 000005f2 000360fa 0017d806 003921d4 00000000 00000000
>         00000000 00000000 00000000 00000000 003ac942 00000000 003912d6
> Call Trace: [<000360fa>] parse_args+0x0/0x2ca
>  [<0017d806>] strlen+0x0/0x1a
>  [<003921d4>] start_kernel+0x23c/0x428
>  [<003912d6>] _sinittext+0x2d6/0x95e
>
> Code: f7e5 4879 002f 69ef 61ff ffca 462a 4e47 <4879> 0035 4b1c 61ff
> fff0 0cc4 7005 23c0 0037 fd20 588f 265f 285f 4e75 48e7 301c
> Disabling lock debugging due to kernel taint
> Kernel panic - not syncing: Attempted to kill the idle task!
> ---[ end Kernel panic - not syncing: Attempted to kill the idle task!
>
> I bisected it to commit a640616822b2c3a8009b0600f20c4a76ea8a0025
> Author: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> Date:   Wed Aug 6 16:04:38 2014 -0700
>
>     slab: remove BAD_ALIEN_MAGIC
>
>     BAD_ALIEN_MAGIC value isn't used anymore. So remove it.
>
>     Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>     Acked-by: Christoph Lameter <cl@linux.com>
>     Cc: Pekka Enberg <penberg@kernel.org>
>     Cc: David Rientjes <rientjes@google.com>
>     Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
>     Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
>
> Error 12 is ENOMEM, so I first thought it went out-of-memory, but just reverting
> the above commit on mainline makes it work again.

Hello,

Thanks for reporting.

This patch only works for !NUMA. And if num_possible_nodes() is 1,
then it doesn't have any effect, because alloc_alien_cache() call is always
skipped. Is it possible !NUMA and num_possible_nodes() != 1?

Could you check your config for CONFIG_NUMA and
CONFIG_NODES_SHIFT?

And, could you check booting with boot param "noaliencache"?

Thanks.

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