This reverts commit a640616822b2 ("slab: remove BAD_ALIEN_MAGIC").
commit a640616822b2 ("slab: remove BAD_ALIEN_MAGIC") assumes that the
system with !CONFIG_NUMA has only one memory node. But, it turns out to
be false by the report from Geert. His system, m68k, has many memory nodes
and is configured in !CONFIG_NUMA. So it couldn't boot with above change.
Here goes his failure report.
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!
Although there is a alternative way to fix this issue such as disabling
use of alien cache on !CONFIG_NUMA, but, reverting issued commit is better
to me in this time.
Reported-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
---
mm/slab.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/mm/slab.c b/mm/slab.c
index c727a16..0376429 100644
--- a/mm/slab.c
+++ b/mm/slab.c
@@ -470,6 +470,8 @@ 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)
@@ -836,7 +838,7 @@ static int transfer_objects(struct array_cache *to,
static inline struct alien_cache **alloc_alien_cache(int node,
int limit, gfp_t gfp)
{
- return NULL;
+ return (struct alien_cache **)BAD_ALIEN_MAGIC;
}
static inline void free_alien_cache(struct alien_cache **ac_ptr)
--
1.7.9.5
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