From edcad25095503c9a390bea0cc2f518793447a6a8 Mon Sep 17 00:00:00 2001 From: Joonsoo Kim Date: Fri, 8 Aug 2014 14:19:15 -0700 Subject: Revert "slab: remove BAD_ALIEN_MAGIC" 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! 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. Signed-off-by: Joonsoo Kim Reported-by: Geert Uytterhoeven Cc: Christoph Lameter Cc: Pekka Enberg Cc: David Rientjes Cc: Vladimir Davydov Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/slab.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'mm') diff --git a/mm/slab.c b/mm/slab.c index 2e60bf3dedbb..a467b308c682 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) -- cgit v1.2.3-59-g8ed1b