From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pa0-f44.google.com (mail-pa0-f44.google.com [209.85.220.44]) by kanga.kvack.org (Postfix) with ESMTP id 49DE86B0035 for ; Fri, 8 Aug 2014 03:00:43 -0400 (EDT) Received: by mail-pa0-f44.google.com with SMTP id eu11so6847714pac.3 for ; Fri, 08 Aug 2014 00:00:42 -0700 (PDT) Received: from lgeamrelo04.lge.com (lgeamrelo04.lge.com. [156.147.1.127]) by mx.google.com with ESMTP id db10si1764234pdb.238.2014.08.08.00.00.41 for ; Fri, 08 Aug 2014 00:00:42 -0700 (PDT) From: Joonsoo Kim Subject: [PATCH for v3.17-rc1] Revert "slab: remove BAD_ALIEN_MAGIC" Date: Fri, 8 Aug 2014 16:00:39 +0900 Message-Id: <1407481239-7572-1-git-send-email-iamjoonsoo.kim@lge.com> Sender: owner-linux-mm@kvack.org List-ID: To: Andrew Morton Cc: Christoph Lameter , Pekka Enberg , David Rientjes , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Geert Uytterhoeven , Vladimir Davydov , Joonsoo Kim 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 Signed-off-by: Joonsoo Kim --- 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org