workqueue: don't perform NUMA-aware allocations on offline nodes in wq_numa_init()

wq_numa_init() builds per-node cpumasks which are later used to make
unbound workqueues NUMA-aware.  The cpumasks are allocated using
alloc_cpumask_var_node() for all possible nodes.  Unfortunately, on
machines with off-line nodes, this leads to NUMA-aware allocations on
existing bug offline nodes, which in turn triggers BUG in the memory
allocation code.

Fix it by using NUMA_NO_NODE for cpumask allocations for offline
nodes.

  kernel BUG at include/linux/gfp.h:323!
  invalid opcode: 0000 [#1] SMP
  Modules linked in:
  CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.9.0+ #1
  Hardware name: ProLiant BL465c G7, BIOS A19 12/10/2011
  task: ffff880234608000 ti: ffff880234602000 task.ti: ffff880234602000
  RIP: 0010:[<ffffffff8117495d>]  [<ffffffff8117495d>] new_slab+0x2ad/0x340
  RSP: 0000:ffff880234603bf8  EFLAGS: 00010246
  RAX: 0000000000000000 RBX: ffff880237404b40 RCX: 00000000000000d0
  RDX: 0000000000000001 RSI: 0000000000000003 RDI: 00000000002052d0
  RBP: ffff880234603c28 R08: 0000000000000000 R09: 0000000000000001
  R10: 0000000000000001 R11: ffffffff812e3aa8 R12: 0000000000000001
  R13: ffff8802378161c0 R14: 0000000000030027 R15: 00000000000040d0
  FS:  0000000000000000(0000) GS:ffff880237800000(0000) knlGS:0000000000000000
  CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
  CR2: ffff88043fdff000 CR3: 00000000018d5000 CR4: 00000000000007f0
  DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
  DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
  Stack:
   ffff880234603c28 0000000000000001 00000000000000d0 ffff8802378161c0
   ffff880237404b40 ffff880237404b40 ffff880234603d28 ffffffff815edba1
   ffff880237816140 0000000000000000 ffff88023740e1c0
  Call Trace:
   [<ffffffff815edba1>] __slab_alloc+0x330/0x4f2
   [<ffffffff81174b25>] kmem_cache_alloc_node_trace+0xa5/0x200
   [<ffffffff812e3aa8>] alloc_cpumask_var_node+0x28/0x90
   [<ffffffff81a0bdb3>] wq_numa_init+0x10d/0x1be
   [<ffffffff81a0bec8>] init_workqueues+0x64/0x341
   [<ffffffff810002ea>] do_one_initcall+0xea/0x1a0
   [<ffffffff819f1f31>] kernel_init_freeable+0xb7/0x1ec
   [<ffffffff815d50de>] kernel_init+0xe/0xf0
   [<ffffffff815ff89c>] ret_from_fork+0x7c/0xb0
  Code: 45  84 ac 00 00 00 f0 41 80 4d 00 40 e9 f6 fe ff ff 66 0f 1f 84 00 00 00 00 00 e8 eb 4b ff ff 49 89 c5 e9 05 fe ff ff <0f> 0b 4c 8b 73 38 44 89 ff 81 cf 00 00 20 00 4c 89 f6 48 c1 ee
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-Tested-by: Lingzhu Xiang <lxiang@redhat.com>

kernel/workqueue.c

@@ -4905,7 +4905,8 @@ static void __init wq_numa_init(void)
 	BUG_ON(!tbl);
 
 	for_each_node(node)
-		BUG_ON(!alloc_cpumask_var_node(&tbl[node], GFP_KERNEL, node));
+		BUG_ON(!alloc_cpumask_var_node(&tbl[node], GFP_KERNEL,
+				node_online(node) ? node : NUMA_NO_NODE));
 
 	for_each_possible_cpu(cpu) {
 		node = cpu_to_node(cpu);