* Rusty Russell <rusty@rustcorp.com.au> wrote:

> Commit-ID:  df7c8e845e8e2030e8ae947e0ace56d184d0e9a0
> Gitweb:     http://git.kernel.org/tip/df7c8e845e8e2030e8ae947e0ace56d184d0e9a0
> Author:     Rusty Russell <rusty@rustcorp.com.au>
> AuthorDate: Thu, 19 Mar 2009 15:22:20 +1030
> Committer:  Ingo Molnar <mingo@elte.hu>
> CommitDate: Thu, 19 Mar 2009 08:15:15 +0100
> 
> cpumask: remove cpumask allocation from idle_balance
> 
> Impact: fix circular locking

this quickly crashed in -tip testing:

[    0.500007] Registering sys device 'memory2'
[    0.503563] Registering sys device of class 'memory'
[    0.506674] Registering sys device 'memory3'
[    0.510012] BUG: unable to handle kernel NULL pointer dereference at (null)
[    0.513332] IP: [<ffffffff8024efc2>] cpumask_setall+0x70/0x8a
[    0.513332] PGD 0 
[    0.513332] Oops: 0002 [#1] SMP DEBUG_PAGEALLOC
[    0.513332] last sysfs file: 
[    0.513332] CPU 0 
[    0.513332] Modules linked in:
[    0.513332] Pid: 1, comm: swapper Not tainted 2.6.29-rc8-tip #21482 
[    0.513332] RIP: 0010:[<ffffffff8024efc2>]  [<ffffffff8024efc2>] cpumask_setall+0x70/0x8a
[    0.513332] RSP: 0018:ffff880008c66d50  EFLAGS: 00010246
[    0.513332] RAX: 0000000000000000 RBX: ffff880008c71b00 RCX: 0000000000000003
[    0.513332] RDX: 0000000000000002 RSI: 0000000000000001 RDI: 0000000000000000
[    0.513332] RBP: ffff880008c66d70 R08: 0000000000000002 R09: 0000000000000000
[    0.513332] R10: 0000000000000040 R11: 0000000000000008 R12: ffff880008c71b00
[    0.513332] R13: ffff880008e3a800 R14: 00000000fffee759 R15: 0000000000000001
[    0.513332] FS:  0000000000000000(0000) GS:ffff880008c63000(0000) knlGS:0000000000000000
[    0.513332] CS:  0010 DS: 0018 ES: 0018 CR0: 000000008005003b
[    0.513332] CR2: 0000000000000000 CR3: 0000000000201000 CR4: 00000000000006e0
[    0.513332] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[    0.513332] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[    0.513332] Process swapper (pid: 1, threadinfo ffff88003fa5e000, task ffff88003fa60000)
[    0.513332] Stack:
[    0.513332]  0000000000000001 ffffffff8227c258 ffff880008c66db0 00000000ec183cbc
[    0.513332]  ffff880008c66e30 ffffffff802546f0 ffff880008c66db0 ffffffff80482e96
[    0.513332]  ffffffff8227c240 ffff880008c66e60 00000000ec183cbc ffffffff8227c240
[    0.513332] Call Trace:
[    0.513332]  <IRQ> <0> [<ffffffff802546f0>] load_balance+0x67/0x434
[    0.513332]  [<ffffffff80482e96>] ? _raw_spin_unlock+0x9e/0xbb
[    0.513332]  [<ffffffff802639ab>] ? run_timer_softirq+0x28c/0x2b2
[    0.513332]  [<ffffffff80254bab>] rebalance_domains+0xee/0x178
[    0.513332]  [<ffffffff80482e96>] ? _raw_spin_unlock+0x9e/0xbb
[    0.513332]  [<ffffffff80254c7e>] run_rebalance_domains+0x49/0x5f
[    0.513332]  [<ffffffff8025ef01>] __do_softirq+0xd0/0x1dd
[    0.513332]  [<ffffffff8021432c>] call_softirq+0x1c/0x30
[    0.513332]  [<ffffffff80215b26>] do_softirq+0x56/0xa2
[    0.513332]  [<ffffffff8027d670>] ? tick_handle_periodic+0x35/0x91
[    0.513332]  [<ffffffff8025e953>] irq_exit+0x57/0x6d
[    0.513332]  [<ffffffff8081f739>] smp_apic_timer_interrupt+0xa0/0xc5
[    0.513332]  [<ffffffff80213d33>] apic_timer_interrupt+0x13/0x20
[    0.513332]  <EOI> <0> [<ffffffff80259b89>] ? vprintk+0x34d/0x394
[    0.513332]  [<ffffffff8046bb88>] ? kobject_add_varg+0x50/0x73
[    0.513332]  [<ffffffff8046b2f1>] ? kobject_init+0x56/0xac
[    0.513332]  [<ffffffff808174af>] ? printk+0x50/0x66
[    0.513332]  [<ffffffff804d6588>] ? sysdev_register+0xa9/0x11a
[    0.513332]  [<ffffffff802f521e>] ? __section_nr+0x32/0x8c
[    0.513332]  [<ffffffff804df923>] ? add_memory_block+0xad/0x130
[    0.513332]  [<ffffffff81e70140>] ? early_idt_handler+0x0/0x71
[    0.513332]  [<ffffffff81e9cee1>] ? memory_dev_init+0x60/0xda
[    0.513332]  [<ffffffff81e70140>] ? early_idt_handler+0x0/0x71
[    0.513332]  [<ffffffff81e9cd28>] ? driver_init+0x3f/0x55
[    0.513332]  [<ffffffff81e70140>] ? early_idt_handler+0x0/0x71
[    0.513332]  [<ffffffff81e70980>] ? kernel_init+0x9f/0x11a
[    0.513332]  [<ffffffff802523a7>] ? schedule_tail+0x3b/0x8a
[    0.513332]  [<ffffffff8021422a>] ? child_rip+0xa/0x20
[    0.513332]  [<ffffffff81e70140>] ? early_idt_handler+0x0/0x71
[    0.513332]  [<ffffffff81e708e1>] ? kernel_init+0x0/0x11a
[    0.513332]  [<ffffffff80214220>] ? child_rip+0x0/0x20
[    0.513332] Code: c0 3f 74 1b 44 89 c0 41 ba 40 00 00 00 99 41 f7 fa b8 01 00 00 00 89 d1 48 d3 e0 48 8d 48 ff b8 01 00 00 00 48 29 f0 48 6b c0 f8 <49> 89 0c 01 48 8b 7d f8 65 48 33 3c 25 28 00 00 00 74 05 e8 d9 
[    0.513332] RIP  [<ffffffff8024efc2>] cpumask_setall+0x70/0x8a
[    0.513332]  RSP <ffff880008c66d50>
[    0.513332] CR2: 0000000000000000
[    0.513338] ---[ end trace 93d72a36b9146f22 ]---
[    0.516668] Kernel panic - not syncing: Fatal exception in interrupt
[    0.520005] Rebooting in 1 seconds..Press any key to enter the menu

Config and crashlog attached.

	Ingo