Re: mmotm 2009-07-30-05-01 uploaded

[Pekka Enberg <penberg@cs.helsinki.fi>]

Hi Kame,

On Tue, Aug 4, 2009 at 6:12 AM, KAMEZAWA
Hiroyuki<kamezawa.hiroyu@jp.fujitsu.com> wrote:
> On Thu, 30 Jul 2009 05:04:28 -0700
> akpm@linux-foundation.org wrote:
>
>> The mm-of-the-moment snapshot 2009-07-30-05-01 has been uploaded to
>>
>>    http://userweb.kernel.org/~akpm/mmotm/
>>
>> and will soon be available at
>>
>>    git://git.zen-sources.org/zen/mmotm.git
>>
>
> I'm sorry if already reported. When using SLQB, this warning is shown.
>
>
> [    0.000000] ------------[ cut here ]------------
> [    0.000000] WARNING: at kernel/lockdep.c:2131 trace_hardirqs_on_caller+0xb1/0x12f()
> [    0.000000] Hardware name: VMware Virtual Platform
> [    0.000000] Modules linked in:
> [    0.000000] Pid: 0, comm: swapper Not tainted 2.6.31-rc4-mm1 #1
> [    0.000000] Call Trace:
> [    0.000000]  [<ffffffff81060189>] ? trace_hardirqs_on_caller+0xb1/0x12f
> [    0.000000]  [<ffffffff8103e14a>] warn_slowpath_common+0x77/0xa4
> [    0.000000]  [<ffffffff814c8f4c>] ? _spin_unlock_irq+0x2b/0x30
> [    0.000000]  [<ffffffff8103e186>] warn_slowpath_null+0xf/0x11
> [    0.000000]  [<ffffffff81060189>] trace_hardirqs_on_caller+0xb1/0x12f
> [    0.000000]  [<ffffffff81060214>] trace_hardirqs_on+0xd/0xf
> [    0.000000]  [<ffffffff814c8f4c>] _spin_unlock_irq+0x2b/0x30
> [    0.000000]  [<ffffffff814c89f2>] ? __down_write_nested+0x1c/0xa9
> [    0.000000]  [<ffffffff814c8a0f>] __down_write_nested+0x39/0xa9
> [    0.000000]  [<ffffffff810b97f6>] ? kmem_cache_open+0x2b1/0x460
> [    0.000000]  [<ffffffff814c8a8a>] __down_write+0xb/0xd
> [    0.000000]  [<ffffffff814c802d>] down_write+0x4a/0x4e
> [    0.000000]  [<ffffffff810b97f6>] ? kmem_cache_open+0x2b1/0x460
> [    0.000000]  [<ffffffff810b97f6>] kmem_cache_open+0x2b1/0x460
> [    0.000000]  [<ffffffff818247bc>] kmem_cache_init+0x4d/0x352
> [    0.000000]  [<ffffffff8181b837>] ? mem_init+0x156/0x161
> [    0.000000]  [<ffffffff81808adf>] start_kernel+0x1cd/0x3ab
> [    0.000000]  [<ffffffff8180829a>] x86_64_start_reservations+0xaa/0xae
> [    0.000000]  [<ffffffff8180837f>] x86_64_start_kernel+0xe1/0xe8
> [    0.000000] ---[ end trace 4eaa2a86a8e2da22 ]---
> [    0.000000] start_kernel(): bug: interrupts were enabled *very* early, fixing it
>
> This is because down_write() uses spin_lock_irq(), not spin_lock_irqsave().
> I think this is sane because down_write() is not called under irq-disabled.
> By this, irq is enabled before init_IRQ().
>
> SLUB don't have this bug because it uses special routine for initializing
> kmalloc area. (See slub.c::create_kmalloc_cache(), it's commented.)

Should be fixed by this:

http://git.kernel.org/?p=linux/kernel/git/penberg/slab-2.6.git;a=commitdiff;h=791738e83b97d2d4fc631d68483430200035bdf3