Re: [Xen-devel] [PATCH 2/2] ACPI / cpuidle: Fix NULL pointer issues when cpuidle is disabled

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Tue, Jan 15, 2013 at 11:45:08PM +0100, Rafael J. Wysocki wrote:
> On Tuesday, January 15, 2013 05:23:24 PM Konrad Rzeszutek Wilk wrote:
> > If cpuidle is disabled, that means the:
> > 
> >     per_cpu(acpi_cpuidle_device, pr->id)
> > 
> > is set to NULL as the acpi_processor_power_init ends up failing at
> > 
> >      retval = cpuidle_register_driver(&acpi_idle_driver)
> > 
> > (in acpi_processor_power_init) and never sets the per_cpu idle
> > device. So when acpi_processor_hotplug on CPU online notification tries
> > to reference said device it crashes:
> > 
> > cpu 3 spinlock event irq 62
> > BUG: unable to handle kernel NULL pointer dereference at 0000000000000004
> > IP: [<ffffffff81381013>] acpi_processor_setup_cpuidle_cx+0x3f/0x105
> > PGD a259b067 PUD ab38b067 PMD 0
> > Oops: 0002 [#1] SMP
> > odules linked in: dm_multipath dm_mod xen_evtchn iscsi_boot_sysfs iscsi_tcp 
> > libiscsi_tcp libiscsi scsi_transport_iscsi libcrc32c crc32c nouveau mxm_wmi 
> > wmi radeon ttm sg sr_mod sd_mod cdrom ata_generic ata_piix libata 
> > crc32c_intel scsi_mod atl1c i915 fbcon tileblit font bitblit softcursor 
> > drm_kms_helper video xen_blkfront xen_netfront fb_sys_fops sysimgblt 
> > sysfillrect syscopyarea xenfs xen_privcmd mperf
> > CPU 1
> > Pid: 3047, comm: bash Not tainted 3.8.0-rc3upstream-00250-g165c029 #1 MSI 
> > MS-7680/H61M-P23 (MS-7680)
> > RIP: e030:[<ffffffff81381013>]  [<ffffffff81381013>] 
> > acpi_processor_setup_cpuidle_cx+0x3f/0x105
> > RSP: e02b:ffff88001742dca8  EFLAGS: 00010202
> > RAX: 0000000000010be9 RBX: ffff8800a0a61800 RCX: ffff880105380000
> > RDX: 0000000000000003 RSI: 0000000000000200 RDI: ffff8800a0a61800
> > RBP: ffff88001742dce8 R08: ffffffff81812360 R09: 0000000000000200
> > R10: aaaaaaaaaaaaaaaa R11: 0000000000000001 R12: ffff8800a0a61800
> > R13: 00000000ffffff01 R14: 0000000000000000 R15: ffffffff81a907a0
> > FS:  00007fd6942f7700(0000) GS:ffff880105280000(0000) knlGS:0000000000000000
> > CS:  e033 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000000000004 CR3: 00000000a6773000 CR4: 0000000000042660
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
> > Process bash (pid: 3047, threadinfo ffff88001742c000, task ffff880017944000)
> > Stack:
> >  0000000000000150 ffff880100f59e00 ffff88001742dcd8 ffff8800a0a61800
> >  0000000000000000 00000000ffffff01 0000000000000000 ffffffff81a907a0
> >  ffff88001742dd18 ffffffff813815b1 ffff88001742dd08 ffffffff810ae336
> > Call Trace:
> >  [<ffffffff813815b1>] acpi_processor_hotplug+0x7c/0x9f
> >  [<ffffffff810ae336>] ? schedule_delayed_work_on+0x16/0x20
> >  [<ffffffff8137ee8f>] acpi_cpu_soft_notify+0x90/0xca
> >  [<ffffffff8166023d>] notifier_call_chain+0x4d/0x70
> >  [<ffffffff810bc369>] __raw_notifier_call_chain+0x9/0x10
> >  [<ffffffff81094a4b>] __cpu_notify+0x1b/0x30
> >  [<ffffffff81652cf7>] _cpu_up+0x103/0x14b
> >  [<ffffffff81652e18>] cpu_up+0xd9/0xec
> >  [<ffffffff8164a254>] store_online+0x94/0xd0
> >  [<ffffffff814122fb>] dev_attr_store+0x1b/0x20
> >  [<ffffffff81216404>] sysfs_write_file+0xf4/0x170
> > 
> > This patch fixes it.
> 
> This appears to be -stable material too.  Which -stable kernels should it
> be applied to?

Oh, 3.1 and onward. I am basing that on 62027aea since that allowed
subsystem to disable the cpuidle API.

Thanks!
> 
> Rafael
> 
> 
> > Cc: Rafael J. Wysocki <rjw@xxxxxxx>
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > ---
> >  drivers/acpi/processor_idle.c | 3 +++
> >  1 file changed, 3 insertions(+)
> > 
> > diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c
> > index f1a5da4..fea6f8d 100644
> > --- a/drivers/acpi/processor_idle.c
> > +++ b/drivers/acpi/processor_idle.c
> > @@ -958,6 +958,9 @@ static int acpi_processor_setup_cpuidle_cx(struct 
> > acpi_processor *pr)
> >             return -EINVAL;
> >     }
> >  
> > +   if (!dev)
> > +           return -EINVAL;
> > +
> >     dev->cpu = pr->id;
> >  
> >     if (max_cstate == 0)
> > 
> -- 
> I speak only for myself.
> Rafael J. Wysocki, Intel Open Source Technology Center.

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