linux-kernel - Re: [3.8-rc7] PCI hotplug wakeup oops

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Date:	Tue, 12 Feb 2013 01:08:42 +0800
From:	Daniel J Blueman <daniel@...ra.org>
To:	Linux Kernel <linux-kernel@...r.kernel.org>,
	Linux PCI <linux-pci@...r.kernel.org>
Cc:	Yijing Wang <wangyijing@...wei.com>,
	Bjorn Helgaas <bhelgaas@...gle.com>
Subject: Re: [3.8-rc7] PCI hotplug wakeup oops

On 11 February 2013 21:03, Daniel J Blueman <daniel@...ra.org> wrote:
> With 3.8-rc7, when unplugging the Thunderbolt ethernet adapter (bus 0a
> [1]) on a Macbook Pro 10,1, we see the PCIe port correctly released:
>
> pciehp 0000:06:03.0:pcie24: Card not present on Slot(3)
> tg3 0000:0a:00.0: tg3_abort_hw timed out, TX_MODE_ENABLE will not
> clear MAC_TX_MODE=ffffffff
> tg3 0000:0a:00.0 eth0: No firmware running
> tg3 0000:0a:00.0 eth0: Link is down
> [sched_delayed] sched: RT throttling activated
> pcieport 0000:00:01.1: System wakeup enabled by ACPI
> pciehp 0000:09:00.0:pcie24: unloading service driver pciehp
> pci_bus 0000:0a: busn_res: [bus 0a] is released
> pci_bus 0000:09: busn_res: [bus 09-0a] is released
>
> After some activity later (eg I can reproduce this by switching to a
> text console and back), often we'll see an oops:
>
> Unable to handle kernel paging request at 0000000000001070
> pci_pme_list_scan+0x3d/0xe0
> Call Trace:
> process_one_work+0x193
> ? process_one_work+0x131
> ? pci_pme_wakeup+0x60
> worker_thread+0x15d
>
> (gdb) list *(pci_pme_list_scan+0x3d)
> 0xffffffff8123f6dd is in pci_pme_list_scan (drivers/pci/pci.c:1556).
> 1551                                    /*
> 1552                                     * If bridge is in low power state, the
> 1553                                     * configuration space of subordinate devices
> 1554                                     * may be not accessible
> 1555                                     */
> 1556                                    if (bridge && bridge->current_state != PCI_D0)
> 1557                                            continue;
> 1558                                    pci_pme_wakeup(pme_dev->dev, NULL);
> 1559                            } else {
> 1560                                    list_del(&pme_dev->list);
>
> Since a panic in vsnprintf happens after the oops (hence I can't catch
> it with EFI pstore), it is almost certainly significant heap
> corruption; this would explain why pme_dev became null (the load has
> been ordered ahead).
>
> I'll see what I can find out with memory poisoning and list debugging.

Enabling a bunch of related debugging, we see pme_dev is non-null and:

BUG: Unable to handle NULL pointer dereference at
pci_bus_read_config_word+0x6c
PGD 26314c067 PUD 2633f9067 PMD 0
Oops: 0000 [#1] SMP
pci_check_pme_status+0x4f
pci_pme_wakeup+0x21
pci_pme_list_scan+0xd5
process_one_work+0x1ca
? process_one_work+0x160
? pci_pme_wakeup+0x60
worker_thread+0x14e

Anyway, it looks like the device being unplugged wasn't removed from
pci_pme_list as pci_pme_active(dev, false) wasn't called.

>From a quick review, I wasn't able to find the right place in the
call-chain which I only see releases the child busses and PCIe port
drivers. Anyone?

Thanks,
  Daniel
-- 
Daniel J Blueman
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