Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754268AbZI3VYp (ORCPT ); Wed, 30 Sep 2009 17:24:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752215AbZI3VYo (ORCPT ); Wed, 30 Sep 2009 17:24:44 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:50238 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751697AbZI3VYn (ORCPT ); Wed, 30 Sep 2009 17:24:43 -0400 From: "Rafael J. Wysocki" To: Danny Feng Subject: Re: [PATCH] acpi: pci_root: fix NULL pointer deref after resume from suspend Date: Wed, 30 Sep 2009 23:26:14 +0200 User-Agent: KMail/1.12.1 (Linux/2.6.31-rjw; KDE/4.3.1; x86_64; ; ) Cc: Alex Chiang , lenb@kernel.org, bjorn.helgaas@hp.com, andrew.patterson@hp.com, jbarnes@virtuousgeek.org, linux-acpi@vger.kernel.org, linux-kernel@vger.kernel.org References: <1254119480-9730-1-git-send-email-dfeng@redhat.com> <200909292212.42697.rjw@sisk.pl> <4AC2C687.8060601@redhat.com> In-Reply-To: <4AC2C687.8060601@redhat.com> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Message-Id: <200909302326.14183.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 5419 Lines: 132 On Wednesday 30 September 2009, Danny Feng wrote: > On 09/30/2009 04:12 AM, Rafael J. Wysocki wrote: > > On Tuesday 29 September 2009, Danny Feng wrote: > >> On 09/29/2009 01:38 AM, Alex Chiang wrote: > >>> Hi Xiaotian, > >>> > >>> Thanks for the bug report. > >>> > >>> * Xiaotian Feng: > >>> > >>>> commit 275582 introduces acpi_get_pci_dev(), but pdev->subordinate > >>>> can be NULL, then a NULL was passed to pci_get_slot, this results > >>>> the kernel oops when resume from suspend. > >>>> > >>>> This patch resolves following kernel oops: > >>>> BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 > >>>> IP: [] pci_get_slot+0x4c/0x8c > >>>> > >>>> Signed-off-by: Xiaotian Feng > >>>> --- > >>>> drivers/acpi/pci_root.c | 6 +++++- > >>>> 1 files changed, 5 insertions(+), 1 deletions(-) > >>>> > >>>> diff --git a/drivers/acpi/pci_root.c b/drivers/acpi/pci_root.c > >>>> index 3112221..3c35144 100644 > >>>> --- a/drivers/acpi/pci_root.c > >>>> +++ b/drivers/acpi/pci_root.c > >>>> @@ -387,7 +387,11 @@ struct pci_dev *acpi_get_pci_dev(acpi_handle handle) > >>>> if (!pdev || hnd == handle) > >>>> break; > >>>> > >>>> - pbus = pdev->subordinate; > >>>> + if (pdev->subordinate) > >>>> + pbus = pdev->subordinate; > >>>> + else > >>>> + pbus = pdev->bus; > >>>> + > >>>> > >>> I'm a little confused by this. If we start from the PCI root > >>> bridge and walk back down the hierarchy, shouldn't everything > >>> between the root and the device be a P2P bridge? > >>> > >>> What is special about suspend/resume that causes the subordinate > >>> bus to become NULL? > >>> > >>> Can you send the full stacktrace? > >>> > >>> Thanks. > >>> > >>> /ac > >>> > >>> > >>> > >> the full call trace is here: > >> > >> BUG: unable to handle kernel NULL pointer dereference at 0000000000000028 > >> IP: [] pci_get_slot+0x4c/0x8c > >> PGD 208b9d067 PUD 208a89067 PMD 0 > >> Oops: 0000 [#1] SMP > >> last sysfs file: /sys/power/state > >> CPU 0 > >> Modules linked in: fuse radeon ttm drm_kms_helper drm i2c_algo_bit sco > >> bridge stp llc bnep l2cap bluetooth sunrpc ip6t_REJECT nf_conntrack_ipv6 > >> ip6table_filter ip6_tables ipv6 dm_multipath uinput snd_hda_codec_analog > >> snd_hda_intel snd_hda_codec snd_hwdep e1000e snd_pcm snd_timer i2c_i801 > >> i2c_core snd soundcore snd_page_alloc iTCO_wdt iTCO_vendor_support > >> serio_raw ppdev parport_pc parport pcspkr dcdbas ata_generic pata_acpi > >> [last unloaded: speedstep_lib] > >> Pid: 35, comm: kacpi_hotplug Not tainted 2.6.32-rc2 #3 OptiPlex 760 > >> RIP: 0010:[] [] pci_get_slot+0x4c/0x8c > >> RSP: 0018:ffff88022ee69aa0 EFLAGS: 00010286 > >> RAX: 0000000000000000 RBX: ffff88022e9b1090 RCX: 00000000000000a0 > >> RDX: 000000000000002f RSI: ffffffff8168ab38 RDI: ffffffff8168ab38 > >> RBP: ffff88022ee69ac0 R08: ffffffff8168ab30 R09: ffff880100000000 > >> R10: ffffffff8168ab50 R11: 0000000000000000 R12: 0000000000000000 > >> R13: 0000000000000001 R14: ffff88022f712000 R15: ffff88022f710dd0 > >> FS: 0000000000000000(0000) GS:ffff880028200000(0000) > >> knlGS:0000000000000000 > >> CS: 0010 DS: 0018 ES: 0018 CR0: 000000008005003b > >> CR2: 0000000000000028 CR3: 00000001fc298000 CR4: 00000000000406f0 > >> DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > >> DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > >> Process kacpi_hotplug (pid: 35, threadinfo ffff88022ee68000, task > >> ffff88022eefc120) > >> Stack: > >> 0000000000000018 ffff88022e9b1090 ffff88020880e9c0 0000000000000000 > >> <0> ffff88022ee69b30 ffffffff81254193 0000000000000000 ffff88022ee69ae0 > >> <0> ffff88020880e340 ffff88020880ee38 ffff88022f710208 0000000000000001 > >> Call Trace: > >> [] acpi_get_pci_dev+0x106/0x167 > > > > Have you checked (using gdb) which source code line this corresponds to? > > > Yep, the code line corresponds to > pdev = pci_get_slot(pbus, PCI_DEVFN(dev, fn)); > > Also gdb shows pci_bus->devices has offset of 0x28. > > I've put some check in acpi_get_pci_dev, it shows that pbus is NULL when > the panic happens. OK, thanks. > >> [] acpi_pci_bind+0x1c/0x86 > >> [] ? sysfs_create_file+0x2a/0x2c > >> [] acpi_add_single_object+0x964/0xa0c > >> [] acpi_bus_check_add+0xe0/0x138 > >> [] acpi_bus_scan+0x68/0xa0 > >> [] acpi_bus_add+0x2a/0x2e > > > > This looks like a device has just been discovered. > > > >> [] hotplug_dock_devices+0x114/0x13e > >> [] acpi_dock_deferred_cb+0xbf/0x192 > > > > Have the machine been docked while suspended? > I was confused too..I didn't touch anything just suspend and then power > up. Are there some devices unplugged or ejected at suspend stage? Well, that's what I'd like to find out. Can you please build the kernel with CONFIG_PM_VERBOSE set and with the $subject patch applied and post a dmesg output from it containing at least one suspend-resume cycle? Best, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/