From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> After commit bcdde7e221a8 (sysfs: make __sysfs_remove_dir() recursive) I'm seeing traces analogous to the one below in Thunderbolt testing: WARNING: CPU: 3 PID: 76 at /scratch/rafael/work/linux-pm/fs/sysfs/group.c:214 sysfs_remove_group+0x59/0xe0() sysfs group ffffffff81c6c500 not found for kobject '0000:08' Modules linked in: fuse hidp af_packet xt_tcpudp xt_pkttype xt_LOG xt_limit ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_raw ipt_REJECT iptable_raw xt_CT iptable_filter ip6table_mangle nf_conntrack_netbios_ns nf_conntrack_broadcast nf_conntrack_ipv4 nf_defrag_ipv4 ip_tables xt_conntrack nf_conntrack rfcomm ip6table_filter bnep ip6_tables x_tables arc4 ath9k mac80211 x86_pkg_temp_thermal intel_powerclamp coretemp crct10dif_pclmul crc32_pclmul iTCO_wdt crc32c_intel iTCO_vendor_support ghash_clmulni_intel aesni_intel ablk_helper acer_wmi sparse_keymap ath9k_common ath9k_hw cryptd lrw gf128mul ath3k glue_helper aes_x86_64 btusb microcode ath pcspkr joydev uvcvideo serio_raw videobuf2_core i2c_i801 videodev snd_hda_codec_hdmi cfg80211 videobuf2_vmalloc tg3 videobuf2_memops sg ptp pps_core lpc_ich mfd_core snd_hda_codec_realtek bluetooth hid_logitech_dj rfkill snd_hda_intel snd_hda_codec shpchp battery ac wmi acpi_cpufreq edd snd_usb_audio snd_pcm snd_page_alloc snd_hwdep snd_usbmidi_lib snd_rawmidi snd_seq snd_timer snd_seq_device snd soundcore autofs4 xhci_hcd processor scsi_dh_hp_sw scsi_dh_rdac scsi_dh_emc scsi_dh_alua scsi_dh CPU: 3 PID: 76 Comm: kworker/u16:7 Not tainted 3.13.0-rc1+ #76 Hardware name: Acer Aspire S5-391/Venus , BIOS V1.02 05/29/2012 Workqueue: kacpi_hotplug acpi_hotplug_work_fn 0000000000000009 ffff8801644b9ac8 ffffffff816b23bf 0000000000000007 ffff8801644b9b18 ffff8801644b9b08 ffffffff81046607 ffff88016925b800 0000000000000000 ffffffff81c6c500 ffff88016924f928 ffff88016924f800 Call Trace: [<ffffffff816b23bf>] dump_stack+0x4e/0x71 [<ffffffff81046607>] warn_slowpath_common+0x87/0xb0 [<ffffffff810466d1>] warn_slowpath_fmt+0x41/0x50 [<ffffffff811e42ef>] ? sysfs_get_dirent_ns+0x6f/0x80 [<ffffffff811e5389>] sysfs_remove_group+0x59/0xe0 [<ffffffff8149f00b>] dpm_sysfs_remove+0x3b/0x50 [<ffffffff81495818>] device_del+0x58/0x1c0 [<ffffffff814959c8>] device_unregister+0x48/0x60 [<ffffffff813254fe>] pci_remove_bus+0x6e/0x80 [<ffffffff81325548>] pci_remove_bus_device+0x38/0x110 [<ffffffff8132555d>] pci_remove_bus_device+0x4d/0x110 [<ffffffff81325639>] pci_stop_and_remove_bus_device+0x19/0x20 [<ffffffff813418d0>] disable_slot+0x20/0xe0 [<ffffffff81341a38>] acpiphp_check_bridge+0xa8/0xd0 [<ffffffff813427ad>] hotplug_event+0x17d/0x220 [<ffffffff81342880>] hotplug_event_work+0x30/0x70 [<ffffffff8136d665>] acpi_hotplug_work_fn+0x18/0x24 [<ffffffff81061331>] process_one_work+0x261/0x450 [<ffffffff81061a7e>] worker_thread+0x21e/0x370 [<ffffffff81061860>] ? rescuer_thread+0x300/0x300 [<ffffffff81068342>] kthread+0xd2/0xe0 [<ffffffff81068270>] ? flush_kthread_worker+0x70/0x70 [<ffffffff816c19bc>] ret_from_fork+0x7c/0xb0 [<ffffffff81068270>] ? flush_kthread_worker+0x70/0x70 (Mika Westerberg sees them too in his tests). Some investigation documented in kernel bug #65281 lead me to the conclusion that the source of the problem is the device_del() in pci_stop_dev() as it now causes the sysfs directory of the device to be removed recursively along with all of its subdirectories. That includes the sysfs directory of the device's subordinate bus (dev->subordinate) and its "power" group. Consequently, when pci_remove_bus() is called for dev->subordinate in pci_remove_bus_device(), it calls device_unregister(&bus->dev), but at this point the sysfs directory of bus->dev doesn't exist any more and its "power" group doesn't exist either. Thus, when dpm_sysfs_remove() called from device_del() tries to remove that group, it triggers the above warning. That indicates a logical mistake in the design of pci_stop_and_remove_bus_device(), which causes bus device objects to be left behind their parents (bridge device objects) and can be fixed by moving the device_del() from pci_stop_dev() into pci_destroy_dev(), so pci_remove_bus() can be called for the device's subordinate bus before the device itself is unregistered from the hierarchy. Still, the driver, if any, should be detached from the device in pci_stop_dev(), so use device_release_driver() directly from there. References: https://bugzilla.kernel.org/show_bug.cgi?id=65281#c6 Reported-by: Mika Westerberg <mika.westerberg@xxxxxxxxxxxxxxx> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> --- drivers/pci/remove.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) Index: linux-pm/drivers/pci/remove.c =================================================================== --- linux-pm.orig/drivers/pci/remove.c +++ linux-pm/drivers/pci/remove.c @@ -24,7 +24,7 @@ static void pci_stop_dev(struct pci_dev if (dev->is_added) { pci_proc_detach_device(dev); pci_remove_sysfs_dev_files(dev); - device_del(&dev->dev); + device_release_driver(&dev->dev); dev->is_added = 0; } @@ -34,6 +34,8 @@ static void pci_stop_dev(struct pci_dev static void pci_destroy_dev(struct pci_dev *dev) { + device_del(&dev->dev); + down_write(&pci_bus_sem); list_del(&dev->bus_list); up_write(&pci_bus_sem); -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
