On Tuesday, November 26, 2013 11:34:24 AM Yinghai Lu wrote: > On Mon, Nov 25, 2013 at 7:38 PM, Bjorn Helgaas <bhelgaas@xxxxxxxxxx> wrote: > > On Mon, Nov 25, 2013 at 6:28 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote: > >> Mutliple removing via /sys will call pci_destroy_dev two times. > >> > >> | When concurent removing pci devices which are in the same pci subtree > >> | via sysfs, such as: > >> | echo -n 1 > /sys/bus/pci/devices/0000\:10\:00.0/remove ; echo -n 1 > > >> | /sys/bus/pci/devices/0000\:1a\:01.0/remove > >> | (1a:01.0 device is downstream from the 10:00.0 bridge) > >> | > >> | the following warning will show: > >> | [ 1799.280918] ------------[ cut here ]------------ > >> | [ 1799.336199] WARNING: CPU: 7 PID: 126 at lib/list_debug.c:53 __list_del_entry+0x63/0xd0() > >> | [ 1799.433093] list_del corruption, ffff8807b4a7c000->next is LIST_POISON1 (dead000000100100) > >> | [ 1800.276623] CPU: 7 PID: 126 Comm: kworker/u512:1 Tainted: G W 3.12.0-rc5+ #196 > >> | [ 1800.508918] Workqueue: sysfsd sysfs_schedule_callback_work > >> | [ 1800.574703] 0000000000000009 ffff8807adbadbd8 ffffffff8168b26c ffff8807c27d08a8 > >> | [ 1800.663860] ffff8807adbadc28 ffff8807adbadc18 ffffffff810711dc ffff8807adbadc68 > >> | [ 1800.753130] ffff8807b4a7c000 ffff8807b4a7c000 ffff8807ad089c00 0000000000000000 > >> | [ 1800.842282] Call Trace: > >> | [ 1800.871651] [<ffffffff8168b26c>] dump_stack+0x55/0x76 > >> | [ 1800.933301] [<ffffffff810711dc>] warn_slowpath_common+0x8c/0xc0 > >> | [ 1801.005283] [<ffffffff810712c6>] warn_slowpath_fmt+0x46/0x50 > >> | [ 1801.074081] [<ffffffff8135a343>] __list_del_entry+0x63/0xd0 > >> | [ 1801.141839] [<ffffffff8135a3c1>] list_del+0x11/0x40 > >> | [ 1801.201320] [<ffffffff813734da>] pci_remove_bus_device+0x6a/0xe0 > >> | [ 1801.274279] [<ffffffff8137356e>] pci_stop_and_remove_bus_device+0x1e/0x30 > >> | [ 1801.356606] [<ffffffff8137b20b>] remove_callback+0x2b/0x40 > >> | [ 1801.423412] [<ffffffff81251848>] sysfs_schedule_callback_work+0x18/0x60 > >> | [ 1801.503744] [<ffffffff8108eab5>] process_one_work+0x1f5/0x540 > >> | [ 1801.573640] [<ffffffff8108ea53>] ? process_one_work+0x193/0x540 > >> | [ 1801.645616] [<ffffffff8108f2ac>] worker_thread+0x11c/0x370 > >> | [ 1801.712337] [<ffffffff8108f190>] ? rescuer_thread+0x350/0x350 > >> | [ 1801.782178] [<ffffffff8109731d>] kthread+0xed/0x100 > >> | [ 1801.841661] [<ffffffff81097230>] ? kthread_create_on_node+0x160/0x160 > >> | [ 1801.919919] [<ffffffff8169cc3c>] ret_from_fork+0x7c/0xb0 > >> | [ 1801.984608] [<ffffffff81097230>] ? kthread_create_on_node+0x160/0x160 > >> | [ 1802.062825] ---[ end trace d77f2054de000fb7 ]--- > >> | > >> | This issue is related to the bug 54411: > >> | https://bugzilla.kernel.org/show_bug.cgi?id=54411 > >> > >> Add is_removed to record if pci_destroy_dev is called already. > >> > >> During second calling, still have extra dev ref hold via > >> device_schedule_call, so we are safe to check dev->is_removed. > >> > >> It fixs the problem In Gu's test. > >> > >> -v2: add partial changelog from Gu Zheng <guz.fnst@xxxxxxxxxxxxxx> > >> refresh after patch of moving device_del from Rafael. > >> > >> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx> > >> --- > >> drivers/pci/remove.c | 8 +++++--- > >> include/linux/pci.h | 1 + > >> 2 files changed, 6 insertions(+), 3 deletions(-) > >> > >> diff --git a/drivers/pci/remove.c b/drivers/pci/remove.c > >> index f452148..b090cec 100644 > >> --- a/drivers/pci/remove.c > >> +++ b/drivers/pci/remove.c > >> @@ -20,9 +20,11 @@ static void pci_stop_dev(struct pci_dev *dev) > >> > >> static void pci_destroy_dev(struct pci_dev *dev) > >> { > >> - device_del(&dev->dev); > >> - > >> - put_device(&dev->dev); > >> + if (!dev->is_removed) { > >> + device_del(&dev->dev); > >> + dev->is_removed = 1; > > > > As Rafael pointed out, this looks like a race. What prevents two > > concurrent calls to pci_destroy_dev() from seeing "dev->is_removed == > > 0" and both calling device_del() on the same device? > > I don't think that is going to happen. as those two pci_destroy_dev is > serialized > during > echo -n 1 > /sys/bus/pci/devices/0000\:10\:00.0/remove ; echo -n 1 > > /sys/bus/pci/devices/0000\:1a\:01.0/remove > is called. And what exactly does serialize that with the removals started via trim_stale_devices() from acpiphp_check_bridge()? Rafael -- 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
