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. Yinghai -- 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
