On Thu, 2014-10-02 at 08:26 -0600, Bjorn Helgaas wrote: > [+ Alex, linux-pci, kvm] > > On Thu, Oct 2, 2014 at 4:11 AM, <bugzilla-daemon@xxxxxxxxxxxxxxxxxxx> wrote: > > https://bugzilla.kernel.org/show_bug.cgi?id=85441 > > > > I retried the same using kernel 3.17-rc7; the Python process messing with /sys > > fs still hangs. I have not been able to reproduce the QEMU hang, but when I > > tried, got the LOCKDEP error report below: I replied in the bz, but for any spectators, the 3.17 deadlock is new to 3.17 and fixed by this, which will hopefully be included in 3.17.1: https://lkml.org/lkml/2014/9/29/745 I believe the locking issues in older kernels are already fixed in newer kernels. Thanks, Alex > > ====================================================== > > [ INFO: possible circular locking dependency detected ] > > 3.17.0-rc7+ #2 Tainted: G E > > ------------------------------------------------------- > > python3/2563 is trying to acquire lock: > > (&group->device_lock){+.+.+.}, at: [<ffffffffa0196ef4>] > > vfio_group_get_device+0x24/0xb0 [vfio] > > > > but task is already holding lock: > > (driver_lock){+.+.+.}, at: [<ffffffffa01d01cd>] vfio_pci_remove+0x1d/0x60 > > [vfio_pci] > > > > which lock already depends on the new lock. > > > > > > the existing dependency chain (in reverse order) is: > > > > -> #1 (driver_lock){+.+.+.}: > > [<ffffffff810bc650>] lock_acquire+0xb0/0x140 > > [<ffffffff817602e0>] mutex_lock_nested+0x50/0x4c0 > > [<ffffffffa01d0618>] vfio_pci_open+0x38/0x270 [vfio_pci] > > [<ffffffffa0197c35>] vfio_group_fops_unl_ioctl+0x265/0x490 [vfio] > > [<ffffffff811fc160>] do_vfs_ioctl+0x300/0x520 > > [<ffffffff811fc401>] SyS_ioctl+0x81/0xa0 > > [<ffffffff817633ad>] system_call_fastpath+0x1a/0x1f > > > > -> #0 (&group->device_lock){+.+.+.}: > > [<ffffffff810bc532>] __lock_acquire+0x1c22/0x1c90 > > [<ffffffff810bc650>] lock_acquire+0xb0/0x140 > > [<ffffffff817602e0>] mutex_lock_nested+0x50/0x4c0 > > [<ffffffffa0196ef4>] vfio_group_get_device+0x24/0xb0 [vfio] > > [<ffffffffa019737f>] vfio_del_group_dev+0x4f/0x140 [vfio] > > [<ffffffffa01d01d9>] vfio_pci_remove+0x29/0x60 [vfio_pci] > > [<ffffffff813d838b>] pci_device_remove+0x3b/0xb0 > > [<ffffffff814c874f>] __device_release_driver+0x7f/0xf0 > > [<ffffffff814c87e5>] device_release_driver+0x25/0x40 > > [<ffffffff814c755f>] unbind_store+0xbf/0xe0 > > [<ffffffff814c6924>] drv_attr_store+0x24/0x40 > > [<ffffffff81263a44>] sysfs_kf_write+0x44/0x60 > > [<ffffffff81263347>] kernfs_fop_write+0xe7/0x170 > > [<ffffffff811e84c7>] vfs_write+0xb7/0x1f0 > > [<ffffffff811e9079>] SyS_write+0x49/0xb0 > > [<ffffffff817633ad>] system_call_fastpath+0x1a/0x1f > > > > other info that might help us debug this: > > > > Possible unsafe locking scenario: > > > > CPU0 CPU1 > > ---- ---- > > lock(driver_lock); > > lock(&group->device_lock); > > lock(driver_lock); > > lock(&group->device_lock); > > > > *** DEADLOCK *** > > > > 6 locks held by python3/2563: > > #0: (sb_writers#5){.+.+.+}, at: [<ffffffff811e85c3>] vfs_write+0x1b3/0x1f0 > > #1: (&of->mutex){+.+.+.}, at: [<ffffffff8126331b>] > > kernfs_fop_write+0xbb/0x170 > > #2: (s_active#3){++++.+}, at: [<ffffffff81263323>] > > kernfs_fop_write+0xc3/0x170 > > #3: (&dev->mutex){......}, at: [<ffffffff814c754f>] unbind_store+0xaf/0xe0 > > #4: (&dev->mutex){......}, at: [<ffffffff814c87dd>] > > device_release_driver+0x1d/0x40 > > #5: (driver_lock){+.+.+.}, at: [<ffffffffa01d01cd>] vfio_pci_remove+0x1d/0x60 > > [vfio_pci] > > > > stack backtrace: > > CPU: 1 PID: 2563 Comm: python3 Tainted: G E 3.17.0-rc7+ #2 > > Hardware name: To Be Filled By O.E.M. To Be Filled By O.E.M./FM2A88X Extreme6+, > > BIOS P3.30 07/31/2014 > > ffffffff826c0870 ffff88038fcdbb60 ffffffff8175971d ffffffff826c0870 > > ffff88038fcdbba0 ffffffff817550e5 ffff88038fcdbbf0 ffff88040bdc4dc0 > > 0000000000000005 ffff88040bdc4d98 ffff88040bdc4dc0 ffff88040bdc4440 > > Call Trace: > > [<ffffffff8175971d>] dump_stack+0x45/0x56 > > [<ffffffff817550e5>] print_circular_bug+0x1f9/0x207 > > [<ffffffff810bc532>] __lock_acquire+0x1c22/0x1c90 > > [<ffffffff810b73ba>] ? __bfs+0x10a/0x220 > > [<ffffffff810bc650>] lock_acquire+0xb0/0x140 > > [<ffffffffa0196ef4>] ? vfio_group_get_device+0x24/0xb0 [vfio] > > [<ffffffff817602e0>] mutex_lock_nested+0x50/0x4c0 > > [<ffffffffa0196ef4>] ? vfio_group_get_device+0x24/0xb0 [vfio] > > [<ffffffff810b96fa>] ? mark_held_locks+0x6a/0x90 > > [<ffffffffa0196ef4>] vfio_group_get_device+0x24/0xb0 [vfio] > > [<ffffffffa019737f>] vfio_del_group_dev+0x4f/0x140 [vfio] > > [<ffffffff810b993d>] ? trace_hardirqs_on+0xd/0x10 > > [<ffffffffa01d01d9>] vfio_pci_remove+0x29/0x60 [vfio_pci] > > [<ffffffff813d838b>] pci_device_remove+0x3b/0xb0 > > [<ffffffff814c874f>] __device_release_driver+0x7f/0xf0 > > [<ffffffff814c87e5>] device_release_driver+0x25/0x40 > > [<ffffffff814c755f>] unbind_store+0xbf/0xe0 > > [<ffffffff814c6924>] drv_attr_store+0x24/0x40 > > [<ffffffff81263a44>] sysfs_kf_write+0x44/0x60 > > [<ffffffff81263347>] kernfs_fop_write+0xe7/0x170 > > [<ffffffff811e84c7>] vfs_write+0xb7/0x1f0 > > [<ffffffff811e9079>] SyS_write+0x49/0xb0 > > [<ffffffff817633ad>] system_call_fastpath+0x1a/0x1f > > ====================================================== > > -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
