On 5/23/20 10:04 AM, syzbot wrote: > Hello, > > syzbot found the following crash on: > > HEAD commit: c11d28ab Add linux-next specific files for 20200522 > git tree: linux-next > console output: https://syzkaller.appspot.com/x/log.txt?x=17330172100000 > kernel config: https://syzkaller.appspot.com/x/.config?x=3f6dbdea4159fb66 > dashboard link: https://syzkaller.appspot.com/bug?extid=e3c234427cd464510547 > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=122eacba100000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12fffa9a100000 > > The bug was bisected to: > > commit 4ef12f7198023c09ad6d25b652bd8748c965c7fa > Author: Heikki Krogerus <heikki.krogerus@xxxxxxxxxxxxxxx> > Date: Wed May 13 15:18:40 2020 +0000 > > kobject: Make sure the parent does not get released before its children Hi, Greg just sent a revert for this patch: https://lore.kernel.org/lkml/20200523152922.GA224858@xxxxxxxxx/ so all 3 of these reports should be cleared up soon. > bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=146b3d22100000 > final crash: https://syzkaller.appspot.com/x/report.txt?x=166b3d22100000 > console output: https://syzkaller.appspot.com/x/log.txt?x=126b3d22100000 > > IMPORTANT: if you fix the bug, please add the following tag to the commit: > Reported-by: syzbot+e3c234427cd464510547@xxxxxxxxxxxxxxxxxxxxxxxxx > Fixes: 4ef12f719802 ("kobject: Make sure the parent does not get released before its children") > > usb 1-1: USB disconnect, device number 2 > ============================================ > WARNING: possible recursive locking detected > 5.7.0-rc6-next-20200522-syzkaller #0 Not tainted > -------------------------------------------- > kworker/1:1/28 is trying to acquire lock: > ffffffff8a4f3aa8 (media_devnode_lock){+.+.}-{3:3}, at: media_devnode_release+0x1a/0xe0 drivers/media/mc/mc-devnode.c:53 > > but task is already holding lock: > ffffffff8a4f3aa8 (media_devnode_lock){+.+.}-{3:3}, at: media_devnode_unregister+0x1c/0x69 drivers/media/mc/mc-devnode.c:283 > > other info that might help us debug this: > Possible unsafe locking scenario: > > CPU0 > ---- > lock(media_devnode_lock); > lock(media_devnode_lock); > > *** DEADLOCK *** > > May be due to missing lock nesting notation > > 6 locks held by kworker/1:1/28: > #0: ffff88821a8e6138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: __write_once_size include/linux/compiler.h:303 [inline] > #0: ffff88821a8e6138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] > #0: ffff88821a8e6138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: atomic64_set include/asm-generic/atomic-instrumented.h:856 [inline] > #0: ffff88821a8e6138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: atomic_long_set include/asm-generic/atomic-long.h:41 [inline] > #0: ffff88821a8e6138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: set_work_data kernel/workqueue.c:615 [inline] > #0: ffff88821a8e6138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: set_work_pool_and_clear_pending kernel/workqueue.c:642 [inline] > #0: ffff88821a8e6138 ((wq_completion)usb_hub_wq){+.+.}-{0:0}, at: process_one_work+0x844/0x16a0 kernel/workqueue.c:2239 > #1: ffffc90000de7dc0 ((work_completion)(&hub->events)){+.+.}-{0:0}, at: process_one_work+0x878/0x16a0 kernel/workqueue.c:2243 > #2: ffff88809e850218 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:768 [inline] > #2: ffff88809e850218 (&dev->mutex){....}-{3:3}, at: hub_event+0x1b6/0x38f0 drivers/usb/core/hub.c:5522 > #3: ffff88809749e218 (&dev->mutex){....}-{3:3}, at: device_lock include/linux/device.h:768 [inline] > #3: ffff88809749e218 (&dev->mutex){....}-{3:3}, at: usb_disconnect+0x91/0x8d0 drivers/usb/core/hub.c:2208 > #4: ffff8880951c01a8 (&dev->mutex){....}-{3:3}, at: device_release_driver_internal+0x23/0x500 drivers/base/dd.c:1141 > #5: ffffffff8a4f3aa8 (media_devnode_lock){+.+.}-{3:3}, at: media_devnode_unregister+0x1c/0x69 drivers/media/mc/mc-devnode.c:283 > > stack backtrace: > CPU: 1 PID: 28 Comm: kworker/1:1 Not tainted 5.7.0-rc6-next-20200522-syzkaller #0 > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 > Workqueue: usb_hub_wq hub_event > Call Trace: > __dump_stack lib/dump_stack.c:77 [inline] > dump_stack+0x18f/0x20d lib/dump_stack.c:118 > print_deadlock_bug kernel/locking/lockdep.c:2391 [inline] > check_deadlock kernel/locking/lockdep.c:2432 [inline] > validate_chain kernel/locking/lockdep.c:3202 [inline] > __lock_acquire.cold+0x240/0x3e2 kernel/locking/lockdep.c:4380 > lock_acquire+0x1f2/0x8f0 kernel/locking/lockdep.c:4959 > __mutex_lock_common kernel/locking/mutex.c:956 [inline] > __mutex_lock+0x156/0x13c0 kernel/locking/mutex.c:1103 > media_devnode_release+0x1a/0xe0 drivers/media/mc/mc-devnode.c:53 > device_release+0x71/0x200 drivers/base/core.c:1541 > kobject_cleanup lib/kobject.c:701 [inline] > kobject_release lib/kobject.c:732 [inline] > kref_put include/linux/kref.h:65 [inline] > kobject_put+0x1c8/0x2f0 lib/kobject.c:749 > cdev_device_del+0x69/0x80 fs/char_dev.c:575 > media_devnode_unregister+0x2b/0x69 drivers/media/mc/mc-devnode.c:285 > media_device_unregister drivers/media/mc/mc-device.c:846 [inline] > media_device_unregister+0x3da/0x570 drivers/media/mc/mc-device.c:800 > uvc_unregister_video+0x1b6/0x210 drivers/media/usb/uvc/uvc_driver.c:1960 > uvc_disconnect+0xbc/0x160 drivers/media/usb/uvc/uvc_driver.c:2270 > usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:436 > __device_release_driver drivers/base/dd.c:1113 [inline] > device_release_driver_internal+0x432/0x500 drivers/base/dd.c:1144 > bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:533 > device_del+0x481/0xd30 drivers/base/core.c:2839 > usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1245 > usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2217 > hub_port_connect drivers/usb/core/hub.c:5059 [inline] > hub_port_connect_change drivers/usb/core/hub.c:5348 [inline] > port_event drivers/usb/core/hub.c:5494 [inline] > hub_event+0x17ca/0x38f0 drivers/usb/core/hub.c:5576 > process_one_work+0x965/0x16a0 kernel/workqueue.c:2268 > worker_thread+0x96/0xe20 kernel/workqueue.c:2414 > kthread+0x3b5/0x4a0 kernel/kthread.c:291 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:351 > > > --- > This bug is generated by a bot. It may contain errors. > See https://goo.gl/tpsmEJ for more information about syzbot. > syzbot engineers can be reached at syzkaller@xxxxxxxxxxxxxxxx. > > syzbot will keep track of this bug report. See: > https://goo.gl/tpsmEJ#status for how to communicate with syzbot. > For information about bisection process see: https://goo.gl/tpsmEJ#bisection > syzbot can test patches for this bug, for details see: > https://goo.gl/tpsmEJ#testing-patches > -- ~Randy Reported-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
