On Sun, 2019-08-11 at 06:11 +0100, Sean Young wrote: > syzbot reports an error on flush_request_modules() for the second device. > This workqueue was never initialised so simply remove the offending line. > > usb 1-1: USB disconnect, device number 2 > em28xx 1-1:1.153: Disconnecting em28xx #1 > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 12 at kernel/workqueue.c:3031 > __flush_work.cold+0x2c/0x36 kernel/workqueue.c:3031 > Kernel panic - not syncing: panic_on_warn set ... > CPU: 0 PID: 12 Comm: kworker/0:1 Not tainted 5.3.0-rc2+ #25 > 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+0xca/0x13e lib/dump_stack.c:113 > panic+0x2a3/0x6da kernel/panic.c:219 > __warn.cold+0x20/0x4a kernel/panic.c:576 > report_bug+0x262/0x2a0 lib/bug.c:186 > fixup_bug arch/x86/kernel/traps.c:179 [inline] > fixup_bug arch/x86/kernel/traps.c:174 [inline] > do_error_trap+0x12b/0x1e0 arch/x86/kernel/traps.c:272 > do_invalid_op+0x32/0x40 arch/x86/kernel/traps.c:291 > invalid_op+0x23/0x30 arch/x86/entry/entry_64.S:1026 > RIP: 0010:__flush_work.cold+0x2c/0x36 kernel/workqueue.c:3031 > Code: 9a 22 00 48 c7 c7 20 e4 c5 85 e8 d9 3a 0d 00 0f 0b 45 31 e4 e9 98 86 > ff ff e8 51 9a 22 00 48 c7 c7 20 e4 c5 85 e8 be 3a 0d 00 <0f> 0b 45 31 e4 > e9 7d 86 ff ff e8 36 9a 22 00 48 c7 c7 20 e4 c5 85 > RSP: 0018:ffff8881da20f720 EFLAGS: 00010286 > RAX: 0000000000000024 RBX: dffffc0000000000 RCX: 0000000000000000 > RDX: 0000000000000000 RSI: ffffffff8128a0fd RDI: ffffed103b441ed6 > RBP: ffff8881da20f888 R08: 0000000000000024 R09: fffffbfff11acd9a > R10: fffffbfff11acd99 R11: ffffffff88d66ccf R12: 0000000000000000 > R13: 0000000000000001 R14: ffff8881c6685df8 R15: ffff8881d2a85b78 > flush_request_modules drivers/media/usb/em28xx/em28xx-cards.c:3325 [inline] > em28xx_usb_disconnect.cold+0x280/0x2a6 > drivers/media/usb/em28xx/em28xx-cards.c:4023 > usb_unbind_interface+0x1bd/0x8a0 drivers/usb/core/driver.c:423 > __device_release_driver drivers/base/dd.c:1120 [inline] > device_release_driver_internal+0x404/0x4c0 drivers/base/dd.c:1151 > bus_remove_device+0x2dc/0x4a0 drivers/base/bus.c:556 > device_del+0x420/0xb10 drivers/base/core.c:2288 > usb_disable_device+0x211/0x690 drivers/usb/core/message.c:1237 > usb_disconnect+0x284/0x8d0 drivers/usb/core/hub.c:2199 > hub_port_connect drivers/usb/core/hub.c:4949 [inline] > hub_port_connect_change drivers/usb/core/hub.c:5213 [inline] > port_event drivers/usb/core/hub.c:5359 [inline] > hub_event+0x1454/0x3640 drivers/usb/core/hub.c:5441 > process_one_work+0x92b/0x1530 kernel/workqueue.c:2269 > process_scheduled_works kernel/workqueue.c:2331 [inline] > worker_thread+0x7ab/0xe20 kernel/workqueue.c:2417 > kthread+0x318/0x420 kernel/kthread.c:255 > ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 > Kernel Offset: disabled > Rebooting in 86400 seconds.. > > Reported-by: syzbot+b7f57261c521087d8...@syzkaller.appspotmail.com > Signed-off-by: Sean Young <s...@mess.org>
I reviewed the syzbot report, but was left head-scratching and failing to see how the module-loading worker was supposed to be used :-) Reviewed-by: Ezequiel Garcia <ezequ...@collabora.com> Also, this seems a bug, so how about this tag? Fixes: be7fd3c3a8c5e ("media: em28xx: Hauppauge DualHD second tuner functionality) > --- > drivers/media/usb/em28xx/em28xx-cards.c | 1 - > 1 file changed, 1 deletion(-) > > diff --git a/drivers/media/usb/em28xx/em28xx-cards.c > b/drivers/media/usb/em28xx/em28xx-cards.c > index 6e33782c3ca6..5983e72a0622 100644 > --- a/drivers/media/usb/em28xx/em28xx-cards.c > +++ b/drivers/media/usb/em28xx/em28xx-cards.c > @@ -4019,7 +4019,6 @@ static void em28xx_usb_disconnect(struct usb_interface > *intf) > dev->dev_next->disconnected = 1; > dev_info(&dev->intf->dev, "Disconnecting %s\n", > dev->dev_next->name); > - flush_request_modules(dev->dev_next); > } > > dev->disconnected = 1;