Messages in this thread | | | From | Andrey Konovalov <> | Date | Thu, 21 May 2020 18:27:32 +0200 | Subject | Re: INFO: task hung in locks_remove_posix |
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On Thu, May 21, 2020 at 4:48 PM Jeff Layton <jlayton@kernel.org> wrote: > > On Thu, 2020-05-21 at 23:09 +0900, Tetsuo Handa wrote: > > On 2020/05/21 5:53, syzbot wrote: > > > Hello, > > > > > > syzbot found the following crash on: > > > > > > HEAD commit: 806d8acc USB: dummy-hcd: use configurable endpoint naming .. > > > git tree: https://github.com/google/kasan.git usb-fuzzer > > > console output: https://syzkaller.appspot.com/x/log.txt?x=16c9ece2100000 > > > kernel config: https://syzkaller.appspot.com/x/.config?x=d800e9bad158025f > > > dashboard link: https://syzkaller.appspot.com/bug?extid=f5bc30abd8916982419c > > > compiler: gcc (GCC) 9.0.0 20181231 (experimental) > > > > > > Unfortunately, I don't have any reproducer for this crash yet. > > > > This seems to be a mislabeling due to '?' in all lines in a trace. > > > > #syz dup: INFO: task hung in wdm_flush > > > I'm not sure I trust those stack traces. The console output shows '?' > characters in front of every frame. Doesn't that mean that that address > it found on the stack is unreliable? > > In principle, unless you're overriding the filp->lock operation (and the > wdm fs doesn't do that, afaict), locks_remove_posix should not block. > I'll also note that there is some of this in the logs before the hung > task warnings: > > [ 182.020388][ T12] usb 5-1: too many endpoints for config 0 interface 107 altsetting 116: 116, using maximum allowed: 30 > [ 182.031661][ T12] usb 5-1: config 0 interface 107 altsetting 116 has 0 endpoint descriptors, different from the interface descriptor's value: 116 > [ 182.045145][ T12] usb 5-1: config 0 interface 107 has no altsetting 0 > [ 182.052028][ T12] usb 5-1: New USB device found, idVendor=0926, idProduct=3333, bcdDevice= 0.40 > [ 182.060120][ T3525] usb 6-1: USB disconnect, device number 20 > [ 182.061148][ C0] xpad 6-1:0.65: xpad_irq_out - usb_submit_urb failed with result -19 > [ 182.075465][ T3525] xpad 6-1:0.65: xpad_try_sending_next_out_packet - usb_submit_urb failed with result -19 > [ 182.075565][ T12] usb 5-1: New USB device strings: Mfr=0, Product=0, SerialNumber=0 > [ 182.109020][ T12] usb 5-1: config 0 descriptor?? > [ 182.136857][ T163] usb usb2-port1: attempt power cycle > [ 182.410396][ T4447] udc-core: couldn't find an available UDC or it's busy > [ 182.417562][ T4447] misc raw-gadget: fail, usb_gadget_probe_driver returned -16 > [ 182.856513][ T163] usb 2-1: new high-speed USB device number 18 using dummy_hcd > [ 183.026601][ T163] usb 2-1: device descriptor read/8, error -61 > [ 183.236577][ T163] usb 2-1: device descriptor read/8, error -71 > [ 184.068991][ T3525] usb 5-1: USB disconnect, device number 21 > [ 206.185571][ T23] INFO: task syz-executor.2:3145 blocked for more than 143 seconds. > [ 206.193630][ T23] Not tainted 5.7.0-rc5-syzkaller #0 > [ 206.199512][ T23] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. > [ 206.208242][ T23] syz-executor.2 D28552 3145 370 0x80004006 > > ...which leads me to believe that this might have more to do with the > USB subsystem than anything in the posix locking code. > > In any case, I doubt there's much we can do here without a more reliable > stack trace to work from. That call stack doesn't seem to make much > sense.
Most likely this is a duplicate of:
https://syzkaller.appspot.com/bug?id=e7b761593b23eb50855b9ea31e3be5472b711186
(with more than 30000 crashes now :)
#syz dup: INFO: task hung in wdm_flush
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