# deadlock in nvidia driver **URL:** \ **Category:** Linux\ **Created:** [October 13, 2017, 7:11pm UTC](https://forums.developer.nvidia.com/t/deadlock-in-nvidia-driver/54193 "2017-10-13T19:11:27Z")\ **Posts on this page:** 1\ **Page:** 1
**Author:** ![joe.korty](https://developer.download.nvidia.com/images/forums/profile-default-devtalk-84.png) [@joe.korty](https://forums.developer.nvidia.com/u/joe.korty)\ **Post date:** [October 13, 2017, 7:11pm UTC](https://forums.developer.nvidia.com/t/deadlock-in-nvidia-driver/54193/1 "2017-10-13T19:11:27Z")
Hi, we are using the Diamond Visionics flight simulator with the NVidia driver, rev 387.12, on an Intel x86\_64 system running Linux 4.4.86. We are getting a lockup of X11 when the simulator is terminated by typing the ESC key. A ‘ps’ command shows a simulator thread stuck in uninterrupible sleep. A ‘bt’ command executed from the ‘crash’ command shows that the thread is asleep on a kernel ‘down()’ service and that the ‘down’ was invoked from the nvidia driver/kernel interface library. I wrote a debug kernel patch that lets me do the missing ‘up()’ by writing to a /proc/$pid/task/$tid/sema file, created by the patch. When I do this ‘up()’ the hung thread exits successfully and X11 recovers and all works (apparently) fine. Not only that, but I can re-run the Diamond Visionics simulator over and over, terminating it with the ESC key each time, and all threads will close down successfully after that point, until the next reboot, at which point the first time the simulator is terminated the hang occurs and the ‘up()’ needs to be redone to get X11/NVidia going again. It is clear there is a path through the driver where a needed ‘up()’ is not being executed. This is probably along some error or early-termination path associated with unexpected (to the NVidia driver) task exit. Please look into this and fix. Thanks, Joe PS: I have attached a ‘crash’ stack traceback of the kernel stack of the hung thread. Hopefully that will have some clues as to where and why the NVidia driver is getting hung up. crash\> bt 11003 PID: 11003 TASK: ffff88101a078000 CPU: 6 COMMAND: “IG64” #0 [ffff8800357e32e0] \_\_schedule at ffffffff81f5a846 #1 [ffff8800357e3350] schedule at ffffffff81f5b347 #2 [ffff8800357e3370] schedule\_timeout at ffffffff81f5f8f5 #3 [ffff8800357e3458] \_\_down at ffffffff81f5c2d9 #4 [ffff8800357e34a0] down at ffffffff810c2163 #5 [ffff8800357e34c8] os\_acquire\_semaphore at ffffffffa0140017 [nvidia] #6 [ffff8800357e34e8] \_nv007928rm at ffffffffa06ad14d [nvidia] #7 [ffff8800357e3518] \_nv032949rm at ffffffffa06ac18f [nvidia] #8 [ffff8800357e3538] \_nv007808rm at ffffffffa06f4be4 [nvidia] #9 [ffff8800357e3548] \_nv007807rm at ffffffffa06f4a78 [nvidia] #10 [ffff8800357e3578] \_nv001117rm at ffffffffa0746d90 [nvidia] #11 [ffff8800357e3598] \_nv001118rm at ffffffffa0746f57 [nvidia] #12 [ffff8800357e35c8] \_nv001265rm at ffffffffa0744cb2 [nvidia] #13 [ffff8800357e35e8] \_nv001286rm at ffffffffa0744e1b [nvidia] #14 [ffff8800357e3618] \_nv001285rm at ffffffffa074503e [nvidia] #15 [ffff8800357e3658] \_nv033138rm at ffffffffa0541b67 [nvidia] #16 [ffff8800357e3688] \_nv003508rm at ffffffffa06ba97d [nvidia] #17 [ffff8800357e3698] \_nv003816rm at ffffffffa06afb95 [nvidia] #18 [ffff8800357e36b8] \_nv010693rm at ffffffffa06addc0 [nvidia] #19 [ffff8800357e36e8] \_nv010692rm at ffffffffa06adf38 [nvidia] #20 [ffff8800357e3718] \_nv032952rm at ffffffffa06ac359 [nvidia] #21 [ffff8800357e3738] \_nv007810rm at ffffffffa06f4d6f [nvidia] #22 [ffff8800357e3768] \_nv007807rm at ffffffffa06f4a78 [nvidia] #23 [ffff8800357e3798] \_nv010692rm at ffffffffa06adf04 [nvidia] #24 [ffff8800357e37c8] \_nv032952rm at ffffffffa06ac359 [nvidia] #25 [ffff8800357e37e8] \_nv007810rm at ffffffffa06f4d6f [nvidia] #26 [ffff8800357e3818] \_nv007807rm at ffffffffa06f4a78 [nvidia] #27 [ffff8800357e3848] \_nv010693rm at ffffffffa06add05 [nvidia] #28 [ffff8800357e3878] \_nv010692rm at ffffffffa06adf38 [nvidia] #29 [ffff8800357e38a8] \_nv032952rm at ffffffffa06ac359 [nvidia] #30 [ffff8800357e38c8] \_nv007810rm at ffffffffa06f4d6f [nvidia] #31 [ffff8800357e38f8] \_nv007807rm at ffffffffa06f4a78 [nvidia] #32 [ffff8800357e3928] \_nv010692rm at ffffffffa06adf04 [nvidia] #33 [ffff8800357e3958] \_nv032952rm at ffffffffa06ac359 [nvidia] #34 [ffff8800357e3978] \_nv007810rm at ffffffffa06f4d6f [nvidia] #35 [ffff8800357e39a8] \_nv007807rm at ffffffffa06f4a78 [nvidia] #36 [ffff8800357e39d8] \_nv010671rm at ffffffffa06d4881 [nvidia] #37 [ffff8800357e3a08] \_nv007923rm at ffffffffa06abb21 [nvidia] #38 [ffff8800357e3a28] \_nv032949rm at ffffffffa06ac1d9 [nvidia] #39 [ffff8800357e3a48] \_nv007808rm at ffffffffa06f4be4 [nvidia] #40 [ffff8800357e3a58] \_nv007807rm at ffffffffa06f4a78 [nvidia] #41 [ffff8800357e3a88] \_nv001153rm at ffffffffa0781e92 [nvidia] #42 [ffff8800357e3ab8] rm\_free\_unused\_clients at ffffffffa07852b1 [nvidia] #43 [ffff8800357e3bc8] nvidia\_frontend\_close at ffffffffa01343fc [nvidia] #44 [ffff8800357e3be8] \_\_fput at ffffffff812160a2 #45 [ffff8800357e3c30] \_\_\_\_fput at ffffffff8121622e #46 [ffff8800357e3c40] task\_work\_run at ffffffff81090346 #47 [ffff8800357e3c80] do\_exit at ffffffff81073767 #48 [ffff8800357e3cf8] do\_group\_exit at ffffffff8107418c #49 [ffff8800357e3d28] get\_signal at ffffffff81080cd1 #50 [ffff8800357e3dd8] do\_signal at ffffffff81005358 #51 [ffff8800357e3ee8] exit\_to\_usermode\_loop at ffffffff8106ae18 #52 [ffff8800357e3f28] syscall\_return\_slowpath at ffffffff81002ce5 #53 [ffff8800357e3f50] int\_ret\_from\_sys\_call at ffffffff81f61e5a RIP: 00007fffdd066d13 RSP: 00007fffbdf843b0 RFLAGS: 00000293 RAX: fffffffffffffffc RBX: 00007fffbdf84ad8 RCX: 00007fffdd066d13 RDX: 0000000000000080 RSI: 00007fffbdf84400 RDI: 000000000000000f RBP: 00007fffbf4b74c0 R8: 0000000000000000 R9: 0000000000002afb R10: 00000000ffffffff R11: 0000000000000293 R12: 00000000ffffffff R13: 00007fffbdf84ad8 R14: 00007fffcc65d3f8 R15: 00007fffcc65d3b8 ORIG\_RAX: 00000000000000e8 CS: 0033 SS: 002b crash\>