https://bugzilla.kernel.org/show_bug.cgi?id=206987 --- Comment #18 from Petteri Aimonen (jpa@xxxxxxxxxxxxxxxxxxxxxxx) --- As best as I can tell, the crash seems to be caused by some floating point exception (such as underflow/overflow) in this function call in dcn_calc_auto.c line 176: dcn_bw_ceil2(v->byte_per_pixel_in_dety[k], 1.0) In dcn_bw_ceil2() the exception occurs in this instruction: addsd 0x0(%rip),%xmm3 which is performing the addition flr + 0.00001. At this point %xmm3 is ((int)(v->byte_per_pixel_in_dety[k] / 1.0)) * 1.0 The variable byte_per_pixel_in_dety is only assigned constant values 1.0, 2.0, 4.0, 8.0 so I don't see any reason for addsd to cause a simd exception. I'm not sure if the exception is precise or if it could be delayed from some prior instruction, but AFAIK it should be precise because in usermode the exception handler would attempt a recovery. Having XMM3 or MXCSR values would help, but they don't seem to get included in the dmesg output and I'm not sure if they are available in a crash dump either. Google search turned up https://beowulf.beowulf.narkive.com/tAHxVcs0/simd-exception-kernel-panic-on-skylake-ep-triggered-by-openfoam where the exception was delayed for some reason. Analyzing the dmesgs attached to this bug report, we have following crash locations: Cyrax 2020-03-26 21:36: divss xmm0,DWORD PTR [r14+0x17f8] Cyrax 2020-04-04 07:40: divss xmm0,DWORD PTR [r14+0x17f8] Cyrax 2020-04-18 13:19: divss xmm0,DWORD PTR [r14+0x17f8] farmboy0 2020-04-19 11:43: not a simd exception Cyrax 2020-04-23 05:15: divss xmm0,DWORD PTR [r14+0x17f8] Cyrax 2020-04-27 19:20: divss xmm0,DWORD PTR [r14+0x17f8] Cyrax 2020-05-02 14:18: divss xmm0,DWORD PTR [r14+0x17f8] PetteriA 2020-05-28 16:05: addsd xmm3,QWORD PTR [rip+0x1de967] So the crash locations appear fairly consistent for Cyrax's machine, but no two machines have the same location. For other users affected by this problem, it could be helpful if you install kernel debugging symbols and use decode_stacktrace.sh to convert the raw stack trace to code locations. Also reported on freedesktop amd bugtracker: https://gitlab.freedesktop.org/drm/amd/-/issues/1154 -- You are receiving this mail because: You are watching the assignee of the bug. _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/dri-devel
