> -----Original Message----- > From: Jani Nikula <jani.nikula@xxxxxxxxxxxxxxx> > Sent: Monday, 11 March 2024 18.03 > To: Saarinen, Jani <jani.saarinen@xxxxxxxxx>; Linux regressions mailing list > <regressions@xxxxxxxxxxxxxxx>; Deak, Imre <imre.deak@xxxxxxxxx> > Cc: Chris Bainbridge <chris.bainbridge@xxxxxxxxx>; intel-gfx <intel- > gfx@xxxxxxxxxxxxxxxxxxxxx>; David Airlie <airlied@xxxxxxxx>; Daniel Vetter > <daniel@xxxxxxxx>; ML dri-devel <dri-devel@xxxxxxxxxxxxxxxxxxxxx> > Subject: RE: [REGRESSION] Divide-by-zero on DisplayPort MST unplug with > nouveau > > On Mon, 11 Mar 2024, "Saarinen, Jani" <jani.saarinen@xxxxxxxxx> wrote: > > Hi, > > > >> -----Original Message----- > >> From: Intel-gfx <intel-gfx-bounces@xxxxxxxxxxxxxxxxxxxxx> On Behalf > >> Of Linux regression tracking (Thorsten Leemhuis) > >> Sent: Monday, 11 March 2024 17.53 > >> To: Deak, Imre <imre.deak@xxxxxxxxx> > >> Cc: regressions@xxxxxxxxxxxxxxx; Chris Bainbridge > >> <chris.bainbridge@xxxxxxxxx>; intel-gfx > >> <intel-gfx@xxxxxxxxxxxxxxxxxxxxx>; > >> David Airlie <airlied@xxxxxxxx>; Daniel Vetter <daniel@xxxxxxxx>; ML > >> dri-devel <dri-devel@xxxxxxxxxxxxxxxxxxxxx> > >> Subject: Re: [REGRESSION] Divide-by-zero on DisplayPort MST unplug > >> with nouveau > >> > >> On 07.03.24 18:58, Chris Bainbridge wrote: > >> > ----- Forwarded message from Chris Bainbridge > >> > <chris.bainbridge@xxxxxxxxx> ----- > >> > > >> > Date: Sat, 10 Feb 2024 21:24:59 +0000 > >> > >> Hmm, it looks like nobody is looking into this regression. Is there a > >> good reason? > >> > >> Imre, or did you maybe just miss that Chris' regression seems to be > >> caused by a commit of yours? He initally proposed a fix (the > >> forwarded mail that is quoted here) more a month ago already here: > >> https://lore.kernel.org/all/ZcfpqwnkSoiJxeT9@debian.local/ > >> > >> Chris recently filed a ticket, too: > >> https://gitlab.freedesktop.org/drm/misc/kernel/-/issues/36 > > Please file > > https://drm.pages.freedesktop.org/intel-docs/how-to-file-i915-bugs.htm > > l > > Well, please don't. It's *not* an i915 bug. Right, sorry about this. Let Imre to comment then. > > BR, > Jani. > > >> > >> Mostly silence there as well. :-/ > >> > >> Ciao, Thorsten (wearing his 'the Linux kernel's regression tracker' > >> hat) > >> > >> P.S: Chris, sorry, I had missed that you initially proposed the fix a > >> month ago; if I had noticed this earlier I had sent a mail like this one earlier. > >> -- > >> Everything you wanna know about Linux kernel regression tracking: > >> https://linux-regtracking.leemhuis.info/about/#tldr > >> If I did something stupid, please tell me, as explained on that page. > >> > >> > From: Chris Bainbridge <chris.bainbridge@xxxxxxxxx> > >> > To: dri-devel@xxxxxxxxxxxxxxxxxxxxx > >> > Cc: lyude@xxxxxxxxxx, ville.syrjala@xxxxxxxxxxxxxxx, > >> stanislav.lisovskiy@xxxxxxxxx, > >> > mripard@xxxxxxxxxx, imre.deak@xxxxxxxxx > >> > Subject: [PATCH] Fix divide-by-zero on DP unplug with nouveau > >> > > >> > The following trace occurs when using nouveau and unplugging a DP > >> > MST > >> > adaptor: > >> >> divide error: 0000 [#1] PREEMPT SMP PTI > >> > CPU: 7 PID: 2962 Comm: Xorg Not tainted 6.8.0-rc3+ #744 Hardware > >> > name: Razer Blade/DANA_MB, BIOS 01.01 08/31/2018 > >> > RIP: 0010:drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > >> > Code: c6 b8 01 00 00 00 75 61 01 c6 41 0f af f3 41 0f af f1 c1 e1 > >> > 04 > >> > 48 63 c7 31 d2 89 ff 48 8b 5d f8 c9 48 0f af f1 48 8d 44 06 ff <48> > >> > f7 > >> > f7 31 d2 31 c9 31 f6 31 ff 45 31 c0 45 31 c9 45 31 d2 45 31 > >> > RSP: 0018:ffffb2c5c211fa30 EFLAGS: 00010206 > >> > RAX: ffffffffffffffff RBX: 0000000000000000 RCX: 0000000000f59b00 > >> > RDX: 0000000000000000 RSI: 0000000000000000 RDI: > >> 0000000000000000 > >> > RBP: ffffb2c5c211fa48 R08: 0000000000000001 R09: > >> 0000000000000020 > >> > R10: 0000000000000004 R11: 0000000000000000 R12: > >> 0000000000023b4a > >> > R13: ffff91d37d165800 R14: ffff91d36fac6d80 R15: ffff91d34a764010 > >> > FS: 00007f4a1ca3fa80(0000) GS:ffff91d6edbc0000(0000) > >> > knlGS:0000000000000000 > >> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > >> > CR2: 0000559491d49000 CR3: 000000011d180002 CR4: > >> 00000000003706f0 > >> > Call Trace: > >> > <TASK> > >> > ? show_regs+0x6d/0x80 > >> > ? die+0x37/0xa0 > >> > ? do_trap+0xd4/0xf0 > >> > ? do_error_trap+0x71/0xb0 > >> > ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > >> > ? exc_divide_error+0x3a/0x70 > >> > ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > >> > ? asm_exc_divide_error+0x1b/0x20 > >> > ? drm_dp_bw_overhead+0xb4/0x110 [drm_display_helper] > >> > ? drm_dp_calc_pbn_mode+0x2e/0x70 [drm_display_helper] > >> > nv50_msto_atomic_check+0xda/0x120 [nouveau] > >> > drm_atomic_helper_check_modeset+0xa87/0xdf0 [drm_kms_helper] > >> > drm_atomic_helper_check+0x19/0xa0 [drm_kms_helper] > >> > nv50_disp_atomic_check+0x13f/0x2f0 [nouveau] > >> > drm_atomic_check_only+0x668/0xb20 [drm] > >> > ? drm_connector_list_iter_next+0x86/0xc0 [drm] > >> > drm_atomic_commit+0x58/0xd0 [drm] > >> > ? __pfx___drm_printfn_info+0x10/0x10 [drm] > >> > drm_atomic_connector_commit_dpms+0xd7/0x100 [drm] > >> > drm_mode_obj_set_property_ioctl+0x1c5/0x450 [drm] > >> > ? __pfx_drm_connector_property_set_ioctl+0x10/0x10 [drm] > >> > drm_connector_property_set_ioctl+0x3b/0x60 [drm] > >> > drm_ioctl_kernel+0xb9/0x120 [drm] > >> > drm_ioctl+0x2d0/0x550 [drm] > >> > ? __pfx_drm_connector_property_set_ioctl+0x10/0x10 [drm] > >> > nouveau_drm_ioctl+0x61/0xc0 [nouveau] > >> > __x64_sys_ioctl+0xa0/0xf0 > >> > do_syscall_64+0x76/0x140 > >> > ? do_syscall_64+0x85/0x140 > >> > ? do_syscall_64+0x85/0x140 > >> > entry_SYSCALL_64_after_hwframe+0x6e/0x76 > >> > RIP: 0033:0x7f4a1cd1a94f > >> > Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 > >> > 48 > >> > 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <41> > >> > 89 > >> > c0 3d 00 f0 ff ff 77 1f 48 8b 44 24 18 64 48 2b 04 25 28 00 > >> > RSP: 002b:00007ffd2f1df520 EFLAGS: 00000246 ORIG_RAX: > >> > 0000000000000010 > >> > RAX: ffffffffffffffda RBX: 00007ffd2f1df5b0 RCX: 00007f4a1cd1a94f > >> > RDX: 00007ffd2f1df5b0 RSI: 00000000c01064ab RDI: > 000000000000000f > >> > RBP: 00000000c01064ab R08: 000056347932deb8 R09: > >> 000056347a7d99c0 > >> > R10: 0000000000000000 R11: 0000000000000246 R12: > >> 000056347938a220 > >> > R13: 000000000000000f R14: 0000563479d9f3f0 R15: > >> 0000000000000000 > >> > </TASK> > >> > Modules linked in: rfcomm xt_conntrack nft_chain_nat xt_MASQUERADE > >> nf_nat nf_conntrack_netlink nf_conntrack nf_defrag_ipv6 > >> nf_defrag_ipv4 xfrm_user xfrm_algo xt_addrtype nft_compat nf_tables > >> nfnetlink br_netfilter bridge stp llc ccm cmac algif_hash overlay > >> algif_skcipher af_alg bnep binfmt_misc snd_sof_pci_intel_cnl > >> snd_sof_intel_hda_common snd_soc_hdac_hda snd_sof_pci > >> snd_sof_xtensa_dsp snd_sof_intel_hda snd_sof snd_sof_utils > >> snd_soc_acpi_intel_match snd_soc_acpi snd_soc_core snd_compress > >> snd_sof_intel_hda_mlink snd_hda_ext_core iwlmvm intel_rapl_msr > >> intel_rapl_common intel_tcc_cooling x86_pkg_temp_thermal > >> intel_powerclamp mac80211 coretemp kvm_intel snd_hda_codec_hdmi > kvm > >> snd_hda_codec_realtek snd_hda_codec_generic uvcvideo libarc4 > >> snd_hda_intel snd_intel_dspcfg snd_hda_codec iwlwifi > >> videobuf2_vmalloc videobuf2_memops uvc irqbypass btusb > videobuf2_v4l2 > >> snd_seq_midi crct10dif_pclmul hid_multitouch crc32_pclmul > >> snd_seq_midi_event btrtl snd_hwdep videodev polyval_clmulni > >> polyval_generic snd_rawmidi > >> > ghash_clmulni_intel aesni_intel btintel crypto_simd snd_hda_core > >> > cryptd snd_seq btbcm ee1004 8250_dw videobuf2_common btmtk rapl > >> > nls_iso8859_1 mei_hdcp thunderbolt bluetooth intel_cstate wmi_bmof > >> > intel_wmi_thunderbolt cfg80211 snd_pcm mc snd_seq_device i2c_i801 > >> > r8169 ecdh_generic snd_timer i2c_smbus ecc snd mei_me > >> > intel_lpss_pci mei ahci intel_lpss soundcore realtek libahci idma64 > >> > intel_pch_thermal i2c_hid_acpi i2c_hid acpi_pad sch_fq_codel msr > >> > parport_pc ppdev lp parport efi_pstore ip_tables x_tables autofs4 > >> > dm_crypt raid10 raid456 libcrc32c async_raid6_recov async_memcpy > >> > async_pq async_xor xor async_tx raid6_pq raid1 raid0 joydev > >> > input_leds hid_generic usbhid hid nouveau i915 drm_ttm_helper > >> > gpu_sched drm_gpuvm drm_exec > >> i2c_algo_bit > >> > drm_buddy ttm drm_display_helper drm_kms_helper cec rc_core drm > >> > nvme nvme_core mxm_wmi xhci_pci xhci_pci_renesas video wmi > >> > pinctrl_cannonlake mac_hid ---[ end trace 0000000000000000 ]--- > >> > > >> > Fix this by avoiding the divide if bpp is 0. > >> > > >> > Fixes: c1d6a22b7219 ("drm/dp: Add helpers to calculate the link BW > >> > overhead") > >> > Signed-off-by: Chris Bainbridge <chris.bainbridge@xxxxxxxxx> > >> > --- > >> > drivers/gpu/drm/display/drm_dp_helper.c | 3 +++ > >> > 1 file changed, 3 insertions(+) > >> > > >> > diff --git a/drivers/gpu/drm/display/drm_dp_helper.c > >> > b/drivers/gpu/drm/display/drm_dp_helper.c > >> > index b1ca3a1100da..bb8794c8f99c 100644 > >> > --- a/drivers/gpu/drm/display/drm_dp_helper.c > >> > +++ b/drivers/gpu/drm/display/drm_dp_helper.c > >> > @@ -4024,6 +4024,9 @@ int drm_dp_bw_overhead(int lane_count, int > >> hactive, > >> > bpp_x16, > >> symbol_size, > >> > is_mst); > >> > > >> > + /* Avoid potential divide by zero in DIV_ROUND_UP_ULL */ > >> > + if (bpp_x16 == 0) > >> > + return 0; > >> > return DIV_ROUND_UP_ULL(mul_u32_u32(symbol_cycles * > >> symbol_size * lane_count, > >> > overhead * 16), > >> > hactive * bpp_x16); > >> > >> P. P.S.: > >> > >> #regzbot duplicate: > >> https://lore.kernel.org/all/ZcfpqwnkSoiJxeT9@debian.local/ > >> #regzbot poke > > -- > Jani Nikula, Intel
