Received-SPF: pass (google.com: domain of linux-wireless-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
MIME-Version: 1.0
References: <5077a953487275837e81bdf1808ded00b9676f9f.camel@pschenker.ch>
In-Reply-To: <5077a953487275837e81bdf1808ded00b9676f9f.camel@pschenker.ch>
From:   =?UTF-8?B?w43DsWlnbyBIdWd1ZXQ=?= <ihuguet@redhat.com>
Date:   Thu, 24 Mar 2022 10:13:53 +0100
Message-ID: <CACT4oudAnhBy2X2pbxd0XJ+bffL64oq=ijRaQE8pt_JHKUXkzA@mail.gmail.com>
Subject: Re: MT7921 Causing Kernel to Freeze after Reboot
To:     dev@pschenker.ch
Cc:     Linux List Kernel Mailing <linux-wireless@vger.kernel.org>,
        Sean Wang <sean.wang@mediatek.com>,
        Ryder Lee <ryder.lee@mediatek.com>,
        Shayne Chen <shayne.chen@mediatek.com>,
        Lorenzo Bianconi <lorenzo.bianconi83@gmail.com>,
        Felix Fietkau <nbd@nbd.name>
Content-Type: text/plain; charset="UTF-8"
Content-Transfer-Encoding: quoted-printable
Precedence: bulk

On Wed, Dec 22, 2021 at 12:52 PM Philippe Schenker <dev@pschenker.ch> wrote=
:
>
> Hello
>
> So I received a new notebook recently, this is a Lenovo P14s that has a
> Mediatek 7961 network controller inside.
>
> -----
>
> 03:00.0 Network controller: MEDIATEK Corp. Device 7961
>         Subsystem: Lenovo Device e0bc
>         Physical Slot: 0
>         Flags: bus master, fast devsel, latency 0, IRQ 91, IOMMU group
> 13
>         Memory at 870200000 (64-bit, prefetchable) [size=3D1M]
>         Memory at 870300000 (64-bit, prefetchable) [size=3D16K]
>         Memory at 870304000 (64-bit, prefetchable) [size=3D4K]
>         Capabilities: <access denied>
>         Kernel driver in use: mt7921e
>         Kernel modules: mt7921e
> ------
>
> I have the issue that on 5.16-rc6 kernel (also on other rcs) it is
> always freezing after I issue a "reboot" command. "poweroff" followed by
> a normal power-on works always.

I have a bug report with this same behaviour and almost identical
kernel logs.: message "Timeout for driver own" followed by traces
related to mt7921 dma stuff, indicating bad page state with refcount
-1 and "page dumped because: nonzero _refcount", finally causing a
crash during boot up, but only after reboot, not after normal power
on.

It happens always, even with v5.17. Commit 602cc0c9618a (mt76:
mt7921e: fix possible probe failure after reboot) doesn't fix the
issue.

I hadn't been able to verify where the problem exactly is, but my guess is =
this:
- In function mt7921_init_hardware, initialization fails because
mt7921e_driver_own doesn't finish before the timeout (thus we see the
"Timeout for driver own")
- Then, before retrying to init, mt7921_init_hardware calls
mt7921e_init_reset, and the latter calls to mt7921_wpdma_reset
- That makes a cleanup of the DMA queues before stopping the DMA,
which had been enabled short before during probe
- Then, my guess is that in the meanwhile, a DMA event arrives with
the queues stillI being cleaned up

Does it make sense?

>
> Since it freezes and showing multiple Call Traces I included 4 logs in
> the attachment, it certainly points always to mt76_dma functions.
>
> One of the traces included down below. I would appreciate any help on
> how to proceed in debugging this, I figure I ask first on here maybe
> someone already has some good hints on where this is leading.
>
> Philippe
>
> -----
>
>
> [   11.195349] Modules linked in: 8021q garp mrp stp llc qrtr cmac
> algif_hash algif_skcipher af_alg bnep wireguard curve25519_x86_64
> libchacha20poly1305 chacha_x86_64 poly1305_x86_64 libblake2s
> blake2s_x86_64 libcurve25519_generic libchacha libblake2s_generic
> ip6_udp_tunnel udp_tunnel uvcvideo btusb btrtl videobuf2_vmalloc joydev
> videobuf2_memops btbcm mousedev videobuf2_v4l2 btintel videobuf2_common
> bluetooth videodev mc ecdh_generic intel_rapl_msr mt7921e(+)
> mt7921_common mt76_connac_lib intel_rapl_common mt76 snd_acp3x_rn
> snd_soc_dmic snd_acp3x_pdm_dma snd_soc_core edac_mce_amd psmouse
> snd_ctl_led serio_raw kvm_amd snd_hda_codec_realtek snd_compress atkbd
> libps2 snd_hda_codec_generic snd_hda_codec_hdmi ac97_bus
> snd_pcm_dmaengine kvm amdgpu mac80211 snd_hda_intel irqbypass
> snd_intel_dspcfg crct10dif_pclmul snd_intel_sdw_acpi think_lmi
> crc32_pclmul firmware_attributes_class wmi_bmof ghash_clmulni_intel
> snd_hda_codec libarc4 aesni_intel snd_hda_core crypto_simd snd_hwdep
> cryptd vfat fat
> [   11.195370]  rapl cfg80211 pcspkr thinkpad_acpi snd_pcm sdhci_pci
> tpm_crb cqhci ucsi_acpi sp5100_tco ledtrig_audio r8169 snd_timer
> gpu_sched sdhci k10temp platform_profile typec_ucsi snd_pci_acp5x
> i2c_piix4 snd drm_ttm_helper typec snd_rn_pci_acp3x i8042 xhci_pci
> mmc_core ccp ttm snd_pci_acp3x xhci_pci_renesas rfkill realtek roles
> soundcore wmi serio tpm_tis tpm_tis_core i2c_scmi video tpm mac_hid
> acpi_cpufreq pinctrl_amd rng_core nfsd auth_rpcgss nfs_acl lockd grace
> sunrpc ipmi_devintf ipmi_msghandler sg crypto_user fuse ip_tables
> x_tables ext4 crc32c_generic crc32c_intel crc16 mbcache jbd2 ftdi_sio
> [   11.195388] CPU: 9 PID: 391 Comm: systemd-udevd Tainted: G    B D W
> OE     5.16.0-1-MANJARO #1 e53f5ca75f8033ff8736c17597ec46c465c565c0
> [   11.195390] Hardware name: LENOVO 21A0CTO1WW/21A0CTO1WW, BIOS
> R1MET43W (1.13 ) 11/05/2021
> [   11.195391] Call Trace:
> [   11.195392]  <TASK>
> [   11.195393]  dump_stack_lvl+0x48/0x66
> [   11.195395]  bad_page.cold+0x63/0x94
> [   11.195397]  free_pcppages_bulk+0x1f2/0x380
> [   11.195400]  free_unref_page+0xbd/0x140
> [   11.195402]  mt76_dma_rx_cleanup+0x94/0x120 [mt76
> 38914422533eea8f7de7062b22740222ae6696aa]
> [   11.195406]  mt7921_wpdma_reset+0xbc/0x1c0 [mt7921e
> c9c5ddc0c86616f123c90aadf837c5b1ca6179c1]
> [   11.195410]  mt7921_register_device+0x32b/0x5e0 [mt7921_common
> de62e6211a822ebe8196f9a6a704d937124a5fd7]
> [   11.195413]  mt7921_pci_probe+0x1f1/0x230 [mt7921e
> c9c5ddc0c86616f123c90aadf837c5b1ca6179c1]
> [   11.195416]  ? __pm_runtime_resume+0x58/0x80
> [   11.195418]  local_pci_probe+0x45/0x90
> [   11.195419]  ? pci_match_device+0xdf/0x140
> [   11.195421]  pci_device_probe+0xcf/0x1c0
> [   11.195422]  really_probe+0x203/0x400
> [   11.195424]  __driver_probe_device+0x112/0x190
> [   11.195426]  driver_probe_device+0x1e/0x90
> [   11.195427]  __driver_attach+0xc8/0x1e0
> [   11.195428]  ? __device_attach_driver+0xf0/0xf0
> [   11.195430]  ? __device_attach_driver+0xf0/0xf0
> [   11.195431]  bus_for_each_dev+0x8d/0xe0
> [   11.195432]  bus_add_driver+0x154/0x200
> [   11.195434]  driver_register+0x8f/0xf0
> [   11.195435]  ? 0xffffffffc05d1000
> [   11.195436]  do_one_initcall+0x57/0x220
> [   11.195438]  do_init_module+0x5c/0x270
> [   11.195440]  load_module+0x25d7/0x27a0
> [   11.195443]  ? __do_sys_init_module+0x12e/0x1b0
> [   11.195444]  __do_sys_init_module+0x12e/0x1b0
> [   11.195446]  do_syscall_64+0x5c/0x90
> [   11.195448]  ? exc_page_fault+0x72/0x180
> [   11.195451]  entry_SYSCALL_64_after_hwframe+0x44/0xae
> [   11.195453] RIP: 0033:0x7f765370732e
> [   11.195454] Code: 48 8b 0d 45 0b 0c 00 f7 d8 64 89 01 48 83 c8 ff c3
> 66 2e 0f 1f 84 00 00 00 00 00 90 f3 0f 1e fa 49 89 ca b8 af 00 00 00 0f
> 0[   12.234716] mt7921e 0000:03:00.0: Timeout for driver own
>
>


--=20
=C3=8D=C3=B1igo Huguet