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References: <20200512085944.222637-1-daniel.vetter@ffwll.ch> <20200512085944.222637-17-daniel.vetter@ffwll.ch>
In-Reply-To: <20200512085944.222637-17-daniel.vetter@ffwll.ch>
From:   Alex Deucher <alexdeucher@gmail.com>
Date:   Tue, 12 May 2020 08:54:45 -0400
Message-ID: <CADnq5_NJTwkUszd-F2d4D+kD4c_+FKD8tuhVJ7VWHGxAyd8fCg@mail.gmail.com>
Subject: Re: [RFC 16/17] drm/amdgpu: gpu recovery does full modesets
To:     Daniel Vetter <daniel.vetter@ffwll.ch>
Cc:     DRI Development <dri-devel@lists.freedesktop.org>,
        linux-rdma@vger.kernel.org,
        Intel Graphics Development <intel-gfx@lists.freedesktop.org>,
        Maarten Lankhorst <maarten.lankhorst@linux.intel.com>,
        LKML <linux-kernel@vger.kernel.org>,
        amd-gfx list <amd-gfx@lists.freedesktop.org>,
        Chris Wilson <chris@chris-wilson.co.uk>,
        "moderated list:DMA BUFFER SHARING FRAMEWORK" 
        <linaro-mm-sig@lists.linaro.org>,
        Daniel Vetter <daniel.vetter@intel.com>,
        =?UTF-8?Q?Christian_K=C3=B6nig?= <christian.koenig@amd.com>,
        linux-media <linux-media@vger.kernel.org>
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Sender: linux-kernel-owner@vger.kernel.org
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On Tue, May 12, 2020 at 5:00 AM Daniel Vetter <daniel.vetter@ffwll.ch> wrot=
e:
>
> ...
>
> I think it's time to stop this little exercise.
>
> The lockdep splat, for the record:
>
> [  132.583381] =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D
> [  132.584091] WARNING: possible circular locking dependency detected
> [  132.584775] 5.7.0-rc3+ #346 Tainted: G        W
> [  132.585461] ------------------------------------------------------
> [  132.586184] kworker/2:3/865 is trying to acquire lock:
> [  132.586857] ffffc90000677c70 (crtc_ww_class_acquire){+.+.}-{0:0}, at: =
drm_atomic_helper_suspend+0x38/0x120 [drm_kms_helper]
> [  132.587569]
>                but task is already holding lock:
> [  132.589044] ffffffff82318c80 (dma_fence_map){++++}-{0:0}, at: drm_sche=
d_job_timedout+0x25/0xf0 [gpu_sched]
> [  132.589803]
>                which lock already depends on the new lock.
>
> [  132.592009]
>                the existing dependency chain (in reverse order) is:
> [  132.593507]
>                -> #2 (dma_fence_map){++++}-{0:0}:
> [  132.595019]        dma_fence_begin_signalling+0x50/0x60
> [  132.595767]        drm_atomic_helper_commit+0xa1/0x180 [drm_kms_helper=
]
> [  132.596567]        drm_client_modeset_commit_atomic+0x1ea/0x250 [drm]
> [  132.597420]        drm_client_modeset_commit_locked+0x55/0x190 [drm]
> [  132.598178]        drm_client_modeset_commit+0x24/0x40 [drm]
> [  132.598948]        drm_fb_helper_restore_fbdev_mode_unlocked+0x4b/0xa0=
 [drm_kms_helper]
> [  132.599738]        drm_fb_helper_set_par+0x30/0x40 [drm_kms_helper]
> [  132.600539]        fbcon_init+0x2e8/0x660
> [  132.601344]        visual_init+0xce/0x130
> [  132.602156]        do_bind_con_driver+0x1bc/0x2b0
> [  132.602970]        do_take_over_console+0x115/0x180
> [  132.603763]        do_fbcon_takeover+0x58/0xb0
> [  132.604564]        register_framebuffer+0x1ee/0x300
> [  132.605369]        __drm_fb_helper_initial_config_and_unlock+0x36e/0x5=
20 [drm_kms_helper]
> [  132.606187]        amdgpu_fbdev_init+0xb3/0xf0 [amdgpu]
> [  132.607032]        amdgpu_device_init.cold+0xe90/0x1677 [amdgpu]
> [  132.607862]        amdgpu_driver_load_kms+0x5a/0x200 [amdgpu]
> [  132.608697]        amdgpu_pci_probe+0xf7/0x180 [amdgpu]
> [  132.609511]        local_pci_probe+0x42/0x80
> [  132.610324]        pci_device_probe+0x104/0x1a0
> [  132.611130]        really_probe+0x147/0x3c0
> [  132.611939]        driver_probe_device+0xb6/0x100
> [  132.612766]        device_driver_attach+0x53/0x60
> [  132.613593]        __driver_attach+0x8c/0x150
> [  132.614419]        bus_for_each_dev+0x7b/0xc0
> [  132.615249]        bus_add_driver+0x14c/0x1f0
> [  132.616071]        driver_register+0x6c/0xc0
> [  132.616902]        do_one_initcall+0x5d/0x2f0
> [  132.617731]        do_init_module+0x5c/0x230
> [  132.618560]        load_module+0x2981/0x2bc0
> [  132.619391]        __do_sys_finit_module+0xaa/0x110
> [  132.620228]        do_syscall_64+0x5a/0x250
> [  132.621064]        entry_SYSCALL_64_after_hwframe+0x49/0xb3
> [  132.621903]
>                -> #1 (crtc_ww_class_mutex){+.+.}-{3:3}:
> [  132.623587]        __ww_mutex_lock.constprop.0+0xcc/0x10c0
> [  132.624448]        ww_mutex_lock+0x43/0xb0
> [  132.625315]        drm_modeset_lock+0x44/0x120 [drm]
> [  132.626184]        drmm_mode_config_init+0x2db/0x8b0 [drm]
> [  132.627098]        amdgpu_device_init.cold+0xbd1/0x1677 [amdgpu]
> [  132.628007]        amdgpu_driver_load_kms+0x5a/0x200 [amdgpu]
> [  132.628920]        amdgpu_pci_probe+0xf7/0x180 [amdgpu]
> [  132.629804]        local_pci_probe+0x42/0x80
> [  132.630690]        pci_device_probe+0x104/0x1a0
> [  132.631583]        really_probe+0x147/0x3c0
> [  132.632479]        driver_probe_device+0xb6/0x100
> [  132.633379]        device_driver_attach+0x53/0x60
> [  132.634275]        __driver_attach+0x8c/0x150
> [  132.635170]        bus_for_each_dev+0x7b/0xc0
> [  132.636069]        bus_add_driver+0x14c/0x1f0
> [  132.636974]        driver_register+0x6c/0xc0
> [  132.637870]        do_one_initcall+0x5d/0x2f0
> [  132.638765]        do_init_module+0x5c/0x230
> [  132.639654]        load_module+0x2981/0x2bc0
> [  132.640522]        __do_sys_finit_module+0xaa/0x110
> [  132.641372]        do_syscall_64+0x5a/0x250
> [  132.642203]        entry_SYSCALL_64_after_hwframe+0x49/0xb3
> [  132.643022]
>                -> #0 (crtc_ww_class_acquire){+.+.}-{0:0}:
> [  132.644643]        __lock_acquire+0x1241/0x23f0
> [  132.645469]        lock_acquire+0xad/0x370
> [  132.646274]        drm_modeset_acquire_init+0xd2/0x100 [drm]
> [  132.647071]        drm_atomic_helper_suspend+0x38/0x120 [drm_kms_helpe=
r]
> [  132.647902]        dm_suspend+0x1c/0x60 [amdgpu]
> [  132.648698]        amdgpu_device_ip_suspend_phase1+0x83/0xe0 [amdgpu]
> [  132.649498]        amdgpu_device_ip_suspend+0x1c/0x60 [amdgpu]
> [  132.650300]        amdgpu_device_gpu_recover.cold+0x4e6/0xe64 [amdgpu]
> [  132.651084]        amdgpu_job_timedout+0xfb/0x150 [amdgpu]
> [  132.651825]        drm_sched_job_timedout+0x8a/0xf0 [gpu_sched]
> [  132.652594]        process_one_work+0x23c/0x580
> [  132.653402]        worker_thread+0x50/0x3b0
> [  132.654139]        kthread+0x12e/0x150
> [  132.654868]        ret_from_fork+0x27/0x50
> [  132.655598]
>                other info that might help us debug this:
>
> [  132.657739] Chain exists of:
>                  crtc_ww_class_acquire --> crtc_ww_class_mutex --> dma_fe=
nce_map
>
> [  132.659877]  Possible unsafe locking scenario:
>
> [  132.661416]        CPU0                    CPU1
> [  132.662126]        ----                    ----
> [  132.662847]   lock(dma_fence_map);
> [  132.663574]                                lock(crtc_ww_class_mutex);
> [  132.664319]                                lock(dma_fence_map);
> [  132.665063]   lock(crtc_ww_class_acquire);
> [  132.665799]
>                 *** DEADLOCK ***
>
> [  132.667965] 4 locks held by kworker/2:3/865:
> [  132.668701]  #0: ffff8887fb81c938 ((wq_completion)events){+.+.}-{0:0},=
 at: process_one_work+0x1bc/0x580
> [  132.669462]  #1: ffffc90000677e58 ((work_completion)(&(&sched->work_td=
r)->work)){+.+.}-{0:0}, at: process_one_work+0x1bc/0x580
> [  132.670242]  #2: ffffffff82318c80 (dma_fence_map){++++}-{0:0}, at: drm=
_sched_job_timedout+0x25/0xf0 [gpu_sched]
> [  132.671039]  #3: ffff8887b84a1748 (&adev->lock_reset){+.+.}-{3:3}, at:=
 amdgpu_device_gpu_recover.cold+0x59e/0xe64 [amdgpu]
> [  132.671902]
>                stack backtrace:
> [  132.673515] CPU: 2 PID: 865 Comm: kworker/2:3 Tainted: G        W     =
    5.7.0-rc3+ #346
> [  132.674347] Hardware name: System manufacturer System Product Name/PRI=
ME X370-PRO, BIOS 4011 04/19/2018
> [  132.675194] Workqueue: events drm_sched_job_timedout [gpu_sched]
> [  132.676046] Call Trace:
> [  132.676897]  dump_stack+0x8f/0xd0
> [  132.677748]  check_noncircular+0x162/0x180
> [  132.678604]  ? stack_trace_save+0x4b/0x70
> [  132.679459]  __lock_acquire+0x1241/0x23f0
> [  132.680311]  lock_acquire+0xad/0x370
> [  132.681163]  ? drm_atomic_helper_suspend+0x38/0x120 [drm_kms_helper]
> [  132.682021]  ? cpumask_next+0x16/0x20
> [  132.682880]  ? module_assert_mutex_or_preempt+0x14/0x40
> [  132.683737]  ? __module_address+0x28/0xf0
> [  132.684601]  drm_modeset_acquire_init+0xd2/0x100 [drm]
> [  132.685466]  ? drm_atomic_helper_suspend+0x38/0x120 [drm_kms_helper]
> [  132.686335]  drm_atomic_helper_suspend+0x38/0x120 [drm_kms_helper]
> [  132.687255]  dm_suspend+0x1c/0x60 [amdgpu]
> [  132.688152]  amdgpu_device_ip_suspend_phase1+0x83/0xe0 [amdgpu]
> [  132.689057]  ? amdgpu_fence_process+0x4c/0x150 [amdgpu]
> [  132.689963]  amdgpu_device_ip_suspend+0x1c/0x60 [amdgpu]
> [  132.690893]  amdgpu_device_gpu_recover.cold+0x4e6/0xe64 [amdgpu]
> [  132.691818]  amdgpu_job_timedout+0xfb/0x150 [amdgpu]
> [  132.692707]  drm_sched_job_timedout+0x8a/0xf0 [gpu_sched]
> [  132.693597]  process_one_work+0x23c/0x580
> [  132.694487]  worker_thread+0x50/0x3b0
> [  132.695373]  ? process_one_work+0x580/0x580
> [  132.696264]  kthread+0x12e/0x150
> [  132.697154]  ? kthread_create_worker_on_cpu+0x70/0x70
> [  132.698057]  ret_from_fork+0x27/0x50
>
> Cc: linux-media@vger.kernel.org
> Cc: linaro-mm-sig@lists.linaro.org
> Cc: linux-rdma@vger.kernel.org
> Cc: amd-gfx@lists.freedesktop.org
> Cc: intel-gfx@lists.freedesktop.org
> Cc: Chris Wilson <chris@chris-wilson.co.uk>
> Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
> Cc: Christian K=C3=B6nig <christian.koenig@amd.com>
> Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm=
/amd/amdgpu/amdgpu_device.c
> index 3584e29323c0..b3b84a0d3baf 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -2415,6 +2415,14 @@ static int amdgpu_device_ip_suspend_phase1(struct =
amdgpu_device *adev)
>                 /* displays are handled separately */
>                 if (adev->ip_blocks[i].version->type =3D=3D AMD_IP_BLOCK_=
TYPE_DCE) {
>                         /* XXX handle errors */
> +
> +                       /*
> +                        * This is dm_suspend, which calls modeset locks,=
 and
> +                        * that a pretty good inversion against dma_fence=
_signal
> +                        * which gpu recovery is supposed to guarantee.
> +                        *
> +                        * Dont ask me how to fix this.
> +                        */

We actually have a fix for this.  Will be out shortly.

Alex

>                         r =3D adev->ip_blocks[i].version->funcs->suspend(=
adev);
>                         /* XXX handle errors */
>                         if (r) {
> --
> 2.26.2
>
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