Hi Dave, > On Tue, 20 Jan 2026 at 22:15, Li Chen <[email protected]> wrote: > > > > Kexec reboot does not reset PCI devices. > > Invoking the full DRM/TTM teardown from ->shutdown can trigger WARNs when > > userspace still holds DRM file descriptors. > > > > Quiesce the GPU through the suspend path and then power down the PCI > > function so the next kernel can re-initialize the device from a consistent > > state. > > > > WARNING: drivers/gpu/drm/drm_mode_config.c:578 at > > drm_mode_config_cleanup+0x2e7/0x300, CPU#2: kexec/1300 > > Call Trace: > > <TASK> > > ? srso_return_thunk+0x5/0x5f > > ? enable_work+0x3a/0x100 > > nouveau_display_destroy+0x39/0x70 [nouveau > > c19e0da7fd83583a023f855c510d9a3903808734] > > nouveau_drm_device_fini+0x7b/0x1f0 [nouveau > > c19e0da7fd83583a023f855c510d9a3903808734] > > nouveau_drm_shutdown+0x52/0xc0 [nouveau > > c19e0da7fd83583a023f855c510d9a3903808734] > > pci_device_shutdown+0x35/0x60 > > device_shutdown+0x11c/0x1b0 > > kernel_kexec+0x13a/0x160 > > __do_sys_reboot+0x209/0x240 > > do_syscall_64+0x81/0x610 > > ? srso_return_thunk+0x5/0x5f > > ? __rtnl_unlock+0x37/0x70 > > ? srso_return_thunk+0x5/0x5f > > ? netdev_run_todo+0x63/0x570 > > ? netif_change_flags+0x54/0x70 > > ? srso_return_thunk+0x5/0x5f > > ? devinet_ioctl+0x1e5/0x790 > > ? srso_return_thunk+0x5/0x5f > > ? inet_ioctl+0x1e9/0x200 > > ? srso_return_thunk+0x5/0x5f > > ? srso_return_thunk+0x5/0x5f > > ? sock_do_ioctl+0x7d/0x130 > > ? srso_return_thunk+0x5/0x5f > > ? __x64_sys_ioctl+0x97/0xe0 > > ? srso_return_thunk+0x5/0x5f > > ? srso_return_thunk+0x5/0x5f > > ? do_syscall_64+0x23b/0x610 > > ? srso_return_thunk+0x5/0x5f > > ? put_user_ifreq+0x7a/0x90 > > ? srso_return_thunk+0x5/0x5f > > ? sock_do_ioctl+0x107/0x130 > > ? srso_return_thunk+0x5/0x5f > > ? __x64_sys_ioctl+0x97/0xe0 > > ? srso_return_thunk+0x5/0x5f > > ? do_syscall_64+0x81/0x610 > > ? srso_return_thunk+0x5/0x5f > > ? exc_page_fault+0x7e/0x1a0 > > entry_SYSCALL_64_after_hwframe+0x76/0x7e > > > > nouveau 0000:26:00.0: [drm] drm_WARN_ON(!list_empty(&fb->filp_head)) > > WARNING: drivers/gpu/drm/drm_framebuffer.c:833 at > > drm_framebuffer_free+0x73/0xa0, CPU#2: kexec/1300 > > Call Trace: > > <TASK> > > drm_mode_config_cleanup+0x248/0x300 > > ? __pfx___drm_printfn_dbg+0x10/0x10 > > ? drm_mode_config_cleanup+0x1dc/0x300 > > nouveau_display_destroy+0x39/0x70 [nouveau > > c19e0da7fd83583a023f855c510d9a3903808734] > > nouveau_drm_device_fini+0x7b/0x1f0 [nouveau > > c19e0da7fd83583a023f855c510d9a3903808734] > > nouveau_drm_shutdown+0x52/0xc0 [nouveau > > c19e0da7fd83583a023f855c510d9a3903808734] > > pci_device_shutdown+0x35/0x60 > > device_shutdown+0x11c/0x1b0 > > kernel_kexec+0x13a/0x160 > > __do_sys_reboot+0x209/0x240 > > do_syscall_64+0x81/0x610 > > ? srso_return_thunk+0x5/0x5f > > ? __rtnl_unlock+0x37/0x70 > > ? srso_return_thunk+0x5/0x5f > > ? netdev_run_todo+0x63/0x570 > > ? netif_change_flags+0x54/0x70 > > ? srso_return_thunk+0x5/0x5f > > ? devinet_ioctl+0x1e5/0x790 > > ? srso_return_thunk+0x5/0x5f > > ? inet_ioctl+0x1e9/0x200 > > ? srso_return_thunk+0x5/0x5f > > ? srso_return_thunk+0x5/0x5f > > ? sock_do_ioctl+0x7d/0x130 > > ? srso_return_thunk+0x5/0x5f > > ? __x64_sys_ioctl+0x97/0xe0 > > ? srso_return_thunk+0x5/0x5f > > ? srso_return_thunk+0x5/0x5f > > ? do_syscall_64+0x23b/0x610 > > ? srso_return_thunk+0x5/0x5f > > ? put_user_ifreq+0x7a/0x90 > > ? srso_return_thunk+0x5/0x5f > > ? sock_do_ioctl+0x107/0x130 > > ? srso_return_thunk+0x5/0x5f > > ? __x64_sys_ioctl+0x97/0xe0 > > ? srso_return_thunk+0x5/0x5f > > ? do_syscall_64+0x81/0x610 > > ? srso_return_thunk+0x5/0x5f > > ? exc_page_fault+0x7e/0x1a0 > > entry_SYSCALL_64_after_hwframe+0x76/0x7e > > > > WARNING: include/drm/ttm/ttm_resource.h:406 at > > nouveau_ttm_fini+0x257/0x270 [nouveau], CPU#2: kexec/1300 > > Call Trace: > > <TASK> > > nouveau_drm_device_fini+0x93/0x1f0 [nouveau > > c19e0da7fd83583a023f855c510d9a3903808734] > > nouveau_drm_shutdown+0x52/0xc0 [nouveau > > c19e0da7fd83583a023f855c510d9a3903808734] > > pci_device_shutdown+0x35/0x60 > > device_shutdown+0x11c/0x1b0 > > kernel_kexec+0x13a/0x160 > > __do_sys_reboot+0x209/0x240 > > do_syscall_64+0x81/0x610 > > ? srso_return_thunk+0x5/0x5f > > ? __rtnl_unlock+0x37/0x70 > > ? srso_return_thunk+0x5/0x5f > > ? netdev_run_todo+0x63/0x570 > > ? netif_change_flags+0x54/0x70 > > ? srso_return_thunk+0x5/0x5f > > ? devinet_ioctl+0x1e5/0x790 > > ? srso_return_thunk+0x5/0x5f > > ? inet_ioctl+0x1e9/0x200 > > ? srso_return_thunk+0x5/0x5f > > ? srso_return_thunk+0x5/0x5f > > ? sock_do_ioctl+0x7d/0x130 > > ? srso_return_thunk+0x5/0x5f > > ? __x64_sys_ioctl+0x97/0xe0 > > ? srso_return_thunk+0x5/0x5f > > ? srso_return_thunk+0x5/0x5f > > ? do_syscall_64+0x23b/0x610 > > ? srso_return_thunk+0x5/0x5f > > ? put_user_ifreq+0x7a/0x90 > > ? srso_return_thunk+0x5/0x5f > > ? sock_do_ioctl+0x107/0x130 > > ? srso_return_thunk+0x5/0x5f > > ? __x64_sys_ioctl+0x97/0xe0 > > ? srso_return_thunk+0x5/0x5f > > ? do_syscall_64+0x81/0x610 > > ? srso_return_thunk+0x5/0x5f > > ? exc_page_fault+0x7e/0x1a0 > > entry_SYSCALL_64_after_hwframe+0x76/0x7e > > > > Signed-off-by: Li Chen <[email protected]> > > --- > > drivers/gpu/drm/nouveau/nouveau_drm.c | 24 ++++++++++++++++++++++++ > > 1 file changed, 24 insertions(+) > > > > diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c > > b/drivers/gpu/drm/nouveau/nouveau_drm.c > > index 1527b801f013..50384462723b 100644 > > --- a/drivers/gpu/drm/nouveau/nouveau_drm.c > > +++ b/drivers/gpu/drm/nouveau/nouveau_drm.c > > @@ -1079,6 +1079,29 @@ nouveau_pmops_resume(struct device *dev) > > return ret; > > } > > > > +static void > > +nouveau_drm_shutdown(struct pci_dev *pdev) > > +{ > > + struct nouveau_drm *drm = pci_get_drvdata(pdev); > > + int ret; > > + > > + if (!drm) > > + return; > > + > > + if (drm->dev->switch_power_state == DRM_SWITCH_POWER_OFF || > > + drm->dev->switch_power_state == DRM_SWITCH_POWER_DYNAMIC_OFF) > > + return; > > + > > + ret = nouveau_do_suspend(drm, false); > > + if (ret) > > + NV_ERROR(drm, "shutdown suspend failed with: %d\n", ret); > > + > > + pci_save_state(pdev); > > + pci_disable_device(pdev); > > + pci_set_power_state(pdev, PCI_D3hot); > > + usleep_range(200, 400);\ > > Why is this needed? it at least needs a comment.
This patch is needed for kexec/KHO/LUO reboot: firmware reset is skipped, so the GPU may remain in an active/DMA state and the next kernel can fail to re-init nouveau. We can’t call the full DRM/TTM teardown from ->shutdown() because userspace may still hold DRM fds during shutdown, which triggers WARNs. So the shutdown hook reuses the suspend/quiesce path (safe with open fds) and then powers down the PCI function (D3hot) to leave the device in a consistent state for the next kernel. Regards, Li
