Re: [PATCH] drm/xe/pm: do not warn about missing runtime PM protection after hot-unplug

On Thu, Aug 06, 2026 at 02:27:12PM +0530, Nitin Gote wrote:
> Exec queues are owned by user fds and are destroyed when the fd is closed.
> After hot-unplug this can happen from a deferred close during process
> exit, after the device has been removed and runtime PM has been disabled.
> The queue destroy path can call xe_pm_runtime_get_noresume(), and since
> runtime PM is disabled pm_runtime_get_if_in_use() returns no reference,
> so it warns about "Missing outer runtime PM protection".
> 
> This is a false positive for the hot-unplug teardown case. The device is
> already unplugged, and the queue destroy path that triggered this warning
> was checked and does not touch hardware state after unplug. GuC has already
> been sanitized by guc_fini_hw(), so no H2G is sent and the hardware
> teardown path is no longer reachable.
> 
> Skip the warning when the DRM device is already unplugged.
> 
> Observed with new IGT core_hotunplug subtests:
>   igt@core_hotunplug@hotreplug-with-load
>   igt@core_hotunplug@hotunplug-rescan-with-load
> 
> v2:
>  - Drop the drm_dev_is_unplugged() bypass from guc_exec_queue_destroy()
>    and instead exclude hot-unplug from the WARN in
>    xe_pm_runtime_get_noresume(). (Matthew Brost)
> 
> v3:
>  - Clarify that the queue destroy path was checked and does not touch
>    hardware state after unplug. (Matthew Auld)
> 
> Link: https://patchwork.freedesktop.org/patch/725773/?series=166744&rev=4
> Cc: Matthew Brost <[email protected]>
> Cc: Matthew Auld <[email protected]>
> Assisted-by: GitHub-Copilot:claude-opus-4.8
> Signed-off-by: Nitin Gote <[email protected]>
> ---
>  drivers/gpu/drm/xe/xe_pm.c | 5 ++++-
>  1 file changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_pm.c b/drivers/gpu/drm/xe/xe_pm.c
> index a5289a9df8d2..a038687d5b2c 100644
> --- a/drivers/gpu/drm/xe/xe_pm.c
> +++ b/drivers/gpu/drm/xe/xe_pm.c
> @@ -10,6 +10,7 @@
>  #include <linux/suspend.h>
>  #include <linux/dmi.h>
>  
> +#include <drm/drm_drv.h>
>  #include <drm/drm_managed.h>
>  #include <drm/ttm/ttm_placement.h>
>  
> @@ -914,7 +915,9 @@ void xe_pm_runtime_get_noresume(struct xe_device *xe)

From the documentation

 * This function should be used in inner places where it is surely already
 * protected by outer-bound callers of `xe_pm_runtime_get`.

>  	if (!ref) {
>  		pm_runtime_get_noresume(xe->drm.dev);
> -		drm_WARN(&xe->drm, !xe_pm_suspending_or_resuming(xe),
> +		drm_WARN(&xe->drm,
> +			 !drm_dev_is_unplugged(&xe->drm) &&
> +			 !xe_pm_suspending_or_resuming(xe),

So IMO this is more of a band-aid.

Raag

>  			 "Missing outer runtime PM protection\n");
>  	}
>  }
> -- 
> 2.50.1
>