Re: [PATCH] drm/xe: Fix circular locking dependency

[Rodrigo Vivi <rodrigo.vivi@intel.com>]

On Fri, Sep 12, 2025 at 12:33:46AM -0500, Lucas De Marchi wrote:
> On Thu, Sep 11, 2025 at 05:20:25PM -0400, Rodrigo Vivi wrote:
> > Fix this:
> > 
> > ======================================================
> > WARNING: possible circular locking dependency detected
> > 6.17.0-rc4-lgci-xe-xe-pw-153723v2+ #1 Tainted: G S   U
> > ------------------------------------------------------
> > xe_pm/11324 is trying to acquire lock:
> > ffff8881085f22a0 (&pc->freq_lock){+.+.}-{3:3}, at:
> > 		  xe_guc_pc_start+0x39f/0xf70 [xe]
> > 
> > but task is already holding lock:
> > 
> > ffffffffa1020420 (xe_rpm_nod3cold_map){+.+.}-{0:0}, at:
> > 		  xe_rpm_lockmap_acquire+0x1a/0x70 [xe]
> > 
> > which lock already depends on the new lock.
> > 
> > Possible unsafe locking scenario:
> >      CPU0                    CPU1
> >      ----                    ----
> > lock(xe_rpm_nod3cold_map);
> >                              lock(&pc->freq_lock);
> >                              lock(xe_rpm_nod3cold_map);
> > lock(&pc->freq_lock);
> > 
> > Reported-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
> > Closes: https://intel-gfx-ci.01.org/tree/intel-xe/xe-pw-153723v2/shard-bmg-8/igt@xe_pm@s2idle-d3hot-basic-exec.html#dmesg-warnings335
> 
> Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/6122

Much better, thank you!
I removed the other one while merging it.

> 
> ?
> 
> thanks
> Lucas De Marchi
> 
> > Fixes: 60d2b7899142 ("drm/xe/guc: Add SLPC power profile interface")
> > Cc: Vinay Belgaumkar <vinay.belgaumkar@intel.com>
> > Signed-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>
> > ---
> > drivers/gpu/drm/xe/xe_gt_freq.c | 2 ++
> > drivers/gpu/drm/xe/xe_guc_pc.c  | 2 +-
> > 2 files changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/drivers/gpu/drm/xe/xe_gt_freq.c b/drivers/gpu/drm/xe/xe_gt_freq.c
> > index 781e4890fb26..4ff1b6b58d6b 100644
> > --- a/drivers/gpu/drm/xe/xe_gt_freq.c
> > +++ b/drivers/gpu/drm/xe/xe_gt_freq.c
> > @@ -246,7 +246,9 @@ static ssize_t power_profile_store(struct kobject *kobj,
> > 	struct xe_guc_pc *pc = dev_to_pc(dev);
> > 	int err;
> > 
> > +	xe_pm_runtime_get(dev_to_xe(dev));
> > 	err = xe_guc_pc_set_power_profile(pc, buff);
> > +	xe_pm_runtime_put(dev_to_xe(dev));
> > 
> > 	return err ?: count;
> > }
> > diff --git a/drivers/gpu/drm/xe/xe_guc_pc.c b/drivers/gpu/drm/xe/xe_guc_pc.c
> > index 68a5bf8e3946..53fdf59524c4 100644
> > --- a/drivers/gpu/drm/xe/xe_guc_pc.c
> > +++ b/drivers/gpu/drm/xe/xe_guc_pc.c
> > @@ -1215,7 +1215,7 @@ int xe_guc_pc_set_power_profile(struct xe_guc_pc *pc, const char *buf)
> > 		return -EINVAL;
> > 
> > 	guard(mutex)(&pc->freq_lock);
> > -	xe_pm_runtime_get(pc_to_xe(pc));
> > +	xe_pm_runtime_get_noresume(pc_to_xe(pc));
> > 
> > 	ret = pc_action_set_param(pc,
> > 				  SLPC_PARAM_POWER_PROFILE,
> > -- 
> > 2.51.0
> >