Luca Abeni reported this: | BUG: scheduling while atomic: kworker/u8:2/15203/0x00000003 | CPU: 1 PID: 15203 Comm: kworker/u8:2 Not tainted 4.19.1-rt3 #10 | Call Trace: | rt_spin_lock+0x3f/0x50 | gen6_read32+0x45/0x1d0 [i915] | g4x_get_vblank_counter+0x36/0x40 [i915] | trace_event_raw_event_i915_pipe_update_start+0x7d/0xf0 [i915]
The tracing events use trace_intel_pipe_update_start() among other events use functions acquire spinlock_t locks which are transformed into sleeping locks on PREEMPT_RT. A few trace points use intel_get_crtc_scanline(), others use ->get_vblank_counter() wich also might acquire a sleeping locks on PREEMPT_RT. At the time the arguments are evaluated within trace point, preemption is disabled and so the locks must not be acquired on PREEMPT_RT. Based on this I don't see any other way than disable trace points on PREMPT_RT. Acked-by: Tvrtko Ursulin <tvrtko.ursu...@igalia.com> Reported-by: Luca Abeni <lucab...@gmail.com> Cc: Steven Rostedt <rost...@goodmis.org> Signed-off-by: Sebastian Andrzej Siewior <bige...@linutronix.de> --- drivers/gpu/drm/i915/display/intel_display_trace.h | 4 ++++ drivers/gpu/drm/i915/i915_trace.h | 4 ++++ drivers/gpu/drm/i915/intel_uncore_trace.h | 4 ++++ 3 files changed, 12 insertions(+) diff --git a/drivers/gpu/drm/i915/display/intel_display_trace.h b/drivers/gpu/drm/i915/display/intel_display_trace.h index 27ebc32cb61a5..a519d94700c36 100644 --- a/drivers/gpu/drm/i915/display/intel_display_trace.h +++ b/drivers/gpu/drm/i915/display/intel_display_trace.h @@ -13,6 +13,10 @@ #if !defined(__INTEL_DISPLAY_TRACE_H__) || defined(TRACE_HEADER_MULTI_READ) #define __INTEL_DISPLAY_TRACE_H__ +#if defined(CONFIG_PREEMPT_RT) && !defined(NOTRACE) +#define NOTRACE +#endif + #include <linux/string.h> #include <linux/string_helpers.h> #include <linux/types.h> diff --git a/drivers/gpu/drm/i915/i915_trace.h b/drivers/gpu/drm/i915/i915_trace.h index 7ed41ce9b7085..6b87ef6005c69 100644 --- a/drivers/gpu/drm/i915/i915_trace.h +++ b/drivers/gpu/drm/i915/i915_trace.h @@ -6,6 +6,10 @@ #if !defined(_I915_TRACE_H_) || defined(TRACE_HEADER_MULTI_READ) #define _I915_TRACE_H_ +#if defined(CONFIG_PREEMPT_RT) && !defined(NOTRACE) +#define NOTRACE +#endif + #include <linux/stringify.h> #include <linux/types.h> #include <linux/tracepoint.h> diff --git a/drivers/gpu/drm/i915/intel_uncore_trace.h b/drivers/gpu/drm/i915/intel_uncore_trace.h index f13ff71edf2db..3c67e267fb602 100644 --- a/drivers/gpu/drm/i915/intel_uncore_trace.h +++ b/drivers/gpu/drm/i915/intel_uncore_trace.h @@ -7,6 +7,10 @@ #if !defined(__INTEL_UNCORE_TRACE_H__) || defined(TRACE_HEADER_MULTI_READ) #define __INTEL_UNCORE_TRACE_H__ +#if defined(CONFIG_PREEMPT_RT) && !defined(NOTRACE) +#define NOTRACE +#endif + #include "i915_reg_defs.h" #include <linux/types.h> -- 2.50.0
