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| author | Maarten Lankhorst <dev@lankhorst.se> | 2025-08-28 12:09:43 +0300 |
|---|---|---|
| committer | Maarten Lankhorst <dev@lankhorst.se> | 2025-10-09 17:10:37 +0300 |
| commit | ed1fbee3debbfcf6fd69a69509545ace00118f82 (patch) | |
| tree | 74ce55a434c8e7831d4dd76c60e453be887bfb41 /drivers/gpu | |
| parent | 0676602f845313ff2ea0a44a39488e5f6b8720d5 (diff) | |
| download | linux-ed1fbee3debbfcf6fd69a69509545ace00118f82.tar.xz | |
drm/i915: Disable tracepoints for PREEMPT_RT
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.
[mlankhorst]
The original patch was insufficient, and since the tracing
infrastructure does not allow for partial disabling of tracepoints.
Completely disable tracing for the entire i915 driver in PREEMPT_RT,
a separate fix for display tracepoints on xe is added to make those
work.
Cc: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Reported-by: Luca Abeni <lucabe72@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Co-developed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Jani Nikula <jani.nikula@intel.com>
Link: https://lore.kernel.org/r/20250828090944.101069-1-dev@lankhorst.se
Signed-off-by: Maarten Lankhorst <dev@lankhorst.se>
Diffstat (limited to 'drivers/gpu')
| -rw-r--r-- | drivers/gpu/drm/i915/Makefile | 5 |
1 files changed, 5 insertions, 0 deletions
diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile index 78a45a6681df..6d7800e25e55 100644 --- a/drivers/gpu/drm/i915/Makefile +++ b/drivers/gpu/drm/i915/Makefile @@ -13,6 +13,11 @@ subdir-ccflags-$(CONFIG_DRM_I915_WERROR) += -Werror # drivers. Define I915 when building i915. subdir-ccflags-y += -DI915 +# FIXME: Disable tracepoints on i915 for PREEMPT_RT, unfortunately +# it's an all or nothing flag. You cannot selectively disable +# only some tracepoints. +subdir-ccflags-$(CONFIG_PREEMPT_RT) += -DNOTRACE + subdir-ccflags-y += -I$(src) # Please keep these build lists sorted! |