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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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.