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McKenney" To: rcu@vger.kernel.org Cc: linux-kernel@vger.kernel.org, kernel-team@meta.com, rostedt@goodmis.org, "Paul E. McKenney" Subject: [PATCH 1/9] doc: Update stallwarn.rst based on RCU Tasks Trace as SRCU Date: Fri, 18 Sep 2026 17:28:52 -0700 Message-Id: <20260919002900.3134117-1-paulmck@kernel.org> X-Mailer: git-send-email 2.40.1 In-Reply-To: <7dc2d858-44cc-4efa-8e94-1fe27d691f2b@paulmck-laptop> References: <7dc2d858-44cc-4efa-8e94-1fe27d691f2b@paulmck-laptop> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Now that RCU Tasks Trace has been re-implemented in terms of SRCU, update stallwarn.rst to remove obsolete verbiage about RCU Tasks Trace stall warnings. Signed-off-by: Paul E. McKenney --- Documentation/RCU/stallwarn.rst | 22 +++++++++------------- 1 file changed, 9 insertions(+), 13 deletions(-) diff --git a/Documentation/RCU/stallwarn.rst b/Documentation/RCU/stallwarn.rst index d7c8eff63317..a986358a5c27 100644 --- a/Documentation/RCU/stallwarn.rst +++ b/Documentation/RCU/stallwarn.rst @@ -122,10 +122,11 @@ warnings: of RCU CPU stall warnings, eventually leading to the realization that the CPU had failed. -The RCU, RCU-sched, RCU-tasks, and RCU-tasks-trace implementations have -CPU stall warning. Note that SRCU does *not* have CPU stall warnings. -Please note that RCU only detects CPU stalls when there is a grace period -in progress. No grace period, no CPU stall warnings. +The RCU and RCU-tasks implementations have CPU stall warning. Note that +SRCU does *not* have CPU stall warnings, and now that RCU-tasks-trace +is implemented in terms of SRCU, neither does it. Please note that +RCU only detects CPU stalls when there is a grace period in progress. +No grace period, no CPU stall warnings. To diagnose the cause of the stall, inspect the stack traces. The offending function will usually be near the top of the stack. @@ -213,21 +214,16 @@ RCU_STALL_RAT_DELAY rcupdate.rcu_task_stall_timeout ------------------------------- - This boot/sysfs parameter controls the RCU-tasks and - RCU-tasks-trace stall warning intervals. A value of zero or less - suppresses RCU-tasks stall warnings. A positive value sets the - stall-warning interval in seconds. An RCU-tasks stall warning - starts with the line: + This boot/sysfs parameter controls the RCU-tasks stall warning + interval. A value of zero or less suppresses RCU-tasks stall + warnings. A positive value sets the stall-warning interval + in seconds. An RCU-tasks stall warning starts with the line: INFO: rcu_tasks detected stalls on tasks: And continues with the output of sched_show_task() for each task stalling the current RCU-tasks grace period. - An RCU-tasks-trace stall warning starts (and continues) similarly: - - INFO: rcu_tasks_trace detected stalls on tasks - Interpreting RCU's CPU Stall-Detector "Splats" ============================================== -- 2.40.1