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Sun, 04 Jan 2026 00:10:33 -0800 (PST) Received: from pengdl-pc.mioffice.cn ([43.224.245.249]) by smtp.gmail.com with ESMTPSA id 98e67ed59e1d1-34f476f9f8bsm3295145a91.7.2026.01.04.00.10.30 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Jan 2026 00:10:32 -0800 (PST) From: Donglin Peng To: paulmck@kernel.org Cc: frederic@kernel.org, neeraj.upadhyay@kernel.org, joelagnelf@nvidia.com, qiang.zhang@linux.dev, rostedt@goodmis.org, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, Donglin Peng Subject: [PATCH] rcu: Align stall warning 'idle=' output with documentation Date: Sun, 4 Jan 2026 16:10:27 +0800 Message-Id: <20260104081027.189234-1-dolinux.peng@gmail.com> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Donglin Peng The RCU stall warning message includes an "idle=3D" field to indicate the dyntick-idle state of a CPU. According to Documentation/RCU/stallwarn.r= st, the hexadecimal number before the first '/' represents the low-order 16 bits of the dynticks counter. An even value denotes that the CPU is in dyntick-idle mode, while an odd value indicates otherwise. This was accurate until commit 171476775d32 ("context_tracking: Convert sta= te to atomic_t"), which merged the context tracking state and the dynticks counter into a single atomic value. Consequently, the value printed in the stall warning no longer directly corresponds to the documented dynticks counter bits. To restore consistency between the code's output and the documentation, right-shift the merged atomic state value to extract and display the correct low-order bits of the dynticks counter. Fixes: 171476775d32 ("context_tracking: Convert state to atomic_t") Signed-off-by: Donglin Peng Reviewed-by: Joel Fernandes --- kernel/rcu/tree_stall.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index b67532cb8770..d25cc826d77a 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -555,7 +555,7 @@ static void print_cpu_stall_info(int cpu) rdp->rcu_iw_pending ? (int)min(delta, 9UL) + '0' : "!."[!delta], ticks_value, ticks_title, - ct_rcu_watching_cpu(cpu) & 0xffff, + (ct_rcu_watching_cpu(cpu) >> ilog2(CT_RCU_WATCHING)) & 0xffff, ct_nesting_cpu(cpu), ct_nmi_nesting_cpu(cpu), rdp->softirq_snap, kstat_softirqs_cpu(RCU_SOFTIRQ, cpu), data_race(rcu_state.n_force_qs) - rcu_state.n_force_qs_gpstart, --=20 2.34.1