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McKenney" To: linux-kernel@vger.kernel.org Cc: mingo@kernel.org, jiangshanlai@gmail.com, dipankar@in.ibm.com, akpm@linux-foundation.org, mathieu.desnoyers@efficios.com, josh@joshtriplett.org, tglx@linutronix.de, peterz@infradead.org, rostedt@goodmis.org, dhowells@redhat.com, edumazet@google.com, fweisbec@gmail.com, oleg@redhat.com, joel@joelfernandes.org, "Paul E. McKenney" Subject: [PATCH tip/core/rcu 10/17] rcu: Print per-CPU callback counts for forward-progress failures Date: Sun, 11 Nov 2018 12:20:20 -0800 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181111201956.GA11935@linux.ibm.com> References: <20181111201956.GA11935@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18111120-0052-0000-0000-00000354249D X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010028; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000270; SDB=6.01116031; UDB=6.00578740; IPR=6.00896132; MB=3.00024115; MTD=3.00000008; XFM=3.00000015; UTC=2018-11-11 20:20:32 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18111120-0053-0000-0000-00005EBB30EF Message-Id: <20181111202027.13585-10-paulmck@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:,, definitions=2018-11-11_13:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=1 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1811110194 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This commit prints out the non-zero per-CPU callback counts when a forware-progress error (OOM event) occurs. Signed-off-by: Paul E. McKenney [ paulmck: Fix a pair of uninitialized locals spotted by kbuild test robot. ] --- kernel/rcu/tree.c | 18 ++++++++++++++++++ 1 file changed, 18 insertions(+) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 67f2c7a055b6..cef7d9867508 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2672,6 +2672,10 @@ rcu_check_gp_start_stall(struct rcu_node *rnp, struct rcu_data *rdp) */ void rcu_fwd_progress_check(unsigned long j) { + unsigned long cbs; + int cpu; + unsigned long max_cbs = 0; + int max_cpu = -1; struct rcu_data *rdp; if (rcu_gp_in_progress()) { @@ -2682,6 +2686,20 @@ void rcu_fwd_progress_check(unsigned long j) rcu_check_gp_start_stall(rdp->mynode, rdp, j); preempt_enable(); } + for_each_possible_cpu(cpu) { + cbs = rcu_get_n_cbs_cpu(cpu); + if (!cbs) + continue; + if (max_cpu < 0) + pr_info("%s: callbacks", __func__); + pr_cont(" %d: %lu", cpu, cbs); + if (cbs <= max_cbs) + continue; + max_cbs = cbs; + max_cpu = cpu; + } + if (max_cpu >= 0) + pr_cont("\n"); } EXPORT_SYMBOL_GPL(rcu_fwd_progress_check); -- 2.17.1