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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 4/4] rcu: Eliminate BUG_ON() for kernel/rcu/update.c Date: Sun, 11 Nov 2018 11:32:17 -0800 X-Mailer: git-send-email 2.17.1 In-Reply-To: <20181111193156.GA3666@linux.ibm.com> References: <20181111193156.GA3666@linux.ibm.com> X-TM-AS-GCONF: 00 x-cbid: 18111119-2213-0000-0000-00000315A76B X-IBM-SpamModules-Scores: X-IBM-SpamModules-Versions: BY=3.00010028; HX=3.00000242; KW=3.00000007; PH=3.00000004; SC=3.00000270; SDB=6.01116015; UDB=6.00578730; IPR=6.00896115; MB=3.00024114; MTD=3.00000008; XFM=3.00000015; UTC=2018-11-11 19:32:21 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18111119-2214-0000-0000-00005C3867C3 Message-Id: <20181111193217.4010-4-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-1811110185 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The update.c file has a number of calls to BUG_ON(), which panics the kernel, which is not a good strategy for devices (like embedded) that don't have a way to capture console output. This commit therefore converts these BUG_ON() calls to WARN_ON_ONCE() and WARN_ONCE(). Reported-by: Linus Torvalds Signed-off-by: Paul E. McKenney --- kernel/rcu/update.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/update.c b/kernel/rcu/update.c index f203b94f6b5b..cb26de25658a 100644 --- a/kernel/rcu/update.c +++ b/kernel/rcu/update.c @@ -822,7 +822,8 @@ static int __init rcu_spawn_tasks_kthread(void) struct task_struct *t; t = kthread_run(rcu_tasks_kthread, NULL, "rcu_tasks_kthread"); - BUG_ON(IS_ERR(t)); + if (WARN_ONCE(IS_ERR(t), "%s: Could not start Tasks-RCU grace-period kthread, OOM is now expected behavior\n", __func__)) + return 0; smp_mb(); /* Ensure others see full kthread. */ WRITE_ONCE(rcu_tasks_kthread_ptr, t); return 0; -- 2.17.1