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authorZhen Lei <thunder.leizhen@huawei.com>2023-07-12 17:15:57 +0200
committerFrederic Weisbecker <frederic@kernel.org>2023-09-11 21:46:54 +0200
commitf3efe02fd56e2498ad8da4c4f444a34aa1456a46 (patch)
tree5046ad3bd1d34090cfe562dd88fd77c73c421179
parentrcu: Delete a redundant check in rcu_check_gp_kthread_starvation() (diff)
downloadlinux-f3efe02fd56e2498ad8da4c4f444a34aa1456a46.tar.xz
linux-f3efe02fd56e2498ad8da4c4f444a34aa1456a46.zip
rcu: Don't redump the stalled CPU where RCU GP kthread last ran
The stacks of all stalled CPUs will be dumped in rcu_dump_cpu_stacks(). If the CPU on where RCU GP kthread last ran is stalled, its stack does not need to be dumped again. We can search the corresponding backtrace based on the printed CPU ID. For example: [ 87.328275] rcu: rcu_sched kthread starved for ... ->cpu=3 <--------| ... ... | [ 89.385007] NMI backtrace for cpu 3 <--------| [ 89.385179] CPU: 3 PID: 0 Comm: swapper/3 Not tainted 5.10.0+ #22 <--| [ 89.385188] Hardware name: linux,dummy-virt (DT) [ 89.385196] pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--) [ 89.385204] pc : arch_cpu_idle+0x40/0xc0 [ 89.385211] lr : arch_cpu_idle+0x2c/0xc0 ... ... [ 89.385566] Call trace: [ 89.385574] arch_cpu_idle+0x40/0xc0 [ 89.385581] default_idle_call+0x100/0x450 [ 89.385589] cpuidle_idle_call+0x2f8/0x460 [ 89.385596] do_idle+0x1dc/0x3d0 [ 89.385604] cpu_startup_entry+0x5c/0xb0 [ 89.385613] secondary_start_kernel+0x35c/0x520 Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
-rw-r--r--kernel/rcu/tree_stall.h4
1 files changed, 3 insertions, 1 deletions
diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h
index b5ce0580074e..fc04a8d7ce96 100644
--- a/kernel/rcu/tree_stall.h
+++ b/kernel/rcu/tree_stall.h
@@ -534,12 +534,14 @@ static void rcu_check_gp_kthread_starvation(void)
data_race(READ_ONCE(rcu_state.gp_state)),
gpk ? data_race(READ_ONCE(gpk->__state)) : ~0, cpu);
if (gpk) {
+ struct rcu_data *rdp = per_cpu_ptr(&rcu_data, cpu);
+
pr_err("\tUnless %s kthread gets sufficient CPU time, OOM is now expected behavior.\n", rcu_state.name);
pr_err("RCU grace-period kthread stack dump:\n");
sched_show_task(gpk);
if (cpu_is_offline(cpu)) {
pr_err("RCU GP kthread last ran on offline CPU %d.\n", cpu);
- } else {
+ } else if (!(data_race(READ_ONCE(rdp->mynode->qsmask)) & rdp->grpmask)) {
pr_err("Stack dump where RCU GP kthread last ran:\n");
dump_cpu_task(cpu);
}