diff options
| author | Neeraj Upadhyay <quic_neeraju@quicinc.com> | 2021-12-11 22:31:39 +0530 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@kernel.org> | 2022-02-01 17:19:02 -0800 |
| commit | 02e3024175274ed4bf7912e7a1281b300cec76b5 (patch) | |
| tree | 117698b38732fd21ccad0814910bbb4792d5bc66 /kernel/rcu/tree_nocb.h | |
| parent | a47f9f131dfe4f765e385fa90e13032eadb00bac (diff) | |
rcu/nocb: Handle concurrent nocb kthreads creation
When multiple CPUs in the same nocb gp/cb group concurrently
come online, they might try to concurrently create the same
rcuog kthread. Fix this by using nocb gp CPU's spawn mutex to
provide mutual exclusion for the rcuog kthread creation code.
[ paulmck: Whitespace fixes per kernel test robot feedback. ]
Acked-by: David Woodhouse <dwmw@amazon.co.uk>
Signed-off-by: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Diffstat (limited to 'kernel/rcu/tree_nocb.h')
| -rw-r--r-- | kernel/rcu/tree_nocb.h | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/kernel/rcu/tree_nocb.h b/kernel/rcu/tree_nocb.h index eeafb546a7a0..1e40519d1a05 100644 --- a/kernel/rcu/tree_nocb.h +++ b/kernel/rcu/tree_nocb.h @@ -1226,6 +1226,7 @@ static void __init rcu_boot_init_nocb_percpu_data(struct rcu_data *rdp) raw_spin_lock_init(&rdp->nocb_gp_lock); timer_setup(&rdp->nocb_timer, do_nocb_deferred_wakeup_timer, 0); rcu_cblist_init(&rdp->nocb_bypass); + mutex_init(&rdp->nocb_gp_kthread_mutex); } /* @@ -1248,13 +1249,17 @@ static void rcu_spawn_cpu_nocb_kthread(int cpu) /* If we didn't spawn the GP kthread first, reorganize! */ rdp_gp = rdp->nocb_gp_rdp; + mutex_lock(&rdp_gp->nocb_gp_kthread_mutex); if (!rdp_gp->nocb_gp_kthread) { t = kthread_run(rcu_nocb_gp_kthread, rdp_gp, "rcuog/%d", rdp_gp->cpu); - if (WARN_ONCE(IS_ERR(t), "%s: Could not start rcuo GP kthread, OOM is now expected behavior\n", __func__)) + if (WARN_ONCE(IS_ERR(t), "%s: Could not start rcuo GP kthread, OOM is now expected behavior\n", __func__)) { + mutex_unlock(&rdp_gp->nocb_gp_kthread_mutex); return; + } WRITE_ONCE(rdp_gp->nocb_gp_kthread, t); } + mutex_unlock(&rdp_gp->nocb_gp_kthread_mutex); /* Spawn the kthread for this CPU. */ t = kthread_run(rcu_nocb_cb_kthread, rdp, |