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[3/8] rcu/exp: Fix RCU expedited parallel grace period kworker allocation failure recovery

Message ID 20231219140843.939329-4-frederic@kernel.org
State New
Headers
Series rcu: Fix expedited GP deadlock (and cleanup some nocb stuff) |

Commit Message

Frederic Weisbecker Dec. 19, 2023, 2:08 p.m. UTC 
  Under CONFIG_RCU_EXP_KTHREAD=y, the nodes initialization for expedited
grace periods is queued to a kworker. However if the allocation of that
kworker failed, the nodes initialization is performed synchronously by
the caller instead.

Now the check for kworker initialization failure relies on the kworker
pointer to be NULL while its value might actually encapsulate an
allocation failure error.

Make sure to handle this case.

Reviewed-by: Kalesh Singh <kaleshsingh@google.com>
Fixes: 9621fbee44df ("rcu: Move expedited grace period (GP) work to RT kthread_worker")
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
---
 kernel/rcu/tree.c | 1 +
 1 file changed, 1 insertion(+)
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Patch

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index de5796ce024f..65d730a2b492 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -4759,6 +4759,7 @@  static void __init rcu_start_exp_gp_kworkers(void)
 	rcu_exp_par_gp_kworker = kthread_create_worker(0, par_gp_kworker_name);
 	if (IS_ERR_OR_NULL(rcu_exp_par_gp_kworker)) {
 		pr_err("Failed to create %s!\n", par_gp_kworker_name);
+		rcu_exp_par_gp_kworker = NULL;
 		kthread_destroy_worker(rcu_exp_gp_kworker);
 		return;
 	}