[PATCH] docs: Document panic_on_rcu_stall default behavior

[Kunwu Chan]

From: Kunwu Chan <kunwu.chan@xxxxxxxxx>

Commit ab875b3e179f ("rcu: Add BOOTPARAM_RCU_STALL_PANIC
Kconfig option") made the default value of
kernel.panic_on_rcu_stall depend on
CONFIG_BOOTPARAM_RCU_STALL_PANIC.

Document this in kernel.rst

Signed-off-by: Kunwu Chan <kunwu.chan@xxxxxxxxx>
---
 Documentation/admin-guide/sysctl/kernel.rst | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/Documentation/admin-guide/sysctl/kernel.rst b/Documentation/admin-guide/sysctl/kernel.rst
index c6994e55d141..99598a83f830 100644
--- a/Documentation/admin-guide/sysctl/kernel.rst
+++ b/Documentation/admin-guide/sysctl/kernel.rst
@@ -948,6 +948,10 @@ panic_on_rcu_stall
 When set to 1, calls panic() after RCU stall detection messages. This
 is useful to define the root cause of RCU stalls using a vmcore.
 
+The default value can be configured at build time via
+``CONFIG_BOOTPARAM_RCU_STALL_PANIC``. Runtime updates to this sysctl
+always override the built-in default.
+
 = ============================================================
 0 Do not panic() when RCU stall takes place, default behavior.
 1 panic() after printing RCU stall messages.
-- 
2.43.0