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stop_machine, rcu: Mark functions as notrace

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Some architectures assume that the stopped CPUs don't make function calls
to traceable functions when they are in the stopped state. See also commit
cb9d7fd51d ("watchdog: Mark watchdog touch functions as notrace").

Violating this assumption causes kernel crashes when switching tracer on
RISC-V.

Mark rcu_momentary_dyntick_idle() and stop_machine_yield() notrace to
prevent this.

Fixes: 4ecf0a43e7 ("processor: get rid of cpu_relax_yield")
Fixes: 366237e7b0 ("stop_machine: Provide RCU quiescent state in multi_cpu_stop()")
Signed-off-by: Zong Li <zong.li@sifive.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Atish Patra <atish.patra@wdc.com>
Tested-by: Colin Ian King <colin.king@canonical.com>
Acked-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Cc: stable@vger.kernel.org
Link: https://lore.kernel.org/r/20201021073839.43935-1-zong.li@sifive.com
This commit is contained in:
Zong Li 2020-10-21 15:38:39 +08:00 committed by Thomas Gleixner
parent 3650b228f8
commit 4230e2deaa
2 changed files with 2 additions and 2 deletions
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2
kernel/rcu/tree.c
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@ -409,7 +409,7 @@ bool rcu_eqs_special_set(int cpu)
* *
* The caller must have disabled interrupts and must not be idle. * The caller must have disabled interrupts and must not be idle.
*/ */
void rcu_momentary_dyntick_idle(void) notrace void rcu_momentary_dyntick_idle(void)
{ {
int special; int special;

2
kernel/stop_machine.c
View File

@ -178,7 +178,7 @@ static void ack_state(struct multi_stop_data *msdata)
set_state(msdata, msdata->state + 1); set_state(msdata, msdata->state + 1);
} }
void __weak stop_machine_yield(const struct cpumask *cpumask) notrace void __weak stop_machine_yield(const struct cpumask *cpumask)
{ {
cpu_relax(); cpu_relax();
} }