From: "Paul E. McKenney" <paulmck@xxxxxxxxxx> In theory, RCU-hotplug operations are supposed to work as soon as there is more than one CPU online. However, in practice, in normal production there is no way to make them happen until userspace is up and running. Besides which, on smaller systems, rcutorture doesn't start doing hotplug operations until 30 seconds after the start of boot, which on most systems also means the better part of 30 seconds after the end of boot. This commit therefore provides a new torture.disable_onoff_at_boot kernel boot parameter that suppresses CPU-hotplug torture operations until about the time that init is spawned. Of course, if you know of a need for boottime CPU-hotplug operations, then you should avoid passing this argument to any of the torture tests. You might also want to look at the splats linked to below. Link: https://lore.kernel.org/lkml/20191206185208.GA25636@paulmck-ThinkPad-P72/ Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx> --- Documentation/admin-guide/kernel-parameters.txt | 4 ++++ kernel/torture.c | 7 +++++++ 2 files changed, 11 insertions(+) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt index ee007b5..868f59a 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -4873,6 +4873,10 @@ topology updates sent by the hypervisor to this LPAR. + torture.disable_onoff_at_boot= [KNL] + Prevent the CPU-hotplug component of torturing + until after init has spawned. + tp720= [HW,PS2] tpm_suspend_pcr=[HW,TPM] diff --git a/kernel/torture.c b/kernel/torture.c index e377b5b..8683375 100644 --- a/kernel/torture.c +++ b/kernel/torture.c @@ -42,6 +42,9 @@ MODULE_LICENSE("GPL"); MODULE_AUTHOR("Paul E. McKenney <paulmck@xxxxxxxxxxxxx>"); +static bool disable_onoff_at_boot; +module_param(disable_onoff_at_boot, bool, 0444); + static char *torture_type; static int verbose; @@ -229,6 +232,10 @@ torture_onoff(void *arg) VERBOSE_TOROUT_STRING("torture_onoff end holdoff"); } while (!torture_must_stop()) { + if (disable_onoff_at_boot && !rcu_inkernel_boot_has_ended()) { + schedule_timeout_interruptible(HZ / 10); + continue; + } cpu = (torture_random(&rand) >> 4) % (maxcpu + 1); if (!torture_offline(cpu, &n_offline_attempts, &n_offline_successes, -- 2.9.5
