diff options
| author | Qian Cai <cai@redhat.com> | 2020-10-28 14:27:42 -0400 |
|---|---|---|
| committer | Heiko Carstens <hca@linux.ibm.com> | 2020-11-03 15:12:16 +0100 |
| commit | de5d9dae150ca1c1b5c7676711a9ca139d1a8dec (patch) | |
| tree | dae2fd360c7df74daa71e216276dcb1e5ac40a62 /arch | |
| parent | 5b35047eb467c8cdd38a31beb9ac109221777843 (diff) | |
s390/smp: move rcu_cpu_starting() earlier
The call to rcu_cpu_starting() in smp_init_secondary() is not early
enough in the CPU-hotplug onlining process, which results in lockdep
splats as follows:
WARNING: suspicious RCU usage
-----------------------------
kernel/locking/lockdep.c:3497 RCU-list traversed in non-reader section!!
other info that might help us debug this:
RCU used illegally from offline CPU!
rcu_scheduler_active = 1, debug_locks = 1
no locks held by swapper/1/0.
Call Trace:
show_stack+0x158/0x1f0
dump_stack+0x1f2/0x238
__lock_acquire+0x2640/0x4dd0
lock_acquire+0x3a8/0xd08
_raw_spin_lock_irqsave+0xc0/0xf0
clockevents_register_device+0xa8/0x528
init_cpu_timer+0x33e/0x468
smp_init_secondary+0x11a/0x328
smp_start_secondary+0x82/0x88
This is avoided by moving the call to rcu_cpu_starting up near the
beginning of the smp_init_secondary() function. Note that the
raw_smp_processor_id() is required in order to avoid calling into
lockdep before RCU has declared the CPU to be watched for readers.
Link: https://lore.kernel.org/lkml/160223032121.7002.1269740091547117869.tip-bot2@tip-bot2/
Signed-off-by: Qian Cai <cai@redhat.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Heiko Carstens <hca@linux.ibm.com>
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/s390/kernel/smp.c | 3 |
1 files changed, 2 insertions, 1 deletions
diff --git a/arch/s390/kernel/smp.c b/arch/s390/kernel/smp.c index ebfe86d097f0..390d97daa2b3 100644 --- a/arch/s390/kernel/smp.c +++ b/arch/s390/kernel/smp.c @@ -855,13 +855,14 @@ void __init smp_detect_cpus(void) static void smp_init_secondary(void) { - int cpu = smp_processor_id(); + int cpu = raw_smp_processor_id(); S390_lowcore.last_update_clock = get_tod_clock(); restore_access_regs(S390_lowcore.access_regs_save_area); set_cpu_flag(CIF_ASCE_PRIMARY); set_cpu_flag(CIF_ASCE_SECONDARY); cpu_init(); + rcu_cpu_starting(cpu); preempt_disable(); init_cpu_timer(); vtime_init(); |