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authorQian Cai <cai@redhat.com>2020-10-28 21:27:42 +0300
committerHeiko Carstens <hca@linux.ibm.com>2020-11-03 17:12:16 +0300
commitde5d9dae150ca1c1b5c7676711a9ca139d1a8dec (patch)
treedae2fd360c7df74daa71e216276dcb1e5ac40a62 /CREDITS
parent5b35047eb467c8cdd38a31beb9ac109221777843 (diff)
downloadlinux-de5d9dae150ca1c1b5c7676711a9ca139d1a8dec.tar.xz
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>
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