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authorQian Cai <cai@redhat.com>2020-10-28 14:26:14 -0400
committerWill Deacon <will@kernel.org>2020-10-30 08:13:18 +0000
commitce3d31ad3cac765484463b4f5a0b6b1f8f1a963e (patch)
tree52d2d66433766f2cc4f0ba90bad4b551137f657a /arch/arm64/lib/memmove.S
parent96d389ca10110d7eefb46feb6af9a0c6832f78f5 (diff)
downloadlinux-ce3d31ad3cac765484463b4f5a0b6b1f8f1a963e.tar.gz
arm64/smp: Move rcu_cpu_starting() earlier
The call to rcu_cpu_starting() in secondary_start_kernel() 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:
  dump_backtrace+0x0/0x3c8
  show_stack+0x14/0x60
  dump_stack+0x14c/0x1c4
  lockdep_rcu_suspicious+0x134/0x14c
  __lock_acquire+0x1c30/0x2600
  lock_acquire+0x274/0xc48
  _raw_spin_lock+0xc8/0x140
  vprintk_emit+0x90/0x3d0
  vprintk_default+0x34/0x40
  vprintk_func+0x378/0x590
  printk+0xa8/0xd4
  __cpuinfo_store_cpu+0x71c/0x868
  cpuinfo_store_cpu+0x2c/0xc8
  secondary_start_kernel+0x244/0x318

This is avoided by moving the call to rcu_cpu_starting up near the
beginning of the secondary_start_kernel() function.

Signed-off-by: Qian Cai <cai@redhat.com>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Link: https://lore.kernel.org/lkml/160223032121.7002.1269740091547117869.tip-bot2@tip-bot2/
Link: https://lore.kernel.org/r/20201028182614.13655-1-cai@redhat.com
Signed-off-by: Will Deacon <will@kernel.org>
Diffstat (limited to 'arch/arm64/lib/memmove.S')
0 files changed, 0 insertions, 0 deletions