]> git.proxmox.com Git - mirror_ubuntu-kernels.git/commit
arm64: smp: Tell RCU about CPUs that fail to come online
authorWill Deacon <will@kernel.org>
Fri, 6 Nov 2020 10:25:49 +0000 (10:25 +0000)
committerWill Deacon <will@kernel.org>
Tue, 10 Nov 2020 13:11:44 +0000 (13:11 +0000)
commit04e613ded8c26489b3e0f9101b44462f780d1a35
tree1dd103a5013da84ee4d8ab4f96f14b5285d80b06
parent891deb87585017d526b67b59c15d38755b900fea
arm64: smp: Tell RCU about CPUs that fail to come online

Commit ce3d31ad3cac ("arm64/smp: Move rcu_cpu_starting() earlier") ensured
that RCU is informed early about incoming CPUs that might end up calling
into printk() before they are online. However, if such a CPU fails the
early CPU feature compatibility checks in check_local_cpu_capabilities(),
then it will be powered off or parked without informing RCU, leading to
an endless stream of stalls:

  | rcu: INFO: rcu_preempt detected stalls on CPUs/tasks:
  | rcu: 2-O...: (0 ticks this GP) idle=002/1/0x4000000000000000 softirq=0/0 fqs=2593
  | (detected by 0, t=5252 jiffies, g=9317, q=136)
  | Task dump for CPU 2:
  | task:swapper/2       state:R  running task     stack:    0 pid:    0 ppid:     1 flags:0x00000028
  | Call trace:
  | ret_from_fork+0x0/0x30

Ensure that the dying CPU invokes rcu_report_dead() prior to being powered
off or parked.

Cc: Qian Cai <cai@redhat.com>
Cc: "Paul E. McKenney" <paulmck@kernel.org>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Suggested-by: Qian Cai <cai@redhat.com>
Link: https://lore.kernel.org/r/20201105222242.GA8842@willie-the-truck
Link: https://lore.kernel.org/r/20201106103602.9849-3-will@kernel.org
Signed-off-by: Will Deacon <will@kernel.org>
arch/arm64/kernel/smp.c
kernel/rcu/tree.c