Re: (bisected) Lock up on sh73a0/kzm9g on cpuidle initialization

From: Daniel Lezcano
Date: Thu Nov 06 2014 - 16:02:38 EST


On 11/06/2014 09:38 PM, Geert Uytterhoeven wrote:
When CONFIG_CPU_IDLE=y, the kernel locks up during cpuidle initialization
on Renesas sh73a0/kzm9g-reference, which has a dual-core Cortex-A9.

Last message is:

DMA: preallocated 256 KiB pool for atomic coherent allocations

After this it's supposed to print:

cpuidle: using governor ladder
cpuidle: using governor menu

I've bisected this to commit 442bf3aaf55a91ebfec71da46a4ee10a3c905bcc
("sched: Let the scheduler see CPU idle states").

Reverting that commit, and commit 83a0a96a5f26d974580fd7251043ff70c8f1823d
("sched/fair: Leverage the idle state info when choosing the "idlest"
cpu") which
depends on it, fixes the problem.

I saw the discussion "lockdep splat in CPU hotplug", so I enabled lockdep
debugging, but didn't see a lockdep splat.

Did you try the fix attached ?

https://lkml.org/lkml/2014/10/22/722

I'm using CONFIG_TREE_RCU=y, as this is SMP without PREEMPT.

Anyone with a clue?





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