From mboxrd@z Thu Jan 1 00:00:00 1970 From: Geert Uytterhoeven Date: Thu, 06 Nov 2014 20:38:26 +0000 Subject: (bisected) Lock up on sh73a0/kzm9g on cpuidle initialization Message-Id: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-arm-kernel@lists.infradead.org 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. I'm using CONFIG_TREE_RCU=y, as this is SMP without PREEMPT. Anyone with a clue? Thanks! Gr{oetje,eeting}s, Geert -- Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org In personal conversations with technical people, I call myself a hacker. But when I'm talking to journalists I just say "programmer" or something like that. -- Linus Torvalds