Re: 2.6.18-rc3-g3b445eea BUG: warning at/usr/src/linux-git/kernel/cpu.c:51/unlock_cpu_hotplug()

From: Linus Torvalds
Date: Fri Aug 04 2006 - 15:22:56 EST

On Fri, 4 Aug 2006, Michal Piotrowski wrote:
> This was reported
> It's time to use git-bisect.
> BUG: warning at /usr/src/linux-git/kernel/cpu.c:51/unlock_cpu_hotplug()

Ok, that really is a pretty scary thing. The warning happens if the lock
is released by somebody else than the person who took it. I don't _think_
that's supposed to happen, but with cpu hotplug locking being as
"creative" as it is, maybe it's valid.

I was planning on shutting the cpu hotplug warnings up for v2.6.18 - at
least the "lukewarm IQ" one for _taking_ the lock recursively. But I had
planned on leaving the unlock_cpu_hotplug() in place, since up until now
it hadn't triggered, and it really smells like a bug if it does.

> [<c0132a04>] unlock_cpu_hotplug+0x2c/0x54
> [<c013a2ec>] stop_machine_run+0x2e/0x34
> [<c0135686>] sys_init_module+0x15a0/0x178a
> [<c015b7b7>] do_sync_read+0xb6/0xf1
> [<c0102d51>] sysenter_past_esp+0x56/0x79

DaveJ, any ideas?

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