linux-kernel - Re: the maxcpus= boot parameter broke somewhere along the line

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Mon, 02 Apr 2012 10:38:27 -0400
From:	Jeff Moyer <jmoyer@...hat.com>
To:	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>
Cc:	Sasha Levin <levinsasha928@...il.com>,
	Nick Bowler <nbowler@...iptictech.com>,
	linux-kernel@...r.kernel.org, Kay Sievers <kay.sievers@...y.org>
Subject: Re: the maxcpus= boot parameter broke somewhere along the line

"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com> writes:

> On 04/02/2012 07:35 PM, Jeff Moyer wrote:
>
>> "Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com> writes:
>> 
>>> Looking at the mention of udev above, and considering the commit you bisected
>>> to, I think it would be good to see whether someone is writing 1 to
>>> /sys/device/system/cpu/cpu*/online and hence the cpus are getting hot-added
>>> towards the end of boot. Maybe that sounds stupid, but worth a try :)
>>>
>>> So can you try the debug patch below? It applies on latest linux-3.3-rc6+
>> 
>> Sorry it took me so long to get back to you.  You're patch did, in fact,
>> trigger:
>> 
>> udev: starting version 147
>> CPU 3 online initated from userspace
>> SMP alternatives: switching to SMP code
>> WARNING! power/level is deprecated; use power/control instead
>> Booting Node 0 Processor 3 APIC 0x3
>> NMI watchdog: enabled, takes one hw-pmu counter.
>> CPU 1 online initated from userspace
>> Booting Node 0 Processor 1 APIC 0x2
>> NMI watchdog: enabled, takes one hw-pmu counter.
>> CPU 2 online initated from userspace
>> Booting Node 0 Processor 2 APIC 0x1
>> NMI watchdog: enabled, takes one hw-pmu counter.
>> CPU 1 online initated from userspace
>> CPU 3 online initated from userspace
>> CPU 2 online initated from userspace
>> 
>
>
> Aha! Just like I thought!
> So there is no kernel bug with respect to the maxcpus= boot parameter :-)

But this IS a change in behaviour (using older kernels, the maxcpus=
boot parameter works just fine).  So, what exactly has changed is my
question, and what is the right way to fix it?

Cheers,
Jeff
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/