Date: Thu, 30 Nov 2006 10:13:34 +0100
From: Jens Axboe <jens.axboe@oracle.com>
To: linux-kernel@vger.kernel.org
Cc: akpm@osdl.org, pavel@ucw.cz, bryce@osdl.org
Subject: Re: CPU hotplug broken with 2GB VMSPLIT
Message-ID: <20061130091334.GM5400@kernel.dk>
References: <20061130090348.GK5400@kernel.dk>
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On Thu, Nov 30 2006, Jens Axboe wrote:
> Hi,
> 
> Just got a new notebook (Lenovo X60), setup a custom kernel and then I
> noticed that suspend to ram doesn't work anymore. The machine suspends
> just fine, on resume it brings back the text display but reboots after
> it has stalled for a few seconds. On the suggestion of Pavel, I tried
> testing CPU hotplug, and indeed he was right: I can offline 1 of the
> cores fine, bringing it back online freezes the machine for 3-4 seconds
> and then reboots.
> 
> carl:/sys/devices/system/cpu/cpu1 # echo 0 > online 
> carl:/sys/devices/system/cpu/cpu1 # dmesg
> Breaking affinity for irq 219
> CPU 1 is now offline
> SMP alternatives: switching to UP code
> carl:/sys/devices/system/cpu/cpu1 # echo 1 > online 
> Read from remote host carl: Connection reset by peer
> 
> Booting with maxcpus=1 and resume works fine. Does this ring a bell with
> anyone? With highmem enabled and the standard vmsplit, cpu hotplug works
> fine for me.

Some more clues - booting with noreplacement doesn't fix it, so I think
the alternatives code is off the hook.

-- 
Jens Axboe

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