Re: [PATCH] numa, mem-hotplug: Fix stack overflow in numa when seting kernel nodes to unhotpluggable.

[Tang Chen <tangchen@cn.fujitsu.com>]

On 01/28/2014 12:47 PM, Dave Jones wrote:
> On Tue, Jan 28, 2014 at 12:47:11PM +0800, Tang Chen wrote:
>   >  On 01/28/2014 11:55 AM, Dave Jones wrote:
>   >  >  On Tue, Jan 28, 2014 at 11:24:37AM +0800, Tang Chen wrote:
>   >  >
>   >  >    >   >   I did a bisect with the patch above applied each step of the way.
>   >  >    >   >   This time I got a plausible looking result....
>   >  >    >
>   >  >    >   I cannot reproduce this. Would you please share how to reproduce it ?
>   >  >    >   Or does it just happen during the booting ?
>   >  >
>   >  >  Just during boot. Very early. So early in fact, I have no logging facilities
>   >  >  like usb-serial, just what is on vga console.
>   >  >
>   >  >  If you want me to add some printk's, I can add a while (1); before
>   >  >  the part that oopses so we can diagnose further..
>   >
>   >  Sure. Would you please do that for me ? Maybe we can find something in
>   >  the early log.
>
> I was hoping you'd have suggestions what you'd like me to dump ;-)

Sorry. I didn't say it clearly. :)

Seeing from your earlier mail, it crashed at:

                 while (zonelist_zone_idx(z) > highest_zoneidx)
   de:   3b 77 08                cmp    0x8(%rdi),%esi


	I stuck this at the top of the function..

	printk(KERN_ERR "z:%p nodes:%p highest:%d\n", z, nodes, highest_zoneidx);

	and got

	z: 1d08   nodes: (null)  highest:3


nodes=null and highest=3, they are correct. When looking into 
next_zones_zonelist(),
I cannot see why it crashed. So, can you print the zone id in the
for_each_zone_zonelist() loop in nr_free_zone_pages() ?

I want to know why it crashed. A NULL pointer ?  Which one ?

Thanks.

>
> 	Dave
>
>