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Date: Tue, 05 Aug 2014 22:02:04 -0500
From: Bryan Drewery <bdrewery@FreeBSD.org>
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To: current@FreeBSD.org
Subject: Re: r269147: NULL mp in getnewvnode() via kern_proc_filedesc_out()
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On 8/5/2014 9:47 PM, Bryan Drewery wrote:
> Has anyone else encountered this? Got it while running poudriere.
>
>> NULL mp in getnewvnode()
>> [...]
>> vn_fullpath1() at vn_fullpath1+0x19d/frame 0xfffffe1247d8e540
>> vn_fullpath() at vn_fullpath+0xc1/frame 0xfffffe1247d8e590
>> export_fd_to_sb() at export_fd_to_sb+0x489/frame 0xfffffe1247d8e7c0
>> kern_proc_filedesc_out() at kern_proc_filedesc_out+0x234/frame
>> 0xfffffe1247d8e840
>> sysctl_kern_proc_filedesc() at sysctl_kern_proc_filedesc+0x84/frame
>> 0xfffffe1247d8e900
>> sysctl_root_handler_locked() at sysctl_root_handler_locked+0x68/frame
>> 0xfffffe1247d8e940
>> sysctl_root() at sysctl_root+0x18e/frame 0xfffffe1247d8e990
>> userland_sysctl() at userland_sysctl+0x192/frame 0xfffffe1247d8ea30
>> sys___sysctl() at sys___sysctl+0x74/frame 0xfffffe1247d8eae0
>> amd64_syscall() at amd64_syscall+0x25a/frame 0xfffffe1247d8ebf0
>> Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe1247d8ebf0
>
> Unfortunately I have no dump as the kmem was too large compared to my
> swap, and I didn't get to the console before some of the text was
> overwritten. Perhaps it will hit it again soon after reboot and I'll get
> a core.
>

It's quite possible that something was unmounting or even mounting 
during this call resulting in a race. I was doing 2 separate builds at once.

-- 
Regards,
Bryan Drewery