fork_findpid() - Fatal trap 12: page fault while in kernel mode

[Shawn Webb]

On Tue, Dec 15, 2015 at 05:42:38PM +0100, Fabian Keil wrote:
> I've seen the following panic a couple of times in the last three
> months, usually while poudriere was running and with sh being the
> current process.
> 
> This one is from a system based on r290926 running with
> kern.randompid=9001 and forking frequently (>1000 forks/second)
> due to poudriere and afl-fuzz:
> 
> Fatal trap 12: page fault while in kernel mode
> cpuid = 1; apic id = 04
> fault virtual address   = 0x618b00a8
> fault code              = supervisor read data, page not present
> instruction pointer     = 0x20:0xffffffff80909158
> stack pointer           = 0x28:0xfffffe011e03b940
> frame pointer           = 0x28:0xfffffe011e03b960
> code segment            = base 0x0, limit 0xfffff, type 0x1b
>                         = DPL 0, pres 1, long 1, def32 0, gran 1
> processor eflags        = interrupt enabled, resume, IOPL = 0
> current process         = 71325 (sh)
> trap number             = 12
> panic: page fault
> cpuid = 1
> KDB: stack backtrace:
> [...]
> Uptime: 13d20h43m20s
> [...]

Hey Fabien,

I'm glad you've seen this, too. We've observed this in HardenedBSD,
especially when running Poudriere and Jenkins. I think Oliver Pinter
might have a potential patch to fix this. I've CC'd him on this thread.

Thanks,

-- 
Shawn Webb
HardenedBSD

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