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Date: Fri, 15 Dec 2017 10:49:43 +0100 (CET)
From: Thomas Gleixner <tglx@linutronix.de>
To: Dmitry Vyukov <dvyukov@google.com>
cc: Linus Torvalds <torvalds@linux-foundation.org>,
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Subject: Re: BUG: unable to handle kernel paging request in __switch_to
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On Fri, 15 Dec 2017, Dmitry Vyukov wrote:
> I've built this exact kernel and here is __switch_to disasm:
> https://gist.githubusercontent.com/dvyukov/8137559f7da08fbe32f9018972a4498c/raw/0ef2abf723b117f0d0f0306fd50e216d50c5cecb/gistfile1.txt
> 
> __switch_to+0x95b seems to point to (?):
> 
> ffffffff81252f6b: 0f 1f 44 00 00        nopl   0x0(%rax,%rax,1)
> 
> which is branch target alignment nop.

Which is a place holder for a trace point as Linus pointed out and the
'faulting' instruction which is int3 shows that there is a tracepoint
install/remove in progress. Are your test cases fiddling with tracepoints?

Thanks,

	tglx