Messages in this thread | | | Date | Tue, 29 Apr 2014 12:19:34 -0400 | From | Steven Rostedt <> | Subject | Re: 64bit x86: NMI nesting still buggy? |
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On Tue, 29 Apr 2014 12:09:08 -0400 Steven Rostedt <rostedt@goodmis.org> wrote:
> Can you reproduce your problem on different platforms, or is this just > one box that exhibits this behavior? If it's only one box, I'm betting > it has a BIOS doing nasty things.
This box probably crashes on all kernels too. My NMI nesting changes did not fix a bug (well, it did as a side effect, see below). It was done to allow NMIs to use IRET so that we could remove stopmachine from ftrace, and instead have it use breakpoints (which return with IRET).
The bug that was fixed by this was the ability to do stack traces (sysrq-t) from NMI context. Stack traces can page fault, and when I was debugging hard lock ups and having the NMI do a stack dump of all tasks, another NMI would trigger and corrupt the stack of the NMI doing the dumps. But that was something that would only be seen while debugging, and not something seen in normal operation.
I don't see a bug to fix in the kernel. I see a bug to fix in the vendor's BIOS.
-- Steve
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