Re: [PATCH] x86/mm: Remove in_nmi() warning from 64bit implementation of vmalloc_fault()

[Jiri Kosina]

On Wed, 24 Apr 2019, Peter Zijlstra wrote:

> > In-NMI warnings have been added to vmalloc_fault() via ebc8827f75 ("x86: 
> > Barf when vmalloc and kmemcheck faults happen in NMI") back in the time 
> > when our NMI entry code could not cope with nested NMIs.
> > 
> > These days, it's perfectly fine to take a fault in NMI context and we 
> > don't have to care about the fact that IRET from the fault handler might 
> > cause NMI nesting.
> > 
> > This warning has already been removed from 32bit implementation of 
> > vmalloc_fault() in 6863ea0cda8 ("x86/mm: Remove in_nmi() warning from 
> > vmalloc_fault()"), but 64bit version was omitted.
> > 
> > Remove the bogus warning also from 64bit implementation of vmalloc_fault().
> 
> Cute; did you actually trigger this?

Nope; Nicolai tripped over it while he was looking into interactions 
between ftrace and pagefaults.

> > Fixes: 6863ea0cda8 ("x86/mm: Remove in_nmi() warning from vmalloc_fault()")
> > Reported-by: Nicolai Stange <nstange@xxxxxxx>
> > Signed-off-by: Jiri Kosina <jkosina@xxxxxxx>
> 
> Acked-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx>

Thanks,

-- 
Jiri Kosina
SUSE Labs