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SubjectRe: [PATCH] x86/mm: Remove in_nmi() warning from 64bit implementation of vmalloc_fault()
On Wed, Apr 24, 2019 at 09:04:57AM +0200, Jiri Kosina wrote:
> From: Jiri Kosina <jkosina@suse.cz>
>
> 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?

> Fixes: 6863ea0cda8 ("x86/mm: Remove in_nmi() warning from vmalloc_fault()")
> Reported-by: Nicolai Stange <nstange@suse.de>
> Signed-off-by: Jiri Kosina <jkosina@suse.cz>

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>

> ---
> arch/x86/mm/fault.c | 2 --
> 1 file changed, 2 deletions(-)
>
> diff --git a/arch/x86/mm/fault.c b/arch/x86/mm/fault.c
> index 667f1da36208..5eaf67e8314f 100644
> --- a/arch/x86/mm/fault.c
> +++ b/arch/x86/mm/fault.c
> @@ -359,8 +359,6 @@ static noinline int vmalloc_fault(unsigned long address)
> if (!(address >= VMALLOC_START && address < VMALLOC_END))
> return -1;
>
> - WARN_ON_ONCE(in_nmi());
> -
> /*
> * Copy kernel mappings over when needed. This can also
> * happen within a race in page table update. In the later
>
> --
> Jiri Kosina
> SUSE Labs
>

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