On Wed, 10 Apr 2024 10:00:06 +0530, Mahesh Salgaonkar wrote:
> nmi_enter()/nmi_exit() touches per cpu variables which can lead to kernel
> crash when invoked during real mode interrupt handling (e.g. early HMI/MCE
> interrupt handler) if percpu allocation comes from vmalloc area.
>
> Early HMI/MCE handlers are called through DEFINE_INTERRUPT_HANDLER_NMI()
> wrapper which invokes nmi_enter/nmi_exit calls. We don't see any issue when
> percpu allocation is from the embedded first chunk. However with
> CONFIG_NEED_PER_CPU_PAGE_FIRST_CHUNK enabled there are chances where percpu
> allocation can come from the vmalloc area.
>
> [...]
Applied to powerpc/next.
[1/1] powerpc: Avoid nmi_enter/nmi_exit in real mode interrupt.
https://git.kernel.org/powerpc/c/0db880fc865ffb522141ced4bfa66c12ab1fbb70
cheers
