[PATCH] powerpc/64s/radix: fix preempt imbalance in TLB flush

[Aneesh Kumar K.V]

On 10/10/2017 03:46 PM, Nicholas Piggin wrote:
> Signed-off-by: Nicholas Piggin <npiggin at gmail.com>
> ---
>   arch/powerpc/mm/tlb-radix.c | 3 ++-
>   1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/powerpc/mm/tlb-radix.c b/arch/powerpc/mm/tlb-radix.c
> index b3e849c4886e..de414460287a 100644
> --- a/arch/powerpc/mm/tlb-radix.c
> +++ b/arch/powerpc/mm/tlb-radix.c
> @@ -358,7 +358,7 @@ void radix__flush_tlb_collapsed_pmd(struct mm_struct *mm, unsigned long addr)
>   	unsigned long ap = mmu_get_ap(mmu_virtual_psize);
>   	unsigned long pid, end;
> 
> -
> +	preempt_disable();
>   	pid = mm ? mm->context.id : 0;
>   	if (unlikely(pid == MMU_NO_CONTEXT))
>   		goto no_context;
> @@ -366,6 +366,7 @@ void radix__flush_tlb_collapsed_pmd(struct mm_struct *mm, unsigned long addr)
>   	/* 4k page size, just blow the world */
>   	if (PAGE_SIZE == 0x1000) {
>   		radix__flush_all_mm(mm);
> +		preempt_enable();
>   		return;
>   	}
> 

Can't we do a preempt_disable before the if (local) check?. That way we 
don't need that prempt_enable in that PAGE_SIZE==0x1000 path.We already 
do disable/enable correctly in radix__flush_all_mm(mm)

-aneesh