Re: mm: kernel BUG at mm/mempolicy.c:1203!

[Sasha Levin <sasha.levin@oracle.com>]

On 12/16/2013 07:44 PM, Bob Liu wrote:
>
> On 12/16/2013 07:37 AM, Sasha Levin wrote:
>> Hi all,
>>
>> While fuzzing with trinity inside a KVM tools guest running latest -next
>> kernel, I've
>> stumbled on the following spew.
>>
>> This seems to be due to commit 0bf598d863e "mbind: add BUG_ON(!vma) in
>> new_vma_page()"
>> which added that BUG_ON.
>
> Could you take a try with this patch from Wanpeng Li?
>
> Thanks,
> -Bob
>
> Subject: [PATCH] mm/mempolicy: fix !vma in new_vma_page()
> ....
> Signed-off-by: Wanpeng Li <liwanp@linux.vnet.ibm.com>
> index eca4a31..73b5a35 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1197,14 +1197,16 @@ static struct page *new_vma_page(struct page
> *page, unsigned long private, int *
>   			break;
>   		vma = vma->vm_next;
>   	}
> +
> +	if (PageHuge(page)) {
> +		if (vma)
> +			return alloc_huge_page_noerr(vma, address, 1);
> +		else
> +			return NULL;
> +	}
>   	/*
> -	 * queue_pages_range() confirms that @page belongs to some vma,
> -	 * so vma shouldn't be NULL.
> +	 * if !vma, alloc_page_vma() will use task or system default policy
>   	 */
> -	BUG_ON(!vma);
> -
> -	if (PageHuge(page))
> -		return alloc_huge_page_noerr(vma, address, 1);
>   	return alloc_page_vma(GFP_HIGHUSER_MOVABLE, vma, address);
>   }
>   #else
>

Hmm... So in essence it's mostly a revert of Naoya's patch, who seemed pretty certain that this
situation shouldn't happen at all. What's the reasoning behind just reverting that?


Thanks,
Sasha

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Don't email: <a href=mailto:"dont@kvack.org"> email@kvack.org </a>