On Mon, 25 Mar 2019 16:13:09 +0800 Yue Hu <zbestahu@xxxxxxxxx> wrote:
> From: Yue Hu <huyue2@xxxxxxxxxx>
>
> A previous commit f022d8cb7ec7 ("mm: cma: Don't crash on allocation
> if CMA area can't be activated") fixes the crash issue when activation
> fails via setting cma->count as 0, same logic exists if bitmap
> allocation fails.
>
> --- a/mm/cma.c
> +++ b/mm/cma.c
> @@ -106,8 +106,10 @@ static int __init cma_activate_area(struct cma *cma)
>
> cma->bitmap = kzalloc(bitmap_size, GFP_KERNEL);
>
> - if (!cma->bitmap)
> + if (!cma->bitmap) {
> + cma->count = 0;
> return -ENOMEM;
> + }
>
> WARN_ON_ONCE(!pfn_valid(pfn));
> zone = page_zone(pfn_to_page(pfn));
I'm unsure whether this is needed.
kmalloc() within __init code is generally considered to be a "can't
fail".
If this was the only issue then I guess I'd take the patch if only for
documentation/clarity purposes. But cma_areas[] is in bss and is
guaranteed to be all-zeroes, so I suspect this bug is a can't-happen.
And we could revert f022d8cb7ec7 if we could be bothered (I can't).
