Re: [PATCH 1/3] swiotlb: don't panic when the swiotlb buffer can't be allocated

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Wed, 11 May 2022, Christoph Hellwig wrote:
> For historical reasons the switlb code paniced when the metadata could
> not be allocated, but just printed a warning when the actual main
> swiotlb buffer could not be allocated.  Restore this somewhat unexpected
> behavior as changing it caused a boot failure on the Microchip RISC-V
> PolarFire SoC Icicle kit.
> 
> Fixes: 6424e31b1c05 ("swiotlb: remove swiotlb_init_with_tbl and 
> swiotlb_init_late_with_tbl")
> Reported-by: Conor Dooley <Conor.Dooley@xxxxxxxxxxxxx>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> Tested-by: Conor Dooley <Conor.Dooley@xxxxxxxxxxxxx>

Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>


> ---
>  kernel/dma/swiotlb.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c
> index e2ef0864eb1e5..3e992a308c8a1 100644
> --- a/kernel/dma/swiotlb.c
> +++ b/kernel/dma/swiotlb.c
> @@ -254,8 +254,10 @@ void __init swiotlb_init_remap(bool addressing_limit, 
> unsigned int flags,
>               tlb = memblock_alloc(bytes, PAGE_SIZE);
>       else
>               tlb = memblock_alloc_low(bytes, PAGE_SIZE);
> -     if (!tlb)
> -             panic("%s: failed to allocate tlb structure\n", __func__);
> +     if (!tlb) {
> +             pr_warn("%s: failed to allocate tlb structure\n", __func__);
> +             return;
> +     }
>  
>       if (remap && remap(tlb, nslabs) < 0) {
>               memblock_free(tlb, PAGE_ALIGN(bytes));
> -- 
> 2.30.2
>