Re: [PATCH for-next v3] RDMA/rxe: Remove redundant page presence check

[Zhu Yanjun <yanjun.zhu@linux.dev>]

在 2025/6/11 9:27, Daisuke Matsuda 写道:
> hmm_pfn_to_page() does not return NULL. ib_umem_odp_map_dma_and_lock()
> should return an error in case the target pages cannot be mapped until
> timeout, so these checks can safely be removed.
> 
> Reviewed-by: Zhu Yanjun <yanjun.zhu@linux.dev>
> Signed-off-by: Daisuke Matsuda <dskmtsd@gmail.com>
> 
> v2->v3:
>    - Move page_offset error check before hmm_pfn_to_page(), as suggested by Zhu

I am fine with this commit.

Thanks a lot for your effort.

Zhu Yanjun

> 
> ---
>   drivers/infiniband/sw/rxe/rxe_odp.c | 23 ++++++-----------------
>   1 file changed, 6 insertions(+), 17 deletions(-)
> 
> diff --git a/drivers/infiniband/sw/rxe/rxe_odp.c b/drivers/infiniband/sw/rxe/rxe_odp.c
> index dbc5a5600eb7..0846bd972e15 100644
> --- a/drivers/infiniband/sw/rxe/rxe_odp.c
> +++ b/drivers/infiniband/sw/rxe/rxe_odp.c
> @@ -203,8 +203,6 @@ static int __rxe_odp_mr_copy(struct rxe_mr *mr, u64 iova, void *addr,
>   
>   		page = hmm_pfn_to_page(umem_odp->map.pfn_list[idx]);
>   		user_va = kmap_local_page(page);
> -		if (!user_va)
> -			return -EFAULT;
>   
>   		src = (dir == RXE_TO_MR_OBJ) ? addr : user_va;
>   		dest = (dir == RXE_TO_MR_OBJ) ? user_va : addr;
> @@ -283,17 +281,15 @@ static enum resp_states rxe_odp_do_atomic_op(struct rxe_mr *mr, u64 iova,
>   		return RESPST_ERR_RKEY_VIOLATION;
>   	}
>   
> -	idx = rxe_odp_iova_to_index(umem_odp, iova);
>   	page_offset = rxe_odp_iova_to_page_offset(umem_odp, iova);
> -	page = hmm_pfn_to_page(umem_odp->map.pfn_list[idx]);
> -	if (!page)
> -		return RESPST_ERR_RKEY_VIOLATION;
> -
>   	if (unlikely(page_offset & 0x7)) {
>   		rxe_dbg_mr(mr, "iova not aligned\n");
>   		return RESPST_ERR_MISALIGNED_ATOMIC;
>   	}
>   
> +	idx = rxe_odp_iova_to_index(umem_odp, iova);
> +	page = hmm_pfn_to_page(umem_odp->map.pfn_list[idx]);
> +
>   	va = kmap_local_page(page);
>   
>   	spin_lock_bh(&atomic_ops_lock);
> @@ -352,10 +348,6 @@ int rxe_odp_flush_pmem_iova(struct rxe_mr *mr, u64 iova,
>   		page_offset = rxe_odp_iova_to_page_offset(umem_odp, iova);
>   
>   		page = hmm_pfn_to_page(umem_odp->map.pfn_list[index]);
> -		if (!page) {
> -			mutex_unlock(&umem_odp->umem_mutex);
> -			return -EFAULT;
> -		}
>   
>   		bytes = min_t(unsigned int, length,
>   			      mr_page_size(mr) - page_offset);
> @@ -396,12 +388,6 @@ enum resp_states rxe_odp_do_atomic_write(struct rxe_mr *mr, u64 iova, u64 value)
>   		return RESPST_ERR_RKEY_VIOLATION;
>   
>   	page_offset = rxe_odp_iova_to_page_offset(umem_odp, iova);
> -	index = rxe_odp_iova_to_index(umem_odp, iova);
> -	page = hmm_pfn_to_page(umem_odp->map.pfn_list[index]);
> -	if (!page) {
> -		mutex_unlock(&umem_odp->umem_mutex);
> -		return RESPST_ERR_RKEY_VIOLATION;
> -	}
>   	/* See IBA A19.4.2 */
>   	if (unlikely(page_offset & 0x7)) {
>   		mutex_unlock(&umem_odp->umem_mutex);
> @@ -409,6 +395,9 @@ enum resp_states rxe_odp_do_atomic_write(struct rxe_mr *mr, u64 iova, u64 value)
>   		return RESPST_ERR_MISALIGNED_ATOMIC;
>   	}
>   
> +	index = rxe_odp_iova_to_index(umem_odp, iova);
> +	page = hmm_pfn_to_page(umem_odp->map.pfn_list[index]);
> +
>   	va = kmap_local_page(page);
>   	/* Do atomic write after all prior operations have completed */
>   	smp_store_release(&va[page_offset >> 3], value);