Re: [PATCH for-next v2] RDMA/rxe: Remove redundant page presence check

[Daisuke Matsuda <dskmtsd@gmail.com>]

On 2025/06/08 20:23, Zhu Yanjun wrote:
> 在 2025/6/8 11:59, 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.
>>
>> Signed-off-by: Daisuke Matsuda <dskmtsd@gmail.com>
>> ---

<...>

> 
>> -    if (!page)
>> -        return RESPST_ERR_RKEY_VIOLATION;
>>       if (unlikely(page_offset & 0x7)) {
> 
> Normally page_offset error handler should be after this line "page_offset = rxe_odp_iova_to_page_offset(umem_odp, iova);"
> 
> Why is this error handler after hmm_pfn_to_page?
> 
>>           rxe_dbg_mr(mr, "iova not aligned\n");
>> @@ -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);
>> @@ -398,10 +390,7 @@ enum resp_states rxe_odp_do_atomic_write(struct rxe_mr *mr, u64 iova, u64 value)
>>       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)) {
> 
> Ditto, page_offset error handler is not after the line "page_offset = rxe_odp_iova_to_page_offset(umem_odp, iova);" ?

That is a sensible question.
I will submit v3 patch to move the error checks.

Thank you,
Daisuke