On 03/11/2023 23:04, Bart Van Assche wrote:
>
> On 11/3/23 02:55, Li Zhijian wrote:
>> - return ib_sg_to_pages(ibmr, sgl, sg_nents, sg_offset, rxe_set_page);
>> + for_each_sg(sgl, sg, sg_nents, i) {
>> + u64 dma_addr = sg_dma_address(sg) + sg_offset;
>> + unsigned int dma_len = sg_dma_len(sg) - sg_offset;
>> + u64 end_dma_addr = dma_addr + dma_len;
>> + u64 page_addr = dma_addr & PAGE_MASK;
>> +
>> + if (sg_dma_len(sg) == 0) {
>> + rxe_dbg_mr(mr, "empty SGE\n");
>> + return -EINVAL;
>> + }
>> + do {
>> + int ret = rxe_store_page(mr, page_addr);
>> + if (ret)
>> + return ret;
>> +
>> + page_addr += PAGE_SIZE;
>> + } while (page_addr < end_dma_addr);
>> + sg_offset = 0;
>> + }
>> +
>> + return ib_sg_to_pages(ibmr, sgl, sg_nents, sg_offset_p, rxe_set_page);
>> }
>
> Is this change necessary?
There is already a loop in ib_sg_to_pages()
> that splits SG entries that are larger than mr->page_size into entries
> with size mr->page_size.
I see.
My thought was that we are only able to safely access PAGE_SIZE memory scope [page_va, page_va + PAGE_SIZE)
from the return of kmap_local_page(page).
However when mr->page_size is larger than PAGE_SIZE, we may access the next pages without mapping it.
Thanks
Zhijian
