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SubjectRe: [PATCH 4/4] RDMA/umem: batch page unpin in __ib_mem_release()
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On 2/4/21 8:00 PM, Jason Gunthorpe wrote:
> On Wed, Feb 03, 2021 at 04:15:53PM -0800, John Hubbard wrote:
>>> diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
>>> index 2dde99a9ba07..ea4ebb3261d9 100644
>>> +++ b/drivers/infiniband/core/umem.c
>>> @@ -47,17 +47,17 @@
>>> static void __ib_umem_release(struct ib_device *dev, struct ib_umem *umem, int dirty)
>>> {
>>> - struct sg_page_iter sg_iter;
>>> - struct page *page;
>>> + bool make_dirty = umem->writable && dirty;
>>> + struct scatterlist *sg;
>>> + int i;
>>
>> Maybe unsigned int is better, so as to perfectly match the scatterlist.length.
>
> Yes please
>
Fixed in v2.

>>> if (umem->nmap > 0)
>>> ib_dma_unmap_sg(dev, umem->sg_head.sgl, umem->sg_nents,
>>> DMA_BIDIRECTIONAL);
>>> - for_each_sg_page(umem->sg_head.sgl, &sg_iter, umem->sg_nents, 0) {
>>> - page = sg_page_iter_page(&sg_iter);
>>> - unpin_user_pages_dirty_lock(&page, 1, umem->writable && dirty);
>>> - }
>>> + for_each_sg(umem->sg_head.sgl, sg, umem->nmap, i)
>>
>> The change from umem->sg_nents to umem->nmap looks OK, although we should get
>> IB people to verify that there is not some odd bug or reason to leave it as is.
>
> No, nmap wouldn't be right here. nmap is the number of dma mapped SGLs
> in the list and should only be used by things doing sg_dma* stuff.
>
> umem->sg_nents is the number of CPU SGL entries and is the correct
> thing here.
>

And this was fixed in v2 as well.

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