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SubjectRe: [PATCH v5 07/24] IB/umem: use get_user_pages_fast() to pin DMA pages
On Thu 14-11-19 21:53:23, John Hubbard wrote:
> And get rid of the mmap_sem calls, as part of that. Note
> that get_user_pages_fast() will, if necessary, fall back to
> __gup_longterm_unlocked(), which takes the mmap_sem as needed.
>
> Reviewed-by: Jason Gunthorpe <jgg@mellanox.com>
> Reviewed-by: Ira Weiny <ira.weiny@intel.com>
> Signed-off-by: John Hubbard <jhubbard@nvidia.com>

Looks good to me. You can add:

Reviewed-by: Jan Kara <jack@suse.cz>

Honza


> ---
> drivers/infiniband/core/umem.c | 17 ++++++-----------
> 1 file changed, 6 insertions(+), 11 deletions(-)
>
> diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
> index 24244a2f68cc..3d664a2539eb 100644
> --- a/drivers/infiniband/core/umem.c
> +++ b/drivers/infiniband/core/umem.c
> @@ -271,16 +271,13 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
> sg = umem->sg_head.sgl;
>
> while (npages) {
> - down_read(&mm->mmap_sem);
> - ret = get_user_pages(cur_base,
> - min_t(unsigned long, npages,
> - PAGE_SIZE / sizeof (struct page *)),
> - gup_flags | FOLL_LONGTERM,
> - page_list, NULL);
> - if (ret < 0) {
> - up_read(&mm->mmap_sem);
> + ret = get_user_pages_fast(cur_base,
> + min_t(unsigned long, npages,
> + PAGE_SIZE /
> + sizeof(struct page *)),
> + gup_flags | FOLL_LONGTERM, page_list);
> + if (ret < 0)
> goto umem_release;
> - }
>
> cur_base += ret * PAGE_SIZE;
> npages -= ret;
> @@ -288,8 +285,6 @@ struct ib_umem *ib_umem_get(struct ib_udata *udata, unsigned long addr,
> sg = ib_umem_add_sg_table(sg, page_list, ret,
> dma_get_max_seg_size(context->device->dma_device),
> &umem->sg_nents);
> -
> - up_read(&mm->mmap_sem);
> }
>
> sg_mark_end(sg);
> --
> 2.24.0
>
--
Jan Kara <jack@suse.com>
SUSE Labs, CR

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