From: Leon Romanovsky <leon@kernel.org>
To: Jason Gunthorpe <jgg@nvidia.com>
Cc: Doug Ledford <dledford@redhat.com>,
linux-rdma@vger.kernel.org,
Shiraz Saleem <shiraz.saleem@intel.com>
Subject: Re: [PATCH 02/14] RDMA/umem: Prevent small pages from being returned by ib_umem_find_best_pgsz()
Date: Wed, 2 Sep 2020 14:51:19 +0300 [thread overview]
Message-ID: <20200902115119.GH59010@unreal> (raw)
In-Reply-To: <2-v1-00f59ce24f1f+19f50-umem_1_jgg@nvidia.com>
On Tue, Sep 01, 2020 at 09:43:30PM -0300, Jason Gunthorpe wrote:
> rdma_for_each_block() makes assumptions about how the SGL is constructed
> that don't work if the block size is below the page size used to to build
> the SGL.
>
> The rules for umem SGL construction require that the SG's all be PAGE_SIZE
> aligned and we don't encode the actual byte offset of the VA range inside
> the SGL using offset and length. So rdma_for_each_block() has no idea
> where the actual starting/ending point is to compute the first/last block
> boundary if the starting address should be within a SGL.
>
> Fixing the SGL construction turns out to be really hard, and will be the
> subject of other patches. For now block smaller pages.
>
> Fixes: 4a35339958f1 ("RDMA/umem: Add API to find best driver supported page size in an MR")
> Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>
> ---
> drivers/infiniband/core/umem.c | 6 ++++++
> 1 file changed, 6 insertions(+)
>
> diff --git a/drivers/infiniband/core/umem.c b/drivers/infiniband/core/umem.c
> index 120e98403c345d..7b5bc969e55630 100644
> --- a/drivers/infiniband/core/umem.c
> +++ b/drivers/infiniband/core/umem.c
> @@ -151,6 +151,12 @@ unsigned long ib_umem_find_best_pgsz(struct ib_umem *umem,
> dma_addr_t mask;
> int i;
>
> + /* rdma_for_each_block() has a bug if the page size is smaller than the
> + * page size used to build the umem. For now prevent smaller page sizes
> + * from being returned.
> + */
> + pgsz_bitmap &= GENMASK(BITS_PER_LONG - 1, PAGE_SHIFT);
> +
Why do we care about such case? Why can't we leave this check forever?
Thanks,
Reviewed-by: Leon Romanovsky <leonro@nvidia.com>
next prev parent reply other threads:[~2020-09-02 11:51 UTC|newest]
Thread overview: 42+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-09-02 0:43 [PATCH 00/14] RDMA: Improve use of umem in DMA drivers Jason Gunthorpe
2020-09-02 0:43 ` [PATCH 01/14] RDMA/umem: Fix ib_umem_find_best_pgsz() for mappings that cross a page boundary Jason Gunthorpe
2020-09-02 9:24 ` Leon Romanovsky
2020-09-03 14:11 ` Saleem, Shiraz
2020-09-04 22:30 ` Jason Gunthorpe
2020-09-02 0:43 ` [PATCH 02/14] RDMA/umem: Prevent small pages from being returned by ib_umem_find_best_pgsz() Jason Gunthorpe
2020-09-02 11:51 ` Leon Romanovsky [this message]
2020-09-02 11:59 ` Jason Gunthorpe
2020-09-02 12:05 ` Leon Romanovsky
2020-09-02 16:34 ` Jason Gunthorpe
2020-09-03 14:11 ` Saleem, Shiraz
2020-09-03 14:17 ` Jason Gunthorpe
2020-09-03 14:18 ` Saleem, Shiraz
2020-09-02 0:43 ` [PATCH 03/14] RDMA/umem: Use simpler logic for ib_umem_find_best_pgsz() Jason Gunthorpe
2020-09-02 0:43 ` [PATCH 04/14] RDMA/umem: Add rdma_umem_for_each_dma_block() Jason Gunthorpe
2020-09-02 3:10 ` Miguel Ojeda
2020-09-03 14:12 ` Saleem, Shiraz
2020-09-02 0:43 ` [PATCH 05/14] RDMA/umem: Replace for_each_sg_dma_page with rdma_umem_for_each_dma_block Jason Gunthorpe
2020-09-02 0:43 ` [PATCH 06/14] RDMA/umem: Split ib_umem_num_pages() into ib_umem_num_dma_blocks() Jason Gunthorpe
2020-09-03 14:12 ` Saleem, Shiraz
2020-09-03 14:14 ` Jason Gunthorpe
2020-09-04 22:32 ` Jason Gunthorpe
2020-09-02 0:43 ` [PATCH 07/14] RDMA/qedr: Use rdma_umem_for_each_dma_block() instead of open-coding Jason Gunthorpe
2020-09-02 15:36 ` [EXT] " Michal Kalderon
2020-09-02 18:44 ` Jason Gunthorpe
2020-09-02 19:53 ` Michal Kalderon
2020-09-02 0:43 ` [PATCH 08/14] RDMA/qedr: Use ib_umem_num_dma_blocks() instead of ib_umem_page_count() Jason Gunthorpe
2020-09-02 15:35 ` [EXT] " Michal Kalderon
2020-09-02 0:43 ` [PATCH 09/14] RDMA/bnxt: Do not use ib_umem_page_count() or ib_umem_num_pages() Jason Gunthorpe
2020-09-03 4:41 ` Selvin Xavier
2020-09-02 0:43 ` [PATCH 10/14] RDMA/hns: Use ib_umem_num_dma_blocks() instead of opencoding Jason Gunthorpe
2020-09-02 0:43 ` [PATCH 11/14] RDMA/ocrdma: Use ib_umem_num_dma_blocks() instead of ib_umem_page_count() Jason Gunthorpe
2020-09-02 0:43 ` [PATCH 12/14] RDMA/pvrdma: " Jason Gunthorpe
2020-09-02 0:43 ` [PATCH 13/14] RDMA/mlx5: Use ib_umem_num_dma_blocks() Jason Gunthorpe
2020-09-02 9:07 ` Gal Pressman
2020-09-03 15:14 ` Saleem, Shiraz
2020-09-02 0:43 ` [PATCH 14/14] RDMA/umem: Rename ib_umem_offset() to ib_umem_dma_offset() Jason Gunthorpe
2020-09-02 0:51 ` Zhu Yanjun
2020-09-02 15:36 ` [EXT] " Michal Kalderon
2020-09-03 18:48 ` Jason Gunthorpe
2020-09-02 9:09 ` [PATCH 00/14] RDMA: Improve use of umem in DMA drivers Gal Pressman
2020-09-02 12:00 ` Jason Gunthorpe
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