From: Jason Gunthorpe <jgg@nvidia.com>
To: "Saleem, Shiraz" <shiraz.saleem@intel.com>
Cc: Doug Ledford <dledford@redhat.com>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>
Subject: Re: [PATCH 02/14] RDMA/umem: Prevent small pages from being returned by ib_umem_find_best_pgsz()
Date: Thu, 3 Sep 2020 11:17:12 -0300 [thread overview]
Message-ID: <20200903141712.GF1152540@nvidia.com> (raw)
In-Reply-To: <9DD61F30A802C4429A01CA4200E302A70107141173@ORSMSX101.amr.corp.intel.com>
On Thu, Sep 03, 2020 at 02:11:37PM +0000, Saleem, Shiraz wrote:
> > Subject: [PATCH 02/14] RDMA/umem: Prevent small pages from being returned by
> > ib_umem_find_best_pgsz()
> >
> > 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.
>
> Not sure if we were exposed today. i.e. rdma drivers working with
> block sizes smaller than system page size?
Yes, it could happen, here are some examples:
drivers/infiniband/hw/i40iw/i40iw_verbs.c:
iwmr->page_size = ib_umem_find_best_pgsz(region, SZ_4K | SZ_2M,
drivers/infiniband/hw/bnxt_re/ib_verbs.c:
page_shift = __ffs(ib_umem_find_best_pgsz(umem,
BNXT_RE_PAGE_SIZE_4K | BNXT_RE_PAGE_SIZE_2M,
virt_addr));
Eg that breaks on a ARM with 16k or 64k page sizes.
Jason
next prev parent reply other threads:[~2020-09-03 14:50 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
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 [this message]
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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