Messages in this thread | | | From | Konstantin Taranov <> | Subject | RE: [PATCH rdma-next v1 1/1] RDMA/mana_ib: Fix bug in creation of dma regions | Date | Thu, 8 Feb 2024 18:53:05 +0000 |
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> From: Long Li <longli@microsoft.com> > Sent: Thursday, 8 February 2024 19:43 > To: Konstantin Taranov <kotaranov@linux.microsoft.com>; Konstantin > Taranov <kotaranov@microsoft.com>; sharmaajay@microsoft.com; > jgg@ziepe.ca; leon@kernel.org > Cc: linux-rdma@vger.kernel.org; linux-kernel@vger.kernel.org > Subject: RE: [PATCH rdma-next v1 1/1] RDMA/mana_ib: Fix bug in creation of > dma regions > > > > > /* Hardware requires dma region to align to chosen page size */ > > - page_sz = ib_umem_find_best_pgsz(umem, PAGE_SZ_BM, 0); > > + page_sz = ib_umem_find_best_pgsz(umem, PAGE_SZ_BM, virt); > > if (!page_sz) { > > ibdev_dbg(&dev->ib_dev, "failed to find page size.\n"); > > return -ENOMEM; > > } > > How about doing: > page_sz = ib_umem_find_best_pgsz(umem, PAGE_SZ_BM, force_zero_offset > ? 0 : virt); > > Will this work? This can get rid of the following while loop. >
I do not think so. I mentioned once, that it was failing for me with existing code with the 4K-aligned addresses and 8K pages. In this case, we miscalculate the number of pages. So, we think that it is one 8K page, but it is in fact two.
> > + > > + if (force_zero_offset) { > > + while (ib_umem_dma_offset(umem, page_sz) && page_sz > > > PAGE_SIZE) > > + page_sz /= 2; > > + if (ib_umem_dma_offset(umem, page_sz) != 0) { > > + ibdev_dbg(&dev->ib_dev, "failed to find page size to > > force zero offset.\n"); > > + return -ENOMEM; > > + } > > + } > > +
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