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486055f5e0
A single scatter-gather entry is limited by a 32 bits "length" field that is practically 4GB - PAGE_SIZE. This means that even when the memory is physically contiguous, we might need more than one entry to represent it. Additionally when using dmabuf, the sg_table might be originated outside the subsystem and optimized for other needs. For instance an SGT of 16GB GPU continuous memory might look like this: (a real life example) dma_address 34401400000, length fffff000 dma_address 345013ff000, length fffff000 dma_address 346013fe000, length fffff000 dma_address 347013fd000, length fffff000 dma_address 348013fc000, length 4000 Since ib_umem_find_best_pgsz works within SG entries, in the above case we will result with the worst possible 4KB page size. Fix this by taking into consideration only the alignment of addresses of real discontinuity points rather than treating SG entries as such, and adjust the page iterator to correctly handle cross SG entry pages. There is currently an assumption that drivers do not ask for pages bigger than maximal DMA size supported by their devices. Reviewed-by: Firas Jahjah <firasj@amazon.com> Reviewed-by: Yonatan Nachum <ynachum@amazon.com> Signed-off-by: Michael Margolin <mrgolin@amazon.com> Link: https://patch.msgid.link/20250217141623.12428-1-mrgolin@amazon.com Signed-off-by: Leon Romanovsky <leon@kernel.org>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.