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When SHAMPO is used, a receive queue currently almost always leaks one
page on shutdown.
A page has MLX5E_SHAMPO_WQ_HEADER_PER_PAGE (8) headers. These headers
are tracked in the SHAMPO bitmap. Each page is released when the last
header index in the group is processed. During header allocation, there
can be leftovers from a page that will be used in a subsequent
allocation. This is normally fine, except for the following scenario
(simplified a bit):
1) Allocate N new page fragments, showing only the relevant last 4
fragments:
0: new page
1: new page
2: new page
3: new page
4: page from previous allocation
5: page from previous allocation
6: page from previous allocation
7: page from previous allocation
2) NAPI processes header indices 4-7 because they are the oldest
allocated. Bit 7 will be set to 0.
3) Receive queue shutdown occurs. All the remaining bits are being
iterated on to release the pages. But the page assigned to header
indices 0-3 will not be freed due to what happened in step 2.
This patch fixes the issue by making sure that on allocation, header
fragments are always allocated in groups of
MLX5E_SHAMPO_WQ_HEADER_PER_PAGE so that there is never a partial page
left over between allocations.
A more appropriate fix would be a refactoring of
mlx5e_alloc_rx_hd_mpwqe() and mlx5e_build_shampo_hd_umr(). But this
refactoring is too big for net. It will be targeted for net-next.
Fixes:
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||
|---|---|---|
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| Documentation | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| io_uring | ||
| ipc | ||
| kernel | ||
| lib | ||
| LICENSES | ||
| mm | ||
| net | ||
| rust | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .editorconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| .rustfmt.toml | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| README | ||
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.