0bd939b60c
Sometimes, under heavy XDP Tx traffic, e.g. when using XDP traffic
generator (%BPF_F_TEST_XDP_LIVE_FRAMES), the machine can catch OOM due
to the driver not freeing all of the pages passed to it by
.ndo_xdp_xmit().
Turned out that during the development of the tagged commit, the check,
which ensures that we have a free descriptor to queue a frame, moved
into the branch happening only when a buffer has frags. Otherwise, we
only run a cleaning cycle, but don't check anything.
ATST, there can be situations when the driver gets new frames to send,
but there are no buffers that can be cleaned/completed and the ring has
no free slots. It's very rare, but still possible (> 6.5 Mpps per ring).
The driver then fills the next buffer/descriptor, effectively
overwriting the data, which still needs to be freed.
Restore the check after the cleaning routine to make sure there is a
slot to queue a new frame. When there are frags, there still will be a
separate check that we can place all of them, but if the ring is full,
there's no point in wasting any more time.
(minor: make `!ready_frames` unlikely since it happens ~1-2 times per
billion of frames)
Fixes:
|
||
|---|---|---|
| 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 | ||
| .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 Restructured Text 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.