Jens Axboe 0ddf92e848 io_uring: provide fallback request for OOM situations
One thing that really sucks for userspace APIs is if the kernel passes
back -ENOMEM/-EAGAIN for resource shortages. The application really has
no idea of what to do in those cases. Should it try and reap
completions? Probably a good idea. Will it solve the issue? Who knows.

This patch adds a simple fallback mechanism if we fail to allocate
memory for a request. If we fail allocating memory from the slab for a
request, we punt to a pre-allocated request. There's just one of these
per io_ring_ctx, but the important part is if we ever return -EBUSY to
the application, the applications knows that it can wait for events and
make forward progress when events have completed. This is the important
part.

Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-11-11 16:32:55 -07:00
2019-10-29 12:43:06 -06:00
2019-11-04 08:50:02 -07:00
2019-10-27 13:19:19 -04:00

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
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    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.
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