Sagi Grimberg f36f3ebdf1 nvmet-rdma: fix possible bogus dereference under heavy load
[ Upstream commit 8407879c4e0d7731f6e7e905893cecf61a7762c7 ]

Currently we always repost the recv buffer before we send a response
capsule back to the host. Since ordering is not guaranteed for send
and recv completions, it is posible that we will receive a new request
from the host before we got a send completion for the response capsule.

Today, we pre-allocate 2x rsps the length of the queue, but in reality,
under heavy load there is nothing that is really preventing the gap to
expand until we exhaust all our rsps.

To fix this, if we don't have any pre-allocated rsps left, we dynamically
allocate a rsp and make sure to free it when we are done. If under memory
pressure we fail to allocate a rsp, we silently drop the command and
wait for the host to retry.

Reported-by: Steve Wise <swise@opengridcomputing.com>
Tested-by: Steve Wise <swise@opengridcomputing.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
[hch: dropped a superflous assignment]
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-10-10 08:54:24 +02:00
2018-09-26 08:38:04 +02:00
2018-10-03 17:01:00 -07:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
See Documentation/00-INDEX for a list of what is contained in each file.

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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