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2645672ffe
If rq_qos_throttle() ends up blocking, then we will have invalidated and
flushed our current plug. Since blk_mq_get_cached_request() hasn't
popped the cached request off the plug list just yet, we end holding a
pointer to a request that is no longer valid. This insta-crashes with
rq->mq_hctx being NULL in the validity checks just after.
Pop the request off the cached list before doing rq_qos_throttle() to
avoid using a potentially stale request.
Fixes: 0a5aa8d161 ("block: fix blk_mq_attempt_bio_merge and rq_qos_throttle protection")
Reported-by: Dylan Yudaken <dylany@fb.com>
Tested-by: Dylan Yudaken <dylany@fb.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
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.