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216578e55a
REQ_F_COMP_LOCKED is used and implemented in a buggy way. The problem is that the flag is set before io_put_req() but not cleared after, and if that wasn't the final reference, the request will be freed with the flag set from some other context, which may not hold a spinlock. That means possible races with removing linked timeouts and unsynchronised completion (e.g. access to CQ). Instead of fixing REQ_F_COMP_LOCKED, kill the flag and use task_work_add() to move such requests to a fresh context to free from it, as was done with __io_free_req_finish(). Signed-off-by: Pavel Begunkov <asml.silence@gmail.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.