mirror of
https://github.com/hardkernel/linux.git
synced 2026-06-05 02:21:52 +09:00
89e3d1a85d
commit41e76c8566upstream. bfq_setup_cooperator() uses bfqd->in_serv_last_pos so detect whether it makes sense to merge current bfq queue with the in-service queue. However if the in-service queue is freshly scheduled and didn't dispatch any requests yet, bfqd->in_serv_last_pos is stale and contains value from the previously scheduled bfq queue which can thus result in a bogus decision that the two queues should be merged. This bug can be observed for example with the following fio jobfile: [global] direct=0 ioengine=sync invalidate=1 size=1g rw=read [reader] numjobs=4 directory=/mnt where the 4 processes will end up in the one shared bfq queue although they do IO to physically very distant files (for some reason I was able to observe this only with slice_idle=1ms setting). Fix the problem by invalidating bfqd->in_serv_last_pos when switching in-service queue. Fixes:058fdecc6d("block, bfq: fix in-service-queue check for queue merging") CC: stable@vger.kernel.org Signed-off-by: Jan Kara <jack@suse.cz> Acked-by: Paolo Valente <paolo.valente@linaro.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.