e8a8a18505
Yang Yang reported the following crash caused by requeueing a flush request in Kyber: [ 2.517297] Unable to handle kernel paging request at virtual address ffffffd8071c0b00 ... [ 2.517468] pc : clear_bit+0x18/0x2c [ 2.517502] lr : sbitmap_queue_clear+0x40/0x228 [ 2.517503] sp : ffffff800832bc60 pstate : 00c00145 ... [ 2.517599] Process ksoftirqd/5 (pid: 51, stack limit = 0xffffff8008328000) [ 2.517602] Call trace: [ 2.517606] clear_bit+0x18/0x2c [ 2.517619] kyber_finish_request+0x74/0x80 [ 2.517627] blk_mq_requeue_request+0x3c/0xc0 [ 2.517637] __scsi_queue_insert+0x11c/0x148 [ 2.517640] scsi_softirq_done+0x114/0x130 [ 2.517643] blk_done_softirq+0x7c/0xb0 [ 2.517651] __do_softirq+0x208/0x3bc [ 2.517657] run_ksoftirqd+0x34/0x60 [ 2.517663] smpboot_thread_fn+0x1c4/0x2c0 [ 2.517667] kthread+0x110/0x120 [ 2.517669] ret_from_fork+0x10/0x18 This happens because Kyber doesn't track flush requests, so kyber_finish_request() reads a garbage domain token. Only call the scheduler's requeue_request() hook if RQF_ELVPRIV is set (like we do for the finish_request() hook in blk_mq_free_request()). Now that we're handling it in blk-mq, also remove the check from BFQ. Reported-by: Yang Yang <yang.yang@vivo.com> Signed-off-by: Omar Sandoval <osandov@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.