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Paolo Valente f718b09327 block, bfq: do not plug I/O for bfq_queues with no proc refs
Commit 478de3380c ("block, bfq: deschedule empty bfq_queues not
referred by any process") fixed commit 3726112ec7 ("block, bfq:
re-schedule empty queues if they deserve I/O plugging") by
descheduling an empty bfq_queue when it remains with not process
reference. Yet, this still left a case uncovered: an empty bfq_queue
with not process reference that remains in service. This happens for
an in-service sync bfq_queue that is deemed to deserve I/O-dispatch
plugging when it remains empty. Yet no new requests will arrive for
such a bfq_queue if no process sends requests to it any longer. Even
worse, the bfq_queue may happen to be prematurely freed while still in
service (because there may remain no reference to it any longer).

This commit solves this problem by preventing I/O dispatch from being
plugged for the in-service bfq_queue, if the latter has no process
reference (the bfq_queue is then prevented from remaining in service).

Fixes: 3726112ec7 ("block, bfq: re-schedule empty queues if they deserve I/O plugging")
Tested-by: Oleksandr Natalenko <oleksandr@natalenko.name>
Reported-by: Patrick Dung <patdung100@gmail.com>
Tested-by: Patrick Dung <patdung100@gmail.com>
Signed-off-by: Paolo Valente <paolo.valente@linaro.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2020-02-03 06:58:14 -07:00
arch It has been a relatively quiet cycle for documentation, but there's still a 2020-01-29 15:27:31 -08:00
block block, bfq: do not plug I/O for bfq_queues with no proc refs 2020-02-03 06:58:14 -07:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2020-01-28 15:38:56 -08:00
Documentation It has been a relatively quiet cycle for documentation, but there's still a 2020-01-29 15:27:31 -08:00
drivers bcache: check return value of prio_read() 2020-02-01 07:55:39 -07:00
fs linux-kselftest-5.6-rc1-kunit 2020-01-29 15:25:34 -08:00
include linux-kselftest-5.6-rc1-kunit 2020-01-29 15:25:34 -08:00
init Driver core changes for 5.6-rc1 2020-01-29 10:18:20 -08:00
ipc treewide: Use sizeof_field() macro 2019-12-09 10:36:44 -08:00
kernel linux-kselftest-5.6-rc1-kunit 2020-01-29 15:25:34 -08:00
lib linux-kselftest-5.6-rc1-kunit 2020-01-29 15:25:34 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm for-5.6-tag 2020-01-28 14:53:31 -08:00
net y2038: core, driver and file system changes 2020-01-29 14:55:47 -08:00
samples Merge branch 'core-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2020-01-29 11:03:21 -08:00
scripts It has been a relatively quiet cycle for documentation, but there's still a 2020-01-29 15:27:31 -08:00
security linux-kselftest-5.6-rc1-kunit 2020-01-29 15:25:34 -08:00
sound sound updates for 5.6-rc1 2020-01-28 16:26:57 -08:00
tools linux-kselftest-5.6-rc1 2020-01-29 15:24:03 -08:00
usr gen_initramfs_list.sh: fix 'bad variable name' error 2020-01-04 00:00:48 +09:00
virt PPC KVM fix for 5.5 2019-12-22 13:18:15 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2020-01-28 15:38:56 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS open: introduce openat2(2) syscall 2020-01-18 09:19:18 -05:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS MAINTAINERS: Add Revanth Rajashekar as a SED-Opal maintainer 2020-01-29 20:50:50 -07:00
Makefile Linux 5.5 2020-01-26 16:23:03 -08:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

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.