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Dennis Zhou c9b3007fec blk-iolatency: fix STS_AGAIN handling 
The iolatency controller is based on rq_qos. It increments on
rq_qos_throttle() and decrements on either rq_qos_cleanup() or
rq_qos_done_bio(). a3fb01ba5a fixes the double accounting issue where
blk_mq_make_request() may call both rq_qos_cleanup() and
rq_qos_done_bio() on REQ_NO_WAIT. So checking STS_AGAIN prevents the
double decrement.

The above works upstream as the only way we can get STS_AGAIN is from
blk_mq_get_request() failing. The STS_AGAIN handling isn't a real
problem as bio_endio() skipping only happens on reserved tag allocation
failures which can only be caused by driver bugs and already triggers
WARN.

However, the fix creates a not so great dependency on how STS_AGAIN can
be propagated. Internally, we (Facebook) carry a patch that kills read
ahead if a cgroup is io congested or a fatal signal is pending. This
combined with chained bios progagate their bi_status to the parent is
not already set can can cause the parent bio to not clean up properly
even though it was successful. This consequently leaks the inflight
counter and can hang all IOs under that blkg.

To nip the adverse interaction early, this removes the rq_qos_cleanup()
callback in iolatency in favor of cleaning up always on the
rq_qos_done_bio() path.

Fixes: a3fb01ba5a ("blk-iolatency: only account submitted bios")
Debugged-by: Tejun Heo <tj@kernel.org>
Debugged-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Dennis Zhou <dennis@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-07-05 15:14:00 -06:00
arch powerpc fixes for 5.2 #5 2019-06-22 09:09:42 -07:00
block blk-iolatency: fix STS_AGAIN handling 2019-07-05 15:14:00 -06:00
certs treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
crypto treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
Documentation Linux 5.2-rc6 2019-07-01 08:16:08 -06:00
drivers Linux 5.2-rc6 2019-07-01 08:16:08 -06:00
fs block: fix .bi_size overflow 2019-07-01 08:18:54 -06:00
include block: fix .bi_size overflow 2019-07-01 08:18:54 -06:00
init block: rename CONFIG_DEBUG_BLK_CGROUP to CONFIG_BFQ_CGROUP_DEBUG 2019-06-20 10:32:35 -06:00
ipc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
kernel Linux 5.2-rc6 2019-07-01 08:16:08 -06:00
lib sbitmap: Replace cmpxchg with xchg 2019-07-01 11:57:12 -06:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
net Bluetooth: Fix regression with minimum encryption key size alignment 2019-06-22 09:07:39 -07:00
samples SPDX update for 5.2-rc6 2019-06-21 09:58:42 -07:00
scripts treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 505 2019-06-19 17:11:22 +02:00
security SPDX update for 5.2-rc6 2019-06-21 09:58:42 -07:00
sound treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 500 2019-06-19 17:09:55 +02:00
tools SPDX update for 5.2-rc6 2019-06-21 09:58:42 -07:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt SPDX update for 5.2-rc6 2019-06-21 09:58:42 -07:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore .gitignore: exclude .get_maintainer.ignore and .gitattributes 2019-05-18 11:49:54 +09:00
.mailmap MAINTAINERS: Update my email address 2019-06-18 14:37:27 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Farewell Martin Schwidefsky 2019-05-31 10:14:11 +02:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Char/Misc driver fixes for 5.2-rc6 2019-06-21 10:18:16 -07:00
Makefile Linux 5.2-rc6 2019-06-22 16:01:36 -07:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

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.