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Jens Axboe 500f9fbade io_uring: fix potential hang with polled IO
If a request issue ends up being punted to async context to avoid
blocking, we can get into a situation where the original application
enters the poll loop for that very request before it has been issued.
This should not be an issue, except that the polling will hold the
io_uring uring_ctx mutex for the duration of the poll. When the async
worker has actually issued the request, it needs to acquire this mutex
to add the request to the poll issued list. Since the application
polling is already holding this mutex, the workqueue sleeps on the
mutex forever, and the application thus never gets a chance to poll for
the very request it was interested in.

Fix this by ensuring that the polling drops the uring_ctx occasionally
if it's not making any progress.

Reported-by: Jeffrey M. Birnbaum <jmbnyc@gmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
2019-08-20 11:01:58 -06:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-18 09:45:42 -07:00
block block: remove REQ_NOWAIT_INLINE 2019-08-15 11:09:16 -06:00
certs Revert "Merge tag 'keys-acl-20190703' of git://git.kernel.org/pub/scm/linux/kernel/git/dhowells/linux-fs" 2019-07-10 18:43:43 -07:00
crypto USB / PHY patches for 5.3-rc1 2019-07-11 15:40:06 -07:00
Documentation Devicetree fixes for 5.3: 2019-08-15 09:18:56 -07:00
drivers This pull request contains a single fix for MTD: 2019-08-18 12:56:42 -07:00
fs io_uring: fix potential hang with polled IO 2019-08-20 11:01:58 -06:00
include USB fixes for 5.3-rc5 2019-08-18 09:11:29 -07:00
init Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
ipc Merge branch 'work.mount0' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2019-07-19 10:42:02 -07:00
kernel SPDX fixes for 5.3-rc5 2019-08-18 09:26:16 -07:00
lib Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-08-06 17:11:59 -07:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm hugetlbfs: fix hugetlb page migration/fault race causing SIGBUS 2019-08-13 16:06:53 -07:00
net net: dsa: sja1105: Fix memory leak on meta state machine error path 2019-08-06 14:37:02 -07:00
samples auxdisplay: Fix a typo in cfag12864b-example.c 2019-08-08 20:00:18 +02:00
scripts SPDX fixes for 5.3-rc5 2019-08-18 09:26:16 -07:00
security KEYS: trusted: allow module init if TPM is inactive or deactivated 2019-08-13 19:59:23 +03:00
sound sound fixes for 5.3-rc5 2019-08-16 08:49:45 -07:00
tools - A few fixes for the userspace hyper-v tools from Adrian Vladu. 2019-08-17 19:31:30 -07:00
usr kbuild: enable arch/s390/include/uapi/asm/zcrypt.h for uapi header test 2019-07-23 10:45:46 +02:00
virt KVM/arm fixes for 5.3, take #2 2019-08-09 16:53:50 +02:00
.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: Add compilation database file 2019-07-27 12:18:19 +09:00
.mailmap MAINTAINERS: Update my email address 2019-07-22 14:57:50 +01:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS Remove references to dead website. 2019-07-19 12:22:04 -07:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-08-18 09:45:42 -07:00
Makefile Linux 5.3-rc5 2019-08-18 14:31:08 -07:00
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.