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Gang He da3627c30d dlm: remove O_NONBLOCK flag in sctp_connect_to_sock
We should remove O_NONBLOCK flag when calling sock->ops->connect()
in sctp_connect_to_sock() function.
Why?
1. up to now, sctp socket connect() function ignores the flag argument,
that means O_NONBLOCK flag does not take effect, then we should remove
it to avoid the confusion (but is not urgent).
2. for the future, there will be a patch to fix this problem, then the flag
argument will take effect, the patch has been queued at https://git.kernel.o
rg/pub/scm/linux/kernel/git/davem/net.git/commit/net/sctp?id=644fbdeacf1d3ed
d366e44b8ba214de9d1dd66a9.
But, the O_NONBLOCK flag will make sock->ops->connect() directly return
without any wait time, then the connection will not be established, DLM kernel
module will call sock->ops->connect() again and again, the bad results are,
CPU usage is almost 100%, even trigger soft_lockup problem if the related
configurations are enabled,
DLM kernel module also prints lots of messages like,
[Fri Apr 27 11:23:43 2018] dlm: connecting to 172167592
[Fri Apr 27 11:23:43 2018] dlm: connecting to 172167592
[Fri Apr 27 11:23:43 2018] dlm: connecting to 172167592
[Fri Apr 27 11:23:43 2018] dlm: connecting to 172167592
The upper application (e.g. ocfs2 mount command) is hanged at new_lockspace(),
the whole backtrace is as below,
tb0307-nd2:~ # cat /proc/2935/stack
[<0>] new_lockspace+0x957/0xac0 [dlm]
[<0>] dlm_new_lockspace+0xae/0x140 [dlm]
[<0>] user_cluster_connect+0xc3/0x3a0 [ocfs2_stack_user]
[<0>] ocfs2_cluster_connect+0x144/0x220 [ocfs2_stackglue]
[<0>] ocfs2_dlm_init+0x215/0x440 [ocfs2]
[<0>] ocfs2_fill_super+0xcb0/0x1290 [ocfs2]
[<0>] mount_bdev+0x173/0x1b0
[<0>] mount_fs+0x35/0x150
[<0>] vfs_kern_mount.part.23+0x54/0x100
[<0>] do_mount+0x59a/0xc40
[<0>] SyS_mount+0x80/0xd0
[<0>] do_syscall_64+0x76/0x140
[<0>] entry_SYSCALL_64_after_hwframe+0x42/0xb7
[<0>] 0xffffffffffffffff

So, I think we should remove O_NONBLOCK flag here, since DLM kernel module can
not handle non-block sockect in connect() properly.

Signed-off-by: Gang He <ghe@suse.com>
Signed-off-by: David Teigland <teigland@redhat.com>
2018-05-29 10:48:35 -05:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-29 10:06:05 -07:00
block Revert "blk-mq: remove code for dealing with remapping queue" 2018-04-25 09:49:22 -06:00
certs
crypto crypto: drbg - set freed buffers to NULL 2018-04-21 00:57:00 +08:00
Documentation Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-29 09:03:25 -07:00
drivers Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-29 09:03:25 -07:00
firmware
fs dlm: remove O_NONBLOCK flag in sctp_connect_to_sock 2018-05-29 10:48:35 -05:00
include Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-29 09:03:25 -07:00
init
ipc
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-29 09:03:25 -07:00
lib Driver core fixes for 4.17-rc3 2018-04-27 10:12:20 -07:00
LICENSES
mm x86/pti: Filter at vma->vm_page_prot population 2018-04-25 11:02:51 +02:00
net A CephFS quota follow-up and fixes for two older issues in the 2018-04-27 10:56:29 -07:00
samples Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching 2018-04-20 08:51:55 -07:00
scripts
security Merge branch 'userns-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2018-04-24 17:58:51 -07:00
sound ALSA: dice: fix error path to destroy initialized stream data 2018-04-26 15:24:54 +02:00
tools Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-04-29 09:36:22 -07:00
usr
virt KVM fixes for v4.17-rc3 2018-04-27 16:13:31 -07:00
.clang-format
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS MAINTAINERS: add myself as maintainer of AFFS 2018-04-28 10:30:47 -07:00
Makefile Linux v4.17-rc3 2018-04-29 14:17:42 -07:00
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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.