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Dan Streetman 32e57f8c55 net: tcp: close sock if net namespace is exiting
[ Upstream commit 4ee806d511 ]

When a tcp socket is closed, if it detects that its net namespace is
exiting, close immediately and do not wait for FIN sequence.

For normal sockets, a reference is taken to their net namespace, so it will
never exit while the socket is open.  However, kernel sockets do not take a
reference to their net namespace, so it may begin exiting while the kernel
socket is still open.  In this case if the kernel socket is a tcp socket,
it will stay open trying to complete its close sequence.  The sock's dst(s)
hold a reference to their interface, which are all transferred to the
namespace's loopback interface when the real interfaces are taken down.
When the namespace tries to take down its loopback interface, it hangs
waiting for all references to the loopback interface to release, which
results in messages like:

unregister_netdevice: waiting for lo to become free. Usage count = 1

These messages continue until the socket finally times out and closes.
Since the net namespace cleanup holds the net_mutex while calling its
registered pernet callbacks, any new net namespace initialization is
blocked until the current net namespace finishes exiting.

After this change, the tcp socket notices the exiting net namespace, and
closes immediately, releasing its dst(s) and their reference to the
loopback interface, which lets the net namespace continue exiting.

Link: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1711407
Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=97811
Signed-off-by: Dan Streetman <ddstreet@canonical.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
History 2018-01-31 14:03:45 +01:00
arch ARM: net: bpf: clarify tail_call index 2018-01-31 14:03:44 +01:00
block block: don't let passthrough IO go into .make_request_fn() 2018-01-02 20:31:05 +01:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto crypto: algapi - fix NULL dereference in crypto_remove_spawns() 2018-01-17 09:45:23 +01:00
Documentation x86/pti: Document fix wrong index 2018-01-23 19:58:20 +01:00
drivers lan78xx: Fix failure in USB Full Speed 2018-01-31 14:03:45 +01:00
firmware License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
fs orangefs: fix deadlock; do not write i_size in read_iter 2018-01-31 14:03:43 +01:00
include net: tcp: close sock if net namespace is exiting 2018-01-31 14:03:45 +01:00
init x86/mm/pti: Add infrastructure for page table isolation 2018-01-02 20:30:56 +01:00
ipc License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
kernel workqueue: avoid hard lockups in show_workqueue_state() 2018-01-23 19:58:18 +01:00
lib x86/unwind: Rename unwinder config options to 'CONFIG_UNWINDER_*' 2017-12-25 14:26:13 +01:00
mm mm, page_alloc: fix potential false positive in __zone_watermark_ok 2018-01-31 14:03:40 +01:00
net net: tcp: close sock if net namespace is exiting 2018-01-31 14:03:45 +01:00
samples samples/bpf: adjust rlimit RLIMIT_MEMLOCK for xdp1 2017-12-20 10:10:31 +01:00
scripts scripts/gdb/linux/tasks.py: fix get_thread_info 2018-01-23 19:58:17 +01:00
security security/Kconfig: Correct the Documentation reference for PTI 2018-01-17 09:45:30 +01:00
sound ALSA: hda - Apply the existing quirk to iMac 14,1 2018-01-23 19:58:12 +01:00
tools objtool: Improve error message for bad file argument 2018-01-23 19:58:13 +01:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM: arm/arm64: Check pagesize when allocating a hugepage at Stage 2 2018-01-23 19:58:19 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore kbuild: Add support to generate LLVM assembly files 2017-04-25 08:13:52 +09:00
.mailmap .mailmap: Add Maciej W. Rozycki's Imagination e-mail address 2017-11-10 12:16:15 -08:00
COPYING [PATCH] update FSF address in COPYING 2005-09-10 10:06:29 -07:00
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS Merge branch 'akpm' (patches from Andrew) 2017-11-09 18:26:51 -08:00
Makefile Linux 4.14.15 2018-01-23 19:58:21 +01:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

Linux kernel
============

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.