linux-stable

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Anoob Soman 2bd624b461 packet: Do not call fanout_release from atomic contexts Commit `6664498280` ("packet: call fanout_release, while UNREGISTERING a netdev"), unfortunately, introduced the following issues. 1. calling mutex_lock(&fanout_mutex) (fanout_release()) from inside rcu_read-side critical section. rcu_read_lock disables preemption, most often, which prohibits calling sleeping functions. [ ] include/linux/rcupdate.h:560 Illegal context switch in RCU read-side critical section! [ ] [ ] rcu_scheduler_active = 1, debug_locks = 0 [ ] 4 locks held by ovs-vswitchd/1969: [ ] #0: (cb_lock){++++++}, at: [<ffffffff8158a6c9>] genl_rcv+0x19/0x40 [ ] #1: (ovs_mutex){+.+.+.}, at: [<ffffffffa04878ca>] ovs_vport_cmd_del+0x4a/0x100 [openvswitch] [ ] #2: (rtnl_mutex){+.+.+.}, at: [<ffffffff81564157>] rtnl_lock+0x17/0x20 [ ] #3: (rcu_read_lock){......}, at: [<ffffffff81614165>] packet_notifier+0x5/0x3f0 [ ] [ ] Call Trace: [ ] [<ffffffff813770c1>] dump_stack+0x85/0xc4 [ ] [<ffffffff810c9077>] lockdep_rcu_suspicious+0x107/0x110 [ ] [<ffffffff810a2da7>] ___might_sleep+0x57/0x210 [ ] [<ffffffff810a2fd0>] __might_sleep+0x70/0x90 [ ] [<ffffffff8162e80c>] mutex_lock_nested+0x3c/0x3a0 [ ] [<ffffffff810de93f>] ? vprintk_default+0x1f/0x30 [ ] [<ffffffff81186e88>] ? printk+0x4d/0x4f [ ] [<ffffffff816106dd>] fanout_release+0x1d/0xe0 [ ] [<ffffffff81614459>] packet_notifier+0x2f9/0x3f0 2. calling mutex_lock(&fanout_mutex) inside spin_lock(&po->bind_lock). "sleeping function called from invalid context" [ ] BUG: sleeping function called from invalid context at kernel/locking/mutex.c:620 [ ] in_atomic(): 1, irqs_disabled(): 0, pid: 1969, name: ovs-vswitchd [ ] INFO: lockdep is turned off. [ ] Call Trace: [ ] [<ffffffff813770c1>] dump_stack+0x85/0xc4 [ ] [<ffffffff810a2f52>] ___might_sleep+0x202/0x210 [ ] [<ffffffff810a2fd0>] __might_sleep+0x70/0x90 [ ] [<ffffffff8162e80c>] mutex_lock_nested+0x3c/0x3a0 [ ] [<ffffffff816106dd>] fanout_release+0x1d/0xe0 [ ] [<ffffffff81614459>] packet_notifier+0x2f9/0x3f0 3. calling dev_remove_pack(&fanout->prot_hook), from inside spin_lock(&po->bind_lock) or rcu_read-side critical-section. dev_remove_pack() -> synchronize_net(), which might sleep. [ ] BUG: scheduling while atomic: ovs-vswitchd/1969/0x00000002 [ ] INFO: lockdep is turned off. [ ] Call Trace: [ ] [<ffffffff813770c1>] dump_stack+0x85/0xc4 [ ] [<ffffffff81186274>] __schedule_bug+0x64/0x73 [ ] [<ffffffff8162b8cb>] __schedule+0x6b/0xd10 [ ] [<ffffffff8162c5db>] schedule+0x6b/0x80 [ ] [<ffffffff81630b1d>] schedule_timeout+0x38d/0x410 [ ] [<ffffffff810ea3fd>] synchronize_sched_expedited+0x53d/0x810 [ ] [<ffffffff810ea6de>] synchronize_rcu_expedited+0xe/0x10 [ ] [<ffffffff8154eab5>] synchronize_net+0x35/0x50 [ ] [<ffffffff8154eae3>] dev_remove_pack+0x13/0x20 [ ] [<ffffffff8161077e>] fanout_release+0xbe/0xe0 [ ] [<ffffffff81614459>] packet_notifier+0x2f9/0x3f0 4. fanout_release() races with calls from different CPU. To fix the above problems, remove the call to fanout_release() under rcu_read_lock(). Instead, call __dev_remove_pack(&fanout->prot_hook) and netdev_run_todo will be happy that &dev->ptype_specific list is empty. In order to achieve this, I moved dev_{add,remove}_pack() out of fanout_{add,release} to __fanout_{link,unlink}. So, call to {,__}unregister_prot_hook() will make sure fanout->prot_hook is removed as well. Fixes: `6664498280` ("packet: call fanout_release, while UNREGISTERING a netdev") Reported-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Anoob Soman <anoob.soman@citrix.com> Acked-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2017-02-17 11:11:35 -05:00
arch	Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip	2017-02-11 10:31:46 -08:00
block	block: don't try Write Same from __blkdev_issue_zeroout	2017-02-06 09:34:46 -07:00
certs	certs: Add a secondary system keyring that can be added to dynamically	2016-04-11 22:48:09 +01:00
crypto	crypto: algif_aead - Fix kernel panic on list_del	2017-02-03 17:45:48 +08:00
Documentation	media fixes for v4.10-rc8	2017-02-14 06:29:21 -08:00
drivers	media fixes for v4.10-rc9	2017-02-16 10:22:41 -08:00
firmware	WHENCE: use https://linuxtv.org for LinuxTV URLs	2015-12-04 10:35:11 -02:00
fs	vfs: fix uninitialized flags in splice_to_pipe()	2017-02-16 09:09:02 -08:00
include	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2017-02-16 08:37:18 -08:00
init	kbuild: modversions: add infrastructure for emitting relative CRCs	2017-02-03 08:28:25 -08:00
ipc	ipc/sem.c: fix incorrect sem_lock pairing	2017-01-10 18:31:55 -08:00
kernel	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2017-02-16 08:37:18 -08:00
lib	rhashtable: Revert nested table changes.	2017-02-15 22:29:51 -05:00
mm	mm/slub.c: fix random_seq offset destruction	2017-02-08 15:41:43 -08:00
net	packet: Do not call fanout_release from atomic contexts	2017-02-17 11:11:35 -05:00
samples	bpf: introduce BPF_F_ALLOW_OVERRIDE flag	2017-02-12 21:52:19 -05:00
scripts	kbuild: modversions: add infrastructure for emitting relative CRCs	2017-02-03 08:28:25 -08:00
security	selinux: fix off-by-one in setprocattr	2017-02-08 19:09:53 +11:00
sound	ALSA: hda - adding a new NV HDMI/DP codec ID in the driver	2017-02-09 08:57:47 +01:00
tools	Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net	2017-02-16 08:37:18 -08:00
usr	kbuild: initramfs cleanup, set target from Kconfig	2017-01-05 09:40:16 -08:00
virt	KVM/ARM updates for 4.10-rc4	2017-01-17 15:04:59 +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	Merge branch 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild	2016-08-02 16:48:52 -04:00
.mailmap	mailmap: add codeaurora.org names for nameless email commits	2017-01-10 18:31:55 -08:00
COPYING
CREDITS	MAINTAINERS: Remove old e-mail address	2017-02-13 12:24:56 -05:00
Kbuild	scripts/gdb: provide linux constants	2016-05-23 17:04:14 -07:00
Kconfig
MAINTAINERS	MAINTAINERS: Remove old e-mail address	2017-02-13 12:24:56 -05:00
Makefile	Linux 4.10-rc8	2017-02-12 13:03:20 -08:00
README	README: add a new README file, pointing to the Documentation/	2016-10-24 08:12:35 -02:00

README

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.