sched: Fix migration thread runtime bogosity

commit 8f6189684eb4e85e6c593cd710693f09c944450a upstream.

Make stop scheduler class do the same accounting as other classes,

Migration threads can be caught in the act while doing exec balancing,
leading to the below due to use of unmaintained ->se.exec_start.  The
load that triggered this particular instance was an apparently out of
control heavily threaded application that does system monitoring in
what equated to an exec bomb, with one of the VERY frequently migrated
tasks being ps.

%CPU   PID USER     CMD
99.3    45 root     [migration/10]
97.7    53 root     [migration/12]
97.0    57 root     [migration/13]
90.1    49 root     [migration/11]
89.6    65 root     [migration/15]
88.7    17 root     [migration/3]
80.4    37 root     [migration/8]
78.1    41 root     [migration/9]
44.2    13 root     [migration/2]

Signed-off-by: Mike Galbraith <mgalbraith@suse.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1344051854.6739.19.camel@marge.simpson.net
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
net/ipv6/addrconf: fix wdog_bark caused by infinite spinning on a deadlock

A synchronization issue may occur while addrconf_ifdown(),
when it updates inet6_addr_lst[] with already destroyed *ifp
by ipv6_add/del_addr(), using the same addrconf_hash_lock.

[core 0]                                        [core 1]
   |                                               |
   |->ipv6_add_addr                                |->addrconf_ifdown
       |                                               |
       |                                               |-> spin_lock(&addrconf_hash_lock);
       |                                               |-> remove ifa->addr_lst from inet6_addr_lst
       |                                               |-> spin_unlock(&addrconf_hash_lock);
       |-> spin_lock(&addrconf_hash_lock);             |
       |-> add ifa->addr_lst to inet6_addr_lst[hash]   |
       |-> spin_unlock(&addrconf_hash_lock);           |
       |-> write_lock(&idev-lock);                     |
       |-> add ifa->if_list to idev->addr_list         |
       |-> write_unlock(&idev->lock);                  |
       |                                               |-> write_lock(&idev->lock);
       |                                               |-> remove ifa->if_list from idev->addr_list
       |                                               |-> write_unlock(&idev->lock);

[28055.378524] ------------[ cut here ]------------
[28055.378591] WARNING: at net/ipv6/addrconf.c:546 inet6_ifa_finish_destroy+0x98/0xc8()
[28055.378691] [<c010de1c>] (unwind_backtrace+0x0/0x144) from [<c09fd08c>] (dump_stack+0x20/0x24)
[28055.378747] [<c09fd08c>] (dump_stack+0x20/0x24) from [<c0192adc>] (warn_slowpath_common+0x58/0x70)
[28055.378840] [<c0192adc>] (warn_slowpath_common+0x58/0x70) from [<c0192bec>] (warn_slowpath_null+0x2c/0x34)
[28055.378931] [<c0192bec>] (warn_slowpath_null+0x2c/0x34) from [<c0911a90>] (inet6_ifa_finish_destroy+0x98/0xc8)
[28055.379026] [<c0911a90>] (inet6_ifa_finish_destroy+0x98/0xc8) from [<c091498c>] (addrconf_ifdown+0x2e4/0x430)
[28055.379120] [<c091498c>] (addrconf_ifdown+0x2e4/0x430) from [<c0915b70>] (addrconf_notify+0xe4/0x3ac)
[28055.379209] [<c0915b70>] (addrconf_notify+0xe4/0x3ac) from [<c01b9df0>] (notifier_call_chain+0x54/0x94)
[28055.379321] [<c01b9df0>] (notifier_call_chain+0x54/0x94) from [<c01ba3ac>] (__raw_notifier_call_chain+0x24/0x2c)
[28055.379379] [<c01ba3ac>] (__raw_notifier_call_chain+0x24/0x2c) from [<c01ba3dc>] (raw_notifier_call_chain+0x28/0x30)
[28055.379475] [<c01ba3dc>] (raw_notifier_call_chain+0x28/0x30) from [<c0840ea4>] (call_netdevice_notifiers+0x38/0x60)
[28055.379568] [<c0840ea4>] (call_netdevice_notifiers+0x38/0x60) from [<c0844d5c>] (__dev_notify_flags+0x3c/0x6c)
[28055.379657] [<c0844d5c>] (__dev_notify_flags+0x3c/0x6c) from [<c0844dcc>] (dev_change_flags+0x40/0x58)
[28055.379747] [<c0844dcc>] (dev_change_flags+0x40/0x58) from [<c08d2834>] (devinet_ioctl+0x79c/0x8bc)
[28055.379837] [<c08d2834>] (devinet_ioctl+0x79c/0x8bc) from [<c08d3488>] (inet_ioctl+0x1c0/0x1d0)
[28055.379928] [<c08d3488>] (inet_ioctl+0x1c0/0x1d0) from [<c082d7f0>] (sock_ioctl+0x80/0x248)
[28055.379982] [<c082d7f0>] (sock_ioctl+0x80/0x248) from [<c0275364>] (do_vfs_ioctl+0x94/0x5bc)
[28055.380071] [<c0275364>] (do_vfs_ioctl+0x94/0x5bc) from [<c0275908>] (sys_ioctl+0x7c/0x8c)
[28055.380164] [<c0275908>] (sys_ioctl+0x7c/0x8c) from [<c0107300>] (ret_fast_syscall+0x0/0x30)
[28055.380252] ---[ end trace 920b8b321354f066 ]---
[28061.735021] Watchdog bark! Now = 28061.735014
[28061.735106] Watchdog last pet at 28050.179294
[28061.735245] cpu alive mask from last pet 0-3
[28061.735321] Causing a watchdog bite!

The addrconf_hash_lock should cover both modification of inet6_addr_list and idev->addr_list
to resolve any possible synchronization issue between addrconf_ifdown() and ipv6_add/del_addr().

Bug: 11293746
Signed-off-by: David C. Park <davidc.park@lge.com>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
ksm: Provide support to use deferred timers for scanner thread

KSM thread to scan pages is getting schedule on definite timeout.
That wakes up CPU from idle state and hence may affect the power
consumption. Provide an optional support to use deferred timer
which suites low-power use-cases.

To enable deferred timers,
$ echo 1 > /sys/kernel/mm/ksm/deferred_timer

Change-Id: I07fe199f97fe1f72f9a9e1b0b757a3ac533719e8
Signed-off-by: Chintan Pandya <cpandya@codeaurora.org>
ksm: enable deferred_timer by default to prevent the CPU to be wakened for ksm activities.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>