ARM: fix rcu stalls on SMP platforms

We can stall RCU processing on SMP platforms if a CPU sits in its idle
loop for a long time.  This happens because we don't call irq_enter()
and irq_exit() around generic_smp_call_function_interrupt() and
friends.  Add the necessary calls, and remove the one from within
ipi_timer(), so that they're all in a common place.

Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
Change-Id: I3383645deba180958b548fbae5aca795ac4094f6
Reviewed-on: http://git-master/r/90691
Reviewed-by: Automatic_Commit_Validation_User
Reviewed-by: Diwakar Tundlam <dtundlam@nvidia.com>
Reviewed-by: Scott Williams <scwilliams@nvidia.com>
Reviewed-by: Krishna Reddy <vdumpa@nvidia.com>
Reviewed-by: Juha Tukkinen <jtukkinen@nvidia.com>
Tested-by: Juha Tukkinen <jtukkinen@nvidia.com>

Conflicts:

	arch/arm/kernel/smp.c
Signed-off-by: revjunkie <gadgetjuan@gmail.com>
block: recursive merge requests

In my workload, thread 1 accesses a, a+2, ..., thread 2 accesses a+1,
a+3,.... When the requests are flushed to queue, a and a+1 are merged
to (a, a+1), a+2 and a+3 too to (a+2, a+3), but (a, a+1) and (a+2, a+3)
aren't merged.
With recursive merge below, the workload throughput gets improved 20%
and context switch drops 60%.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Signed-off-by: revjunkie <gadgetjuan@gmail.com>
memcg: replace ss->id_lock with a rwlock

While back-porting Johannes Weiner's patch "mm: memcg-aware global
reclaim" for an internal effort, we noticed a significant performance
regression during page-reclaim heavy workloads due to high contention of
the ss->id_lock.  This lock protects idr map, and serializes calls to
idr_get_next() in css_get_next() (which is used during the memcg hierarchy
walk).

Since idr_get_next() is just doing a look up, we need only serialize it
with respect to idr_remove()/idr_get_new().  By making the ss->id_lock a
rwlock, contention is greatly reduced and performance improves.

Tested: cat a 256m file from a ramdisk in a 128m container 50 times on
each core (one file + container per core) in parallel on a NUMA machine.
Result is the time for the test to complete in 1 of the containers.
Both kernels included Johannes' memcg-aware global reclaim patches.

Before rwlock patch: 1710.778s
After rwlock patch: 152.227s

Signed-off-by: Andrew Bresticker <abrestic@google.com>
Cc: Paul Menage <menage@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: revjunkie <gadgetjuan@gmail.com>
backlight: rename corgibl_limit_intensity() to genericbl_limit_intensity()

The rename of corgibl_limit_intensity is missed in commit d00ba726
("backlight: Rename the corgi backlight driver to generic").  Let's fix it
now.

Signed-off-by: Axel Lin <axel.lin@gmail.com>
Cc: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: revjunkie <gadgetjuan@gmail.com>