mm: slub: Default slub_max_order to 0

To avoid locking and per-cpu overhead, SLUB optimisically uses
high-order allocations up to order-3 by default and falls back to
lower allocations if they fail. While care is taken that the caller
and kswapd take no unusual steps in response to this, there are
further consequences like shrinkers who have to free more objects to
release any memory. There is anecdotal evidence that significant time
is being spent looping in shrinkers with insufficient progress being
made (https://lkml.org/lkml/2011/4/28/361) and keeping kswapd awake.

SLUB is now the default allocator and some bug reports have been
pinned down to SLUB using high orders during operations like
copying large amounts of data. SLUBs use of high-orders benefits
applications that are sized to memory appropriately but this does not
necessarily apply to large file servers or desktops.  This patch
causes SLUB to use order-0 pages like SLAB does by default.
There is further evidence that this keeps kswapd's usage lower
(https://lkml.org/lkml/2011/5/10/383).

Signed-off-by: Mel Gorman <mgorman@suse.de>
SELinux: Reduce overhead of mls_level_isvalid() function call

Date	Mon, 10 Jun 2013 13:55:08 -0400

v4->v5:
  - Fix scripts/checkpatch.pl warning.

v3->v4:
  - Merge the 2 separate while loops in ebitmap_contains() into
    a single one.

v2->v3:
  - Remove unused local variables i, node from mls_level_isvalid().

v1->v2:
 - Move the new ebitmap comparison logic from mls_level_isvalid()
   into the ebitmap_contains() helper function.
 - Rerun perf and performance tests on the latest v3.10-rc4 kernel.

While running the high_systime workload of the AIM7 benchmark on
a 2-socket 12-core Westmere x86-64 machine running 3.10-rc4 kernel
(with HT on), it was found that a pretty sizable amount of time was
spent in the SELinux code. Below was the perf trace of the "perf
record -a -s" of a test run at 1500 users:

  5.04%            ls  [kernel.kallsyms]     [k] ebitmap_get_bit
  1.96%            ls  [kernel.kallsyms]     [k] mls_level_isvalid
  1.95%            ls  [kernel.kallsyms]     [k] find_next_bit

The ebitmap_get_bit() was the hottest function in the perf-report
output.  Both the ebitmap_get_bit() and find_next_bit() functions
were, in fact, called by mls_level_isvalid(). As a result, the
mls_level_isvalid() call consumed 8.95% of the total CPU time of
all the 24 virtual CPUs which is quite a lot. The majority of the
mls_level_isvalid() function invocations come from the socket creation
system call.

Looking at the mls_level_isvalid() function, it is checking to see
if all the bits set in one of the ebitmap structure are also set in
another one as well as the highest set bit is no bigger than the one
specified by the given policydb data structure. It is doing it in
a bit-by-bit manner. So if the ebitmap structure has many bits set,
the iteration loop will be done many times.

The current code can be rewritten to use a similar algorithm as the
ebitmap_contains() function with an additional check for the
highest set bit. The ebitmap_contains() function was extended to
cover an optional additional check for the highest set bit, and the
mls_level_isvalid() function was modified to call ebitmap_contains().

With that change, the perf trace showed that the used CPU time drop
down to just 0.08% (ebitmap_contains + mls_level_isvalid) of the
total which is about 100X less than before.

  0.07%            ls  [kernel.kallsyms]     [k] ebitmap_contains
  0.05%            ls  [kernel.kallsyms]     [k] ebitmap_get_bit
  0.01%            ls  [kernel.kallsyms]     [k] mls_level_isvalid
  0.01%            ls  [kernel.kallsyms]     [k] find_next_bit

The remaining ebitmap_get_bit() and find_next_bit() functions calls
are made by other kernel routines as the new mls_level_isvalid()
function will not call them anymore.

This patch also improves the high_systime AIM7 benchmark result,
though the improvement is not as impressive as is suggested by the
reduction in CPU time spent in the ebitmap functions. The table below
shows the performance change on the 2-socket x86-64 system (with HT
on) mentioned above.

+--------------+---------------+----------------+-----------------+
|   Workload   | mean % change | mean % change  | mean % change   |
|              | 10-100 users  | 200-1000 users | 1100-2000 users |
+--------------+---------------+----------------+-----------------+
| high_systime |     +0.1%     |     +0.9%      |     +2.6%       |
+--------------+---------------+----------------+-----------------+
Signed-off-by: Waiman Long <Waiman.Long@hp.com>
Signed-off-by: Paul Reioux <reioux@gmail.com>
Input: Send events one packet at a time

On heavy event loads, such as a multitouch driver, the irqsoff latency
can be as high as 250 us.  By accumulating a frame worth of data
before passing it on, the latency can be dramatically reduced.  As a
side effect, the special EV_SYN handling can be removed, since the
frame is now atomic.

This patch adds the events() handler callback and uses it if it
exists. The latency is improved by 50 us even without the callback.

Change-Id: Iebd9b1868ae6300a922a45b6d104e7c2b38e4cf5
Cc: Daniel Kurtz <djkurtz@chromium.org>
Tested-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Tested-by: Ping Cheng <pingc@wacom.com>
Tested-by: Sedat Dilek <sedat.dilek@gmail.com>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>

Input: Improve the events-per-packet estimate

The events-per-packet estimate has so far been used by MT devices
only. This patch adjusts the packet buffer size to also accomodate the
KEY and MSC events.  Keyboards normally send one or two keys at a
time. MT devices normally send a number of button keys along with the
MT information.  The buffer size chosen here covers those cases, and
matches the default buffer size in evdev. Since the input estimate is
now preferred, remove the special input-mt estimate.

Reviewed-and-tested-by: Ping Cheng <pingc@wacom.com>
Tested-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Acked-by: Dmitry Torokhov <dmitry.torokhov@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
Signed-off-by: Francisco Franco <franciscofranco.1990@gmail.com>
ARM: 7746/1: mm: lazy cache flushing on non-mapped pages

Currently flush_dcache_page() thinks pages as non-mapped if
mapping_mapped(mapping) return false. This approach is very
coase:
	- mmap on part of file may cause all pages backed on
	the file being thought as mmaped

	- file-backed pages aren't mapped into user space actually
	if the memory mmaped on the file isn't accessed

This patch uses page_mapped() to decide if the page has been
mapped.

From the attached test code, I find there is much performance
improvement(>25%) when accessing page caches via read under this
situations, so memcpy benefits a lot from not flushing cache
under this situation.

No.   read time without the patch	No. read time with the patch
================================================================
No. 0, time  22615636 us		No. 0, time  22014717 us
No. 1, time  4387851 us 		No. 1, time  3113184 us
No. 2, time  4276535 us 		No. 2, time  3005244 us
No. 3, time  4259821 us 		No. 3, time  3001565 us
No. 4, time  4263811 us 		No. 4, time  3002748 us
No. 5, time  4258486 us 		No. 5, time  3004104 us
No. 6, time  4253009 us 		No. 6, time  3002188 us
No. 7, time  4262809 us 		No. 7, time  2998196 us
No. 8, time  4264525 us 		No. 8, time  3007255 us
No. 9, time  4267795 us 		No. 9, time  3005094 us

1), No.0. is to read the file from storage device, and others are
to read the file from page caches basically.
2), file size is 512M, and is on ext4 over usb mass storage.
3), the test is done on Pandaboard.

unsigned int  sum = 0;
unsigned long sum_val = 0;

static unsigned long tv_diff(struct timeval *tv1, struct timeval *tv2)
{
	return (tv2->tv_sec - tv1->tv_sec) * 1000000 +
		(tv2->tv_usec - tv1->tv_usec);
}

int main(int argc, char *argv[])
{
	char *mbuf, fbuf;
	int fd;
	int i;
	unsigned long page_size, size;
	struct stat stat;
	struct timeval t1, t2;
	unsigned char *rbuf = malloc(32 * page_size);

	if (!rbuf) {
		printf("	%sn", "malloc failed");
		exit(-1);
	}

	page_size = getpagesize();
	fd = open(argv[1], O_RDWR);
	assert(fd >= 0);

	fstat(fd, &stat);
	size = stat.st_size;
	printf("%s: file %s, size %lu, page size %lun",
		argv[0],
		argv[1], size, page_size);

	gettimeofday(&t1, NULL);
	mbuf = mmap(NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	if (!mbuf) {
		printf("	%sn", "mmap failed");
		exit(-1);
	}

	for (i = 0 ; i < size ; i += (page_size * 32)) {
		int rcnt;
		lseek(fd, i, SEEK_SET);
		rcnt = read(fd, rbuf, page_size * 32);
		if (rcnt != page_size * 32) {
			printf("%s: read faildn", __func__);
			exit(-1);
		}
	}
	free(rbuf);
	munmap(mbuf, size);
	gettimeofday(&t2, NULL);
	printf("tread mmaped time: %luusn", tv_diff(&t1, &t2));

	close(fd);
}

Cc: Michel Lespinasse <walken@google.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nicolas Pitre <nicolas.pitre@linaro.org>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Acked-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
jiffies conversions: Use compile time constants when possible

Date	Fri, 04 Jan 2013 13:15:43 -0800

Do the multiplications and divisions at compile time
instead of runtime when the converted value is a constant.

Make the calculation functions static __always_inline to jiffies.h.

Add #defines with __builtin_constant_p to test and use the
static inline or the runtime functions as appropriate.

Prefix the old exported symbols/functions with __

Signed-off-by: Paul Reioux <reioux@gmail.com>
SELinux: add a ugly workaround to bail early when selinux tries to free a socket

That is still in use and it ends in a Kernel panic.
These lines are from opensource.samsung.com.
While this will most likely put a bandaid over this Kernel panic it does
not fix the bug so it might occur somewhere else if the
same conditions are met but since I have only seen panics from this hook then we may as well sleep in peace.

Signed-off-by: franciscofranco <franciscofranco.1990@gmail.com>
SELinux: ipv4: Dump stack on attempt to release alive inet socket

We hide the bug, that will make SELinux bomb out. Let's dump the stack
when it happens to have at least a chance to find the cause.
lowmemorykiller.c: convert to use for_each_thread

Signed-off-by: Paul Reioux <reioux@gmail.com>
introduce for_each_thread() to replace the buggy while_each_thread() (fix)

fix a merge derp. pointed out by neobuddy89

Signed-off-by: Paul Reioux <reioux@gmail.com>
input: evdev: daisy-chain header and client buffers

The evdev driver calculates memory required to hold
client data using power-of-2 math, and then adds header
size, which pushes the request over the power of 2 and
requires 2x larger allocation.

Change the logic to daisy-chain the header and client array.
That way instead of single order4 allocation, we will make
order0+order2.

Signed-off-by: Igor Kovalenko <cik009@motorola.com>
SLT-Approved: Slta Waiver <sltawvr@motorola.com>
Tested-by: Jira Key <jirakey@motorola.com>
Reviewed-by: Christopher Fries <qcf001@motorola.com>
Reviewed-by: Jason Hrycay <jason.hrycay@motorola.com>
Reviewed-by: Klocwork kwcheck <klocwork-kwcheck@sourceforge.mot.com>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
af_unix: speedup /proc/net/unix
/proc/net/unix has quadratic behavior, and can hold unix_table_lock for
a while if high number of unix sockets are alive. (90 ms for 200k
sockets...)

We already have a hash table, so its quite easy to use it.

Problem is unbound sockets are still hashed in a single hash slot
(unix_socket_table[UNIX_HASH_TABLE])

This patch also spreads unbound sockets to 256 hash slots, to speedup
both /proc/net/unix and unix_diag.

Time to read /proc/net/unix with 200k unix sockets :
(time dd if=/proc/net/unix of=/dev/null bs=4k)

before : 520 secs
after : 2 secs

Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
epoll: Add a flag, EPOLLWAKEUP, to prevent suspend while epoll events are ready

When an epoll_event, that has the EPOLLWAKEUP flag set, is ready, a
wakeup_source will be active to prevent suspend. This can be used to
handle wakeup events from a driver that support poll, e.g. input, if
that driver wakes up the waitqueue passed to epoll before allowing
suspend.

Signed-off-by: Arve Hjønnevåg <arve@android.com>
Reviewed-by: NeilBrown <neilb@suse.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
epoll: Fix user space breakage related to EPOLLWAKEUP

Commit 324bd59a8d193cae6a4e0957ccc4460d606a9091 (epoll: Add a flag, EPOLLWAKEUP, to prevent
suspend while epoll events are ready) caused some applications to
malfunction, because they set the bit corresponding to the new
EPOLLWAKEUP flag in their eventpoll flags and they don't have the
new CAP_EPOLLWAKEUP capability.

To prevent that from happening, change epoll_ctl() to clear
EPOLLWAKEUP in epds.events if the caller doesn't have the
CAP_EPOLLWAKEUP capability instead of failing and returning an
error code, which allows the affected applications to function
normally.

Reported-and-tested-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
PM: Rename CAP_EPOLLWAKEUP to CAP_BLOCK_SUSPEND

As discussed in
http://thread.gmane.org/gmane.linux.kernel/1249726/focus=1288990,
the capability introduced in 4d7e30d98939a0340022ccd49325a3d70f7e0238
to govern EPOLLWAKEUP seems misnamed: this capability is about governing
the ability to suspend the system, not using a particular API flag
(EPOLLWAKEUP). We should make the name of the capability more general
to encourage reuse in related cases. (Whether or not this capability
should also be used to govern the use of /sys/power/wake_lock is a
question that needs to be separately resolved.)

This patch renames the capability to CAP_BLOCK_SUSPEND. In order to ensure
that the old capability name doesn't make it out into the wild, could you
please apply and push up the tree to ensure that it is incorporated
for the 3.5 release.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
eventpoll: use-after-possible-free in epoll_create1()

As soon as we'd installed the file into descriptor table, it can
get closed by another thread.  Freeing ep in process...

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
switch epoll_wait(2) to fget_light()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
epoll: switch simple cases of fget_light to fdget

Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
epoll: trim epitem by one cache line

It is common for epoll users to have thousands of epitems, so saving a
cache line on every allocation leads to large memory savings.

Since epitem allocations are cache-aligned, reducing sizeof(struct
epitem) from 136 bytes to 128 bytes will allow it to squeeze under a
cache line boundary on x86_64.

Via /sys/kernel/slab/eventpoll_epi, I see the following changes on my
x86_64 Core2 Duo (which has 64-byte cache alignment):

	object_size  :  192 => 128
	objs_per_slab:   21 =>  32

Also, add a BUILD_BUG_ON() to check for future accidental breakage.

[akpm@linux-foundation.org: use __packed, for all architectures]
Signed-off-by: Eric Wong <normalperson@yhbt.net>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
epoll: use RCU to protect wakeup_source in epitem

This prevents wakeup_source destruction when a user hits the item with
EPOLL_CTL_MOD while ep_poll_callback is running.

Tested with CONFIG_SPARSE_RCU_POINTER=y and "make fs/eventpoll.o C=2"

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: NeilBrown <neilb@suse.de>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>
epoll: lock ep->mtx in ep_free to silence lockdep

Technically we do not need to hold ep->mtx during ep_free since we are
certain there are no other users of ep at that point.  However, lockdep
complains with a "suspicious rcu_dereference_check() usage!" message; so
lock the mutex before ep_remove to silence the warning.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Arve Hjønnevåg <arve@android.com>
Cc: Davide Libenzi <davidel@xmailserver.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: NeilBrown <neilb@suse.de>,
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Pranav Vashi <neobuddy89@gmail.com>