Remove the old readahead algorithm.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert ext3/ext4 dir reads to use on-demand readahead.

Readahead for dirs operates _not_ on file level, but on blockdev level.  This
makes a difference when the data blocks are not continuous.  And the read
routine is somehow opaque: there's no handy info about the status of current
page.  So a simplified call scheme is employed: to call into readahead
whenever the current page falls out of readahead windows.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert splice reads to use on-demand readahead.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Jens Axboe <axboe@suse.de>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert filemap reads to use on-demand readahead.

The new call scheme is to
- call readahead on non-cached page
- call readahead on look-ahead page
- update prev_index when finished with the read request
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is a minimal readahead algorithm that aims to replace the current one.
It is more flexible and reliable, while maintaining almost the same behavior
and performance.  Also it is full integrated with adaptive readahead.

It is designed to be called on demand:
	- on a missing page, to do synchronous readahead
	- on a lookahead page, to do asynchronous readahead

In this way it eliminated the awkward workarounds for cache hit/miss,
readahead thrashing, retried read, and unaligned read.  It also adopts the
data structure introduced by adaptive readahead, parameterizes readahead
pipelining with `lookahead_index', and reduces the current/ahead windows to
one single window.

HEURISTICS

The logic deals with four cases:

	- sequential-next
		found a consistent readahead window, so push it forward

	- random
		standalone small read, so read as is

	- sequential-first
		create a new readahead window for a sequential/oversize request

	- lookahead-clueless
		hit a lookahead page not associated with the readahead window,
		so create a new readahead window and ramp it up

In each case, three parameters are determined:

	- readahead index: where the next readahead begins
	- readahead size:  how much to readahead
	- lookahead size:  when to do the next readahead (for pipelining)

BEHAVIORS

The old behaviors are maximally preserved for trivial sequential/random reads.
Notable changes are:

	- It no longer imposes strict sequential checks.
	  It might help some interleaved cases, and clustered random reads.
	  It does introduce risks of a random lookahead hit triggering an
	  unexpected readahead. But in general it is more likely to do good
	  than to do evil.

	- Interleaved reads are supported in a minimal way.
	  Their chances of being detected and proper handled are still low.

	- Readahead thrashings are better handled.
	  The current readahead leads to tiny average I/O sizes, because it
	  never turn back for the thrashed pages.  They have to be fault in
	  by do_generic_mapping_read() one by one.  Whereas the on-demand
	  readahead will redo readahead for them.

OVERHEADS

The new code reduced the overheads of

	- excessively calling the readahead routine on small sized reads
	  (the current readahead code insists on seeing all requests)

	- doing a lot of pointless page-cache lookups for small cached files
	  (the current readahead only turns itself off after 256 cache hits,
	  unfortunately most files are < 1MB, so never see that chance)

That accounts for speedup of
	- 0.3% on 1-page sequential reads on sparse file
	- 1.2% on 1-page cache hot sequential reads
	- 3.2% on 256-page cache hot sequential reads
	- 1.3% on cache hot `tar /lib`

However, it does introduce one extra page-cache lookup per cache miss, which
impacts random reads slightly. That's 1% overheads for 1-page random reads on
sparse file.

PERFORMANCE

The basic benchmark setup is
	- 2.6.20 kernel with on-demand readahead
	- 1MB max readahead size
	- 2.9GHz Intel Core 2 CPU
	- 2GB memory
	- 160G/8M Hitachi SATA II 7200 RPM disk

The benchmarks show that
	- it maintains the same performance for trivial sequential/random reads
	- sysbench/OLTP performance on MySQL gains up to 8%
	- performance on readahead thrashing gains up to 3 times

iozone throughput (KB/s): roughly the same
==========================================
iozone -c -t1 -s 4096m -r 64k

			       2.6.20          on-demand      gain
first run
	  "  Initial write "   61437.27        64521.53      +5.0%
	  "        Rewrite "   47893.02        48335.20      +0.9%
	  "           Read "   62111.84        62141.49      +0.0%
	  "        Re-read "   62242.66        62193.17      -0.1%
	  "   Reverse Read "   50031.46        49989.79      -0.1%
	  "    Stride read "    8657.61         8652.81      -0.1%
	  "    Random read "   13914.28        13898.23      -0.1%
	  " Mixed workload "   19069.27        19033.32      -0.2%
	  "   Random write "   14849.80        14104.38      -5.0%
	  "         Pwrite "   62955.30        65701.57      +4.4%
	  "          Pread "   62209.99        62256.26      +0.1%

second run
	  "  Initial write "   60810.31        66258.69      +9.0%
	  "        Rewrite "   49373.89        57833.66     +17.1%
	  "           Read "   62059.39        62251.28      +0.3%
	  "        Re-read "   62264.32        62256.82      -0.0%
	  "   Reverse Read "   49970.96        50565.72      +1.2%
	  "    Stride read "    8654.81         8638.45      -0.2%
	  "    Random read "   13901.44        13949.91      +0.3%
	  " Mixed workload "   19041.32        19092.04      +0.3%
	  "   Random write "   14019.99        14161.72      +1.0%
	  "         Pwrite "   64121.67        68224.17      +6.4%
	  "          Pread "   62225.08        62274.28      +0.1%

In summary, writes are unstable, reads are pretty close on average:

			  access pattern  2.6.20  on-demand   gain
				   Read  62085.61  62196.38  +0.2%
				Re-read  62253.49  62224.99  -0.0%
			   Reverse Read  50001.21  50277.75  +0.6%
			    Stride read   8656.21   8645.63  -0.1%
			    Random read  13907.86  13924.07  +0.1%
	 		 Mixed workload  19055.29  19062.68  +0.0%
				  Pread  62217.53  62265.27  +0.1%

aio-stress: roughly the same
============================
aio-stress -l -s4096 -r128 -t1 -o1 knoppix511-dvd-cn.iso
aio-stress -l -s4096 -r128 -t1 -o3 knoppix511-dvd-cn.iso

					2.6.20      on-demand  delta
			sequential	 92.57s      92.54s    -0.0%
			random		311.87s     312.15s    +0.1%

sysbench fileio: roughly the same
=================================
sysbench --test=fileio --file-io-mode=async --file-test-mode=rndrw \
	 --file-total-size=4G --file-block-size=64K \
	 --num-threads=001 --max-requests=10000 --max-time=900 run

				threads    2.6.20   on-demand    delta
		first run
				      1   59.1974s    59.2262s  +0.0%
				      2   58.0575s    58.2269s  +0.3%
				      4   48.0545s    47.1164s  -2.0%
				      8   41.0684s    41.2229s  +0.4%
				     16   35.8817s    36.4448s  +1.6%
				     32   32.6614s    32.8240s  +0.5%
				     64   23.7601s    24.1481s  +1.6%
				    128   24.3719s    23.8225s  -2.3%
				    256   23.2366s    22.0488s  -5.1%

		second run
				      1   59.6720s    59.5671s  -0.2%
				      8   41.5158s    41.9541s  +1.1%
				     64   25.0200s    23.9634s  -4.2%
				    256   22.5491s    20.9486s  -7.1%

Note that the numbers are not very stable because of the writes.
The overall performance is close when we sum all seconds up:

                sum all up               495.046s    491.514s   -0.7%

sysbench oltp (trans/sec): up to 8% gain
========================================
sysbench --test=oltp --oltp-table-size=10000000 --oltp-read-only \
	 --mysql-socket=/var/run/mysqld/mysqld.sock \
	 --mysql-user=root --mysql-password=readahead \
	 --num-threads=064 --max-requests=10000 --max-time=900 run

	10000-transactions run
				threads    2.6.20   on-demand    gain
				      1     62.81       64.56   +2.8%
				      2     67.97       70.93   +4.4%
				      4     81.81       85.87   +5.0%
				      8     94.60       97.89   +3.5%
				     16     99.07      104.68   +5.7%
				     32     95.93      104.28   +8.7%
				     64     96.48      103.68   +7.5%
	5000-transactions run
				      1     48.21       48.65   +0.9%
				      8     68.60       70.19   +2.3%
				     64     70.57       74.72   +5.9%
	2000-transactions run
				      1     37.57       38.04   +1.3%
				      2     38.43       38.99   +1.5%
				      4     45.39       46.45   +2.3%
				      8     51.64       52.36   +1.4%
				     16     54.39       55.18   +1.5%
				     32     52.13       54.49   +4.5%
				     64     54.13       54.61   +0.9%

That's interesting results. Some investigations show that
	- MySQL is accessing the db file non-uniformly: some parts are
	  more hot than others
	- It is mostly doing 4-page random reads, and sometimes doing two
	  reads in a row, the latter one triggers a 16-page readahead.
	- The on-demand readahead leaves many lookahead pages (flagged
	  PG_readahead) there. Many of them will be hit, and trigger
	  more readahead pages. Which might save more seeks.
	- Naturally, the readahead windows tend to lie in hot areas,
	  and the lookahead pages in hot areas is more likely to be hit.
	- The more overall read density, the more possible gain.

That also explains the adaptive readahead tricks for clustered random reads.

readahead thrashing: 3 times better
===================================
We boot kernel with "mem=128m single", and start a 100KB/s stream on every
second, until reaching 200 streams.

			      max throughput     min avg I/O size
		2.6.20:            5MB/s               16KB
		on-demand:        15MB/s              140KB
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Extend struct file_ra_state to support the on-demand readahead logic.  Also
define some helpers for it.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Define two convenient macros for read-ahead:
	- MAX_RA_PAGES: rounded down counterpart of VM_MAX_READAHEAD
	- MIN_RA_PAGES: rounded _up_ counterpart of VM_MIN_READAHEAD

Note that the rounded up MIN_RA_PAGES will work flawlessly with _large_
page sizes like 64k.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add look-ahead support to __do_page_cache_readahead().

It works by
	- mark the Nth backwards page with PG_readahead,
	(which instructs the page's first reader to invoke readahead)
	- and only do the marking for newly allocated pages.
	(to prevent blindly doing readahead on already cached pages)

Look-ahead is a technique to achieve I/O pipelining:

While the application is working through a chunk of cached pages, the kernel
reads-ahead the next chunk of pages _before_ time of need.  It effectively
hides low level I/O latencies to high level applications.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Introduce a new page flag: PG_readahead.

It acts as a look-ahead mark, which tells the page reader: Hey, it's time to
invoke the read-ahead logic.  For the sake of I/O pipelining, don't wait until
it runs out of cached pages!
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix type issue reported by latest 'sparse': kiocb.ki_flags should be
"unsigned long" (not "long"), to match bitop type signature.
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NBenjamin LaHaise <bcrl@kvack.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is another bug recently introduced into the ecryptfs_setattr()
function in 2.6.22.  eCryptfs will attempt to treat special files like
regular eCryptfs files on chmod, chown, and so forth.  This leads to a NULL
pointer dereference.  This patch validates that the file is a regular file
before proceeding with operations related to the inode's crypt_stat.

Thanks to Ryusuke Konishi for finding this bug and suggesting the fix.
Signed-off-by: NMichael Halcrow <mhalcrow@us.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

MBCS has a collection of things that searches say are not used elsewhere
and could be static.  If this is the case they should be static, if not
then someone at SGI should rename things like "soft_list" so they don't
pollute the global namespace with generic names...
Signed-off-by: NAlan Cox <alan@redhat.com>
Acked-by: NBruce Losure <blosure@sgi.com>
Cc: Jes Sorensen <jes@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Optimize show_stat to collect per-irq information just once.

On x86_64, with newer kernel versions, kstat_irqs is a bit of a problem.
On every call to kstat_irqs, the process brings in per-cpu data from all
online cpus.  Doing this for NR_IRQS, which is now 256 + 32 * NR_CPUS
results in (256+32*63) * 63 remote cpu references on a 64 cpu config.
Considering the fact that we already compute this value per-cpu, we can
save on the remote references as below.
Signed-off-by: NAlok N Kataria <alok.kataria@calsoftinc.com>
Signed-off-by: NRavikiran Thirumalai <kiran@scalex86.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Clarify that drivers using the GPIO operations don't need to issue io
barrier instructions themselves.  Previously this wasn't clear, and at
least one platform assumed otherwise (and would thus break various
otherwise-portable drivers which don't issue barriers).
Signed-off-by: NDavid Brownell <dbrownell@users.sourceforge.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

unregister_chrdev() does not return meaningful value.  This patch makes it
return void like most unregister_* functions.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

unregister_chrdev() always returns 0.  There is no need to check the return
value.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Takashi Iwai <tiwai@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch converts UDF coding style to kernel coding style using Lindent.
Signed-off-by: NCyrill Gorcunov <gorcunov@gmail.com>
Cc: Jan Kara <jack@ucw.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I guess it is time to clarify that suspend and hibernation are separate
things, and add Rafael as a maintainer.  Plus, people blame us for suspend
problems, anyway, I guess it is fair to mark us as suspend maintainers,
too.
Signed-off-by: NPavel Machek <pavel@suse.cz>
Acked-by: NRafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move "debug during resume from s2ram" into the variable we already use
for real-mode flags to simplify code. It also closes nasty trap for
the user in acpi_sleep_setup; order of parameters actually mattered there,
acpi_sleep=s3_bios,s3_mode doing something different from
acpi_sleep=s3_mode,s3_bios.
Signed-off-by: NPavel Machek <pavel@suse.cz>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add a feature allowing the user to make the system beep during a resume from
suspend to RAM, on x86_64 and i386.

This is useful for the users with broken resume from RAM, so that they can
verify if the control reaches the kernel after a wake-up event.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Introduce the pm_power_off_prepare() callback that can be registered by the
interested platforms in analogy with pm_idle() and pm_power_off(), used for
preparing the system to power off (needed by ACPI).

This allows us to drop acpi_sysclass and device_acpi that are only defined in
order to register the ACPI power off preparation callback, which is needed by
pm_power_off() registered in a much different way.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since we are now explicitly calling hibernation_ops->prepare() before
hibernation_ops->enter() in hibernation_platform_enter() (defined in
kernel/power/disk.c), ACPI should not call acpi_sleep_prepare(ACPI_STATE_S4)
from acpi_shutdown().
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Len Brown <lenb@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The SNAPSHOT_S2RAM ioctl code is outdated and it should not duplicate the
suspend code in kernel/power/main.c.  Fix that.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

At present, if a user mode helper is running while
usermodehelper_pm_callback() is executed, the helper may be frozen and the
completion in call_usermodehelper_exec() won't be completed until user
space processes are thawed.  As a result, the freezing of kernel threads
may fail, which is not desirable.

Prevent this from happening by introducing a counter of running user mode
helpers and allowing usermodehelper_pm_callback() to succeed for action =
PM_HIBERNATION_PREPARE or action = PM_SUSPEND_PREPARE only if there are no
helpers running.  [Namely, usermodehelper_pm_callback() waits for at most
RUNNING_HELPERS_TIMEOUT for the number of running helpers to become zero
and fails if that doesn't happen.]

Special thanks to Uli Luckas <u.luckas@road.de>, Pavel Machek
<pavel@ucw.cz> and Oleg Nesterov <oleg@tv-sign.ru> for reviewing the
previous versions of this patch and for very useful comments.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NUli Luckas <u.luckas@road.de>
Acked-by: NNigel Cunningham <nigel@nigel.suspend2.net>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use a hibernation and suspend notifier to disable the user mode helper before
a hibernation/suspend and enable it after the operation.

[akpm@linux-foundation.org: build fix]
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Acked-by: NNigel Cunningham <nigel@nigel.suspend2.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make it possible to register hibernation and suspend notifiers, so that
subsystems can perform hibernation-related or suspend-related operations that
should not be carried out by device drivers' .suspend() and .resume()
routines.

[akpm@linux-foundation.org: build fixes]
[akpm@linux-foundation.org: cleanups]
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We don't need to check if todo is positive before calling time_after() in
try_to_freeze_tasks(), because if todo is zero at this point, the loop will be
broken anyway due to the while () condition being false.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make try_to_freeze_tasks() and freeze_processes() return -EBUSY on failure
instead of the number of unfrozen tasks (none of the callers actually uses
this number).
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use __set_current_state() as appropriate in refrigerator() instead of
accessing current->state directly.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Kernel threads should not have TIF_FREEZE set when user space processes are
being frozen, since otherwise some of them might be frozen prematurely.
To prevent this from happening we can (1) make exit_mm() unset TIF_FREEZE
unconditionally just after clearing tsk->mm and (2) make try_to_freeze_tasks()
check if p->mm is different from zero and PF_BORROWED_MM is unset in p->flags
when user space processes are to be frozen.

Namely, when user space processes are being frozen, we only should set
TIF_FREEZE for tasks that have p->mm different from NULL and don't have
PF_BORROWED_MM set in p->flags.  For this reason task_lock() must be used to
prevent try_to_freeze_tasks() from racing with use_mm()/unuse_mm(), in which
p->mm and p->flags.PF_BORROWED_MM are changed under task_lock(p).  Also, we
need to prevent the following scenario from happening:

* daemonize() is called by a task spawned from a user space code path
* freezer checks if the task has p->mm set and the result is positive
* task enters exit_mm() and clears its TIF_FREEZE
* freezer sets TIF_FREEZE for the task
* task calls try_to_freeze() and goes to the refrigerator, which is wrong at
  that point

This requires us to acquire task_lock(p) before p->flags.PF_BORROWED_MM and
p->mm are examined and release it after TIF_FREEZE is set for p (or it turns
out that TIF_FREEZE should not be set).
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

During hibernation we call hibernation_ops->prepare() before creating the image,
but then, before saving it, we cancel the power transition by calling
hibernation_ops->finish().  Thus prior to calling hibernation_ops->enter() we
should let the platform firmware know that we're going to enter the low power
state after all.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change the code ordering so that hibernation_ops->prepare() is called after
device_suspend().  This is needed so that we don't violate the ACPI
specification, which states that the _PTS and _GTS system-control methods,
executed from acpi_sleep_prepare(), ought to be called after devices have been
put in low power states.

The "Finish" label in hibernation_restore() is moved, because device_suspend()
resumes devices if the suspending of them fails and the restore code ordering
should reflect the hibernation code ordering.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

At least on some machines it is necessary to prepare the ACPI firmware for the
restoration of the system memory state from the hibernation image if the
"platform" mode of hibernation has been used.  Namely, in that cases we need
to disable the GPEs before replacing the "boot" kernel with the "frozen"
kernel (cf.  http://bugzilla.kernel.org/show_bug.cgi?id=7887).  After the
restore they will be re-enabled by hibernation_ops->finish(), but if the
restore fails, they have to be re-enabled by the restore code explicitly.

For this purpose we can introduce two additional hibernation operations,
called pre_restore() and restore_cleanup() and call them from the restore code
path.  Still, they should be called if the "platform" mode of hibernation has
been used, so we need to pass the information about the hibernation mode from
the "frozen" kernel to the "boot" kernel in the image header.

Apparently, we can't drop the disabling of GPEs before the restore because of
Bug #7887 .   We also can't do it unconditionally, because the GPEs wouldn't
have been enabled after a successful restore if the suspend had been done in
the 'shutdown' or 'reboot' mode.

In principle we could (and probably should) unconditionally disable the GPEs
before each snapshot creation *and* before the restore, but then we'd have to
unconditionally enable them after the snapshot creation as well as after the
restore (or restore failure)   Still, for this purpose we'd need to modify
acpi_enter_sleep_state_prep() and acpi_leave_sleep_state() and we'd have to
introduce some mechanism synchronizing the disablind/enabling of the GPEs with
the device drivers' .suspend()/.resume() routines and with
disable_/enable_nonboot_cpus().   However, this would have affected the
suspend (ie.  s2ram) code as well as the hibernation, which I'd like to avoid
in this patch series.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, much of the code in kernel/power/disk.c is duplicated in
kernel/power/user.c , mainly for historical reasons.  By eliminating this code
duplication we can reduce the size of user.c quite substantially and remove
the maintenance difficulty resulting from it.

[bunk@stusta.de: kernel/power/disk.c: make code static]
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In the face of the recent change of suspend code ordering (cf.
http://marc.info/?l=linux-acpi&m=117938245931603&w=2) we should also modify
the code ordering in swsusp so that hibernation_ops->prepare() is executed
after device_suspend().

However, for this purpose it seems reasonable to eliminate the code
duplication between kernel/power/disk.c and kernel/power/user.c first.  By
eliminating it we can reduce the size of user.c quite substantially and remove
the maintenance difficulty with making essentially the same changes in two
different places.

Moreover, we should also remove the calls to "platform" functions from the
restore code path, since it doesn't carry out any power transition of the
system, but we generally need to disable the GPEs before the restore if the
'platform' hibernation mode has been used.  To do this, we can introduce two
new hibernation_ops to be used in the restore code.

This patch:

Make the code hibernation code in kernel/power/user.c be functionally
equivalent to the corresponding code in kernel/power/disk.c , as it should be.

The calls to the platform functions removed by this patch are incorrect.  They
should be replaced with some other "platform" invocations that will be
introduced in one of the subsequent patches.
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Nigel Cunningham <nigel@nigel.suspend2.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In order to enable things like PM_TRACE, you're required to enable
PM_DEBUG, which sends a large spew of messages on boot, and often times can
overflow dmesg buffer.

Create new PM_VERBOSE and shift that to be the option that enables
drivers/base/power's messages.
Signed-off-by: NBen Collins <bcollins@ubuntu.com>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

To see which tasks are stuck where.

Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

page_mkclean() doesn't re-protect ptes for non-linear mappings, so a later
re-dirty through such a mapping will not generate a fault, PG_dirty will
not reflect the dirty state and the dirty count will be skewed.  This
implies that msync() is also currently broken for nonlinear mappings.

The easiest solution is to emulate remap_file_pages on non-linear mappings
with simple mmap() for non ram-backed filesystems.  Applications continue
to work (albeit slower), as long as the number of remappings remain below
the maximum vma count.

However all currently known real uses of non-linear mappings are for ram
backed filesystems, which this patch doesn't affect.
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

alloc_zeroed_user_highpage() has no in-tree users and it is not exported.
As it is not exported, it can simply be removed.
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Acked-by: NAndy Whitcroft <apw@shadowen.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix msync data loss and (less importantly) dirty page accounting
inaccuracies due to the race remaining in clear_page_dirty_for_io().

The deleted comment explains what the race was, and the added comments
explain how it is fixed.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Acked-by: NLinus Torvalds <torvalds@linux-foundation.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>