seek_mean could be very big sometimes, using it as close criteria is meaningless
as this doen't improve any performance. So if it's big, let's fallback to
default value.
Reviewed-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Shaohua Li<shaohua.li@intel.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

Cc: "Ed L. Cashin" <ecashin@coraid.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Ilya Loginov <isloginov@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Horton <phorton@bitbox.co.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

Use resource_size() for ioremap.

The ioremap appears to be passing the incorrect size for the platform
resource.  Unfortunately, I can't locate a user in mainline to verify
this.  Using resource_size should be the correct fix.
Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Acked-by: unsik Kim <donari75@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

DAC960_LP_Controller and DAC960_V2_Controller have the same value, but
elsewhere it is DAC960_V1_Controller or DAC960_V2_Controller that is used
in the FirmwareType field.
Signed-off-by: Julia Lawall <julia@diku.dk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

The stacking code incorrectly scaled up the data offset in some cases
causing misaligned devices to report alignment.  Rewrite the stacking
algorithm to remedy this and apply the same alignment principles to the
discard handling.
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

Remove unused #include <linux/version.h>('s) in
  drivers/block/drbd/drbd_main.c
  drivers/block/drbd/drbd_receiver.c
  drivers/block/drbd/drbd_worker.c
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>

Remove duplicated #include('s) in
  drivers/block/drbd/drbd_worker.c
Signed-off-by: Huang Weiyi <weiyi.huang@gmail.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>

rsp->count is unsigned so the test does not work.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>

Signed-off-by: Emese Revfy <re.emese@gmail.com>
Signed-off-by: Philipp Reisner <philipp.reisner@linbit.com>

o CFQ now internally divides cfq queues in therr workload categories. sync-idle,
  sync-noidle and async. Which workload to run depends primarily on rb_key
  offset across three service trees. Which is a combination of mulitiple things
  including what time queue got queued on the service tree.

  There is one exception though. That is if we switched the prio class, say
  we served some RT tasks and again started serving BE class, then with-in
  BE class we always started with sync-noidle workload irrespective of rb_key
  offset in service trees.

  This can provide better latencies for sync-noidle workload in the presence
  of RT tasks.

o This patch gets rid of that exception and which workload to run with-in
  class always depends on lowest rb_key across service trees. The reason
  being that now we have multiple BE class groups and if we always switch
  to sync-noidle workload with-in group, we can potentially starve a sync-idle
  workload with-in group. Same is true for async workload which will be in
  root group. Also the workload-switching with-in group will become very
  unpredictable as it now depends whether some RT workload was running in
  the system or not.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Acked-by: Corrado Zoccolo <czoccolo@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

o Currently code does not seem to be using cfqd->nr_groups. Get rid of it.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

o allow_merge() already checks if submitting task is pointing to same cfqq
  as rq has been queued in. If everything is fine, we should not be having
  a task in one cgroup and having a pointer to cfqq in other cgroup.

  Well I guess in some situations it can happen and that is, when a random
  IO queue has been moved into root cgroup for group_isolation=0. In
  this case, tasks's cgroup/group is different from where actually cfqq is,
  but this is intentional and in this case merging should be allowed.

  The second situation is where due to close cooperator patches, multiple
  processes can be sharing a cfqq. If everything implemented right, we should
  not end up in a situation where tasks from different processes in different
  groups are sharing the same cfqq as we allow merging of cooperating queues
  only if they are in same group.
Signed-off-by: Vivek Goyal <vgoyal@redhat.com>
Reviewed-by: Gui Jianfeng <guijianfeng@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

rsp->count is unsigned so the test does not work.
Signed-off-by: Roel Kluin <roel.kluin@gmail.com>
Cc: Lars Ellenberg <drbd-dev@lists.linbit.com>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

Commit 492af635 removed
the AS IO scheduler, so remove its documentation too.
Signed-off-by: FUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>

Merge branch 'cpumask-cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus

* 'cpumask-cleanups' of git://git.kernel.org/pub/scm/linux/kernel/git/rusty/linux-2.6-for-linus:
  cpumask: rename tsk_cpumask to tsk_cpus_allowed
  cpumask: don't recommend set_cpus_allowed hack in Documentation/cpu-hotplug.txt
  cpumask: avoid dereferencing struct cpumask
  cpumask: convert drivers/idle/i7300_idle.c to cpumask_var_t
  cpumask: use modern cpumask style in drivers/scsi/fcoe/fcoe.c
  cpumask: avoid deprecated function in mm/slab.c
  cpumask: use cpu_online in kernel/perf_event.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6:
  Keys: KEYCTL_SESSION_TO_PARENT needs TIF_NOTIFY_RESUME architecture support
  NOMMU: Optimise away the {dac_,}mmap_min_addr tests
  security/min_addr.c: make init_mmap_min_addr() static
  keys: PTR_ERR return of wrong pointer in keyctl_get_security()

Merge branch 'omap-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap-2.6

* 'omap-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tmlind/linux-omap-2.6:
  OMAP3: serial - fix bug introduced in
  mfd: twl: fix twl4030 rename for remaining driver, board files
  USB ehci: replace mach header with plat
  omap3: Allow EHCI to be built on OMAP3

* 'hwmon-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jdelvare/staging:
  hwmon: (w83627hf) Fix for "No such device"
  hwmon: (sht15) Off-by-one error in array index + incorrect constants
  hwmon: Add driver for VIA CPU core temperature
  hwmon: (smsc47m1) Enable device if needed
  hwmon: (smsc47m1) Fail module loading on error
  hwmon: (smsc47m1) Only request I/O ports we really use
  hwmon: New driver for AMD Family 10h/11h CPUs

* git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6: (40 commits)
  [SCSI] 3w-9xxx fix bug in sgl loading
  [SCSI] fcoe, libfc: adds enable/disable for fcoe interface
  [SCSI] libfc: reduce hold time on SCSI host lock
  [SCSI] libfc: remote port gets stuck in restart state without really restarting
  [SCSI] pm8001: misc code cleanup
  [SCSI] pm8001: enable read HBA SAS address from VPD
  [SCSI] pm8001: do not reset local sata as it will not be found if reset
  [SCSI] pm8001: bit set pm8001_ha->flags
  [SCSI] pm8001:fix potential NULL pointer dereference
  [SCSI] pm8001: set SSC down-spreading only to get less errors on some 6G device.
  [SCSI] pm8001: fix endian issues with SAS address
  [SCSI] pm8001: enhance error handle for IO patch
  [SCSI] pm8001: Fix for sata io circular lock dependency.
  [SCSI] hpsa: add driver for HP Smart Array controllers.
  [SCSI] cxgb3i: always use negative errno in case of error
  [SCSI] bnx2i: minor code cleanup and update driver version
  [SCSI] bnx2i: Task management ABORT TASK fixes
  [SCSI] bnx2i: update CQ arming algorith for 5771x chipsets
  [SCSI] bnx2i: Adjust sq_size module parametr to power of 2 only if a non-zero value is specified
  [SCSI] bnx2i: Add 5771E device support to bnx2i driver
  ...

* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus: (71 commits)
  MIPS: Lasat: Fix botched changes to sysctl code.
  RTC: rtc-cmos.c: Fix warning on MIPS
  MIPS: Cleanup random differences beween lmo and Linus' kernel.
  MIPS: No longer hardwire CONFIG_EMBEDDED to y
  MIPS: Fix and enhance built-in kernel command line
  MIPS: eXcite: Remove platform.
  MIPS: Loongson: Cleanups of serial port support
  MIPS: Lemote 2F: Suspend CS5536 MFGPT Timer
  MIPS: Excite: move iodev_remove to .devexit.text
  MIPS: Lasat: Convert to proc_fops / seq_file
  MIPS: Cleanup signal code initialization
  MIPS: Modularize COP2 handling
  MIPS: Move EARLY_PRINTK to Kconfig.debug
  MIPS: Yeeloong 2F: Cleanup reset logic using the new ec_write function
  MIPS: Yeeloong 2F: Add LID open event as the wakeup event
  MIPS: Yeeloong 2F: Add basic EC operations
  MIPS: Move several variables from .bss to .init.data
  MIPS: Tracing: Make function graph tracer work with -mmcount-ra-address
  MIPS: Tracing: Reserve $12(t0) for mcount-ra-address of gcc 4.5
  MIPS: Tracing: Make ftrace for MIPS work without -fno-omit-frame-pointer
  ...

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/btrfs-unstable:
  Btrfs: make sure fallocate properly starts a transaction
  Btrfs: make metadata chunks smaller
  Btrfs: Show discard option in /proc/mounts
  Btrfs: deny sys_link across subvolumes.
  Btrfs: fail mount on bad mount options
  Btrfs: don't add extent 0 to the free space cache v2
  Btrfs: Fix per root used space accounting
  Btrfs: Fix btrfs_drop_extent_cache for skip pinned case
  Btrfs: Add delayed iput
  Btrfs: Pass transaction handle to security and ACL initialization functions
  Btrfs: Make truncate(2) more ENOSPC friendly
  Btrfs: Make fallocate(2) more ENOSPC friendly
  Btrfs: Avoid orphan inodes cleanup during committing transaction
  Btrfs: Avoid orphan inodes cleanup while replaying log
  Btrfs: Fix disk_i_size update corner case
  Btrfs: Rewrite btrfs_drop_extents
  Btrfs: Add btrfs_duplicate_item
  Btrfs: Avoid superfluous tree-log writeout

* 'kmemleak' of git://linux-arm.org/linux-2.6:
  kmemleak: fix kconfig for crc32 build error
  kmemleak: Reduce the false positives by checking for modified objects
  kmemleak: Show the age of an unreferenced object
  kmemleak: Release the object lock before calling put_object()
  kmemleak: Scan the _ftrace_events section in modules
  kmemleak: Simplify the kmemleak_scan_area() function prototype
  kmemleak: Do not use off-slab management with SLAB_NOLEAKTRACE

* 'next-spi' of git://git.secretlab.ca/git/linux-2.6:
  spi: spi_txx9.c: use resource_size()
  spi: spi_sh_sci.c: use resource_size()
  spi: spi_mpc8xxx.c: use resource_size()
  spi: spi_bfin5xx.c: use resource_size()
  spi: atmel_spi.c: use resource_size()
  spi: Add s3c64xx SPI Controller driver
  atmel_spi: fix dma addr calculation for len > BUFFER_SIZE
  spi_s3c24xx: add FIQ pseudo-DMA support
  spi: controller driver for Designware SPI core
  spidev: add proper section markers
  spidev: use DECLARE_BITMAP instead of declaring the array

* 'for-linus' of git://git.o-hand.com/linux-rpurdie-backlight:
  backlight: mbp_nvidia_bl - add two more MacBookPro variants
  backlight: Pass device through notify callback in the pwm driver
  backlight: PTR_ERR return of wrong pointer in cr_backlight_probe()
  backlight: Constify struct backlight_ops
  backlight/thinkpad-acpi: issue backlight class events

Fix up trivial conflicts in thinkpad-acpi support (backlight support
already merged earlier).

* 'for-linus' of git://git.o-hand.com/linux-rpurdie-leds:
  leds: leds-pwm: Set led_classdev max_brightness
  leds: leds-lp3944.h - remove unneeded includes
  leds: use default-on trigger for Cobalt Qube
  leds: drivers/leds/leds-ss4200.c: fix return statement
  leds: leds-pca9532.h- indent with tabs, not spaces
  leds: Add LED class driver for regulator driven LEDs.
  leds: leds-cobalt-qube.c: use resource_size()
  leds: leds-cobalt-raq.c - use resource_size()
  leds: Add driver for ADP5520/ADP5501 MFD PMICs
  leds: Add driver for LT3593 controlled LEDs
  leds-ss4200: Check pci_enable_device return
  leds: leds-alix2c - take port address from MSR
  leds: LED driver for Intel NAS SS4200 series (v5)

* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm:
  PCMCIA: fix pxa2xx_lubbock modular build error
  [ARM] Update mach-types
  [ARM] pxa: fix no reference of cpu_is_pxa25x() in devices.c
  [ARM] pxa/cm-x300: add PWM backlight support
  revert "[ARM] pxa/cm-x300: add PWM backlight support"
  ARM: use flush_kernel_dcache_area() for dmabounce
  ARM: add size argument to __cpuc_flush_dcache_page
  ARM: 5848/1: kill flush_ioremap_region()
  ARM: cache-l2x0: make better use of background cache handling
  ARM: cache-l2x0: avoid taking spinlock for every iteration
  [ARM] Kirkwood: Add LaCie Network Space v2 support
  ARM: dove: fix the mm mmu flags of the pj4 procinfo

Fix kernel-doc warnings in printk.c:

Warning(kernel/printk.c:1422): No description found for parameter 'dumper'
Warning(kernel/printk.c:1422): Excess function parameter 'dump' description in 'kmsg_dump_register'
Warning(kernel/printk.c:1451): No description found for parameter 'dumper'
Warning(kernel/printk.c:1451): Excess function parameter 'dump' description in 'kmsg_dump_unregister'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

I added blk_run_backing_dev on page_cache_async_readahead so readahead I/O
is unpluged to improve throughput on especially RAID environment.

The normal case is, if page N become uptodate at time T(N), then T(N) <=
T(N+1) holds.  With RAID (and NFS to some degree), there is no strict
ordering, the data arrival time depends on runtime status of individual
disks, which breaks that formula.  So in do_generic_file_read(), just
after submitting the async readahead IO request, the current page may well
be uptodate, so the page won't be locked, and the block device won't be
implicitly unplugged:

               if (PageReadahead(page))
                        page_cache_async_readahead()
                if (!PageUptodate(page))
                                goto page_not_up_to_date;
                //...
page_not_up_to_date:
                lock_page_killable(page);

Therefore explicit unplugging can help.

Following is the test result with dd.

#dd if=testdir/testfile of=/dev/null bs=16384

-2.6.30-rc6
1048576+0 records in
1048576+0 records out
17179869184 bytes (17 GB) copied, 224.182 seconds, 76.6 MB/s

-2.6.30-rc6-patched
1048576+0 records in
1048576+0 records out
17179869184 bytes (17 GB) copied, 206.465 seconds, 83.2 MB/s

(7Disks RAID-0 Array)

-2.6.30-rc6
1054976+0 records in
1054976+0 records out
17284726784 bytes (17 GB) copied, 212.233 seconds, 81.4 MB/s

-2.6.30-rc6-patched
1054976+0 records out
17284726784 bytes (17 GB) copied, 198.878 seconds, 86.9 MB/s

(7Disks RAID-5 Array)

The patch was found to improve performance with the SCST scsi target
driver.  See
http://sourceforge.net/mailarchive/forum.php?thread_name=a0272b440906030714g67eabc5k8f847fb1e538cc62%40mail.gmail.com&forum_name=scst-devel

[akpm@linux-foundation.org: unbust comment layout]
[akpm@linux-foundation.org: "fix" CONFIG_BLOCK=n]
Signed-off-by: Hisashi Hifumi <hifumi.hisashi@oss.ntt.co.jp>
Acked-by: Wu Fengguang <fengguang.wu@intel.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Tested-by: Ronald <intercommit@gmail.com>
Cc: Bart Van Assche <bart.vanassche@gmail.com>
Cc: Vladislav Bolkhovitin <vst@vlnb.net>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

RTC core won't allow wakeup alarms to be set if RTC devices' parent (i.e.
i2c_client or spi_device) isn't wakeup capable.

For I2C devices there is I2C_CLIENT_WAKE flag exists that we can pass via
board info, and if set, I2C core will initialize wakeup capability.  For
SPI devices there is no such flag at all.

I believe that it's not platform code responsibility to allow or disallow
wakeups, instead, drivers themselves should set the capability if a device
can trigger wakeups.

That's what drivers/base/power/sysfs.c says:

 * It is the responsibility of device drivers to enable (or disable)
 * wakeup signaling as part of changing device power states, respecting
 * the policy choices provided through the driver model.

I2C and SPI RTC devices send wakeup events via interrupt lines, so we
should set the wakeup capability if IRQ is routed.

Ideally we should also check irq for wakeup capability before setting
device's capability, i.e.

	if (can_irq_wake(irq))
		device_set_wakeup_capable(&client->dev, 1);

But there is no can_irq_wake() call exist, and it is not that trivial to
implement it for all interrupts controllers and complex/cascaded setups.

drivers/base/power/sysfs.c also covers these cases:

 * Devices may not be able to generate wakeup events from all power
 * states.  Also, the events may be ignored in some configurations;
 * for example, they might need help from other devices that aren't
 * active

So there is no guarantee that wakeup will actually work, and so I think
there is no point in being pedantic wrt checking IRQ wakeup capability.
Signed-off-by: Anton Vorontsov <avorontsov@ru.mvista.com>
Cc: David Brownell <dbrownell@users.sourceforge.net>
Cc: Ben Dooks <ben-linux@fluff.org>
Cc: Jean Delvare <khali@linux-fr.org>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Add support for the Secure Digital Host Controller Interface found on the
"Hollywood" chipset of the Nintendo Wii video game console.
Signed-off-by: Albert Herranz <albert_herranz@yahoo.es>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This patch breaks down sdhci-of into a core portion and a eSDHC portion,
clearing the path to easily support additional hardware using the same OF
driver.
Signed-off-by: Albert Herranz <albert_herranz@yahoo.es>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

This patch renames sdhci-of.c to sdhci-of-core.c before reorganizing the
driver to support additional hardware.

The driver is still built as sdhci-of despite the rename of the file.  No
functional change.
Signed-off-by: Albert Herranz <albert_herranz@yahoo.es>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Albert Herranz <albert_herranz@yahoo.es>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Daniel Drake noticed a crash in the error path of mmc_attach_sdio().  This
bug is discussed at http://dev.laptop.org/ticket/9707.

BUG: unable to handle kernel paging request at 6b6b6c57
IP: [<b066d6e2>] sdio_remove_func+0x9/0x27
Call Trace:
[<b066cfb4>] ? mmc_sdio_remove+0x34/0x65
[<b066d1fc>] ? mmc_attach_sdio+0x217/0x240
[<b066a22f>] ? mmc_rescan+0x1a2/0x20f
[<b042e9a0>] ? worker_thread+0x156/0x1e

We need to accurately track how many SDIO functions have been initialised
(and keep card->sdio_funcs in sync) so that we don't try to remove more
functions than we initialised if we hit the error path in
mmc_attach_sdio().

Without this patch if we hit the error path in mmc_attach_sdio() we run
the risk of deferencing invalid memory in sdio_remove_func(), leading to a
crash.
Signed-off-by: Matt Fleming <matt@console-pimps.org>
Cc: Daniel Drake <dsd@laptop.org>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sdio_remove_func() needs to be more careful about reference counting.  It
can be called in error paths where sdio_add_func() has never been called
e.g.  mmc_attach_sdio error path --> mmc_sdio_remove --> sdio_remove_func
Signed-off-by: Daniel Drake <dsd@laptop.org>
Reviewed-by: Matt Fleming <matt@console-pimps.org>
Cc: <linux-mmc@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Introduce coredump parameter data structure (struct coredump_params) to
simplify binfmt->core_dump() arguments.
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
Suggested-by: Ingo Molnar <mingo@elte.hu>
Cc: Hidehiro Kawai <hidehiro.kawai.ez@hitachi.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Thanks to Roland who pointed out de_thread() issues.

Currently we add sub-threads to ->real_parent->children list.  This buys
nothing but slows down do_wait().

With this patch ->children contains only main threads (group leaders).
The only complication is that forget_original_parent() should iterate over
sub-threads by hand, and de_thread() needs another list_replace() when it
changes ->group_leader.

Henceforth do_wait_thread() can never see task_detached() && !EXIT_DEAD
tasks, we can remove this check (and we can unify do_wait_thread() and
ptrace_do_wait()).

This change can confuse the optimistic search in mm_update_next_owner(),
but this is fixable and minor.

Perhaps badness() and oom_kill_process() should be updated, but they
should be fixed in any case.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Ratan Nalumasu <rnalumasu@gmail.com>
Cc: Vitaly Mayatskikh <vmayatsk@redhat.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: David Howells <dhowells@redhat.com>
Acked-by: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>