Currently, following test programs don't finished.

% ruby -e '
Thread.new { sleep }
File.read("/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies")
'

strace expose the reason.

...
open("/sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies", O_RDONLY|O_LARGEFILE) = 3
ioctl(3, SNDCTL_TMR_TIMEBASE or TCGETS, 0xbf9fa6b8) = -1 ENOTTY (Inappropriate ioctl for device)
fstat64(3, {st_mode=S_IFREG|0444, st_size=4096, ...}) = 0
_llseek(3, 0, [0], SEEK_CUR)            = 0
select(4, [3], NULL, NULL, NULL)        = 1 (in [3])
read(3, "1400000 1300000 1200000 1100000 1"..., 4096) = 62
select(4, [3], NULL, NULL, NULL


Because Ruby (the scripting language) VM assume select system-call
against regular file don't block.  it because SUSv3 says "Regular files
shall always poll TRUE for reading and writing".  see
http://www.opengroup.org/onlinepubs/009695399/functions/poll.html it
seems valid assumption.

But sysfs_poll() don't keep this rule although sysfs file can read and
write always.

This patch restore proper poll behavior to sysfs.
/sys/block/md*/md/sync_action polling application and another sysfs
updating sensitive application still can use POLLERR and POLLPRI.

Cc: Neil Brown <neilb@suse.de>
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Users can read sysfs files, there is no reason they should not be
allowed to listen to uevents.  This lets xorg and other userspace
programs properly get these messages without having to be root.
Signed-off-by: NKay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

This patch fixes a bug introduced in commit
49b420a1.

If a instance of bus_type doesn't have  .match method,
all .probe of drivers in the bus should be called, or else
the .probe have not a chance to be called.
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
Reported-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

A sysfs attribute using sysfs_schedule_callback() to commit suicide
may end up calling device_unregister(), which will eventually call
a driver's ->remove function.

Drivers may call flush_scheduled_work() in their shutdown routines,
in which case lockdep will complain with something like the following:

  =============================================
  [ INFO: possible recursive locking detected ]
  2.6.29-rc8-kk #1
  ---------------------------------------------
  events/4/56 is trying to acquire lock:
  (events){--..}, at: [<ffffffff80257fc0>] flush_workqueue+0x0/0xa0

  but task is already holding lock:
  (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230

  other info that might help us debug this:
  3 locks held by events/4/56:
  #0:  (events){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230
  #1:  (&ss->work){--..}, at: [<ffffffff80257648>] run_workqueue+0x108/0x230
  #2:  (pci_remove_rescan_mutex){--..}, at: [<ffffffff803c10d1>] remove_callback+0x21/0x40

  stack backtrace:
  Pid: 56, comm: events/4 Not tainted 2.6.29-rc8-kk #1
  Call Trace:
  [<ffffffff8026dfcd>] validate_chain+0xb7d/0x1260
  [<ffffffff8026eade>] __lock_acquire+0x42e/0xa40
  [<ffffffff8026f148>] lock_acquire+0x58/0x80
  [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0
  [<ffffffff8025800d>] flush_workqueue+0x4d/0xa0
  [<ffffffff80257fc0>] ? flush_workqueue+0x0/0xa0
  [<ffffffff80258070>] flush_scheduled_work+0x10/0x20
  [<ffffffffa0144065>] e1000_remove+0x55/0xfe [e1000e]
  [<ffffffff8033ee30>] ? sysfs_schedule_callback_work+0x0/0x50
  [<ffffffff803bfeb2>] pci_device_remove+0x32/0x70
  [<ffffffff80441da9>] __device_release_driver+0x59/0x90
  [<ffffffff80441edb>] device_release_driver+0x2b/0x40
  [<ffffffff804419d6>] bus_remove_device+0xa6/0x120
  [<ffffffff8043e46b>] device_del+0x12b/0x190
  [<ffffffff8043e4f6>] device_unregister+0x26/0x70
  [<ffffffff803ba969>] pci_stop_dev+0x49/0x60
  [<ffffffff803baab0>] pci_remove_bus_device+0x40/0xc0
  [<ffffffff803c10d9>] remove_callback+0x29/0x40
  [<ffffffff8033ee4f>] sysfs_schedule_callback_work+0x1f/0x50
  [<ffffffff8025769a>] run_workqueue+0x15a/0x230
  [<ffffffff80257648>] ? run_workqueue+0x108/0x230
  [<ffffffff8025846f>] worker_thread+0x9f/0x100
  [<ffffffff8025bce0>] ? autoremove_wake_function+0x0/0x40
  [<ffffffff802583d0>] ? worker_thread+0x0/0x100
  [<ffffffff8025b89d>] kthread+0x4d/0x80
  [<ffffffff8020d4ba>] child_rip+0xa/0x20
  [<ffffffff8020cebc>] ? restore_args+0x0/0x30
  [<ffffffff8025b850>] ? kthread+0x0/0x80
  [<ffffffff8020d4b0>] ? child_rip+0x0/0x20

Although we know that the device_unregister path will never acquire
a lock that a driver might try to acquire in its ->remove, in general
we should never attempt to flush a workqueue from within the same
workqueue, and lockdep rightly complains.

So as long as sysfs attributes cannot commit suicide directly and we
are stuck with this callback mechanism, put the sysfs callbacks on
their own workqueue instead of the global one.

This has the side benefit that if a suicidal sysfs attribute kicks
off a long chain of ->remove callbacks, we no longer induce a long
delay on the global queue.

This also fixes a missing module_put in the error path introduced
by sysfs-only-allow-one-scheduled-removal-callback-per-kobj.patch.

We never destroy the workqueue, but I'm not sure that's a
problem.
Reported-by: NKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Tested-by: NKenji Kaneshige <kaneshige.kenji@jp.fujitsu.com>
Signed-off-by: NAlex Chiang <achiang@hp.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
  ata: Report 16/32bit PIO as best we can
  libata: use ATA_ID_CFA_*
  pata_legacy: fix no device fail path
  pata_hpt37x: fix HPT370 DMA timeouts
  libata: handle SEMB signature better

Tetsuo Handa reports seeing the WARN_ON(current->mm == NULL) in
security_vm_enough_memory(), when do_execve() is touching the
target mm's stack, to set up its args and environment.

Yes, a UMH_NO_WAIT or UMH_WAIT_PROC call_usermodehelper() spawns
an mm-less kernel thread to do the exec.  And in any case, that
vm_enough_memory check when growing stack ought to be done on the
target mm, not on the execer's mm (though apart from the warning,
it only makes a slight tweak to OVERCOMMIT_NEVER behaviour).
Reported-by: NTetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Cc: stable@kernel.org
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This reverts commit f520360d.

Tetsuo Handa, running a kernel with CONFIG_DEBUG_PAGEALLOC=y and
CONFIG_UEVENT_HELPER_PATH=/sbin/hotplug, has been hitting RCU detected
CPU stalls: it's been spinning in the loop where do_execve() counts up
the args (but why wasn't fixup_exception working? dunno).

The recent change, switching kobject_uevent_env() from UMH_WAIT_EXEC
to UMH_NO_WAIT, is broken: the exec uses args on the local stack here,
and an env which is kfreed as soon as call_usermodehelper() returns.
It very much needs to wait for the exec to be done.

An alternative would be to keep the UMH_NO_WAIT, and complicate the code
to allocate and free these resources correctly? but no, as GregKH
pointed out when making the commit, CONFIG_UEVENT_HELPER_PATH="" is a
much better optimization - though some distros are still saying
/sbin/hotplug in their .config, yet with no such binary in their initrd
or their root.
Reported-by: NTetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Acked-by: NWill Newton <will.newton@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The legacy old IDE ioctl API for this is a bit primitive so we try
and map stuff sensibly onto it.

- Set PIO over DMA devices to report 32bit
- Add ability to change the PIO32 settings if the controller permits it
- Add that functionality into the sff drivers
- Add that functionality into the VLB legacy driver
- Turn on the 32bit PIO on the ninja32 and add support there
Signed-off-by: NAlan Cox <alan@linux.intel.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Use ATA_ID_CFA_* constants for CFA specific identify data words 162 and 163.
Signed-off-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

When pata_legacy can't detect any device, it unregisters the
platform_device and fails detection.  However, it forgets to detach
ata host triggering weird failures as the host later gets freed by
devres while still attached.  Fix it.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

The libata driver has copied the code from the IDE driver which caused a post
2.4.18 regression on many HPT370[A] chips -- DMA stopped to work completely,
only causing timeouts.  Now remove hpt370_bmdma_start() for good...
Signed-off-by: NSergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

WDC WD1600JS-62MHB5 successfully hits the window between ATA/ATAPI-7
and Serial ATA II standards and reports 3c/c3 signature which now is
assigned to SEMB.  Make ata_dev_classify() report ATA_DEV_SEMB on the
sig and let ata_dev_read_id() work around it by trying IDENTIFY once.

This fixes bko#11579.
Signed-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NDavid Haun <drhaun88@gmail.com>
Reported-by: NLars Wirzenius <liw@liw.fi>
Reported-by: NJuan Manuel <jmcarranza@gmail.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

block_write_full_page doesn't allow the caller to control what happens
when the IO is over.  This adds a new call named block_write_full_page_endio
so the buffer head end_io handler can be provided by the caller.

This will be used by the ext3 data=guarded mode to do i_size updates in
a workqueue based end_io handler.  end_buffer_async_write is also
exported so it can be called to do the dirty work of managing page
writeback for the higher level end_io handler.
Signed-off-by: NChris Mason <chris.mason@oracle.com>
Acked-by: NTheodore Tso <tytso@mit.edu>
Acked-by: NJan Kara <jack@suse.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This wasn't exported before and is useful (used by the experimental ext3
data=guarded code)
Signed-off-by: NChris Mason <chris.mason@oracle.com>
Acked-by: NTheodore Tso <tytso@mit.edu>
Acked-by: NJan Kara <jack@suse.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6: (64 commits)
  phylib: Fix delay argument of schedule_delayed_work
  NET/ixgbe: Fix powering off during shutdown
  NET/e1000e: Fix powering off during shutdown
  NET/e1000: Fix powering off during shutdown
  packet: avoid warnings when high-order page allocation fails
  gianfar: stop send queue before resetting gianfar
  myr10ge: again fix lro_gen_skb() alignment
  declance: convert to net_device_ops
  bfin_mac: convert to net_device_ops
  au1000: convert to net_device_ops
  atarilance: convert to net_device_ops
  a2065: convert to net_device_ops
  ixgbe: update real_num_tx_queues on changing num_rx_queues
  ixgbe: fix tx queue index
  Revert "rose: zero length frame filtering in af_rose.c"
  sfc: Use correct macro to set event bitfield
  sfc: Match calls to netif_napi_add() and netif_napi_del()
  bonding: Remove debug printk
  e1000/e1000: fix compile warning
  ehea: Fix incomplete conversion to net_device_ops
  ...

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
  sparc: remove some pointless conditionals before kfree()
  sbus: changed ioctls to unlocked
  sparc: asm/atomic.h on 32bit should include asm/system.h for xchg
  sparc64: Fix smp_callin() locking.

The commit a390d1f3 ("phylib: convert state_queue work to
delayed_work") missed converting 'expires' value to 'delay' value.
Signed-off-by: NAtsushi Nemoto <anemo@mba.ocn.ne.jp>
Acked-by: NMarcin Slusarz <marcin.slusarz@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Prevent ixgbe from putting the adapter into D3 during shutdown except when
we're going to power off the system, since doing that may generally cause
problems with kexec to happen (such problems were observed for igb and
forcedeth).  For this purpose seperate ixgbe_shutdown() from ixgbe_suspend()
and use the appropriate PCI PM callbacks in both of them.
Signed-off-by: N"Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Prevent e1000e from putting the adapter into D3 during shutdown except when
we're going to power off the system, since doing that may generally cause
problems with kexec to happen (such problems were observed for igb and
forcedeth).  For this purpose seperate e1000e_shutdown() from e1000e_suspend()
and use the appropriate PCI PM callbacks in both of them.
Signed-off-by: N"Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Prevent e1000 from putting the adapter into D3 during shutdown except when
we're going to power off the system, since doing that may generally cause
problems with kexec to happen (such problems were observed for igb and
forcedeth).  For this purpose seperate e1000_shutdown() from e1000_suspend()
and use the appropriate PCI PM callbacks in both of them.
Signed-off-by: N"Rafael J. Wysocki" <rjw@sisk.pl>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Don't try and predeclare inline funcs like this:

	static inline void wait_migrated_callbacks(void)
	...
	static void _rcu_barrier(enum rcu_barrier type)
	{
		...
		wait_migrated_callbacks();
	}
	...
	static inline void wait_migrated_callbacks(void)
	{
		wait_event(rcu_migrate_wq, !atomic_read(&rcu_migrate_type_count));
	}

as it upsets some versions of gcc under some circumstances:

	kernel/rcupdate.c: In function `_rcu_barrier':
	kernel/rcupdate.c:125: sorry, unimplemented: inlining failed in call to 'wait_migrated_callbacks': function body not available
	kernel/rcupdate.c:152: sorry, unimplemented: called from here

This can be dealt with by simply putting the static variables (rcu_migrate_*)
at the top, and moving the implementation of the function up so that it
replaces its forward declaration.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Cc: Dipankar Sarma <dipankar@in.ibm.com>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The default CONFIG_BUG=n version of BUG() should incorporate an empty a
do...while statement to avoid compilation weirdness.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Stop gcc from generating uninitialised variable warnings after BUG().  The
problem is that MN10300's implementation of BUG() invokes system call 15 which
doesn't return - but there's no way to tell the compiler that and also emit the
bug table element with the correct file and line data.

So instead, we make the do...while wrapper in _debug_bug_trap() an endless loop
from which there's no escape.

Also, while we're at it, (1) get rid of _debug_bug_trap() and just implement
directly as BUG(), and (2) make the implementation of BUG() contingent on
CONFIG_BUG=y.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Wire up missing system calls preadv() and pwritev().
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Discard duplicate PFN_xxx() macros from arch code as they're now in the
general headers.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* 'for-linus' of git://git390.marist.edu/pub/scm/linux-2.6:
  [S390] boot cputime accounting
  [S390] add read_persistent_clock
  [S390] cpu hotplug and accounting values
  [S390] fix idle time accounting
  [S390] smp: fix cpu_possible_map initialization
  [S390] dasd: fix idaw boundary checking for track based ccw
  [S390] dasd: Use the new async framework for autoonlining.
  [S390] qdio: remove dead timeout handler
  [S390] appldata: Use new mod_virt_timer_periodic() function.
  [S390] extend virtual timer interface by mod_virt_timer_periodic
  [S390] stp synchronization retry timer
  [S390] call nmi_enter/nmi_exit on machine checks
  [S390] wire up preadv/pwritev system calls
  [S390] s390: move machine flags to lowcore

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tiwai/sound-2.6:
  ALSA: hda - Fix the cmd cache keys for amp verbs
  ALSA: add missing definitions(letters) to HD-Audio.txt
  ALSA: hda - Add quirk mask for Fujitsu Amilo laptops with ALC883
  [ALSA] intel8x0: add one retry to the ac97_clock measurement routine
  [ALSA] intel8x0: fix wrong conditions in ac97_clock measure routine
  ALSA: hda - Avoid call of snd_jack_report at release
  ALSA: add private_data to struct snd_jack
  ALSA: snd-usb-caiaq: rename files to remove redundant information in file pathes
  ALSA: snd-usb-caiaq: clean up header includes
  ALSA: sound/pci: use memdup_user()
  ALSA: sound/usb: use memdup_user()
  ALSA: sound/isa: use memdup_user()
  ALSA: sound/core: use memdup_user()
  [ALSA] intel8x0: do not use zero value from PICB register
  [ALSA] intel8x0: an attempt to make ac97_clock measurement more reliable
  [ALSA] pcm-midlevel: Add more strict buffer position checks based on jiffies
  [ALSA] hda_intel: fix unexpected ring buffer positions
  ASoC: Disable S3C64xx support in Kconfig
  ASoC: magician: remove un-necessary #include of pxa-regs.h and hardware.h

* git://git.kernel.org/pub/scm/linux/kernel/git/steve/gfs2-2.6-fixes:
  GFS2: Use DEFINE_SPINLOCK
  GFS2: cleanup file_operations mess
  GFS2: Move umount flush rwsem
  GFS2: Fix symlink creation race
  GFS2: Make quotad's waiting interruptible

* 'for-linus' of git://git.kernel.dk/linux-2.6-block: (28 commits)
  cfq-iosched: add close cooperator code
  cfq-iosched: log responsible 'cfqq' in idle timer arm
  cfq-iosched: tweak kick logic a bit more
  cfq-iosched: no need to save interrupts in cfq_kick_queue()
  brd: fix cacheflushing
  brd: support barriers
  swap: Remove code handling bio_alloc failure with __GFP_WAIT
  gfs2: Remove code handling bio_alloc failure with __GFP_WAIT
  ext4: Remove code handling bio_alloc failure with __GFP_WAIT
  dio: Remove code handling bio_alloc failure with __GFP_WAIT
  block: Remove code handling bio_alloc failure with __GFP_WAIT
  bio: add documentation to bio_alloc()
  splice: add helpers for locking pipe inode
  splice: remove generic_file_splice_write_nolock()
  ocfs2: fix i_mutex locking in ocfs2_splice_to_file()
  splice: fix i_mutex locking in generic_splice_write()
  splice: remove i_mutex locking in splice_from_pipe()
  splice: split up __splice_from_pipe()
  block: fix SG_IO to return a proper error value
  cfq-iosched: don't delay queue kick for a merged request
  ...

* topic/hda:
  ALSA: hda - Fix the cmd cache keys for amp verbs
  ALSA: add missing definitions(letters) to HD-Audio.txt

Fix the key value generation for get/set amp verbs.  The upper bits of
the parameter have to be combined with the verb value to be unique for
each direction/index of amp access.

This fixes the resume problem on some hardwares like Macbook after
the channel mode is changed.
Tested-by: NJohannes Berg <johannes@sipsolutions.net>
Cc: <stable@kernel.org>
Signed-off-by: NTakashi Iwai <tiwai@suse.de>

* 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/paulus/powerpc:
  powerpc: pseries/dtl.c should include asm/firmware.h
  powerpc: Fix data-corrupting bug in __futex_atomic_op
  powerpc/pseries: Set error_state to pci_channel_io_normal in eeh_report_reset()
  powerpc: Allow 256kB pages with SHMEM
  powerpc: Document new FSL I2C bindings and cleanup
  powerpc/mm: Fix compile warning
  powerpc/85xx: TQM8548: update defconfig
  powerpc/85xx: TQM8548: use proper phy-handles for enet2 and enet3
  powerpc/85xx: TQM85xx: correct address of LM75 I2C device nodes
  powerpc: Add support for early tlbilx opcode
  powerpc: Fix tlbilx opcode

It turns out that 'smp_call_function_many()' doesn't work at all like
'smp_call_function_single()', and my change to Andrew's patch to use it
rather than a loop over all CPU's acpi-cpufreq doesn't work.

My bad.

'smp_call_function_many()' has two "features" (aka "documented bugs"):

 (a) it needs to be called with preemption disabled, because it uses
     smp_processor_id() without guarding the CPU lookup with 'get_cpu()'
     and 'put_cpu()' like the 'single' variant does.

 (b) even if the current CPU is part of the CPU mask, it won't do the
     call on that CPU.

Still, we're better off trying to use 'smp_call_function_many()' than
looping over CPU's, since it at least in theory allows us to use a
broadcast IPI and do it all in parallel.  So let's just work around the
silly semantic bugs in that function.
Reported-and-tested-by: NAli Gholami Rudi <ali@rudi.ir>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Latest tcpdump/libpcap triggers annoying messages because of high order page
allocation failures (when lowmem exhausted or fragmented)

These allocation errors are correctly handled so could be silent.

[22660.208901] tcpdump: page allocation failure. order:5, mode:0xc0d0
[22660.208921] Pid: 13866, comm: tcpdump Not tainted 2.6.30-rc2 #170
[22660.208936] Call Trace:
[22660.208950]  [<c04e2b46>] ? printk+0x18/0x1a
[22660.208965]  [<c02760f7>] __alloc_pages_internal+0x357/0x460
[22660.208980]  [<c0276251>] __get_free_pages+0x21/0x40
[22660.208995]  [<c04cc835>] packet_set_ring+0x105/0x3d0
[22660.209009]  [<c04ccd1d>] packet_setsockopt+0x21d/0x4d0
[22660.209025]  [<c0270400>] ? filemap_fault+0x0/0x450
[22660.209040]  [<c0449e34>] sys_setsockopt+0x54/0xa0
[22660.209053]  [<c044b97f>] sys_socketcall+0xef/0x270
[22660.209067]  [<c0202e34>] sysenter_do_call+0x12/0x26
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

If we have processes that are working in close proximity to each
other on disk, we don't want to idle wait. Instead allow the close
process to issue a request, getting better aggregate bandwidth.
The anticipatory scheduler has similar checks, noop and deadline do
not need it since they don't care about process <-> io mappings.

The code for CFQ is a little more involved though, since we split
request queues into per-process contexts.

This fixes a performance problem with eg dump(8), since it uses
several processes in some silly attempt to speed IO up. Even if
dump(8) isn't really a valid case (it should be fixed by using
CLONE_IO), there are other cases where we see close processes
and where idling ends up hurting performance.

Credit goes to Jeff Moyer <jmoyer@redhat.com> for writing the
initial implementation.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

Makes it easier to read the traces.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

We only kick the dispatch for an idling queue, if we think it's a
(somewhat) fully merged request. Also allow a kick if we have other
busy queues in the system, since we don't want to risk waiting for
a potential merge in that case. It's better to get some work done and
proceed.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

It's called from the workqueue handlers from process context, so
we always have irqs enabled when entered.
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

brd is missing a flush_dcache_page. On 2nd thoughts, perhaps it is the
pagecache's responsibility to flush user virtual aliases (the driver of
course should flush kernel virtual mappings)... but anyway, there
already exists cache flushing for one direction of transfer, so we
should add the other.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>

brd is always ordered (not that it matters, as it is defined not to
survive when the system goes down). So tell the block layer it is
ordered, which might be of help with testing filesystems.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>