The buf_lock cannot be held while populating the inodes, so make the backend
pass forward an allocated and filled buffer instead. This solves the following
backtrace. The effect is that "buf" is only ever used to notify the backends
that something was written to it, and shouldn't be used in the read path.

To replace the buf_lock during the read path, isolate the open/read/close
loop with a separate mutex to maintain serialized access to the backend.

Note that is is up to the pstore backend to cope if the (*write)() path is
called in the middle of the read path.

[   59.691019] BUG: sleeping function called from invalid context at .../mm/slub.c:847
[   59.691019] in_atomic(): 0, irqs_disabled(): 1, pid: 1819, name: mount
[   59.691019] Pid: 1819, comm: mount Not tainted 3.0.8 #1
[   59.691019] Call Trace:
[   59.691019]  [<810252d5>] __might_sleep+0xc3/0xca
[   59.691019]  [<810a26e6>] kmem_cache_alloc+0x32/0xf3
[   59.691019]  [<810b53ac>] ? __d_lookup_rcu+0x6f/0xf4
[   59.691019]  [<810b68b1>] alloc_inode+0x2a/0x64
[   59.691019]  [<810b6903>] new_inode+0x18/0x43
[   59.691019]  [<81142447>] pstore_get_inode.isra.1+0x11/0x98
[   59.691019]  [<81142623>] pstore_mkfile+0xae/0x26f
[   59.691019]  [<810a2a66>] ? kmem_cache_free+0x19/0xb1
[   59.691019]  [<8116c821>] ? ida_get_new_above+0x140/0x158
[   59.691019]  [<811708ea>] ? __init_rwsem+0x1e/0x2c
[   59.691019]  [<810b67e8>] ? inode_init_always+0x111/0x1b0
[   59.691019]  [<8102127e>] ? should_resched+0xd/0x27
[   59.691019]  [<8137977f>] ? _cond_resched+0xd/0x21
[   59.691019]  [<81142abf>] pstore_get_records+0x52/0xa7
[   59.691019]  [<8114254b>] pstore_fill_super+0x7d/0x91
[   59.691019]  [<810a7ff5>] mount_single+0x46/0x82
[   59.691019]  [<8114231a>] pstore_mount+0x15/0x17
[   59.691019]  [<811424ce>] ? pstore_get_inode.isra.1+0x98/0x98
[   59.691019]  [<810a8199>] mount_fs+0x5a/0x12d
[   59.691019]  [<810b9174>] ? alloc_vfsmnt+0xa4/0x14a
[   59.691019]  [<810b9474>] vfs_kern_mount+0x4f/0x7d
[   59.691019]  [<810b9d7e>] do_kern_mount+0x34/0xb2
[   59.691019]  [<810bb15f>] do_mount+0x5fc/0x64a
[   59.691019]  [<810912fb>] ? strndup_user+0x2e/0x3f
[   59.691019]  [<810bb3cb>] sys_mount+0x66/0x99
[   59.691019]  [<8137b537>] sysenter_do_call+0x12/0x26
Signed-off-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NTony Luck <tony.luck@intel.com>

Signed-off-by: NKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This patch moves PORT_xx helper macro to sh_pfc.h,
and it expects CPU_ALL_PORT() macro for each CPU
Signed-off-by: NKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This patch move PORT_DATA_xx helper macro to sh_pfc.h.
and pfc-sh7372.c used it
Signed-off-by: NKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

Now that all of the named string association with clocks has been
migrated to clkdev lookups there's no meaningful named topology that can
be constructed for a debugfs tree view. Get rid of the left over bits,
and shrink struct clk a bit in the process.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

when pinctl subsystem is not selected, when compiling drivers including
the include/linux/pinctrl/pinctrl.h, we will get the warning as below:
In file included from include/linux/pinctrl/pinmux.h:17,
                 from drivers/tty/serial/sirfsoc_uart.c:25:
include/linux/pinctrl/pinctrl.h:126: warning: 'struct pinctrl_dev'
		declared inside parameter list
include/linux/pinctrl/pinctrl.h:126: warning: its scope is only this
      definition or declaration, which is probably not what you want
Signed-off-by: NBarry Song <Baohua.Song@csr.com>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>

Signed-off-by: NKeng-Yu Lin <kengyu@canonical.com>
Signed-off-by: NJeff Garzik <jgarzik@redhat.com>

Fix below build warning:

  CC      arch/arm/mach-omap2/hwspinlock.o
In file included from arch/arm/mach-omap2/hwspinlock.c:22:
include/linux/hwspinlock.h: In function '__hwspin_unlock':
include/linux/hwspinlock.h:121: warning: 'return' with a value, in function returning void
Signed-off-by: NAxel Lin <axel.lin@gmail.com>
Signed-off-by: NOhad Ben-Cohen <ohad@wizery.com>

The "private_date" field in struct devfreq_dev_status almost certainly
wants to be "private_data"; since there are no in-tree users of this
functionality, now seems like an easy time to make the fix.
Signed-off-by: NJonathan Corbet <corbet@lwn.net>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

This patch makes the cpuidle_states structure global (single copy)
instead of per-cpu. The statistics needed on per-cpu basis
by the governor are kept per-cpu. This simplifies the cpuidle
subsystem as state registration is done by single cpu only.
Having single copy of cpuidle_states saves memory. Rare case
of asymmetric C-states can be handled within the cpuidle driver
and architectures such as POWER do not have asymmetric C-states.

Having single/global registration of all the idle states,
dynamic C-state transitions on x86 are handled by
the boot cpu. Here, the boot cpu  would disable all the devices,
re-populate the states and later enable all the devices,
irrespective of the cpu that would receive the notification first.

Reference:
https://lkml.org/lkml/2011/4/25/83Signed-off-by: NDeepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: NTrinabh Gupta <g.trinabh@gmail.com>
Tested-by: NJean Pihet <j-pihet@ti.com>
Reviewed-by: NKevin Hilman <khilman@ti.com>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Acked-by: NKevin Hilman <khilman@ti.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

This is the first step towards global registration of cpuidle
states. The statistics used primarily by the governor are per-cpu
and have to be split from rest of the fields inside cpuidle_state,
which would be made global i.e. single copy. The driver_data field
is also per-cpu and moved.
Signed-off-by: NDeepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: NTrinabh Gupta <g.trinabh@gmail.com>
Tested-by: NJean Pihet <j-pihet@ti.com>
Reviewed-by: NKevin Hilman <khilman@ti.com>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Acked-by: NKevin Hilman <khilman@ti.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

The cpuidle_device->prepare() mechanism causes updates to the
cpuidle_state[].flags, setting and clearing CPUIDLE_FLAG_IGNORE
to tell the governor not to chose a state on a per-cpu basis at
run-time. State demotion is now handled by the driver and it returns
the actual state entered. Hence, this mechanism is not required.
Also this removes per-cpu flags from cpuidle_state enabling
it to be made global.

Reference:
https://lkml.org/lkml/2011/3/25/52Signed-off-by: NDeepthi Dharwar <deepthi@linux.vnet.ibm>
Signed-off-by: NTrinabh Gupta <g.trinabh@gmail.com>
Tested-by: NJean Pihet <j-pihet@ti.com>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Reviewed-by: NKevin Hilman <khilman@ti.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

Cpuidle governor only suggests the state to enter using the
governor->select() interface, but allows the low level driver to
override the recommended state. The actual entered state
may be different because of software or hardware demotion. Software
demotion is done by the back-end cpuidle driver and can be accounted
correctly. Current cpuidle code uses last_state field to capture the
actual state entered and based on that updates the statistics for the
state entered.

Ideally the driver enter routine should update the counters,
and it should return the state actually entered rather than the time
spent there. The generic cpuidle code should simply handle where
the counters live in the sysfs namespace, not updating the counters.

Reference:
https://lkml.org/lkml/2011/3/25/52Signed-off-by: NDeepthi Dharwar <deepthi@linux.vnet.ibm.com>
Signed-off-by: NTrinabh Gupta <g.trinabh@gmail.com>
Tested-by: NJean Pihet <j-pihet@ti.com>
Reviewed-by: NKevin Hilman <khilman@ti.com>
Acked-by: NArjan van de Ven <arjan@linux.intel.com>
Acked-by: NKevin Hilman <khilman@ti.com>
Signed-off-by: NLen Brown <len.brown@intel.com>

Use of the GPL or a compatible licence doesn't necessarily make the code
any good.  We already consider staging modules to be suspect, and this
should also be true for out-of-tree modules which may receive very
little review.
Signed-off-by: NBen Hutchings <ben@decadent.org.uk>
Reviewed-by: NDave Jones <davej@redhat.com>
Acked-by: NGreg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (patched oops-tracing.txt)

Occasionally we may see an accessory reported before we have a stable
impedance for the accessory. If this happens then reread the status in
order to ensure that the handler can take the appropriate action for the
status change.
Signed-off-by: NMark Brown <broonie@opensource.wolfsonmicro.com>

slave->duplex is a u8 type so the in bond_info_show_slave() when we
check "if (slave->duplex == -1)", it's always false.
Signed-off-by: NDan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Commit 27920651 "PM / Freezer: Make fake_signal_wake_up() wake
TASK_KILLABLE tasks too" updated fake_signal_wake_up() used by freezer
to wake up KILLABLE tasks.  Sending unsolicited wakeups to tasks in
killable sleep is dangerous as there are code paths which depend on
tasks not waking up spuriously from KILLABLE sleep.

For example. sys_read() or page can sleep in TASK_KILLABLE assuming
that wait/down/whatever _killable can only fail if we can not return
to the usermode.  TASK_TRACED is another obvious example.

The offending commit was to resolve freezer hang during system PM
operations caused by KILLABLE sleeps in network filesystems.
wait_event_freezekillable(), which depends on the spurious KILLABLE
wakeup, was added by f06ac72e "cifs, freezer: add
wait_event_freezekillable and have cifs use it" to be used to
implement killable & freezable sleeps in network filesystems.

To prepare for reverting of 27920651, this patch reimplements
wait_event_freezekillable() using freezer_do_not_count/freezer_count()
so that it doesn't depend on the spurious KILLABLE wakeup.  This isn't
very nice but should do for now.

[tj: Refreshed patch to apply to linus/master and updated commit
    description on Rafael's request.]
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Signed-off-by: NTejun Heo <tj@kernel.org>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Commit 03ca370f (PM / OPP: Add
OPP availability change notifier) does not compile if CONFIG_PM_OPP
is not set:

arch/arm/plat-omap/omap-pm-noop.o: In function `opp_get_notifier':
include/linux/opp.h:103: multiple definition of `opp_get_notifier'
include/linux/opp.h:103: first defined here

Also fix incorrect comment.
Signed-off-by: NTony Lindgren <tony@atomide.com>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

Remove the suspend_cpu_hotplug declaration, which doesn't correspond
to an existing variable.

[rjw: Added the changelog.]
Signed-off-by: NSrivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>

This provides a clk_rate_mult_range_round() helper for use by some of the
CPG PLL ranged multipliers, following the same approach as used by the
div ranges.
Signed-off-by: NKuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

This fixes up support for SH-2(A) SCIFs by introducing a new regtype. As
expected, it's close to the SH-4A SCIF with fifodata, but still different
enough to warrant its own type.

Fixes up a number of FIFO overflows and similar for both SH7203/SH7264.
Signed-off-by: NPhil Edworthy <phil.edworthy@renesas.com>
Tested-by: NFederico Fuga <fuga@studiofuga.com>
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>

The patch adds an empty function for non-dt build, so that
drivers migrating to dt can save some '#ifdef CONFIG_OF'.

v3: New patch
Signed-off-by: NStephen Warren <swarren@nvidia.com>
Signed-off-by: NGrant Likely <grant.likely@secretlab.ca>

V4L2_CID_POWER_LINE_FREQUENCY control allows applications to instruct
a driver what is the power line frequency so an appropriate filter
can be used by the device to cancel flicker by compensating the light
intensity ripple. Currently in the menu we have entries for 50 Hz and
60 Hz and for entirely disabling the anti-flicker filter.
However some devices are capable of automatically detecting the
frequency, so add V4L2_CID_POWER_LINE_FREQUENCY_AUTO entry for them.
Signed-off-by: NSylwester Nawrocki <s.nawrocki@samsung.com>
Signed-off-by: NKyungmin Park <kyungmin.park@samsung.com>
Acked-by: NLaurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

A possibility to preallocate and initialise buffers of different sizes
in V4L2 is required for an efficient implementation of a snapshot
mode. This patch adds two new ioctl()s: VIDIOC_CREATE_BUFS and
VIDIOC_PREPARE_BUF and defines respective data structures.
Signed-off-by: NGuennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: NMauro Carvalho Chehab <mchehab@redhat.com>

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

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

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

Before rwlock patch: 1710.778s
After rwlock patch: 152.227s
Signed-off-by: NAndrew Bresticker <abrestic@google.com>
Cc: Paul Menage <menage@gmail.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In testing aio on a fast storage device, I found that the context lock
takes up a fair amount of cpu time in the I/O submission path.  The reason
is that we take it for every I/O submitted (see __aio_get_req).  Since we
know how many I/Os are passed to io_submit, we can preallocate the kiocbs
in batches, reducing the number of times we take and release the lock.

In my testing, I was able to reduce the amount of time spent in
_raw_spin_lock_irq by .56% (average of 3 runs).  The command I used to
test this was:

   aio-stress -O -o 2 -o 3 -r 8 -d 128 -b 32 -i 32 -s 16384 <dev>

I also tested the patch with various numbers of events passed to
io_submit, and I ran the xfstests aio group of tests to ensure I didn't
break anything.
Signed-off-by: NJeff Moyer <jmoyer@redhat.com>
Cc: Daniel Ehrenberg <dehrenberg@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This client driver allows you to use a GPIO pin as a source for PPS
signals.  Platform data [1] are used to specify the GPIO pin number,
label, assert event edge type, and whether clear events are captured.

This driver is based on the work by Ricardo Martins who submitted an
initial implementation [2] of a PPS IRQ client driver to the linuxpps
mailing-list on Dec 3 2010.

[1] include/linux/pps-gpio.h
[2] http://ml.enneenne.com/pipermail/linuxpps/2010-December/004155.html

[akpm@linux-foundation.org: remove unneeded cast of void*]
Signed-off-by: NJames Nuss <jamesnuss@nanometrics.ca>
Cc: Ricardo Martins <rasm@fe.up.pt>
Acked-by: NRodolfo Giometti <giometti@linux.it>
Signed-off-by: NRicardo Martins <rasm@fe.up.pt>
Cc: Alexander Gordeev <lasaine@lvk.cs.msu.su>
Cc: Igor Plyatov <plyatov@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Lots of driver code does a dma_alloc_coherent() and then zeroes out the
memory with a memset.  Make it easy for them.

Cc: Alexandre Bounine <alexandre.bounine@idt.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Adding support for poll() in sysctl fs allows userspace to receive
notifications of changes in sysctl entries.  This adds a infrastructure to
allow files in sysctl fs to be pollable and implements it for hostname and
domainname.

[akpm@linux-foundation.org: s/declare/define/ for definitions]
Signed-off-by: NLucas De Marchi <lucas.demarchi@profusion.mobi>
Cc: Greg KH <gregkh@suse.de>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add RapidIO mport driver for IDT TSI721 PCI Express-to-SRIO bridge device.
 The driver provides full set of callback functions defined for mport
devices in RapidIO subsystem.  It also is compatible with current version
of RIONET driver (Ethernet over RapidIO messaging services).

This patch is applicable to kernel versions starting from 2.6.39.
Signed-off-by: NAlexandre Bounine <alexandre.bounine@idt.com>
Signed-off-by: NChul Kim <chul.kim@idt.com>
Cc: Kumar Gala <galak@kernel.crashing.org>
Cc: Matt Porter <mporter@kernel.crashing.org>
Cc: Li Yang <leoli@freescale.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

For the sysvsem undo, each task struct contains a sysv_sem structure with
a pointer to the undo information.

This pointer is only necessary if sysvipc is enabled - thus the pointer
can be made conditional on CONFIG_SYSVIPC.
Signed-off-by: NManfred Spraul <manfred@colorfullife.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

include/linux/sem.h contains several structures that are only used within
ipc/sem.c.

The patch moves them into ipc/sem.c - there is no need to expose the
structures to the whole kernel.

No functional changes, only whitespace cleanups and 80-char per line
fixes.
Signed-off-by: NManfred Spraul <manfred@colorfullife.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Reclaim decides to skip scanning an active list when the corresponding
inactive list is above a certain size in comparison to leave the assumed
working set alone while there are still enough reclaim candidates around.

The memcg implementation of comparing those lists instead reports whether
the whole memcg is low on the requested type of inactive pages,
considering all nodes and zones.

This can lead to an oversized active list not being scanned because of the
state of the other lists in the memcg, as well as an active list being
scanned while its corresponding inactive list has enough pages.

Not only is this wrong, it's also a scalability hazard, because the global
memory state over all nodes and zones has to be gathered for each memcg
and zone scanned.

Make these calculations purely based on the size of the two LRU lists
that are actually affected by the outcome of the decision.
Signed-off-by: NJohannes Weiner <jweiner@redhat.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Reviewed-by: NYing Han <yinghan@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The memcg code sometimes uses "struct mem_cgroup *mem" and sometimes uses
"struct mem_cgroup *memcg".  Rename all mem variables to memcg in source
file.
Signed-off-by: NRaghavendra K T <raghavendra.kt@linux.vnet.ibm.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: NMichal Hocko <mhocko@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

One can get this information from minix/inode.c, but adding the
explanations at the definition sites is more appropriate.
Signed-off-by: NSami Kerola <kerolasa@iki.fi>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This avoids duplicating the function in every arch gup_fast.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Michel while working on the working set estimation code, noticed that
calling get_page_unless_zero() on a random pfn_to_page(random_pfn)
wasn't safe, if the pfn ended up being a tail page of a transparent
hugepage under splitting by __split_huge_page_refcount().

He then found the problem could also theoretically materialize with
page_cache_get_speculative() during the speculative radix tree lookups
that uses get_page_unless_zero() in SMP if the radix tree page is freed
and reallocated and get_user_pages is called on it before
page_cache_get_speculative has a chance to call get_page_unless_zero().

So the best way to fix the problem is to keep page_tail->_count zero at
all times.  This will guarantee that get_page_unless_zero() can never
succeed on any tail page.  page_tail->_mapcount is guaranteed zero and
is unused for all tail pages of a compound page, so we can simply
account the tail page references there and transfer them to
tail_page->_count in __split_huge_page_refcount() (in addition to the
head_page->_mapcount).

While debugging this s/_count/_mapcount/ change I also noticed get_page is
called by direct-io.c on pages returned by get_user_pages.  That wasn't
entirely safe because the two atomic_inc in get_page weren't atomic.  As
opposed to other get_user_page users like secondary-MMU page fault to
establish the shadow pagetables would never call any superflous get_page
after get_user_page returns.  It's safer to make get_page universally safe
for tail pages and to use get_page_foll() within follow_page (inside
get_user_pages()).  get_page_foll() is safe to do the refcounting for tail
pages without taking any locks because it is run within PT lock protected
critical sections (PT lock for pte and page_table_lock for
pmd_trans_huge).

The standard get_page() as invoked by direct-io instead will now take
the compound_lock but still only for tail pages.  The direct-io paths
are usually I/O bound and the compound_lock is per THP so very
finegrined, so there's no risk of scalability issues with it.  A simple
direct-io benchmarks with all lockdep prove locking and spinlock
debugging infrastructure enabled shows identical performance and no
overhead.  So it's worth it.  Ideally direct-io should stop calling
get_page() on pages returned by get_user_pages().  The spinlock in
get_page() is already optimized away for no-THP builds but doing
get_page() on tail pages returned by GUP is generally a rare operation
and usually only run in I/O paths.

This new refcounting on page_tail->_mapcount in addition to avoiding new
RCU critical sections will also allow the working set estimation code to
work without any further complexity associated to the tail page
refcounting with THP.
Signed-off-by: NAndrea Arcangeli <aarcange@redhat.com>
Reported-by: NMichel Lespinasse <walken@google.com>
Reviewed-by: NMichel Lespinasse <walken@google.com>
Reviewed-by: NMinchan Kim <minchan.kim@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hugh Dickins <hughd@google.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: <stable@kernel.org>
Cc: <stable@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I missed to include a patch adding the new silicon revision define
CUT3P3 and remove the retired CUT0 versions of AB8500. Also delete
the reference to the retired AB3550 from the header.
Reported-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NSamuel Ortiz <sameo@linux.intel.com>

This adds a d_prune dentry operation that is called by the VFS prior to
pruning (i.e. unhashing and killing) a hashed dentry from the dcache.
Wrap dentry_lru_del() and use the new _prune() helper in the cases where we
are about to unhash and kill the dentry.

This will be used by Ceph to maintain a flag indicating whether the
complete contents of a directory are contained in the dcache, allowing it
to satisfy lookups and readdir without addition server communication.

Renumber a few DCACHE_* #defines to group DCACHE_OP_PRUNE with the other
DCACHE_OP_ bits.
Signed-off-by: NSage Weil <sage@newdream.net>
Signed-off-by: NChristoph Hellwig <hch@lst.de>