Locking init improvement:

 - introduce and use __SPIN_LOCK_UNLOCKED for array initializations,
   to pass in the name string of locks, used by debugging
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Generic lock debugging:

 - generalized lock debugging framework. For example, a bug in one lock
   subsystem turns off debugging in all lock subsystems.

 - got rid of the caller address passing (__IP__/__IP_DECL__/etc.) from
   the mutex/rtmutex debugging code: it caused way too much prototype
   hackery, and lockdep will give the same information anyway.

 - ability to do silent tests

 - check lock freeing in vfree too.

 - more finegrained debugging options, to allow distributions to
   turn off more expensive debugging features.

There's no separate 'held mutexes' list anymore - but there's a 'held locks'
stack within lockdep, which unifies deadlock detection across all lock
classes.  (this is independent of the lockdep validation stuff - lockdep first
checks whether we are holding a lock already)

Here are the current debugging options:

CONFIG_DEBUG_MUTEXES=y
CONFIG_DEBUG_LOCK_ALLOC=y

which do:

 config DEBUG_MUTEXES
          bool "Mutex debugging, basic checks"

 config DEBUG_LOCK_ALLOC
         bool "Detect incorrect freeing of live mutexes"
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

It turns out that it is advantageous to leave a small portion of unmapped file
backed pages if all of a zone's pages (or almost all pages) are allocated and
so the page allocator has to go off-node.

This allows recently used file I/O buffers to stay on the node and
reduces the times that zone reclaim is invoked if file I/O occurs
when we run out of memory in a zone.

The problem is that zone reclaim runs too frequently when the page cache is
used for file I/O (read write and therefore unmapped pages!) alone and we have
almost all pages of the zone allocated.  Zone reclaim may remove 32 unmapped
pages.  File I/O will use these pages for the next read/write requests and the
unmapped pages increase.  After the zone has filled up again zone reclaim will
remove it again after only 32 pages.  This cycle is too inefficient and there
are potentially too many zone reclaim cycles.

With the 1% boundary we may still remove all unmapped pages for file I/O in
zone reclaim pass.  However.  it will take a large number of read and writes
to get back to 1% again where we trigger zone reclaim again.

The zone reclaim 2.6.16/17 does not show this behavior because we have a 30
second timeout.

[akpm@osdl.org: rename the /proc file and the variable]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Post and discussion:
http://marc.theaimsgroup.com/?t=115074342800003&r=1&w=2

Code in __shrink_node() duplicates code in cache_reap()

Add a new function drain_freelist that removes slabs with objects that are
already free and use that in various places.

This eliminates the __node_shrink() function and provides the interrupt
holdoff reduction from slab_free to code that used to call __node_shrink.

[akpm@osdl.org: build fixes]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The remaining counters in page_state after the zoned VM counter patches
have been applied are all just for show in /proc/vmstat.  They have no
essential function for the VM.

We use a simple increment of per cpu variables.  In order to avoid the most
severe races we disable preempt.  Preempt does not prevent the race between
an increment and an interrupt handler incrementing the same statistics
counter.  However, that race is exceedingly rare, we may only loose one
increment or so and there is no requirement (at least not in kernel) that
the vm event counters have to be accurate.

In the non preempt case this results in a simple increment for each
counter.  For many architectures this will be reduced by the compiler to a
single instruction.  This single instruction is atomic for i386 and x86_64.
 And therefore even the rare race condition in an interrupt is avoided for
both architectures in most cases.

The patchset also adds an off switch for embedded systems that allows a
building of linux kernels without these counters.

The implementation of these counters is through inline code that hopefully
results in only a single instruction increment instruction being emitted
(i386, x86_64) or in the increment being hidden though instruction
concurrency (EPIC architectures such as ia64 can get that done).

Benefits:
- VM event counter operations usually reduce to a single inline instruction
  on i386 and x86_64.
- No interrupt disable, only preempt disable for the preempt case.
  Preempt disable can also be avoided by moving the counter into a spinlock.
- Handling is similar to zoned VM counters.
- Simple and easily extendable.
- Can be omitted to reduce memory use for embedded use.

References:

RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=113512330605497&w=2
RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=114988082814934&w=2
local_t http://marc.theaimsgroup.com/?l=linux-kernel&m=114991748606690&w=2
V2 http://marc.theaimsgroup.com/?t=115014808400007&r=1&w=2
V3 http://marc.theaimsgroup.com/?l=linux-kernel&m=115024767022346&w=2
V4 http://marc.theaimsgroup.com/?l=linux-kernel&m=115047968808926&w=2Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The numa statistics are really event counters.  But they are per node and
so we have had special treatment for these counters through additional
fields on the pcp structure.  We can now use the per zone nature of the
zoned VM counters to realize these.

This will shrink the size of the pcp structure on NUMA systems.  We will
have some room to add additional per zone counters that will all still fit
in the same cacheline.

 Bits	Prior pcp size	  	Size after patch	We can add
 ------------------------------------------------------------------
 64	128 bytes (16 words)	80 bytes (10 words)	48
 32	 76 bytes (19 words)	56 bytes (14 words)	8 (64 byte cacheline)
							72 (128 byte)

Remove the special statistics for numa and replace them with zoned vm
counters.  This has the side effect that global sums of these events now
show up in /proc/vmstat.

Also take the opportunity to move the zone_statistics() function from
page_alloc.c into vmstat.c.

Discussions:
V2 http://marc.theaimsgroup.com/?t=115048227000002&r=1&w=2Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Acked-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

No callers.

Cc: Christoph Lameter <clameter@engr.sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Remove writeback state

We can remove some functions now that were needed to calculate the page state
for writeback control since these statistics are now directly available.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Conversion of nr_bounce to a per zone counter

nr_bounce is only used for proc output.  So it could be left as an event
counter.  However, the event counters may not be accurate and nr_bounce is
categorizing types of pages in a zone.  So we really need this to also be a
per zone counter.

[akpm@osdl.org: bugfix]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Conversion of nr_unstable to a per zone counter

We need to do some special modifications to the nfs code since there are
multiple cases of disposition and we need to have a page ref for proper
accounting.

This converts the last critical page state of the VM and therefore we need to
remove several functions that were depending on GET_PAGE_STATE_LAST in order
to make the kernel compile again.  We are only left with event type counters
in page state.

[akpm@osdl.org: bugfixes]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Conversion of nr_writeback to per zone counter.

This removes the last page_state counter from arch/i386/mm/pgtable.c so we
drop the page_state from there.

[akpm@osdl.org: bugfix]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This makes nr_dirty a per zone counter.  Looping over all processors is
avoided during writeback state determination.

The counter aggregation for nr_dirty had to be undone in the NFS layer since
we summed up the page counts from multiple zones.  Someone more familiar with
NFS should probably review what I have done.

[akpm@osdl.org: bugfix]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Conversion of nr_page_table_pages to a per zone counter

[akpm@osdl.org: bugfix]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

- Allows reclaim to access counter without looping over processor counts.

- Allows accurate statistics on how many pages are used in a zone by
  the slab. This may become useful to balance slab allocations over
  various zones.

[akpm@osdl.org: bugfix]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The zone_reclaim_interval was necessary because we were not able to determine
how many unmapped pages exist in a zone.  Therefore we had to scan in
intervals to figure out if any pages were unmapped.

With the zoned counters and NR_ANON_PAGES we now know the number of pagecache
pages and the number of mapped pages in a zone.  So we can simply skip the
reclaim if there is an insufficient number of unmapped pages.  We use
SWAP_CLUSTER_MAX as the boundary.

Drop all support for /proc/sys/vm/zone_reclaim_interval.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The current NR_FILE_MAPPED is used by zone reclaim and the dirty load
calculation as the number of mapped pagecache pages.  However, that is not
true.  NR_FILE_MAPPED includes the mapped anonymous pages.  This patch
separates those and therefore allows an accurate tracking of the anonymous
pages per zone.

It then becomes possible to determine the number of unmapped pages per zone
and we can avoid scanning for unmapped pages if there are none.

Also it may now be possible to determine the mapped/unmapped ratio in
get_dirty_limit.  Isnt the number of anonymous pages irrelevant in that
calculation?

Note that this will change the meaning of the number of mapped pages reported
in /proc/vmstat /proc/meminfo and in the per node statistics.  This may affect
user space tools that monitor these counters!  NR_FILE_MAPPED works like
NR_FILE_DIRTY.  It is only valid for pagecache pages.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We can now access the number of pages in a mapped state in an inexpensive way
in shrink_active_list.  So drop the nr_mapped field from scan_control.

[akpm@osdl.org: bugfix]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Currently a single atomic variable is used to establish the size of the page
cache in the whole machine.  The zoned VM counters have the same method of
implementation as the nr_pagecache code but also allow the determination of
the pagecache size per zone.

Remove the special implementation for nr_pagecache and make it a zoned counter
named NR_FILE_PAGES.

Updates of the page cache counters are always performed with interrupts off.
We can therefore use the __ variant here.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

nr_mapped is important because it allows a determination of how many pages of
a zone are not mapped, which would allow a more efficient means of determining
when we need to reclaim memory in a zone.

We take the nr_mapped field out of the page state structure and define a new
per zone counter named NR_FILE_MAPPED (the anonymous pages will be split off
from NR_MAPPED in the next patch).

We replace the use of nr_mapped in various kernel locations.  This avoids the
looping over all processors in try_to_free_pages(), writeback, reclaim (swap +
zone reclaim).

[akpm@osdl.org: bugfix]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Per zone counter infrastructure

The counters that we currently have for the VM are split per processor.  The
processor however has not much to do with the zone these pages belong to.  We
cannot tell f.e.  how many ZONE_DMA pages are dirty.

So we are blind to potentially inbalances in the usage of memory in various
zones.  F.e.  in a NUMA system we cannot tell how many pages are dirty on a
particular node.  If we knew then we could put measures into the VM to balance
the use of memory between different zones and different nodes in a NUMA
system.  For example it would be possible to limit the dirty pages per node so
that fast local memory is kept available even if a process is dirtying huge
amounts of pages.

Another example is zone reclaim.  We do not know how many unmapped pages exist
per zone.  So we just have to try to reclaim.  If it is not working then we
pause and try again later.  It would be better if we knew when it makes sense
to reclaim unmapped pages from a zone.  This patchset allows the determination
of the number of unmapped pages per zone.  We can remove the zone reclaim
interval with the counters introduced here.

Futhermore the ability to have various usage statistics available will allow
the development of new NUMA balancing algorithms that may be able to improve
the decision making in the scheduler of when to move a process to another node
and hopefully will also enable automatic page migration through a user space
program that can analyse the memory load distribution and then rebalance
memory use in order to increase performance.

The counter framework here implements differential counters for each processor
in struct zone.  The differential counters are consolidated when a threshold
is exceeded (like done in the current implementation for nr_pageache), when
slab reaping occurs or when a consolidation function is called.

Consolidation uses atomic operations and accumulates counters per zone in the
zone structure and also globally in the vm_stat array.  VM functions can
access the counts by simply indexing a global or zone specific array.

The arrangement of counters in an array also simplifies processing when output
has to be generated for /proc/*.

Counters can be updated by calling inc/dec_zone_page_state or
_inc/dec_zone_page_state analogous to *_page_state.  The second group of
functions can be called if it is known that interrupts are disabled.

Special optimized increment and decrement functions are provided.  These can
avoid certain checks and use increment or decrement instructions that an
architecture may provide.

We also add a new CONFIG_DMA_IS_NORMAL that signifies that an architecture can
do DMA to all memory and therefore ZONE_NORMAL will not be populated.  This is
only currently set for IA64 SGI SN2 and currently only affects
node_page_state().  In the best case node_page_state can be reduced to
retrieving a single counter for the one zone on the node.

[akpm@osdl.org: cleanups]
[akpm@osdl.org: export vm_stat[] for filesystems]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

NOTE: ZVC are *not* the lightweight event counters.  ZVCs are reliable whereas
event counters do not need to be.

Zone based VM statistics are necessary to be able to determine what the state
of memory in one zone is.  In a NUMA system this can be helpful for local
reclaim and other memory optimizations that may be able to shift VM load in
order to get more balanced memory use.

It is also useful to know how the computing load affects the memory
allocations on various zones.  This patchset allows the retrieval of that data
from userspace.

The patchset introduces a framework for counters that is a cross between the
existing page_stats --which are simply global counters split per cpu-- and the
approach of deferred incremental updates implemented for nr_pagecache.

Small per cpu 8 bit counters are added to struct zone.  If the counter exceeds
certain thresholds then the counters are accumulated in an array of
atomic_long in the zone and in a global array that sums up all zone values.
The small 8 bit counters are next to the per cpu page pointers and so they
will be in high in the cpu cache when pages are allocated and freed.

Access to VM counter information for a zone and for the whole machine is then
possible by simply indexing an array (Thanks to Nick Piggin for pointing out
that approach).  The access to the total number of pages of various types does
no longer require the summing up of all per cpu counters.

Benefits of this patchset right now:

- Ability for UP and SMP configuration to determine how memory
  is balanced between the DMA, NORMAL and HIGHMEM zones.

- loops over all processors are avoided in writeback and
  reclaim paths. We can avoid caching the writeback information
  because the needed information is directly accessible.

- Special handling for nr_pagecache removed.

- zone_reclaim_interval vanishes since VM stats can now determine
  when it is worth to do local reclaim.

- Fast inline per node page state determination.

- Accurate counters in /sys/devices/system/node/node*/meminfo. Current
  counters are counting simply which processor allocated a page somewhere
  and guestimate based on that. So the counters were not useful to show
  the actual distribution of page use on a specific zone.

- The swap_prefetch patch requires per node statistics in order to
  figure out when processors of a node can prefetch. This patch provides
  some of the needed numbers.

- Detailed VM counters available in more /proc and /sys status files.

References to earlier discussions:
V1 http://marc.theaimsgroup.com/?l=linux-kernel&m=113511649910826&w=2
V2 http://marc.theaimsgroup.com/?l=linux-kernel&m=114980851924230&w=2
V3 http://marc.theaimsgroup.com/?l=linux-kernel&m=115014697910351&w=2
V4 http://marc.theaimsgroup.com/?l=linux-kernel&m=115024767318740&w=2

Performance tests with AIM7 did not show any regressions.  Seems to be a tad
faster even.  Tested on ia64/NUMA.  Builds fine on i386, SMP / UP.  Includes
fixes for s390/arm/uml arch code.

This patch:

Move counter code from page_alloc.c/page-flags.h to vmstat.c/h.

Create vmstat.c/vmstat.h by separating the counter code and the proc
functions.

Move the vm_stat_text array before zoneinfo_show.

[akpm@osdl.org: s390 build fix]
[akpm@osdl.org: HOTPLUG_CPU build fix]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NJörn Engel <joern@wohnheim.fh-wedel.de>
Signed-off-by: NAdrian Bunk <bunk@stusta.de>

Memory hotplug code of i386 adds memory to only highmem.  So, if
CONFIG_HIGHMEM is not set, CONFIG_MEMORY_HOTPLUG shouldn't be set.
Otherwise, it causes compile error.

In addition, many architecture can't use memory hotplug feature yet.  So, I
introduce CONFIG_ARCH_ENABLE_MEMORY_HOTPLUG.
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The recent generic_file_write() deadlock fix caused
generic_file_buffered_write() to loop inifinitely when presented with a
zero-length iovec segment.  Fix.

Note that this fix deliberately avoids calling ->prepare_write(),
->commit_write() etc with a zero-length write.  This is because I don't trust
all filesystems to get that right.

This is a cautious approach, for 2.6.17.x.  For 2.6.18 we should just go ahead
and call ->prepare_write() and ->commit_write() with the zero length and fix
any broken filesystems.  So I'll make that change once this code is stabilised
and backported into 2.6.17.x.

The reason for preferring to call ->prepare_write() and ->commit_write() with
the zero-length segment: a zero-length segment _should_ be sufficiently
uncommon that this is the correct way of handling it.  We don't want to
optimise for poorly-written userspace at the expense of well-written
userspace.

Cc: "Vladimir V. Saveliev" <vs@namesys.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Cc: Greg KH <greg@kroah.com>
Cc: <stable@kernel.org>
Cc: walt <wa1ter@myrealbox.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Same as with already do with the file operations: keep them in .rodata and
prevents people from doing runtime patching.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: Steven French <sfrench@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Runtime debugging functionality for rt-mutexes.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add debug_check_no_locks_freed(), as a central inline to add
bad-lock-free-debugging functionality to.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Make notifier_calls associated with cpu_notifier as __cpuinit.

__cpuinit makes sure that the function is init time only unless
CONFIG_HOTPLUG_CPU is defined.

[akpm@osdl.org: section fix]
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Make notifier_blocks associated with cpu_notifier as __cpuinitdata.

__cpuinitdata makes sure that the data is init time only unless
CONFIG_HOTPLUG_CPU is defined.
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

In 2.6.17, there was a problem with cpu_notifiers and XFS.  I provided a
band-aid solution to solve that problem.  In the process, i undid all the
changes you both were making to ensure that these notifiers were available
only at init time (unless CONFIG_HOTPLUG_CPU is defined).

We deferred the real fix to 2.6.18.  Here is a set of patches that fixes the
XFS problem cleanly and makes the cpu notifiers available only at init time
(unless CONFIG_HOTPLUG_CPU is defined).

If CONFIG_HOTPLUG_CPU is defined then cpu notifiers are available at run
time.

This patch reverts the notifier_call changes made in 2.6.17
Signed-off-by: NChandra Seetharaman <sekharan@us.ibm.com>
Cc: Ashok Raj <ashok.raj@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

generic_file_buffered_write() prefaults in user pages in order to avoid
deadlock on copying from the same page as write goes to.

However, it looks like there is a problem when write is vectored:
fault_in_pages_readable brings in current segment or its part (maxlen).
OTOH, filemap_copy_from_user_iovec is called to copy number of bytes
(bytes) which may exceed current segment, so filemap_copy_from_user_iovec
switches to the next segment which is not brought in yet.  Pagefault is
generated.  That causes the deadlock if pagefault is for the same page
write goes to: page being written is locked and not uptodate, pagefault
will deadlock trying to lock locked page.

[akpm@osdl.org: somewhat rewritten]
Cc: Neil Brown <neilb@suse.de>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

locking init cleanups:

 - convert " = SPIN_LOCK_UNLOCKED" to spin_lock_init() or DEFINE_SPINLOCK()
 - convert rwlocks in a similar manner

this patch was generated automatically.

Motivation:

 - cleanliness
 - lockdep needs control of lock initialization, which the open-coded
   variants do not give
 - it's also useful for -rt and for lock debugging in general
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Localize poison values into one header file for better documentation and
easier/quicker debugging and so that the same values won't be used for
multiple purposes.

Use these constants in core arch., mm, driver, and fs code.
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Acked-by: NMatt Mackall <mpm@selenic.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

When new node becomes enable by hot-add, new sysfs file must be created for
new node.  So, if new node is enabled by add_memory(), register_one_node() is
called to create it.  In addition, I386's arch_register_node() and a part of
register_nodes() of powerpc are consolidated to register_one_node() as a
generic_code().

This is tested by Tiger4(IPF) with node hot-plug emulation.
Signed-off-by: NKeiichiro Tokunaga <tokuanga.keiich@jp.fujitsu.com>
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix "undefined reference to `arch_add_memory'" on sparc64 allmodconfig.

sparc64 doesn't support memory hotplug.  But we want it to support
sparsemem.
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
Cc: "David S. Miller" <davem@davemloft.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch allows hot-add memory which is not aligned to section.

Now, hot-added memory has to be aligned to section size.  Considering big
section sized archs, this is not useful.

When hot-added memory is registerd as iomem resoruce by iomem resource
patch, we can make use of that information to detect valid memory range.

Note: With this, not-aligned memory can be registerd. To allow hot-add
      memory with holes, we have to do more work around add_memory().
      (It doesn't allows add memory to already existing mem section.)
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Register hot-added memory to iomem_resource.  With this, /proc/iomem can
show hot-added memory.

Note: kdump uses /proc/iomem to catch memory range when it is installed.
      So, kdump should be re-installed after /proc/iomem change.
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Vivek Goyal <vgoyal@in.ibm.com>
Cc: Greg KH <greg@kroah.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add node-hot-add support to add_memory().

node hotadd uses this sequence.
1. allocate pgdat.
2. refresh NODE_DATA()
3. call free_area_init_node() to initialize
4. create sysfs entry
5. add memory (old add_memory())
6. set node online
7. run kswapd for new node.
(8). update zonelist after pages are onlined. (This is already merged in -mm
   due to update phase is difference.)

Note:
  To make common function as much as possible,
  there is 2 changes from v2.
    - The old add_memory(), which is defiend by each archs,
      is renamed to arch_add_memory(). New add_memory becomes
      caller of arch dependent function as a common code.

    - This patch changes add_memory()'s interface
        From: add_memory(start, end)
        TO  : add_memory(nid, start, end).
      It was cause of similar code that finding node id from
      physical address is inside of old add_memory() on each arch.

      In addition, acpi memory hotplug driver can find node id easier.
      In v2, it must walk DSDT'S _CRS by matching physical address to
      get the handle of its memory device, then get _PXM and node id.
      Because input is just physical address.
      However, in v3, the acpi driver can use handle to get _PXM and node id
      for the new memory device. It can pass just node id to add_memory().

Fix interface of arch_add_memory() is in next patche.
Signed-off-by: NYasunori Goto     <y-goto@jp.fujitsu.com>
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: "Brown, Len" <len.brown@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

When node is hot-added, kswapd for the node should start.  This export kswapd
start function as kswapd_run() to use at add_memory().

[akpm@osdl.org: daemonize() isn't needed when using the kthread API]
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
Signed-off-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: "Brown, Len" <len.brown@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Change the name of old add_memory() to arch_add_memory.  And use node id to
get pgdat for the node at NODE_DATA().

Note: Powerpc's old add_memory() is defined as __devinit. However,
      add_memory() is usually called only after bootup.
      I suppose it may be redundant. But, I'm not well known about powerpc.
      So, I keep it. (But, __meminit is better at least.)
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: "Brown, Len" <len.brown@intel.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>