CONFIG_DEBUG_SPINLOCK adds 12 or 16 bytes to a 32- or 64-bit spinlock_t,
and CONFIG_DEBUG_LOCK_ALLOC adds another 12 or 24 bytes to it: lockdep
enables both of those, and CONFIG_LOCK_STAT adds 8 or 16 bytes to that.

When 2.6.15 placed the split page table lock inside struct page (usually
sized 32 or 56 bytes), only CONFIG_DEBUG_SPINLOCK was a possibility, and
we ignored the enlargement (but fitted in CONFIG_GENERIC_LOCKBREAK's 4 by
letting the spinlock_t occupy both page->private and page->mapping).

Should these debugging options be allowed to double the size of a struct
page, when only one minority use of the page (as a page table) needs to
fit a spinlock in there?  Perhaps not.

Take the easy way out: switch off SPLIT_PTLOCK_CPUS when DEBUG_SPINLOCK or
DEBUG_LOCK_ALLOC is in force.  I've sometimes tried to be cleverer,
kmallocing a cacheline for the spinlock when it doesn't fit, but given up
each time.  Falling back to mm->page_table_lock (as we do when ptlock is
not split) lets lockdep check out the strictest path anyway.

And now that some arches allow 8192 cpus, use 999999 for infinity.

(What has this got to do with KSM swapping?  It doesn't care about the
size of struct page, but may care about random junk in page->mapping - to
be explained separately later.)
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

KSM swapping will know where page_referenced_one() and try_to_unmap_one()
should look.  It could hack page->index to get them to do what it wants,
but it seems cleaner now to pass the address down to them.

Make the same change to page_mkclean_one(), since it follows the same
pattern; but there's no real need in its case.
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove three degrees of obfuscation, left over from when we had
CONFIG_UNEVICTABLE_LRU.  MLOCK_PAGES is CONFIG_HAVE_MLOCKED_PAGE_BIT is
CONFIG_HAVE_MLOCK is CONFIG_MMU.  rmap.o (and memory-failure.o) are only
built when CONFIG_MMU, so don't need such conditions at all.

Somehow, I feel no compulsion to remove the CONFIG_HAVE_MLOCK* lines from
169 defconfigs: leave those to evolve in due course.
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There's contorted mlock/munlock handling in try_to_unmap_anon() and
try_to_unmap_file(), which we'd prefer not to repeat for KSM swapping.
Simplify it by moving it all down into try_to_unmap_one().

One thing is then lost, try_to_munlock()'s distinction between when no vma
holds the page mlocked, and when a vma does mlock it, but we could not get
mmap_sem to set the page flag.  But its only caller takes no interest in
that distinction (and is better testing SWAP_MLOCK anyway), so let's keep
the code simple and return SWAP_AGAIN for both cases.

try_to_unmap_file()'s TTU_MUNLOCK nonlinear handling was particularly
amusing: once unravelled, it turns out to have been choosing between two
different ways of doing the same nothing.  Ah, no, one way was actually
returning SWAP_FAIL when it meant to return SWAP_SUCCESS.

[kosaki.motohiro@jp.fujitsu.com: comment adding to mlocking in try_to_unmap_one]
[akpm@linux-foundation.org: remove test of MLOCK_PAGES]
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

At present we define PageAnon(page) by the low PAGE_MAPPING_ANON bit set
in page->mapping, with the higher bits a pointer to the anon_vma; and have
defined PageKsm(page) as that with NULL anon_vma.

But KSM swapping will need to store a pointer there: so in preparation for
that, now define PAGE_MAPPING_FLAGS as the low two bits, including
PAGE_MAPPING_KSM (always set along with PAGE_MAPPING_ANON, until some
other use for the bit emerges).

Declare page_rmapping(page) to return the pointer part of page->mapping,
and page_anon_vma(page) to return the anon_vma pointer when that's what it
is.  Use these in a few appropriate places: notably, unuse_vma() has been
testing page->mapping, but is better to be testing page_anon_vma() (cases
may be added in which flag bits are set without any pointer).
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Izik Eidus <ieidus@redhat.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Minchan Kim <minchan.kim@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If reclaim fails to make sufficient progress, the priority is raised.
Once the priority is higher, kswapd starts waiting on congestion.
However, if the zone is below the min watermark then kswapd needs to
continue working without delay as there is a danger of an increased rate
of GFP_ATOMIC allocation failure.

This patch changes the conditions under which kswapd waits on congestion
by only going to sleep if the min watermarks are being met.

[mel@csn.ul.ie: add stats to track how relevant the logic is]
[mel@csn.ul.ie: make kswapd only check its own zones and rename the relevant counters]
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Reviewed-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

After kswapd balances all zones in a pgdat, it goes to sleep.  In the
event of no IO congestion, kswapd can go to sleep very shortly after the
high watermark was reached.  If there are a constant stream of allocations
from parallel processes, it can mean that kswapd went to sleep too quickly
and the high watermark is not being maintained for sufficient length time.

This patch makes kswapd go to sleep as a two-stage process.  It first
tries to sleep for HZ/10.  If it is woken up by another process or the
high watermark is no longer met, it's considered a premature sleep and
kswapd continues work.  Otherwise it goes fully to sleep.

This adds more counters to distinguish between fast and slow breaches of
watermarks.  A "fast" premature sleep is one where the low watermark was
hit in a very short time after kswapd going to sleep.  A "slow" premature
sleep indicates that the high watermark was breached after a very short
interval.
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Cc: Frans Pop <elendil@planet.nl>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When the code jumps to the `out', `referenced' is still zero.  So there is
no need to check it.
Signed-off-by: NHuang Shijie <shijie8@gmail.com>
Acked-by: NWu Fengguang <fengguang.wu@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Just simplify the code when `mlocked' is true.
Signed-off-by: NHuang Shijie <shijie8@gmail.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix the comment for try_to_unmap_anon() with the new arguments.
Signed-off-by: NHuang Shijie <shijie8@gmail.com>
Acked-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Commit 543ade1f ("Streamline generic_file_* interfaces and filemap
cleanups") removed generic_file_write() in filemap.  Change the comment in
vmscan pageout() to __generic_file_aio_write().
Signed-off-by: NVincent Li <macli@brc.ubc.ca>
Cc: Christoph Hellwig <hch@lst.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Seems that page_io.c doesn't really need to know that page_private(page)
is the swp_entry 'val'.  Rework map_swap_page() to do what its name says
and map a page to a page offset in the swap space.

The only other caller of map_swap_page() is internal to mm/swapfile.c and
it does want to map a swap entry to the 'sector'.  So rename
map_swap_page() to map_swap_entry(), make it 'static' and and implement
map_swap_page() as a wrapper around that.
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

While we're fiddling with the swap_map values, let's assign a particular
value to shmem/tmpfs swap pages: their swap counts are never incremented,
and it helps swapoff's try_to_unuse() a little if it can immediately
distinguish those pages from process pages.

Since we've no use for SWAP_MAP_BAD | COUNT_CONTINUED,
we might as well use that 0xbf value for SWAP_MAP_SHMEM.
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Swap is duplicated (reference count incremented by one) whenever the same
swap page is inserted into another mm (when forking finds a swap entry in
place of a pte, or when reclaim unmaps a pte to insert the swap entry).

swap_info_struct's vmalloc'ed swap_map is the array of these reference
counts: but what happens when the unsigned short (or unsigned char since
the preceding patch) is full? (and its high bit is kept for a cache flag)

We then lose track of it, never freeing, leaving it in use until swapoff:
at which point we _hope_ that a single pass will have found all instances,
assume there are no more, and will lose user data if we're wrong.

Swapping of KSM pages has not yet been enabled; but it is implemented,
and makes it very easy for a user to overflow the maximum swap count:
possible with ordinary process pages, but unlikely, even when pid_max
has been raised from PID_MAX_DEFAULT.

This patch implements swap count continuations: when the count overflows,
a continuation page is allocated and linked to the original vmalloc'ed
map page, and this used to hold the continuation counts for that entry
and its neighbours.  These continuation pages are seldom referenced:
the common paths all work on the original swap_map, only referring to
a continuation page when the low "digit" of a count is incremented or
decremented through SWAP_MAP_MAX.
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Halve the vmalloc'ed swap_map array from unsigned shorts to unsigned
chars: it's still very unusual to reach a swap count of 126, and the
next patch allows it to be extended indefinitely.
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Though swap_count() is useful, I'm finding that swap_has_cache() and
encode_swapmap() obscure what happens in the swap_map entry, just at
those points where I need to understand it.  Remove them, and pass
more usable "usage" values to scan_swap_map(), swap_entry_free() and
__swap_duplicate(), instead of the SWAP_MAP and SWAP_CACHE enum.
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move CONFIG_HIBERNATION's swapdev_block() into the main CONFIG_HIBERNATION
block, remove extraneous whitespace and return, fix typo in a comment.
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make better use of the space by folding first swap_extent into its
swap_info_struct, instead of just the list_head: swap partitions need
only that one, and for others it's used as a circular list anyway.

[jirislaby@gmail.com: fix crash on double swapon]
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NJiri Slaby <jirislaby@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The swap_info_struct is only 76 or 104 bytes, but it does seem wrong
to reserve an array of about 30 of them in bss, when most people will
want only one.  Change swap_info[] to an array of pointers.

That does need a "type" field in the structure: pack it as a char with
next type and short prio (aha, char is unsigned by default on PowerPC).
Use the (admittedly peculiar) name "type" throughout for this index.

/proc/swaps does not take swap_lock: I wouldn't want it to, but do take
care with barriers when adding a new item to the array (never removed).
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Reviewed-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The swap_info_struct is mostly private to mm/swapfile.c, with only
one other in-tree user: get_swap_bio().  Adjust its interface to
map_swap_page(), so that we can then remove get_swap_info_struct().

But there is a popular user out-of-tree, TuxOnIce: so leave the
declaration of swap_info_struct in linux/swap.h.
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Nigel Cunningham <ncunningham@crca.org.au>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

- avoid wasting more precious resources (DMA or DMA32 pools), when
  being called through vmalloc_32{,_user}()
- explicitly allow using high memory here even if the outer allocation
  request doesn't allow it
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Acked-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Objects passed to NODEMASK_ALLOC() are relatively small in size and are
backed by slab caches that are not of large order, traditionally never
greater than PAGE_ALLOC_COSTLY_ORDER.

Thus, using GFP_KERNEL for these allocations on large machines when
CONFIG_NODES_SHIFT > 8 will cause the page allocator to loop endlessly in
the allocation attempt, each time invoking both direct reclaim or the oom
killer.

This is of particular interest when using NODEMASK_ALLOC() from a
mempolicy context (either directly in mm/mempolicy.c or the mempolicy
constrained hugetlb allocations) since the oom killer always kills current
when allocations are constrained by mempolicies.  So for all present use
cases in the kernel, current would end up being oom killed when direct
reclaim fails.  That would allow the NODEMASK_ALLOC() to succeed but
current would have sacrificed itself upon returning.

This patch adds gfp flags to NODEMASK_ALLOC() to pass to kmalloc() on
CONFIG_NODES_SHIFT > 8; this parameter is a nop on other configurations.
All current use cases either directly from hugetlb code or indirectly via
NODEMASK_SCRATCH() union __GFP_NORETRY to avoid direct reclaim and the oom
killer when the slab allocator needs to allocate additional pages.

The side-effect of this change is that all current use cases of either
NODEMASK_ALLOC() or NODEMASK_SCRATCH() need appropriate -ENOMEM handling
when the allocation fails (never for CONFIG_NODES_SHIFT <= 8).  All
current use cases were audited and do have appropriate error handling at
this time.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When memory is hot-removed, its node must be cleared in N_HIGH_MEMORY if
there are no present pages left.

In such a situation, kswapd must also be stopped since it has nothing left
to do.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Rik van Riel <riel@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Register per node hstate sysfs attributes only for nodes with memory.
Global replacement of 'all online nodes" with "all nodes with memory" in
mm/hugetlb.c.  Suggested by David Rientjes.

A subsequent patch will handle adding/removing of per node hstate sysfs
attributes when nodes transition to/from memoryless state via memory
hotplug.

NOTE: this patch has not been tested with memoryless nodes.
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Reviewed-by: NAndi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add the per huge page size control/query attributes to the per node
sysdevs:

/sys/devices/system/node/node<ID>/hugepages/hugepages-<size>/
	nr_hugepages       - r/w
	free_huge_pages    - r/o
	surplus_huge_pages - r/o

The patch attempts to re-use/share as much of the existing global hstate
attribute initialization and handling, and the "nodes_allowed" constraint
processing as possible.

Calling set_max_huge_pages() with no node indicates a change to global
hstate parameters.  In this case, any non-default task mempolicy will be
used to generate the nodes_allowed mask.  A valid node id indicates an
update to that node's hstate parameters, and the count argument specifies
the target count for the specified node.  From this info, we compute the
target global count for the hstate and construct a nodes_allowed node mask
contain only the specified node.

Setting the node specific nr_hugepages via the per node attribute
effectively ignores any task mempolicy or cpuset constraints.

With this patch:

(me):ls /sys/devices/system/node/node0/hugepages/hugepages-2048kB
./  ../  free_hugepages  nr_hugepages  surplus_hugepages

Starting from:
Node 0 HugePages_Total:     0
Node 0 HugePages_Free:      0
Node 0 HugePages_Surp:      0
Node 1 HugePages_Total:     0
Node 1 HugePages_Free:      0
Node 1 HugePages_Surp:      0
Node 2 HugePages_Total:     0
Node 2 HugePages_Free:      0
Node 2 HugePages_Surp:      0
Node 3 HugePages_Total:     0
Node 3 HugePages_Free:      0
Node 3 HugePages_Surp:      0
vm.nr_hugepages = 0

Allocate 16 persistent huge pages on node 2:
(me):echo 16 >/sys/devices/system/node/node2/hugepages/hugepages-2048kB/nr_hugepages

[Note that this is equivalent to:
	numactl -m 2 hugeadmin --pool-pages-min 2M:+16
]

Yields:
Node 0 HugePages_Total:     0
Node 0 HugePages_Free:      0
Node 0 HugePages_Surp:      0
Node 1 HugePages_Total:     0
Node 1 HugePages_Free:      0
Node 1 HugePages_Surp:      0
Node 2 HugePages_Total:    16
Node 2 HugePages_Free:     16
Node 2 HugePages_Surp:      0
Node 3 HugePages_Total:     0
Node 3 HugePages_Free:      0
Node 3 HugePages_Surp:      0
vm.nr_hugepages = 16

Global controls work as expected--reduce pool to 8 persistent huge pages:
(me):echo 8 >/sys/kernel/mm/hugepages/hugepages-2048kB/nr_hugepages

Node 0 HugePages_Total:     0
Node 0 HugePages_Free:      0
Node 0 HugePages_Surp:      0
Node 1 HugePages_Total:     0
Node 1 HugePages_Free:      0
Node 1 HugePages_Surp:      0
Node 2 HugePages_Total:     8
Node 2 HugePages_Free:      8
Node 2 HugePages_Surp:      0
Node 3 HugePages_Total:     0
Node 3 HugePages_Free:      0
Node 3 HugePages_Surp:      0
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Reviewed-by: NAndi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch derives a "nodes_allowed" node mask from the numa mempolicy of
the task modifying the number of persistent huge pages to control the
allocation, freeing and adjusting of surplus huge pages when the pool page
count is modified via the new sysctl or sysfs attribute
"nr_hugepages_mempolicy".  The nodes_allowed mask is derived as follows:

* For "default" [NULL] task mempolicy, a NULL nodemask_t pointer
  is produced.  This will cause the hugetlb subsystem to use
  node_online_map as the "nodes_allowed".  This preserves the
  behavior before this patch.
* For "preferred" mempolicy, including explicit local allocation,
  a nodemask with the single preferred node will be produced.
  "local" policy will NOT track any internode migrations of the
  task adjusting nr_hugepages.
* For "bind" and "interleave" policy, the mempolicy's nodemask
  will be used.
* Other than to inform the construction of the nodes_allowed node
  mask, the actual mempolicy mode is ignored.  That is, all modes
  behave like interleave over the resulting nodes_allowed mask
  with no "fallback".

See the updated documentation [next patch] for more information
about the implications of this patch.

Examples:

Starting with:

	Node 0 HugePages_Total:     0
	Node 1 HugePages_Total:     0
	Node 2 HugePages_Total:     0
	Node 3 HugePages_Total:     0

Default behavior [with or without this patch] balances persistent
hugepage allocation across nodes [with sufficient contiguous memory]:

	sysctl vm.nr_hugepages[_mempolicy]=32

yields:

	Node 0 HugePages_Total:     8
	Node 1 HugePages_Total:     8
	Node 2 HugePages_Total:     8
	Node 3 HugePages_Total:     8

Of course, we only have nr_hugepages_mempolicy with the patch,
but with default mempolicy, nr_hugepages_mempolicy behaves the
same as nr_hugepages.

Applying mempolicy--e.g., with numactl [using '-m' a.k.a.
'--membind' because it allows multiple nodes to be specified
and it's easy to type]--we can allocate huge pages on
individual nodes or sets of nodes.  So, starting from the
condition above, with 8 huge pages per node, add 8 more to
node 2 using:

	numactl -m 2 sysctl vm.nr_hugepages_mempolicy=40

This yields:

	Node 0 HugePages_Total:     8
	Node 1 HugePages_Total:     8
	Node 2 HugePages_Total:    16
	Node 3 HugePages_Total:     8

The incremental 8 huge pages were restricted to node 2 by the
specified mempolicy.

Similarly, we can use mempolicy to free persistent huge pages
from specified nodes:

	numactl -m 0,1 sysctl vm.nr_hugepages_mempolicy=32

yields:

	Node 0 HugePages_Total:     4
	Node 1 HugePages_Total:     4
	Node 2 HugePages_Total:    16
	Node 3 HugePages_Total:     8

The 8 huge pages freed were balanced over nodes 0 and 1.

[rientjes@google.com: accomodate reworked NODEMASK_ALLOC]
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Reviewed-by: NAndi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In preparation for constraining huge page allocation and freeing by the
controlling task's numa mempolicy, add a "nodes_allowed" nodemask pointer
to the allocate, free and surplus adjustment functions.  For now, pass
NULL to indicate default behavior--i.e., use node_online_map.  A
subsqeuent patch will derive a non-default mask from the controlling
task's numa mempolicy.

Note that this method of updating the global hstate nr_hugepages under the
constraint of a nodemask simplifies keeping the global state
consistent--especially the number of persistent and surplus pages relative
to reservations and overcommit limits.  There are undoubtedly other ways
to do this, but this works for both interfaces: mempolicy and per node
attributes.

[rientjes@google.com: fix HIGHMEM compile error]
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Reviewed-by: NMel Gorman <mel@csn.ul.ie>
Acked-by: NDavid Rientjes <rientjes@google.com>
Reviewed-by: NAndi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Modify the hstate_next_node* functions to allow them to be called to
obtain the "start_nid".  Then, whereas prior to this patch we
unconditionally called hstate_next_node_to_{alloc|free}(), whether or not
we successfully allocated/freed a huge page on the node, now we only call
these functions on failure to alloc/free to advance to next allowed node.

Factor out the next_node_allowed() function to handle wrap at end of
node_online_map.  In this version, the allowed nodes include all of the
online nodes.
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Reviewed-by: NMel Gorman <mel@csn.ul.ie>
Acked-by: NDavid Rientjes <rientjes@google.com>
Reviewed-by: NAndi Kleen <andi@firstfloor.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Nishanth Aravamudan <nacc@us.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Adam Litke <agl@us.ibm.com>
Cc: Andy Whitcroft <apw@canonical.com>
Cc: Eric Whitney <eric.whitney@hp.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Christoph pointed out inc_zone_page_state(NR_ISOLATED) should be placed
in right after isolate_page().

This patch does it.
Reviewed-by: NChristoph Lameter <cl@linux-foundation.org>
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

On ia64, the following test program exit abnormally, because glibc thread
library called abort().

 ========================================================
 (gdb) bt
 #0  0xa000000000010620 in __kernel_syscall_via_break ()
 #1  0x20000000003208e0 in raise () from /lib/libc.so.6.1
 #2  0x2000000000324090 in abort () from /lib/libc.so.6.1
 #3  0x200000000027c3e0 in __deallocate_stack () from /lib/libpthread.so.0
 #4  0x200000000027f7c0 in start_thread () from /lib/libpthread.so.0
 #5  0x200000000047ef60 in __clone2 () from /lib/libc.so.6.1
 ========================================================

The fact is, glibc call munmap() when thread exitng time for freeing
stack, and it assume munlock() never fail.  However, munmap() often make
vma splitting and it with many mapcount make -ENOMEM.

Oh well, that's crazy, because stack unmapping never increase mapcount.
The maxcount exceeding is only temporary.  internal temporary exceeding
shouldn't make ENOMEM.

This patch does it.

 test_max_mapcount.c
 ==================================================================
  #include<stdio.h>
  #include<stdlib.h>
  #include<string.h>
  #include<pthread.h>
  #include<errno.h>
  #include<unistd.h>

  #define THREAD_NUM 30000
  #define MAL_SIZE (8*1024*1024)

 void *wait_thread(void *args)
 {
 	void *addr;

 	addr = malloc(MAL_SIZE);
 	sleep(10);

 	return NULL;
 }

 void *wait_thread2(void *args)
 {
 	sleep(60);

 	return NULL;
 }

 int main(int argc, char *argv[])
 {
 	int i;
 	pthread_t thread[THREAD_NUM], th;
 	int ret, count = 0;
 	pthread_attr_t attr;

 	ret = pthread_attr_init(&attr);
 	if(ret) {
 		perror("pthread_attr_init");
 	}

 	ret = pthread_attr_setdetachstate(&attr, PTHREAD_CREATE_DETACHED);
 	if(ret) {
 		perror("pthread_attr_setdetachstate");
 	}

 	for (i = 0; i < THREAD_NUM; i++) {
 		ret = pthread_create(&th, &attr, wait_thread, NULL);
 		if(ret) {
 			fprintf(stderr, "[%d] ", count);
 			perror("pthread_create");
 		} else {
 			printf("[%d] create OK.\n", count);
 		}
 		count++;

 		ret = pthread_create(&thread[i], &attr, wait_thread2, NULL);
 		if(ret) {
 			fprintf(stderr, "[%d] ", count);
 			perror("pthread_create");
 		} else {
 			printf("[%d] create OK.\n", count);
 		}
 		count++;
 	}

 	sleep(3600);
 	return 0;
 }
 ==================================================================

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The oom killer header, including information such as the allocation order
and gfp mask, current's cpuset and memory controller, call trace, and VM
state information is currently only shown when the oom killer has selected
a task to kill.

This information is omitted, however, when the oom killer panics either
because of panic_on_oom sysctl settings or when no killable task was
found.  It is still relevant to know crucial pieces of information such as
the allocation order and VM state when diagnosing such issues, especially
at boot.

This patch displays the oom killer header whenever it panics so that bug
reports can include pertinent information to debug the issue, if possible.
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Slightly adjust the logic for determining the size of the
copy_form_user() in do_pages_stat(); with this change, gcc can see
that the copying is safe.

Without this, we get a build error for i386 allyesconfig:

/home/hpa/kernel/linux-2.6-tip.urgent/arch/x86/include/asm/uaccess_32.h:213:
error: call to ‘copy_from_user_overflow’ declared with attribute
error: copy_from_user() buffer size is not provably correct

Unlike an earlier patch from Arjan, this doesn't introduce new
variables; merely reshuffles the compare so that gcc can see that an
overflow cannot happen.
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>
Cc: Brice Goglin <Brice.Goglin@inria.fr>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
LKML-Reference: <20090926205406.30d55b08@infradead.org>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Acked-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

New helper - sys_mmap_pgoff(); switch syscalls to using it.
Acked-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Acked-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Acked-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Take the check for being able to expand vma in place into a separate
helper.
Acked-by: NRussell King <rmk+kernel@arm.linux.org.uk>
Acked-by: NHugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>