2.6.16-rc3 uses hugetlb on-demand paging, but it doesn_t support hugetlb
mprotect.

From: David Gibson <david@gibson.dropbear.id.au>

  Remove a test from the mprotect() path which checks that the mprotect()ed
  range on a hugepage VMA is hugepage aligned (yes, really, the sense of
  is_aligned_hugepage_range() is the opposite of what you'd guess :-/).

  In fact, we don't need this test.  If the given addresses match the
  beginning/end of a hugepage VMA they must already be suitably aligned.  If
  they don't, then mprotect_fixup() will attempt to split the VMA.  The very
  first test in split_vma() will check for a badly aligned address on a
  hugepage VMA and return -EINVAL if necessary.

From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>

  On i386 and x86-64, pte flag _PAGE_PSE collides with _PAGE_PROTNONE.  The
  identify of hugetlb pte is lost when changing page protection via mprotect.
  A page fault occurs later will trigger a bug check in huge_pte_alloc().

  The fix is to always make new pte a hugetlb pte and also to clean up
  legacy code where _PAGE_PRESENT is forced on in the pre-faulting day.
Signed-off-by: NZhang Yanmin <yanmin.zhang@intel.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: NKen Chen <kenneth.w.chen@intel.com>
Signed-off-by: NNishanth Aravamudan <nacc@us.ibm.com>
Cc: Andi Kleen <ak@muc.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The current current get_init_ra_size is not optimal across different IO
sizes and max_readahead values.  Here is a quick summary of sizes computed
under current design and under the attached patch.  All of these assume 1st
IO at offset 0, or 1st detected sequential IO.

	32k max, 4k request

	old         new
	-----------------
	 8k        8k
	16k       16k
	32k       32k

	128k max, 4k request
	old         new
	-----------------
	32k         16k
	64k         32k
	128k        64k
	128k       128k

	128k max, 32k request
	old         new
	-----------------
	32k         64k    <-----
	64k        128k
	128k       128k

	512k max, 4k request
	old         new
	-----------------
	4k         32k     <----
	16k        64k
	64k       128k
	128k      256k
	512k      512k

Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.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>

If get_next_ra_size() does not grow fast enough, ->prev_page can overrun
the ahead window.  This means the caller will read the pages from
->ahead_start + ->ahead_size to ->prev_page synchronously.
Signed-off-by: NOleg Nesterov <oleg@tv-sign.ru>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.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>

shmem.c was named and shamed in Jesper's "Building 100 kernels" warnings:
shmem_parse_mpol is only used when CONFIG_TMPFS parses mount options; and
only called from that one site, so mark it inline like its non-NUMA stub.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

As suggested by Marcelo:

1. The optimization introduced recently for not calling
   page_referenced() during zone reclaim makes two additional checks in
   shrink_list unnecessary.

2. The if (unlikely(sc->may_swap)) in refill_inactive_zone is optimized
   for the zone_reclaim case.  However, most peoples system only does swap.
   Undo that.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Marcelo Tosatti <marcelo.tosatti@cyclades.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Remove the inlining of the new vs old mmap system call common code.  This
reduces the size of the resulting vmlinux for defconfig as follows:

mb@pc1:~/develop/git/linux-2.6$ size vmlinux.mmap*
   text    data     bss     dec     hex filename
3303749  521524  186564 4011837  3d373d vmlinux.mmapinline
3303557  521524  186564 4011645  3d367d vmlinux.mmapnoinline

The new sys_mmap2() has also one function call overhead removed, now.
(probably it was already optimized to a jmp before, but anyway...)
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Optimise page_count compound page test and make it consistent with similar
functions.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Put a few more checks under CONFIG_DEBUG_VM
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

prep_zero_page() uses KM_USER0 and hence may not be used from IRQ context, at
least for highmem pages.

Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Move the prep_ stuff into prep_new_page.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

set_page_count usage outside mm/ is limited to setting the refcount to 1.
Remove set_page_count from outside mm/, and replace those users with
init_page_count() and set_page_refcounted().

This allows more debug checking, and tighter control on how code is allowed
to play around with page->_count.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

A couple of places set_page_count(page, 1) that don't need to.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Now that compound page handling is properly fixed in the VM, move nommu
over to using compound pages rather than rolling their own refcounting.

nommu vm page refcounting is broken anyway, but there is no need to have
divergent code in the core VM now, nor when it gets fixed.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Cc: David Howells <dhowells@redhat.com>

(Needs testing, please).
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Remove __put_page from outside the core mm/.  It is dangerous because it does
not handle compound pages nicely, and misses 1->0 transitions.  If a user
later appears that really needs the extra speed we can reevaluate.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Remove page_count and __put_page from x86-64 pageattr
Signed-off-by: NNick Piggin <npiggin@suse.de>
Acked-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Use page->lru.next to implement the singly linked list of pages rather than
the struct deferred_page which needs to be allocated and freed for each
page.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Acked-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Stop using __put_page and page_count in i386 pageattr.c
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

sg increments the refcount of constituent pages in its higher order memory
allocations when they are about to be mapped by userspace.  This is done so
the subsequent get_page/put_page when doing the mapping and unmapping does not
free the page.

Move over to the preferred way, that is, using compound pages instead.  This
fixes a whole class of possible obscure bugs where a get_user_pages on a
constituent page may outlast the user mappings or even the driver.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Douglas Gilbert <dougg@torque.net>
Cc: James Bottomley <James.Bottomley@steeleye.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Now that it's madvisable, remove two pieces of VM_DONTCOPY bogosity:

1. There was and is no logical reason why VM_DONTCOPY should be in the
   list of flags which forbid vma merging (and those drivers which set
   it are also setting VM_IO, which itself forbids the merge).

2. It's hard to understand the purpose of the VM_HUGETLB, VM_DONTCOPY
   block in vm_stat_account: but never mind, it's under CONFIG_HUGETLB,
   which (unlike CONFIG_HUGETLB_PAGE or CONFIG_HUGETLBFS) has never been
   defined.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

In shrink_inactive_list(), nr_scan is not accounted when nr_taken is 0.
But 0 pages taken does not mean 0 pages scanned.

Move the goto statement below the accounting code to fix it.
Signed-off-by: NWu Fengguang <wfg@mail.ustc.edu.cn>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

In isolate_lru_pages(), *scanned reports one more scan because the scan
counter is increased one more time on exit of the while-loop.

Change the while-loop to for-loop to fix it.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NWu Fengguang <wfg@mail.ustc.edu.cn>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Add some comments to explain how zone reclaim works.  And it fixes the
following issues:

- PF_SWAPWRITE needs to be set for RECLAIM_SWAP to be able to write
  out pages to swap. Currently RECLAIM_SWAP may not do that.

- remove setting nr_reclaimed pages after slab reclaim since the slab shrinking
  code does not use that and the nr_reclaimed pages is just right for the
  intended follow up action.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We have:

	try_to_free_pages
	->shrink_caches(struct zone **zones, ..)
	  ->shrink_zone(struct zone *, ...)
	    ->shrink_cache(struct zone *, ...)
	      ->shrink_list(struct list_head *, ...)
	    ->refill_inactive_list((struct zone *, ...)

which is fairly irrational.

Rename things so that we have

 	try_to_free_pages
 	->shrink_zones(struct zone **zones, ..)
 	  ->shrink_zone(struct zone *, ...)
 	    ->shrink_inactive_list(struct zone *, ...)
 	      ->shrink_page_list(struct list_head *, ...)
	    ->shrink_active_list(struct zone *, ...)

Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Change all the vmscan functions to retunr the number-of-reclaimed pages and
remove scan_conrtol.nr_reclaimed.

Saves ten-odd bytes of text and makes things clearer and more consistent.

The patch also changes the behaviour of zone_reclaim() when it falls back to slab shrinking.  Christoph says

  "Setting this to one means that we will rescan and shrink the slab for
  each allocation if we are out of zone memory and RECLAIM_SLAB is set.  Plus
  if we do an order 0 allocation we do not go off node as intended.

  "We better set this to zero.  This means the allocation will go offnode
  despite us having potentially freed lots of memory on the zone.  Future
  allocations can then again be done from this zone."

Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Turn basically everything in vmscan.c into `unsigned long'.  This is to avoid
the possibility that some piece of code in there might decide to operate upon
more than 4G (or even 2G) of pages in one hit.

This might be silly, but we'll need it one day.

Cc: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Initialise as much of scan_control as possible at the declaration site.  This
tidies things up a bit and assures us that all unmentioned fields are zeroed
out.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Make nr_to_scan and priority a parameter instead of putting it into scan
control.  This allows various small optimizations and IMHO makes the code
easier to read.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Slab duplicates on_each_cpu().
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

When on_each_cpu() runs the callback on other CPUs, it runs with local
interrupts disabled.  So we should run the function with local interrupts
disabled on this CPU, too.

And do the same for UP, so the callback is run in the same environment on both
UP and SMP.  (strictly it should do preempt_disable() too, but I think
local_irq_disable is sufficiently equivalent).

Also uninlines on_each_cpu().  softirq.c was the most appropriate file I could
find, but it doesn't seem to justify creating a new file.

Oh, and fix up that comment over (under?) x86's smp_call_function().  It
drives me nuts.
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

SLAB_NO_REAP is documented as an option that will cause this slab not to be
reaped under memory pressure.  However, that is not what happens.  The only
thing that SLAB_NO_REAP controls at the moment is the reclaim of the unused
slab elements that were allocated in batch in cache_reap().  Cache_reap()
is run every few seconds independently of memory pressure.

Could we remove the whole thing?  Its only used by three slabs anyways and
I cannot find a reason for having this option.

There is an additional problem with SLAB_NO_REAP.  If set then the recovery
of objects from alien caches is switched off.  Objects not freed on the
same node where they were initially allocated will only be reused if a
certain amount of objects accumulates from one alien node (not very likely)
or if the cache is explicitly shrunk.  (Strangely __cache_shrink does not
check for SLAB_NO_REAP)

Getting rid of SLAB_NO_REAP fixes the problems with alien cache freeing.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix kernel-doc warnings in mm/slab.c.
Signed-off-by: NRandy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We have struct kmem_cache now so use it instead of the old typedef.
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Remove cachep->spinlock.  Locking has moved to the kmem_list3 and most of
the structures protected earlier by cachep->spinlock is now protected by
the l3->list_lock.  slab cache tunables like batchcount are accessed always
with the cache_chain_mutex held.

Patch tested on SMP and NUMA kernels with dbench processes running,
constant onlining/offlining, and constant cache tuning, all at the same
time.
Signed-off-by: NRavikiran Thirumalai <kiran@scalex86.org>
Cc: Christoph Lameter <christoph@lameter.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Manfred Spraul <manfred@colorfullife.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

slab.c has become a bit revolting again.  Try to repair it.

- Coding style fixes

- Don't do assignments-in-if-statements.

- Don't typecast assignments to/from void*
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Extract setup_cpu_cache() function from kmem_cache_create() to make the
latter a little less complex.
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Clean up the object to index mapping that has been spread around mm/slab.c.
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Since size_t has the same size as a long on all architectures, it's enough
for overflow checks to check against ULONG_MAX.

This change could allow a compiler better optimization (especially in the
n=1 case).

The practical effect seems to be positive, but quite small:

    text           data     bss      dec            hex filename
21762380        5859870 1848928 29471178        1c1b1ca vmlinux-old
21762211        5859870 1848928 29471009        1c1b121 vmlinux-patched
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Insert "fresh" huge pages into the hugepage allocator by the same means as
they are freed back into it.  This reduces code size and allows
enqueue_huge_page to be inlined into the hugepage free fastpath.

Eliminate occurances of hugepages on the free list with non-zero refcount.
This can allow stricter refcount checks in future.  Also required for
lockless pagecache.
Signed-off-by: NNick Piggin <npiggin@suse.de>

"This patch also eliminates a leak "cleaned up" by re-clobbering the
refcount on every allocation from the hugepage freelists.  With respect to
the lockless pagecache, the crucial aspect is to eliminate unconditional
set_page_count() to 0 on pages with potentially nonzero refcounts, though
closer inspection suggests the assignments removed are entirely spurious."
Acked-by: NWilliam Irwin <wli@holomorphy.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The bootmem code added to page_alloc.c duplicated some page freeing code
that it really doesn't need to because it is not so performance critical.

While we're here, make prefetching work properly by actually prefetching
the page we're about to use before prefetching ahead to the next one (ie.
get the most important transaction started first).  Also prefetch just a
single page ahead rather than leaving a gap of 16.

Jack Steiner reported no problems with SGI's ia64 simulator.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Clarify that preemption needs to be guarded against with the
__xxx_page_state functions.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>