Fixes the problem identified by Miles Bader on extremely small zones:
calling hash_long with `bits = 0' is treated as `bits = 32'.

So don't permit the zone to have a one-slot waitqueue hashtable.

This allows us to control the aggressiveness of the lower-zone defense
algorithm.  The `incremental min'.  For workloads which are using a
serious amount of mlocked memory, a few megabytes is not enough.

So the `lower_zone_protection' tunable allows the administrator to
increase the amount of protection which lower zones receive against
allocations which _could_ use higher zones.

The default value of lower_zone_protection is zero, giving unchanged
behaviour.  We should not normally make large amounts of memory
unavailable for pagecache just in case someone mlocks many hundreds of
megabytes.

I've revisited all the superblock->inode->page writeback paths.  There
were several silly things in there, and things were not as clear as they
could be.

scenario 1: create and dirty a MAP_SHARED segment over a sparse file,
then exit.

  All the memory turns into dirty pagecache, but the kupdate function
  only writes it out at a trickle - 4 megabytes every thirty seconds.
  We should sync it all within 30 seconds.

  What's happening is that when writeback tries to write those pages,
  the filesystem needs to instantiate new blocks for them (they're over
  holes).  The filesystem runs mark_inode_dirty() within the writeback
  function.

  This redirtying of the inode while we're writing it out triggers
  some livelock avoidance code in __sync_single_inode().  That function
  says "ah, someone redirtied the file while I was writing it.  Let's
  move the file to the new end of the superblock dirty list and write
  it out later." Problem is, writeback dirtied the inode itself.

  (It is rather silly that mark_inode_dirty() sets I_DIRTY_PAGES when
  clearly no pages have been dirtied.  Fixing that up would be a
  largish work, so work around it here).

  So this patch just removes the livelock avoidance from
  __sync_single_inode().  It is no longer needed anyway - writeback
  livelock is now avoided (in all writeback paths) by writing a finite
  number of pages.

scenario 2: an application is continuously dirtying a 200 megabyte
file, and your disk has a bandwidth of less than 40 megabytes/sec.

  What happens is that once 30 seconds passes, pdflush starts writing
  out the file.  And because that writeout will take more than five
  seconds (a `kupdate' interval), pdflush just keeps writing it out
  forever - continuous I/O.

  What we _want_ to happen is that the 200 megabytes gets written,
  and then IO stops for thirty seconds (minus the writeout period).  So
  the file is fully synced every thirty seconds.

The patch solves this by using mapping->io_pages more intelligently.
When the time comes to write the file out, move all the dirty pages
onto io_pages.  That is a "batch of pages for this kupdate round".
When io_pages is empty, we know we're done.

The address_space_operations.writepages() API is changed!  It now only
needs to write the pages which the caller placed on mapping->io_pages.

This conceptually cleans things up a bit, by more clearly defining the
role of ->io_pages, and the motion between the various mapping lists.

The treatment of sb->s_dirty and sb->s_io is now conceptually identical
to mapping->dirty_pages and mapping->io_pages: move the items-to-be
written onto ->s_io/io_pages, alk walk that list.  As inodes (or pages)
are written, move them over to the clean/locked/dirty lists.

Oh, scenario 3: start an app whcih continuously overwrites a 5 meg
file.  Wait five seconds, start another, wait 5 seconds, start another.
 What we _should_ see is three 5-meg writes, five seconds apart, every
thirty seconds.  That did all sorts of odd things.  It now does the
right thing.

From Rohit

1) hugetlbfs_zero_setup returns ENOMEM in case the request size can
   not be easily handleed.

2) Preference is given to LOW_MEM while freeing the pages from
   hugetlbpage free list.

- /proc/vmstat:pageoutrun and /proc/vmstat:allocstall are always
  identical.  Rework this so that

  - "allocstall" is the number of times a page allocator ran diect reclaim

  - "pageoutrun" is the number of times kswapd ran page reclaim

- Add a new stat: "pgrotated".  The number of pages which were
  rotated to the tail of the LRU for immediate reclaim by
  rotate_reclaimable_page().

- Document things a bit.

Check for usercopy faults in filldir().

ext3_sync_fs will start a commit and will wait on that commit.  This
means that on its return, all journalled file data has been dirtied and
exposed to sync_inodes_sb().  Which is sufficient to fix the umount
data loss problem.

This is infrastructure for fixing the journalled-data ext3 unmount data
loss problem. It was sent for comment to linux-fsdevel a week ago; there
was none.

Add a `sync_fs' superblock operation whose mandate is to perform
filesystem-specific operations to ensure a successful sync.

It is called in two places:

1: fsync_super() - for umount.

2: sys_sync() - for global sync.

In the sys_sync() case we call all the ->write_super() methods first.
write_super() is an async flushing operation.  It should not block.

After that, we call all the ->sync_fs functions.  This is independent
of the state of s_dirt!  That was all confused up before, and in this
patch ->write_super() and ->sync_fs() are quite separate.

With ext3 as an example, the initial ->write_super() will start a
transaction, but will not wait on it.  (But only if s_dirt was set!)

The first ->sync_fs() call will get the IO underway.

The second ->sync_fs() call will wait on the IO.

And we really do need to be this elaborate, because all the testing of
s_dirt in there makes ->write_super() an unreliable way of detecting
when the VFS is trying to sync the filesystem.

Fix a radix-tree bug spotted by Vladimir Saveliev <vs@namesys.com>.

Each step in the radix tree spans six address bits.  So a height=6 tree
spans 36-bits worth of nodes.

On 32-bit machines radix_tree_gang_lookup() doesn't handle this right -
at the 12TB mark it wraps back to zero, and returns pages at quite
wrong indices.

The patch fixes all that up, and tidies a couple of things.

A user-space test harness was developed so that the code can be sanely
tested.  It is at

	http://www.zip.com.au/~akpm/linux/patches/stuff/rtth.tar.gz

Patch from Martin Bligh and Dave Hansen

If a PAE machine has 1G of memory and you set PAGE_OFFSET to 2G, the
kernel will only instantiate a PMD to cover the 2G-3G region.  But
another PMD is needed for the 3G-4G region for the APIC and possibly an
extended vmalloc region.

So the patch changes the code to instantiate PMDs out to the end of
physical memory.

It's a no-op for PAGE_OFFSET=3G, and _could_ be part of the
CONFIG_PAGE_OFFSET patch.  But it seems a reasonable generalisation
anyway.

Ancient patch From Bill Irwin

The patch is intended to show improved information about where the
memory went during OOM-killing events.

- when the OOM killer fails and the system panics, calls
  show_free_areas()

- reorganize show_free_areas() to use for_each_zone()

- add per-cpu stats to show_free_areas()

- tags output from show_free_areas() with node and zone information

fail_writepage() does not work.  Its activate_page() call cannot
activate the page because it is not on the LRU.

So perform that function (more efficiently) in the VM.  Remove
fail_writepage() and, if the filesystem does not implement
->writepage() then activate the page from shrink_list().

A special case is tmpfs, which does have a writepage, but which
sometimes wants to activate the pages anyway.  The most important case
is when there is no swap online and we don't want to keep all those
pages on the inactive list.  So just as a tmpfs special-case, allow
writepage() to return WRITEPAGE_ACTIVATE, and handle that in the VM.

Also, the whole idea of allowing ->writepage() to return -EAGAIN, and
handling that in the caller has been reverted.  If a writepage()
implementation wants to back out and not write the page, it must
redirty the page, unlock it and return zero.  (This is Hugh's preferred
way).

And remove the now-unneeded shmem_writepages() - shmem inodes are
marked as `memory backed' so it will not be called.

And remove the test for non-null ->writepage() in generic_file_mmap().
Memory-backed files _are_ mmappable, and they do not have a
writepage().  It just isn't called.

So the locking rules for writepage() are unchanged.  They are:

- Called with the page locked
- Returns with the page unlocked
- Must redirty the page itself if it wasn't all written.

But there is a new, special, hidden, undocumented, secret hack for
tmpfs: writepage may return WRITEPAGE_ACTIVATE to tell the VM to move
the page to the active list.  The page must be kept locked in this one
case.

There's nopoint in walking through a lot of tmpfs or ramdisk pages when
we're trying to clean memory.  So if a memory-backed inode is
discovered during writeback, skip the entire superblock.

Patch from Mark Fasheh <mark.fasheh@oracle.com> (plus a few cleanups
and a speedup from yours truly)

Adds the semtimedop() function - semop with a timeout.  Solaris has
this.  It's apparently worth a couple of percent to Oracle throughput
and given the simplicity, that is sufficient benefit for inclusion IMO.

This patch hooks up semtimedop() only for ia64 and ia32.

The pte_chain_unlock() needs to be outside the ifdef.

The read_zero() implementation for !CONFIG_MMU was very inefficient.
This sped-up version has been tested and acked by Greg Ungerer.

Back out the sys_syslog()-based printk-from-userspace and replace
it with Ben's /proc/kmsg version.

Requires a `mknod /dev/kmsg c 1 11'.

Patch from Robert Love <rml@tech9.net>

We can never get rid of it if we do not deprecate it - so do so and
print a stern warning to those who still run bdflush daemons.

The PF_MEMALLOC handling got broken somewhere, and it is now possible
for a PF_MEMALLOC process to reenter page reclaim.

Change it to fail the allocation if we're PF_MEMALLOC and there are
zero pages free.

This removes calls to function which disappeared during last Iphase
driver update.  Since this update, Iphase driver has been using plain
modern pci style init.

Problem wasn't noticed until Adrian Bunk tried to build non-modular kernel
(I only tested the modularized driver). Everybody else seemed happy :o)

scrup is using memcpy even when the memory areas src, dest overlap.  The
key is to use memmove which handles overlapping memory gracefully.

into home.transmeta.com:/home/torvalds/v2.5/linux

2.5 currently tries to register disk sda twice. Not nice and now we use
sysfs to do name to dev_t mapping, I couldnt mount my root filesystem.

This driver does not need to use atomic operations on local variables.

Trivial but annoying: two printk() calls in drivers/scsi/hosts.c are
missing '\n'

Also, for some reason I have not yet investigated, shost_tp->name is
NULL here.  This should not be, eh?  If it can be, we should do
something to tidy up the printing of it.

This error message is uber annoying and needs to go.  Non-root can flood
the console with this junk on invalid SCSI CD-ROM ioctl(), and that is
exactly what gnome-cd does.

An illegal ioctl() returns an error to the program.  That is sufficient
- we do not need KERN_ERROR warnings all over the place.  Especially
when any user can cause them at any rate.

In some configurations, parport and bttv request a module inside their
module_init function.  Drop the lock around mod->init(), change
module->live to module->state so we can detect modules which are in
init.

module-init-tools 0.9 and newer supply a replacement depmod, so
it's safe to run again.

Also, some external programs like PCMCIA and mkinitrd really want the
directory hierarchy in /lib/modules back again: it makes no difference
to the tools (since 0.9), so revert it.

into home.transmeta.com:/home/torvalds/v2.5/linux

Relatively straightforward fixes for intermezzo problems in 2.5.50.  I
think all of them related to:
 - two missing headers
 - use of timespec instead of time_t.

into home.transmeta.com:/home/torvalds/v2.5/linux

into home.transmeta.com:/home/torvalds/v2.5/linux

I made the changes to the set/get_registers code.

Cset exclude: rth@dorothy.sfbay.redhat.com|ChangeSet|20021207231352|30637

 - remove NATIVE_CHAR typedef
 - remove ACPI_{GET,VALID}_ADDRESS macros
 - fix memory corruption in deletion of a static AML buffer
 - fix fault caused by 0-length AML
 - fix user-buffer overwrite/corruption of buffer is too small
 - fix buffer-to-string conversion

This allowed a lock to be removed.
Also removed the MOD_* functions, and some remove logic was cleaned
up by Oliver Neukum.