The "Adding %dk swap" message shows the number of swap extents, as a guide to
how fragmented the swapfile may be.  But a useful further guide is what total
extent they span across (sometimes scarily large).

And there's no need to keep nr_extents in swap_info: it's unused after the
initial message, so save a little space by keeping it on stack.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

There are several comments that swap's extent_list.prev points to the lowest
extent: that's not so, it's extent_list.next which points to it, as you'd
expect.  And a couple of loops in add_swap_extent which go all the way through
the list, when they should just add to the other end.

Fix those up, and let map_swap_page search the list forwards: profiles shows
it to be twice as quick that way - because prefetch works better on how the
structs are typically kmalloc'ed?  or because usually more is written to than
read from swap, and swap is allocated ascendingly?
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

sys_swapon's call to destroy_swap_extents on failure is made after the final
swap_list_unlock, which is faintly unsafe: another sys_swapon might already be
setting up that swap_info_struct.  Calling it earlier, before taking
swap_list_lock, is safe.  sys_swapoff's call to destroy_swap_extents was safe,
but likewise move it earlier, before taking the locks (once try_to_unuse has
completed, nothing can be needing the swap extents).
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

If a regular swapfile lies on a filesystem whose blocksize is less than
PAGE_SIZE, then setup_swap_extents may have to cut the number of usable swap
pages; but sys_swapon's nr_good_pages was not expecting that.  Also,
setup_swap_extents takes no account of badpages listed in the swap header: not
worth doing so, but ensure nr_badpages is 0 for a regular swapfile.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Update swap extents comment: nowadays we guard with S_SWAPFILE not i_sem.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This splits up sparse_index_alloc() into two pieces.  This is needed
because we'll allocate the memory for the second level in a different place
from where we actually consume it to keep the allocation from happening
underneath a lock
Signed-off-by: NDave Hansen <haveblue@us.ibm.com>
Signed-off-by: NBob Picco <bob.picco@hp.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

With cleanups from Dave Hansen <haveblue@us.ibm.com>

SPARSEMEM_EXTREME makes mem_section a one dimensional array of pointers to
mem_sections.  This two level layout scheme is able to achieve smaller
memory requirements for SPARSEMEM with the tradeoff of an additional shift
and load when fetching the memory section.  The current SPARSEMEM
implementation is a one dimensional array of mem_sections which is the
default SPARSEMEM configuration.  The patch attempts isolates the
implementation details of the physical layout of the sparsemem section
array.

SPARSEMEM_EXTREME requires bootmem to be functioning at the time of
memory_present() calls.  This is not always feasible, so architectures
which do not need it may allocate everything statically by using
SPARSEMEM_STATIC.
Signed-off-by: NAndy Whitcroft <apw@shadowen.org>
Signed-off-by: NBob Picco <bob.picco@hp.com>
Signed-off-by: NDave Hansen <haveblue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

A new option for SPARSEMEM is ARCH_SPARSEMEM_EXTREME.  Architecture
platforms with a very sparse physical address space would likely want to
select this option.  For those architecture platforms that don't select the
option, the code generated is equivalent to SPARSEMEM currently in -mm.
I'll be posting a patch on ia64 ml which uses this new SPARSEMEM feature.

ARCH_SPARSEMEM_EXTREME makes mem_section a one dimensional array of
pointers to mem_sections.  This two level layout scheme is able to achieve
smaller memory requirements for SPARSEMEM with the tradeoff of an
additional shift and load when fetching the memory section.  The current
SPARSEMEM -mm implementation is a one dimensional array of mem_sections
which is the default SPARSEMEM configuration.  The patch attempts isolates
the implementation details of the physical layout of the sparsemem section
array.

ARCH_SPARSEMEM_EXTREME depends on 64BIT and is by default boolean false.

I've boot tested under aim load ia64 configured for ARCH_SPARSEMEM_EXTREME.
 I've also boot tested a 4 way Opteron machine with !ARCH_SPARSEMEM_EXTREME
and tested with aim.
Signed-off-by: NAndy Whitcroft <apw@shadowen.org>
Signed-off-by: NBob Picco <bob.picco@hp.com>
Signed-off-by: NDave Hansen <haveblue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Defer copying of ptes until fault time when it is possible to reconstruct
the pte from backing store. Idea from Andi Kleen and Nick Piggin.

Thanks to input from Rik van Riel and Linus and to Hugh for correcting
my blundering.

Ray Fucillo <fucillo@intersystems.com> reports:

  "I applied this latest patch to a 2.6.12 kernel and found that it does
   resolve the problem.  Prior to the patch on this machine, I was
   seeing about 23ms spent in fork for ever 100MB of shared memory
   segment.

   After applying the patch, fork is taking about 1ms regardless of the
   shared memory size."
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This bug could cause oopses and page state corruption, because ncpfs
used the generic page-cache symlink handlign functions.  But those
functions only work if the page cache is guaranteed to be "stable", ie a
page that was installed when the symlink walk was started has to still
be installed in the page cache at the end of the walk.

We could have fixed ncpfs to not use the generic helper routines, but it
is in many ways much cleaner to instead improve on the symlink walking
helper routines so that they don't require that absolute stability.

We do this by allowing "follow_link()" to return a error-pointer as a
cookie, which is fed back to the cleanup "put_link()" routine.  This
also simplifies NFS symlink handling.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch fixes a crash in the hugepage code.  unmap_hugepage_area() was
assuming that (due to prefault) PTEs must exist for all the area in
question.  However, this may not be the case, if mmap() encounters an error
before the prefault and calls unmap_region() to clean up any partial
mapping.

Depending on the hugepage configuration, this crash can be triggered by an
unpriveleged user.
Signed-off-by: NDavid Gibson <david@gibson.dropbear.id.au>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We have found what seems to be a small bug in __vm_enough_memory() when
sysctl_overcommit_memory is set to OVERCOMMIT_NEVER.

When this bug occurs the systems fails to boot, with /sbin/init whining
about fork() returning ENOMEM.

We hunted down the problem to this:

The deferred update mecanism used in vm_acct_memory(), on a SMP system,
allows the vm_committed_space counter to have a negative value.

This should not be a problem since this counter is known to be inaccurate.

But in __vm_enough_memory() this counter is compared to the `allowed'
variable, which is an unsigned long.  This comparison is broken since it
will consider the negative values of vm_committed_space to be huge positive
values, resulting in a memory allocation failure.

Signed-off-by: <Jean-Marc.Saffroy@ext.bull.net>
Signed-off-by: <Simon.Derr@bull.net>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

mremap's move_vma is applying __vm_stat_account to the old vma which may
have already been freed: move it to just before the do_munmap.

mremapping to and fro with CONFIG_DEBUG_SLAB=y showed /proc/<pid>/status
VmSize and VmData wrapping just like in kernel bugzilla #4842, and fixed by
this patch - worth including in 2.6.13, though not yet confirmed that it
fixes that specific report from Frank van Maarseveen.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The VM_FAULT_WRITE thing is an extra bit, not a valid return value, and
has to be treated as such by get_user_pages().
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Checking pte_dirty instead of pte_write in __follow_page is problematic
for s390, and for copy_one_pte which leaves dirty when clearing write.

So revert __follow_page to check pte_write as before, and make
do_wp_page pass back a special extra VM_FAULT_WRITE bit to say it has
done its full job: once get_user_pages receives this value, it no longer
requires pte_write in __follow_page.

But most callers of handle_mm_fault, in the various architectures, have
switch statements which do not expect this new case.  To avoid changing
them all in a hurry, make an inline wrapper function (using the old
name) that masks off the new bit, and use the extended interface with
double underscores.

Yes, we do have a call to do_wp_page from do_swap_page, but no need to
change that: in rare case it's needed, another do_wp_page will follow.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
[ Cleanups by Nick Piggin ]
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

A kernel BUG() is triggered by a call to set_mempolicy() with a negative
first argument.  This is because the mode is declared as an int, and the
validity check doesnt check < 0 values.  Alternatively, mode could be
declared as unsigned int or unsigned long.
Signed-off-by: NEric Dumazet <dada1@cosmosbay.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

x86_64 has a large sparse gate area between VSYSCALL_START and
VSYSCALL_END, not all of it presently backed by pmds.  Alexander Nyberg has
found that in some circumstances gdb may try to ptrace here, and hit
get_user_pages BUG_ON.  It seems odd that gdb should be accessing here, but
it certainly shouldn't crash in this way: relax BUG_ON to -EFAULT.  Fixes
kernel bugzilla #4801.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Cc: Andi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

There's no real guarantee that handle_mm_fault() will always be able to
break a COW situation - if an update from another thread ends up
modifying the page table some way, handle_mm_fault() may end up
requiring us to re-try the operation.

That's normally fine, but get_user_pages() ended up re-trying it as a
read, and thus a write access could in theory end up losing the dirty
bit or be done on a page that had not been properly COW'ed.

This makes get_user_pages() always retry write accesses as write
accesses by making "follow_page()" require that a writable follow has
the dirty bit set.  That simplifies the code and solves the race: if the
COW break fails for some reason, we'll just loop around and try again.
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We are iterating over all nodes in nr_free_zone_pages().  Because the
fallback zonelists contain all nodes in the system, and we walk all the
zonelists, we're counting memory multiple times (once for each node).  This
caused us to make a size estimate of 32GB for an 8GB AMD64 box, which makes
all the dirty ratio calculations, etc incorrect.

There's still a further bug to fix from e820 holes causing overestimation
as well, but this fix is separate, and good as is, and fixes one class of
problems.  Problem found by Badari, and tested by Ram Pai - thanks!
Signed-off-by: NMartin J. Bligh <mbligh@mbligh.org>
Signed-off-by: NMatt Dobson <colpatch@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Originally __free_pages_bulk used the relative page number within a zone to
define its buddies.  This meant that to maintain the "maximally aligned"
requirements (that an allocation of size N will be aligned at least to N
physically) zones had to also be aligned to 1<<MAX_ORDER pages.  When
__free_pages_bulk was updated to use the relative page frame numbers of the
free'd pages to pair buddies this released the alignment constraint on the
'left' edge of the zone.  This allows _either_ edge of the zone to contain
partial MAX_ORDER sized buddies.  These simply never will have matching
buddies and thus will never make it to the 'top' of the pyramid.

The patch below removes a now redundant check ensuring that the mem_map was
aligned to MAX_ORDER.
Signed-off-by: NAndy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <christoph@lameter.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

The madvise() system call returns -EBADF for areas which does not map to
files, only for *behaviour* request MADV_WILLNEED.

According to man pages, madvise returns :

EBADF - the map exists, but the area maps something that isn't a file.

Fixes bug 2995.
Signed-off-by: NSuzuki K P <suzuki@in.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix bug identifued by Richard Purdie <rpurdie@rpsys.net>.

oprofile calls check_user_page_readable() from interrupt context, so we
deadlock over various VFS locks.

But check_user_page_readable() doesn't imply either a read or a write of the
page's contents.  Change __follow_page() so that check_user_page_readable()
can tell __follow_page() that we're not accessing the page's contents, and use
that info to avoid the troublesome lock-takings.

Also, make follow_page() inline for the single callsite in memory.c to save a
bit of stack space.
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

All mempolicy changes must be inside the spinlock and readding the rb_erase
prevents a crash while doing:

> echo "1" > /tmp/numatest
> numactl --length=0x4000 --shm /tmp/numatest --localalloc
> numactl --length=0x2000 --offset=0 --shm /tmp/numatest --membind=0
> numactl --length=0x2000 --offset=0x2000 --shm /tmp/numatest --membind=1
> ipcs
> ipcrm -M "the_key_value_of_this_shm_area"

Based on a patch by John Blackwood

Cc: <john.blackwood@ccur.com>
Cc: <andrea@suse.de>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch includes feedback from Andrew and Christoph. Thanks for
taking time to review.

Use of empty_zero_page was eliminated to fix compilation for architectures
that don't have it.

This patch removes setting pages up-to-date in ext2_get_xip_page and all
bug checks to verify that the page is indeed up to date.  Setting the page
state on mapping to userland is bogus.  None of the code patchs involved
with these pages in mm cares about the page state.

still on my ToDo list: identify a place outside second extended where
__inode_direct_access should reside
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

mm/filemap_xip.c: In function `__xip_unmap':
mm/filemap_xip.c:194: request for member `pte' in something not a structure or union

Apparently pte_pfn() takes a pte_t, not a pointer to a pte_t.  From looking
at asm/page.h, it seems to be the same on ia32 or ppc (iff
STRICT_MM_TYPECHECKS is enabled, which is disabled by default on ppc).
Acked-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

We now print statistics when invoking the OOM killer, however this
information is not rate limited and you can get into situations where the
console is continually spammed.

For example, when a task is exiting the OOM killer will simply return
(waiting for that task to exit and clear up memory).  If the VM continually
calls back into the OOM killer we get thousands of copies of show_mem() on
the console.

Use printk_ratelimit() to quieten it.
Signed-off-by: NAnton Blanchard <anton@samba.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Remove completly bogus comment from did_some_progress != 0 handling (that
same comment is a few lines below on did_some_progress = 0 case, where it
belongs).
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Dump the current allocation order when OOM killing.
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch used to be in Andrew's tree before the NUMA slab allocator went
in. Either this patch or the NUMA slab allocator is needed in order for
kmalloc_node to work correctly.

pcibus_to_node may be used to generate the node information passed to
kmalloc_node. pcibus_to_node returns -1 if it was not able to determine
on which node a pcibus is located. For that case kmalloc_node must
work like kmalloc.
Signed-off-by: NChristoph Lameter <christoph@lameter.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

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>

I spotted this issue while in memmap_init last week.  I can't say the
change has any test coverage by me.  start_pfn was formerly used in main
"for" loop.  The fix is replace start_pfn with pfn.
Signed-off-by: NBob Picco <bob.picco@hp.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

1. Establish a simple API for process freezing defined in linux/include/sched.h:

   frozen(process)		Check for frozen process
   freezing(process)		Check if a process is being frozen
   freeze(process)		Tell a process to freeze (go to refrigerator)
   thaw_process(process)	Restart process
   frozen_process(process)	Process is frozen now

2. Remove all references to PF_FREEZE and PF_FROZEN from all
   kernel sources except sched.h

3. Fix numerous locations where try_to_freeze is manually done by a driver

4. Remove the argument that is no longer necessary from two function calls.

5. Some whitespace cleanup

6. Clear potential race in refrigerator (provides an open window of PF_FREEZE
   cleared before setting PF_FROZEN, recalc_sigpending does not check
   PF_FROZEN).

This patch does not address the problem of freeze_processes() violating the rule
that a task may only modify its own flags by setting PF_FREEZE. This is not clean
in an SMP environment. freeze(process) is therefore not SMP safe!
Signed-off-by: NChristoph Lameter <christoph@lameter.com>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch makes use of ALIGN() to remove duplicate round-up code.
Signed-off-by: NNick Wilson <njw@osdl.org>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

This patch retrieves the max_pfn being used by previous kernel and stores it
in a safe location (saved_max_pfn) before it is overwritten due to user
defined memory map.  This pfn is used to make sure that user does not try to
read the physical memory beyond saved_max_pfn.
Signed-off-by: NVivek Goyal <vgoyal@in.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Here is the fix for the problem described in

	http://bugzilla.kernel.org/show_bug.cgi?id=4721

Basically, problem is generic_file_buffered_write() is accessing beyond end
of the iov[] vector after handling the last vector.  If we happen to cross
page boundary, we get a fault.

I think this simple patch is good enough.  If we really don't want to
depend on the "count", then we need pass nr_segs to
filemap_set_next_iovec() and decrement it and check it.
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

CONFIG_PM_DISK is long gone, but it still managed to survived at few
places.
Signed-off-by: NPavel Machek <pavel@suse.cz>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Out-of-tree user of remap_pfn_range hit kernel BUG at mm/memory.c:1112!  It
passes an unrounded size to remap_pfn_range, which was okay before 2.6.12,
but misses remap_pte_range's new end condition.  An audit of all the other
ptwalks confirms that this is the only one so exposed.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Fix a bug on error handling in the direct I/O function.

Currently, if a file is opened with the O_DIRECT|O_SYNC flag, the write()
syscall cannot receive the EIO error after an I/O error (SCSI cable is
disconnected etc.).

Return values of other points that call generic_osync_inode() are treated
appropriately.
Signed-off-by: NHisashi Hifumi  <hifumi.hisashi@lab.ntt.co.jp>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>

Make sys_madvice/fadvice return sane with xip.
Signed-off-by: NCarsten Otte <cotte@de.ibm.com>
Signed-off-by: NAndrew Morton <akpm@osdl.org>
Signed-off-by: NLinus Torvalds <torvalds@osdl.org>