FASTCALL() is always expanded to empty, remove it.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NHarvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Background: I've implemented 1K/2K page tables for s390.  These sub-page
page tables are required to properly support the s390 virtualization
instruction with KVM.  The SIE instruction requires that the page tables
have 256 page table entries (pte) followed by 256 page status table entries
(pgste).  The pgstes are only required if the process is using the SIE
instruction.  The pgstes are updated by the hardware and by the hypervisor
for a number of reasons, one of them is dirty and reference bit tracking.
To avoid wasting memory the standard pte table allocation should return
1K/2K (31/64 bit) and 2K/4K if the process is using SIE.

Problem: Page size on s390 is 4K, page table size is 1K or 2K.  That means
the s390 version for pte_alloc_one cannot return a pointer to a struct
page.  Trouble is that with the CONFIG_HIGHPTE feature on x86 pte_alloc_one
cannot return a pointer to a pte either, since that would require more than
32 bit for the return value of pte_alloc_one (and the pte * would not be
accessible since its not kmapped).

Solution: The only solution I found to this dilemma is a new typedef: a
pgtable_t.  For s390 pgtable_t will be a (pte *) - to be introduced with a
later patch.  For everybody else it will be a (struct page *).  The
additional problem with the initialization of the ptl lock and the
NR_PAGETABLE accounting is solved with a constructor pgtable_page_ctor and
a destructor pgtable_page_dtor.  The page table allocation and free
functions need to call these two whenever a page table page is allocated or
freed.  pmd_populate will get a pgtable_t instead of a struct page pointer.
 To get the pgtable_t back from a pmd entry that has been installed with
pmd_populate a new function pmd_pgtable is added.  It replaces the pmd_page
call in free_pte_range and apply_to_pte_range.
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Introduce a general page table walker
Signed-off-by: NMatt Mackall <mpm@selenic.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Both slab defrag and the large blocksize patches need to ability to take
refcounts on compound pages.  May be useful in other places as well.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Checking if an address is a vmalloc address is done in a couple of places.
Define a common version in mm.h and replace the other checks.

Again the include structures suck.  The definition of VMALLOC_START and
VMALLOC_END is not available in vmalloc.h since highmem.c cannot be included
there.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
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>

Make vmalloc functions work the same way as kfree() and friends that
take a const void * argument.

[akpm@linux-foundation.org: fix consts, coding-style]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We already have page table manipulation for vmalloc in vmalloc.c. Move the
vmalloc_to_page() function there as well.

Move the definitions for vmalloc related functions in mm.h to a newly created
section.  A better place would be vmalloc.h but mm.h is basic and may depend
on these functions.  An alternative would be to include vmalloc.h in mm.h
(like done for vmstat.h).
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

get more testing of the c_p_a() code done by not turning off
PSE on DEBUG_PAGEALLOC.

this simplifies the early pagetable setup code, and tests
the largepage-splitup code quite heavily.

In the end, all the largepages will be split up pretty quickly,
so there's no difference to how DEBUG_PAGEALLOC worked before.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

They now look like:

hal-resmgr[13791]: segfault at 3c rip 2b9c8caec182 rsp 7fff1e825d30 error 4 in libacl.so.1.1.0[2b9c8caea000+6000]

This makes it easier to pinpoint bugs to specific libraries.

And printing the offset into a mapping also always allows to find the
correct fault point in a library even with randomized mappings. Previously
there was no way to actually find the correct code address inside
the randomized mapping.

Relies on earlier patch to shorten the printk formats.

They are often now longer than 80 characters, but I think that's worth it.

[includes fix from Eric Dumazet to check d_path error value]
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

Remove security.h include from mm.h, as it is only needed for a single
extern declaration, and pulls in all kinds of crud.

Fine-by-me: David Chinner <dgc@sgi.com>
Acked-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NJames Morris <jmorris@namei.org>

If mmap_min_addr is set and a process attempts to mmap (not fixed) with a
non-null hint address less than mmap_min_addr the mapping will fail the
security checks.  Since this is just a hint address this patch will round
such a hint address above mmap_min_addr.

gcj was found to try to be very frugal with vm usage and give hint addresses
in the 8k-32k range.  Without this patch all such programs failed and with
the patch they happily get a higher address.

This patch is wrappad in CONFIG_SECURITY since mmap_min_addr doesn't exist
without it and there would be no security check possible no matter what.  So
we should not bother compiling in this rounding if it is just a waste of
time.
Signed-off-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NJames Morris <jmorris@namei.org>

mm.h doesn't use directly anything from mutex.h and backing-dev.h, so
remove them and add them back to files which need them.

Cross-compile tested on many configs and archs.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch makes three needlessly global functions static.
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch is to avoid panic when memory hot-add is executed with
sparsemem-vmemmap.  Current vmemmap-sparsemem code doesn't support memory
hot-add.  Vmemmap must be populated when hot-add.  This is for
2.6.23-rc2-mm2.

Todo: # Even if this patch is applied, the message "[xxxx-xxxx] potential
        offnode page_structs" is displayed. To allocate memmap on its node,
        memmap (and pgdat) must be initialized itself like chicken and
        egg relationship.

      # vmemmap_unpopulate will be necessary for followings.
         - For cancel hot-add due to error.
         - For unplug.
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

After moving the lockless_freelist to kmem_cache_cpu we no longer need
page->lockless_freelist. Restructure the use of the struct page fields in
such a way that we never touch the mapping field.

This is turn allows us to remove the special casing of SLUB when determining
the mapping of a page (needed for corner cases of virtual caches machines that
need to flush caches of processors mapping a page).
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move the definitions of struct mm_struct and struct vma_area_struct to
include/mm_types.h.  This allows to define more function in asm/pgtable.h
and friends with inline assemblies instead of macros.  Compile tested on
i386, powerpc, powerpc64, s390-32, s390-64 and x86_64.

[aurelien@aurel32.net: build fix]
Signed-off-by: NMartin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: NAurelien Jarno <aurelien@aurel32.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The commit b5810039 contains the note

  A last caveat: the ZERO_PAGE is now refcounted and managed with rmap
  (and thus mapcounted and count towards shared rss).  These writes to
  the struct page could cause excessive cacheline bouncing on big
  systems.  There are a number of ways this could be addressed if it is
  an issue.

And indeed this cacheline bouncing has shown up on large SGI systems.
There was a situation where an Altix system was essentially livelocked
tearing down ZERO_PAGE pagetables when an HPC app aborted during startup.
This situation can be avoided in userspace, but it does highlight the
potential scalability problem with refcounting ZERO_PAGE, and corner
cases where it can really hurt (we don't want the system to livelock!).

There are several broad ways to fix this problem:
1. add back some special casing to avoid refcounting ZERO_PAGE
2. per-node or per-cpu ZERO_PAGES
3. remove the ZERO_PAGE completely

I will argue for 3. The others should also fix the problem, but they
result in more complex code than does 3, with little or no real benefit
that I can see.

Why? Inserting a ZERO_PAGE for anonymous read faults appears to be a
false optimisation: if an application is performance critical, it would
not be doing many read faults of new memory, or at least it could be
expected to write to that memory soon afterwards. If cache or memory use
is critical, it should not be working with a significant number of
ZERO_PAGEs anyway (a more compact representation of zeroes should be
used).

As a sanity check -- mesuring on my desktop system, there are never many
mappings to the ZERO_PAGE (eg. 2 or 3), thus memory usage here should not
increase much without it.

When running a make -j4 kernel compile on my dual core system, there are
about 1,000 mappings to the ZERO_PAGE created per second, but about 1,000
ZERO_PAGE COW faults per second (less than 1 ZERO_PAGE mapping per second
is torn down without being COWed). So removing ZERO_PAGE will save 1,000
page faults per second when running kbuild, while keeping it only saves
less than 1 page clearing operation per second. 1 page clear is cheaper
than a thousand faults, presumably, so there isn't an obvious loss.

Neither the logical argument nor these basic tests give a guarantee of no
regressions. However, this is a reasonable opportunity to try to remove
the ZERO_PAGE from the pagefault path. If it is found to cause regressions,
we can reintroduce it and just avoid refcounting it.

The /dev/zero ZERO_PAGE usage and TLB tricks also get nuked.  I don't see
much use to them except on benchmarks.  All other users of ZERO_PAGE are
converted just to use ZERO_PAGE(0) for simplicity. We can look at
replacing them all and maybe ripping out ZERO_PAGE completely when we are
more satisfied with this solution.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus "snif" Torvalds <torvalds@linux-foundation.org>

Remove VM_MAX_CACHE_HIT, MAX_RA_PAGES and MIN_RA_PAGES.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Convert the common vmemmap population into initialisation helpers for use by
architecture vmemmap populators.  All architecture implementing the
SPARSEMEM_VMEMMAP variant supply an architecture specific vmemmap_populate()
initialiser, which may make use of the helpers.

This allows us to clean up and remove the initialisation Kconfig entries.
With this patch there is a single SPARSEMEM_VMEMMAP_ENABLE Kconfig option to
indicate use of that variant.
Signed-off-by: NAndy Whitcroft <apw@shadowen.org>
Acked-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

SPARSEMEM is a pretty nice framework that unifies quite a bit of code over all
the arches.  It would be great if it could be the default so that we can get
rid of various forms of DISCONTIG and other variations on memory maps.  So far
what has hindered this are the additional lookups that SPARSEMEM introduces
for virt_to_page and page_address.  This goes so far that the code to do this
has to be kept in a separate function and cannot be used inline.

This patch introduces a virtual memmap mode for SPARSEMEM, in which the memmap
is mapped into a virtually contigious area, only the active sections are
physically backed.  This allows virt_to_page page_address and cohorts become
simple shift/add operations.  No page flag fields, no table lookups, nothing
involving memory is required.

The two key operations pfn_to_page and page_to_page become:

   #define __pfn_to_page(pfn)      (vmemmap + (pfn))
   #define __page_to_pfn(page)     ((page) - vmemmap)

By having a virtual mapping for the memmap we allow simple access without
wasting physical memory.  As kernel memory is typically already mapped 1:1
this introduces no additional overhead.  The virtual mapping must be big
enough to allow a struct page to be allocated and mapped for all valid
physical pages.  This vill make a virtual memmap difficult to use on 32 bit
platforms that support 36 address bits.

However, if there is enough virtual space available and the arch already maps
its 1-1 kernel space using TLBs (f.e.  true of IA64 and x86_64) then this
technique makes SPARSEMEM lookups even more efficient than CONFIG_FLATMEM.
FLATMEM needs to read the contents of the mem_map variable to get the start of
the memmap and then add the offset to the required entry.  vmemmap is a
constant to which we can simply add the offset.

This patch has the potential to allow us to make SPARSMEM the default (and
even the only) option for most systems.  It should be optimal on UP, SMP and
NUMA on most platforms.  Then we may even be able to remove the other memory
models: FLATMEM, DISCONTIG etc.

[apw@shadowen.org: config cleanups, resplit code etc]
[kamezawa.hiroyu@jp.fujitsu.com: Fix sparsemem_vmemmap init]
[apw@shadowen.org: vmemmap: remove excess debugging]
[apw@shadowen.org: simplify initialisation code and reduce duplication]
[apw@shadowen.org: pull out the vmemmap code into its own file]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAndy Whitcroft <apw@shadowen.org>
Acked-by: NMel Gorman <mel@csn.ul.ie>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Andi Kleen <ak@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: NKAMEZAWA 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 new exec code inserts an accounted vma into an mm struct which is not
current->mm.  The existing memory check code has a hard coded assumption
that this does not happen as does the security code.

As the correct mm is known we pass the mm to the security method and the
helper function.  A new security test is added for the case where we need
to pass the mm and the existing one is modified to pass current->mm to
avoid the need to change large amounts of code.

(Thanks to Tobias for fixing rejects and testing)
Signed-off-by: NAlan Cox <alan@redhat.com>
Cc: WU Fengguang <wfg@mail.ustc.edu.cn>
Cc: James Morris <jmorris@redhat.com>
Cc: Tobias Diedrich <ranma+kernel@tdiedrich.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove fs.h from mm.h. For this,
 1) Uninline vma_wants_writenotify(). It's pretty huge anyway.
 2) Add back fs.h or less bloated headers (err.h) to files that need it.

As result, on x86_64 allyesconfig, fs.h dependencies cut down from 3929 files
rebuilt down to 3444 (-12.3%).

Cross-compile tested without regressions on my two usual configs and (sigh):

alpha              arm-mx1ads        mips-bigsur          powerpc-ebony
alpha-allnoconfig  arm-neponset      mips-capcella        powerpc-g5
alpha-defconfig    arm-netwinder     mips-cobalt          powerpc-holly
alpha-up           arm-netx          mips-db1000          powerpc-iseries
arm                arm-ns9xxx        mips-db1100          powerpc-linkstation
arm-assabet        arm-omap_h2_1610  mips-db1200          powerpc-lite5200
arm-at91rm9200dk   arm-onearm        mips-db1500          powerpc-maple
arm-at91rm9200ek   arm-picotux200    mips-db1550          powerpc-mpc7448_hpc2
arm-at91sam9260ek  arm-pleb          mips-ddb5477         powerpc-mpc8272_ads
arm-at91sam9261ek  arm-pnx4008       mips-decstation      powerpc-mpc8313_rdb
arm-at91sam9263ek  arm-pxa255-idp    mips-e55             powerpc-mpc832x_mds
arm-at91sam9rlek   arm-realview      mips-emma2rh         powerpc-mpc832x_rdb
arm-ateb9200       arm-realview-smp  mips-excite          powerpc-mpc834x_itx
arm-badge4         arm-rpc           mips-fulong          powerpc-mpc834x_itxgp
arm-carmeva        arm-s3c2410       mips-ip22            powerpc-mpc834x_mds
arm-cerfcube       arm-shannon       mips-ip27            powerpc-mpc836x_mds
arm-clps7500       arm-shark         mips-ip32            powerpc-mpc8540_ads
arm-collie         arm-simpad        mips-jazz            powerpc-mpc8544_ds
arm-corgi          arm-spitz         mips-jmr3927         powerpc-mpc8560_ads
arm-csb337         arm-trizeps4      mips-malta           powerpc-mpc8568mds
arm-csb637         arm-versatile     mips-mipssim         powerpc-mpc85xx_cds
arm-ebsa110        i386              mips-mpc30x          powerpc-mpc8641_hpcn
arm-edb7211        i386-allnoconfig  mips-msp71xx         powerpc-mpc866_ads
arm-em_x270        i386-defconfig    mips-ocelot          powerpc-mpc885_ads
arm-ep93xx         i386-up           mips-pb1100          powerpc-pasemi
arm-footbridge     ia64              mips-pb1500          powerpc-pmac32
arm-fortunet       ia64-allnoconfig  mips-pb1550          powerpc-ppc64
arm-h3600          ia64-bigsur       mips-pnx8550-jbs     powerpc-prpmc2800
arm-h7201          ia64-defconfig    mips-pnx8550-stb810  powerpc-ps3
arm-h7202          ia64-gensparse    mips-qemu            powerpc-pseries
arm-hackkit        ia64-sim          mips-rbhma4200       powerpc-up
arm-integrator     ia64-sn2          mips-rbhma4500       s390
arm-iop13xx        ia64-tiger        mips-rm200           s390-allnoconfig
arm-iop32x         ia64-up           mips-sb1250-swarm    s390-defconfig
arm-iop33x         ia64-zx1          mips-sead            s390-up
arm-ixp2000        m68k              mips-tb0219          sparc
arm-ixp23xx        m68k-amiga        mips-tb0226          sparc-allnoconfig
arm-ixp4xx         m68k-apollo       mips-tb0287          sparc-defconfig
arm-jornada720     m68k-atari        mips-workpad         sparc-up
arm-kafa           m68k-bvme6000     mips-wrppmc          sparc64
arm-kb9202         m68k-hp300        mips-yosemite        sparc64-allnoconfig
arm-ks8695         m68k-mac          parisc               sparc64-defconfig
arm-lart           m68k-mvme147      parisc-allnoconfig   sparc64-up
arm-lpd270         m68k-mvme16x      parisc-defconfig     um-x86_64
arm-lpd7a400       m68k-q40          parisc-up            x86_64
arm-lpd7a404       m68k-sun3         powerpc              x86_64-allnoconfig
arm-lubbock        m68k-sun3x        powerpc-cell         x86_64-defconfig
arm-lusl7200       mips              powerpc-celleb       x86_64-up
arm-mainstone      mips-atlas        powerpc-chrp32
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Nathan Lynch <ntl@pobox.com> reported:
2.6.23-rc1 breaks the build for 64-bit powerpc for me (using
maple_defconfig):

  LD      vmlinux.o
powerpc64-unknown-linux-gnu-ld: dynreloc miscount for
kernel/built-in.o, section .opd
powerpc64-unknown-linux-gnu-ld: can not edit opd Bad value
make: *** [vmlinux.o] Error 1

However, I see a possibly related binutils patch:
http://article.gmane.org/gmane.comp.gnu.binutils/33650

It was tracked down to be caused by the weak prototype
declaration in mm.h:
__attribute__((weak)) const char *arch_vma_name(struct vm_area_struct *vma);

But there is no need to make the declaration weak - only the definition
needs to be marked weak.  So drop the weak declaration.  And in the process
drop the duplicate definition in page.h for powerpc.

Note: the arch_vma_name fix for x86_64 needs to be applied first to avoid
breaking x86_64
Signed-off-by: NSam Ravnborg <sam@ravnborg.org>
Cc: Nathan Lynch <ntl@pobox.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove the arg+env limit of MAX_ARG_PAGES by copying the strings directly from
the old mm into the new mm.

We create the new mm before the binfmt code runs, and place the new stack at
the very top of the address space.  Once the binfmt code runs and figures out
where the stack should be, we move it downwards.

It is a bit peculiar in that we have one task with two mm's, one of which is
inactive.

[a.p.zijlstra@chello.nl: limit stack size]
Signed-off-by: NOllie Wild <aaw@google.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <linux-arch@vger.kernel.org>
Cc: Hugh Dickins <hugh@veritas.com>
[bunk@stusta.de: unexport bprm_mm_init]
Signed-off-by: NAdrian Bunk <bunk@stusta.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Split ondemand readahead interface into two functions.  I think this makes it
a little clearer for non-readahead experts (like Rusty).

Internally they both call ondemand_readahead(), but the page argument is
changed to an obvious boolean flag.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove the old readahead algorithm.
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is a minimal readahead algorithm that aims to replace the current one.
It is more flexible and reliable, while maintaining almost the same behavior
and performance.  Also it is full integrated with adaptive readahead.

It is designed to be called on demand:
	- on a missing page, to do synchronous readahead
	- on a lookahead page, to do asynchronous readahead

In this way it eliminated the awkward workarounds for cache hit/miss,
readahead thrashing, retried read, and unaligned read.  It also adopts the
data structure introduced by adaptive readahead, parameterizes readahead
pipelining with `lookahead_index', and reduces the current/ahead windows to
one single window.

HEURISTICS

The logic deals with four cases:

	- sequential-next
		found a consistent readahead window, so push it forward

	- random
		standalone small read, so read as is

	- sequential-first
		create a new readahead window for a sequential/oversize request

	- lookahead-clueless
		hit a lookahead page not associated with the readahead window,
		so create a new readahead window and ramp it up

In each case, three parameters are determined:

	- readahead index: where the next readahead begins
	- readahead size:  how much to readahead
	- lookahead size:  when to do the next readahead (for pipelining)

BEHAVIORS

The old behaviors are maximally preserved for trivial sequential/random reads.
Notable changes are:

	- It no longer imposes strict sequential checks.
	  It might help some interleaved cases, and clustered random reads.
	  It does introduce risks of a random lookahead hit triggering an
	  unexpected readahead. But in general it is more likely to do good
	  than to do evil.

	- Interleaved reads are supported in a minimal way.
	  Their chances of being detected and proper handled are still low.

	- Readahead thrashings are better handled.
	  The current readahead leads to tiny average I/O sizes, because it
	  never turn back for the thrashed pages.  They have to be fault in
	  by do_generic_mapping_read() one by one.  Whereas the on-demand
	  readahead will redo readahead for them.

OVERHEADS

The new code reduced the overheads of

	- excessively calling the readahead routine on small sized reads
	  (the current readahead code insists on seeing all requests)

	- doing a lot of pointless page-cache lookups for small cached files
	  (the current readahead only turns itself off after 256 cache hits,
	  unfortunately most files are < 1MB, so never see that chance)

That accounts for speedup of
	- 0.3% on 1-page sequential reads on sparse file
	- 1.2% on 1-page cache hot sequential reads
	- 3.2% on 256-page cache hot sequential reads
	- 1.3% on cache hot `tar /lib`

However, it does introduce one extra page-cache lookup per cache miss, which
impacts random reads slightly. That's 1% overheads for 1-page random reads on
sparse file.

PERFORMANCE

The basic benchmark setup is
	- 2.6.20 kernel with on-demand readahead
	- 1MB max readahead size
	- 2.9GHz Intel Core 2 CPU
	- 2GB memory
	- 160G/8M Hitachi SATA II 7200 RPM disk

The benchmarks show that
	- it maintains the same performance for trivial sequential/random reads
	- sysbench/OLTP performance on MySQL gains up to 8%
	- performance on readahead thrashing gains up to 3 times

iozone throughput (KB/s): roughly the same
==========================================
iozone -c -t1 -s 4096m -r 64k

			       2.6.20          on-demand      gain
first run
	  "  Initial write "   61437.27        64521.53      +5.0%
	  "        Rewrite "   47893.02        48335.20      +0.9%
	  "           Read "   62111.84        62141.49      +0.0%
	  "        Re-read "   62242.66        62193.17      -0.1%
	  "   Reverse Read "   50031.46        49989.79      -0.1%
	  "    Stride read "    8657.61         8652.81      -0.1%
	  "    Random read "   13914.28        13898.23      -0.1%
	  " Mixed workload "   19069.27        19033.32      -0.2%
	  "   Random write "   14849.80        14104.38      -5.0%
	  "         Pwrite "   62955.30        65701.57      +4.4%
	  "          Pread "   62209.99        62256.26      +0.1%

second run
	  "  Initial write "   60810.31        66258.69      +9.0%
	  "        Rewrite "   49373.89        57833.66     +17.1%
	  "           Read "   62059.39        62251.28      +0.3%
	  "        Re-read "   62264.32        62256.82      -0.0%
	  "   Reverse Read "   49970.96        50565.72      +1.2%
	  "    Stride read "    8654.81         8638.45      -0.2%
	  "    Random read "   13901.44        13949.91      +0.3%
	  " Mixed workload "   19041.32        19092.04      +0.3%
	  "   Random write "   14019.99        14161.72      +1.0%
	  "         Pwrite "   64121.67        68224.17      +6.4%
	  "          Pread "   62225.08        62274.28      +0.1%

In summary, writes are unstable, reads are pretty close on average:

			  access pattern  2.6.20  on-demand   gain
				   Read  62085.61  62196.38  +0.2%
				Re-read  62253.49  62224.99  -0.0%
			   Reverse Read  50001.21  50277.75  +0.6%
			    Stride read   8656.21   8645.63  -0.1%
			    Random read  13907.86  13924.07  +0.1%
	 		 Mixed workload  19055.29  19062.68  +0.0%
				  Pread  62217.53  62265.27  +0.1%

aio-stress: roughly the same
============================
aio-stress -l -s4096 -r128 -t1 -o1 knoppix511-dvd-cn.iso
aio-stress -l -s4096 -r128 -t1 -o3 knoppix511-dvd-cn.iso

					2.6.20      on-demand  delta
			sequential	 92.57s      92.54s    -0.0%
			random		311.87s     312.15s    +0.1%

sysbench fileio: roughly the same
=================================
sysbench --test=fileio --file-io-mode=async --file-test-mode=rndrw \
	 --file-total-size=4G --file-block-size=64K \
	 --num-threads=001 --max-requests=10000 --max-time=900 run

				threads    2.6.20   on-demand    delta
		first run
				      1   59.1974s    59.2262s  +0.0%
				      2   58.0575s    58.2269s  +0.3%
				      4   48.0545s    47.1164s  -2.0%
				      8   41.0684s    41.2229s  +0.4%
				     16   35.8817s    36.4448s  +1.6%
				     32   32.6614s    32.8240s  +0.5%
				     64   23.7601s    24.1481s  +1.6%
				    128   24.3719s    23.8225s  -2.3%
				    256   23.2366s    22.0488s  -5.1%

		second run
				      1   59.6720s    59.5671s  -0.2%
				      8   41.5158s    41.9541s  +1.1%
				     64   25.0200s    23.9634s  -4.2%
				    256   22.5491s    20.9486s  -7.1%

Note that the numbers are not very stable because of the writes.
The overall performance is close when we sum all seconds up:

                sum all up               495.046s    491.514s   -0.7%

sysbench oltp (trans/sec): up to 8% gain
========================================
sysbench --test=oltp --oltp-table-size=10000000 --oltp-read-only \
	 --mysql-socket=/var/run/mysqld/mysqld.sock \
	 --mysql-user=root --mysql-password=readahead \
	 --num-threads=064 --max-requests=10000 --max-time=900 run

	10000-transactions run
				threads    2.6.20   on-demand    gain
				      1     62.81       64.56   +2.8%
				      2     67.97       70.93   +4.4%
				      4     81.81       85.87   +5.0%
				      8     94.60       97.89   +3.5%
				     16     99.07      104.68   +5.7%
				     32     95.93      104.28   +8.7%
				     64     96.48      103.68   +7.5%
	5000-transactions run
				      1     48.21       48.65   +0.9%
				      8     68.60       70.19   +2.3%
				     64     70.57       74.72   +5.9%
	2000-transactions run
				      1     37.57       38.04   +1.3%
				      2     38.43       38.99   +1.5%
				      4     45.39       46.45   +2.3%
				      8     51.64       52.36   +1.4%
				     16     54.39       55.18   +1.5%
				     32     52.13       54.49   +4.5%
				     64     54.13       54.61   +0.9%

That's interesting results. Some investigations show that
	- MySQL is accessing the db file non-uniformly: some parts are
	  more hot than others
	- It is mostly doing 4-page random reads, and sometimes doing two
	  reads in a row, the latter one triggers a 16-page readahead.
	- The on-demand readahead leaves many lookahead pages (flagged
	  PG_readahead) there. Many of them will be hit, and trigger
	  more readahead pages. Which might save more seeks.
	- Naturally, the readahead windows tend to lie in hot areas,
	  and the lookahead pages in hot areas is more likely to be hit.
	- The more overall read density, the more possible gain.

That also explains the adaptive readahead tricks for clustered random reads.

readahead thrashing: 3 times better
===================================
We boot kernel with "mem=128m single", and start a 100KB/s stream on every
second, until reaching 200 streams.

			      max throughput     min avg I/O size
		2.6.20:            5MB/s               16KB
		on-demand:        15MB/s              140KB
Signed-off-by: NFengguang Wu <wfg@mail.ustc.edu.cn>
Cc: Steven Pratt <slpratt@austin.ibm.com>
Cc: Ram Pai <linuxram@us.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch completes Linus's wish that the fault return codes be made into
bit flags, which I agree makes everything nicer.  This requires requires
all handle_mm_fault callers to be modified (possibly the modifications
should go further and do things like fault accounting in handle_mm_fault --
however that would be for another patch).

[akpm@linux-foundation.org: fix alpha build]
[akpm@linux-foundation.org: fix s390 build]
[akpm@linux-foundation.org: fix sparc build]
[akpm@linux-foundation.org: fix sparc64 build]
[akpm@linux-foundation.org: fix ia64 build]
Signed-off-by: NNick Piggin <npiggin@suse.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Ian Molton <spyro@f2s.com>
Cc: Bryan Wu <bryan.wu@analog.com>
Cc: Mikael Starvik <starvik@axis.com>
Cc: David Howells <dhowells@redhat.com>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Cc: "Luck, Tony" <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Greg Ungerer <gerg@uclinux.org>
Cc: Matthew Wilcox <willy@debian.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Kazumoto Kojima <kkojima@rr.iij4u.or.jp>
Cc: Richard Curnow <rc@rc0.org.uk>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Cc: Miles Bader <uclinux-v850@lsi.nec.co.jp>
Cc: Chris Zankel <chris@zankel.net>
Acked-by: NKyle McMartin <kyle@mcmartin.ca>
Acked-by: NHaavard Skinnemoen <hskinnemoen@atmel.com>
Acked-by: NRalf Baechle <ralf@linux-mips.org>
Acked-by: NAndi Kleen <ak@muc.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
[ Still apparently needs some ARM and PPC loving - Linus ]
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change ->fault prototype.  We now return an int, which contains
VM_FAULT_xxx code in the low byte, and FAULT_RET_xxx code in the next byte.
 FAULT_RET_ code tells the VM whether a page was found, whether it has been
locked, and potentially other things.  This is not quite the way he wanted
it yet, but that's changed in the next patch (which requires changes to
arch code).

This means we no longer set VM_CAN_INVALIDATE in the vma in order to say
that a page is locked which requires filemap_nopage to go away (because we
can no longer remain backward compatible without that flag), but we were
going to do that anyway.

struct fault_data is renamed to struct vm_fault as Linus asked. address
is now a void __user * that we should firmly encourage drivers not to use
without really good reason.

The page is now returned via a page pointer in the vm_fault struct.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Nonlinear mappings are (AFAIKS) simply a virtual memory concept that encodes
the virtual address -> file offset differently from linear mappings.

->populate is a layering violation because the filesystem/pagecache code
should need to know anything about the virtual memory mapping.  The hitch here
is that the ->nopage handler didn't pass down enough information (ie.  pgoff).
 But it is more logical to pass pgoff rather than have the ->nopage function
calculate it itself anyway (because that's a similar layering violation).

Having the populate handler install the pte itself is likewise a nasty thing
to be doing.

This patch introduces a new fault handler that replaces ->nopage and
->populate and (later) ->nopfn.  Most of the old mechanism is still in place
so there is a lot of duplication and nice cleanups that can be removed if
everyone switches over.

The rationale for doing this in the first place is that nonlinear mappings are
subject to the pagefault vs invalidate/truncate race too, and it seemed stupid
to duplicate the synchronisation logic rather than just consolidate the two.

After this patch, MAP_NONBLOCK no longer sets up ptes for pages present in
pagecache.  Seems like a fringe functionality anyway.

NOPAGE_REFAULT is removed.  This should be implemented with ->fault, and no
users have hit mainline yet.

[akpm@linux-foundation.org: cleanup]
[randy.dunlap@oracle.com: doc. fixes for readahead]
[akpm@linux-foundation.org: build fix]
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: Mark Fasheh <mark.fasheh@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix the race between invalidate_inode_pages and do_no_page.

Andrea Arcangeli identified a subtle race between invalidation of pages from
pagecache with userspace mappings, and do_no_page.

The issue is that invalidation has to shoot down all mappings to the page,
before it can be discarded from the pagecache.  Between shooting down ptes to
a particular page, and actually dropping the struct page from the pagecache,
do_no_page from any process might fault on that page and establish a new
mapping to the page just before it gets discarded from the pagecache.

The most common case where such invalidation is used is in file truncation.
This case was catered for by doing a sort of open-coded seqlock between the
file's i_size, and its truncate_count.

Truncation will decrease i_size, then increment truncate_count before
unmapping userspace pages; do_no_page will read truncate_count, then find the
page if it is within i_size, and then check truncate_count under the page
table lock and back out and retry if it had subsequently been changed (ptl
will serialise against unmapping, and ensure a potentially updated
truncate_count is actually visible).

Complexity and documentation issues aside, the locking protocol fails in the
case where we would like to invalidate pagecache inside i_size.  do_no_page
can come in anytime and filemap_nopage is not aware of the invalidation in
progress (as it is when it is outside i_size).  The end result is that
dangling (->mapping == NULL) pages that appear to be from a particular file
may be mapped into userspace with nonsense data.  Valid mappings to the same
place will see a different page.

Andrea implemented two working fixes, one using a real seqlock, another using
a page->flags bit.  He also proposed using the page lock in do_no_page, but
that was initially considered too heavyweight.  However, it is not a global or
per-file lock, and the page cacheline is modified in do_no_page to increment
_count and _mapcount anyway, so a further modification should not be a large
performance hit.  Scalability is not an issue.

This patch implements this latter approach.  ->nopage implementations return
with the page locked if it is possible for their underlying file to be
invalidated (in that case, they must set a special vm_flags bit to indicate
so).  do_no_page only unlocks the page after setting up the mapping
completely.  invalidation is excluded because it holds the page lock during
invalidation of each page (and ensures that the page is not mapped while
holding the lock).

This also allows significant simplifications in do_no_page, because we have
the page locked in the right place in the pagecache from the start.
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Detect slab objects being passed to the page oriented functions of the VM.

It is not sufficient to simply return NULL because the functions calling
page_mapping may depend on other items of the page_struct also to be setup
properly.  Moreover slab object may not be properly aligned.  The page
oriented functions of the VM expect to operate on page aligned, page sized
objects.  Operations on object straddling page boundaries may only affect the
objects partially which may lead to surprising results.

It is better to detect eventually remaining uses and eliminate them.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I can never remember what the function to register to receive VM pressure
is called.  I have to trace down from __alloc_pages() to find it.

It's called "set_shrinker()", and it needs Your Help.

1) Don't hide struct shrinker.  It contains no magic.
2) Don't allocate "struct shrinker".  It's not helpful.
3) Call them "register_shrinker" and "unregister_shrinker".
4) Call the function "shrink" not "shrinker".
5) Reduce the 17 lines of waffly comments to 13, but document it properly.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: David Chinner <dgc@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch adds the kernelcore= parameter for x86.

Once all patches are applied, a new command-line parameter exist and a new
sysctl.  This patch adds the necessary documentation.

From: Yasunori Goto <y-goto@jp.fujitsu.com>

  When "kernelcore" boot option is specified, kernel can't boot up on ia64
  because of an infinite loop.  In addition, the parsing code can be handled
  in an architecture-independent manner.

  This patch uses common code to handle the kernelcore= parameter.  It is
  only available to architectures that support arch-independent zone-sizing
  (i.e.  define CONFIG_ARCH_POPULATES_NODE_MAP).  Other architectures will
  ignore the boot parameter.

[bunk@stusta.de: make cmdline_parse_kernelcore() static]
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
Acked-by: NAndy Whitcroft <apw@shadowen.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The following 8 patches against 2.6.20-mm2 create a zone called ZONE_MOVABLE
that is only usable by allocations that specify both __GFP_HIGHMEM and
__GFP_MOVABLE.  This has the effect of keeping all non-movable pages within a
single memory partition while allowing movable allocations to be satisfied
from either partition.  The patches may be applied with the list-based
anti-fragmentation patches that groups pages together based on mobility.

The size of the zone is determined by a kernelcore= parameter specified at
boot-time.  This specifies how much memory is usable by non-movable
allocations and the remainder is used for ZONE_MOVABLE.  Any range of pages
within ZONE_MOVABLE can be released by migrating the pages or by reclaiming.

When selecting a zone to take pages from for ZONE_MOVABLE, there are two
things to consider.  First, only memory from the highest populated zone is
used for ZONE_MOVABLE.  On the x86, this is probably going to be ZONE_HIGHMEM
but it would be ZONE_DMA on ppc64 or possibly ZONE_DMA32 on x86_64.  Second,
the amount of memory usable by the kernel will be spread evenly throughout
NUMA nodes where possible.  If the nodes are not of equal size, the amount of
memory usable by the kernel on some nodes may be greater than others.

By default, the zone is not as useful for hugetlb allocations because they are
pinned and non-migratable (currently at least).  A sysctl is provided that
allows huge pages to be allocated from that zone.  This means that the huge
page pool can be resized to the size of ZONE_MOVABLE during the lifetime of
the system assuming that pages are not mlocked.  Despite huge pages being
non-movable, we do not introduce additional external fragmentation of note as
huge pages are always the largest contiguous block we care about.

Credit goes to Andy Whitcroft for catching a large variety of problems during
review of the patches.

This patch creates an additional zone, ZONE_MOVABLE.  This zone is only usable
by allocations which specify both __GFP_HIGHMEM and __GFP_MOVABLE.  Hot-added
memory continues to be placed in their existing destination as there is no
mechanism to redirect them to a specific zone.

[y-goto@jp.fujitsu.com: Fix section mismatch of memory hotplug related code]
[akpm@linux-foundation.org: various fixes]
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Cc: Andy Whitcroft <apw@shadowen.org>
Signed-off-by: NYasunori Goto <y-goto@jp.fujitsu.com>
Cc: William Lee Irwin III <wli@holomorphy.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I forgot to remove capability.h from mm.h while removing sched.h!  This
patch remedies that, because the only inline function which was using
CAP_something was made out of line.

Cross-compile tested without regressions on:

	all powerpc defconfigs
	all mips defconfigs
	all m68k defconfigs
	all arm defconfigs
	all ia64 defconfigs

	alpha alpha-allnoconfig alpha-defconfig alpha-up
	arm
	i386 i386-allnoconfig i386-defconfig i386-up
	ia64 ia64-allnoconfig ia64-defconfig ia64-up
	m68k
	mips
	parisc parisc-allnoconfig parisc-defconfig parisc-up
	powerpc powerpc-up
	s390 s390-allnoconfig s390-defconfig s390-up
	sparc sparc-allnoconfig sparc-defconfig sparc-up
	sparc64 sparc64-allnoconfig sparc64-defconfig sparc64-up
	um-x86_64
	x86_64 x86_64-allnoconfig x86_64-defconfig x86_64-up

as well as my two usual configs.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is a straightforward split of do_mmap_pgoff() into two functions:

 - do_mmap_pgoff() checks the parameters, and calculates the vma
   flags.  Then it calls

 - mmap_region(), which does the actual mapping
Signed-off-by: NMiklos Szeredi <mszeredi@suse.cz>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This symbol got orphaned quite a while ago.
Signed-off-by: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Nicolas Ferre reports oops from flush_dcache_page() on ARM when using
SLUB: which reuses page->mapping as page->slab.  The page_mapping()
function, used by ARM and PA-RISC flush_dcache_page() implementations,
must not confuse SLUB pages with those which have page->mapping set.
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Cc: Nicolas Ferre <nicolas.ferre@rfo.atmel.com>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

First thing mm.h does is including sched.h solely for can_do_mlock() inline
function which has "current" dereference inside. By dealing with can_do_mlock()
mm.h can be detached from sched.h which is good. See below, why.

This patch
a) removes unconditional inclusion of sched.h from mm.h
b) makes can_do_mlock() normal function in mm/mlock.c
c) exports can_do_mlock() to not break compilation
d) adds sched.h inclusions back to files that were getting it indirectly.
e) adds less bloated headers to some files (asm/signal.h, jiffies.h) that were
   getting them indirectly

Net result is:
a) mm.h users would get less code to open, read, preprocess, parse, ... if
   they don't need sched.h
b) sched.h stops being dependency for significant number of files:
   on x86_64 allmodconfig touching sched.h results in recompile of 4083 files,
   after patch it's only 3744 (-8.3%).

Cross-compile tested on

	all arm defconfigs, all mips defconfigs, all powerpc defconfigs,
	alpha alpha-up
	arm
	i386 i386-up i386-defconfig i386-allnoconfig
	ia64 ia64-up
	m68k
	mips
	parisc parisc-up
	powerpc powerpc-up
	s390 s390-up
	sparc sparc-up
	sparc64 sparc64-up
	um-x86_64
	x86_64 x86_64-up x86_64-defconfig x86_64-allnoconfig

as well as my two usual configs.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>