Currently twofish cipher key setup code
has unrolled loops - approximately 70-100
instructions are repeated 40 times.

As a result, twofish module is the biggest module
in crypto/*.

Unrolling produces x2.5 more code (+18k on i386), and speeds up key
setup by 7%:

	unrolled: twofish_setkey/sec: 41128
	    loop: twofish_setkey/sec: 38148
	CALC_K256: ~100 insns each
	CALC_K192: ~90 insns
	   CALC_K: ~70 insns

Attached patch removes this unrolling.

$ size */twofish_common.o
   text    data     bss     dec     hex filename
  37920       0       0   37920    9420 crypto.org/twofish_common.o
  13209       0       0   13209    3399 crypto/twofish_common.o

Run tested (modprobe tcrypt reports ok). Please apply.
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch moves macros in geode-aes.c into geode-aes.h.
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

The code waits in a busy loop until the hardware finishes the encryption
or decryption process. This wants a cpu_relax() :)
The busy loop finishes either if the encryption is done or if the counter
is zero. If the latter is true than the hardware failed. Since this
should not happen, leave sith a BUG().
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

It is enough if the IV is copied before and after the while loop.
With DM-Crypt is seems not be required to save the IV after encrytion
because a new one is used in the request (dunno about other users).
It is not save to load the IV within while loop and not save afterwards
because we mill end up with the wrong IV if the request goes consists
of more than one page.
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This three defines are used in all AES related hardware.
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

alias isn't required because the module provides PCI ids.
Signed-off-by: Sebastian Siewior <sebastian@breakpoint.cc>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

HIFN driver update to use DES weak key checks (exported in this patch).
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch creates include/crypto/des.h for common macros shared between
DES implementations.
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This is a driver for HIFN 795x crypto accelerator chips.

It passed all tests for AES, DES and DES3_EDE except weak test for DES,
since hardware can not determine weak keys.
Signed-off-by: Evgeniy Polyakov <johnpol@2ka.mipt.ru>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

This patch implements CTR mode for IPsec.
It is based off of RFC 3686.

Please note:
1. CTR turns a block cipher into a stream cipher.
Encryption is done in blocks, however the last block
may be a partial block.

A "counter block" is encrypted, creating a keystream
that is xor'ed with the plaintext. The counter portion
of the counter block is incremented after each block
of plaintext is encrypted.
Decryption is performed in same manner.

2. The CTR counterblock is composed of,
        nonce + IV + counter

The size of the counterblock is equivalent to the
blocksize of the cipher.
        sizeof(nonce) + sizeof(IV) + sizeof(counter) = blocksize

The CTR template requires the name of the cipher
algorithm, the sizeof the nonce, and the sizeof the iv.
        ctr(cipher,sizeof_nonce,sizeof_iv)

So for example,
        ctr(aes,4,8)
specifies the counterblock will be composed of 4 bytes
from a nonce, 8 bytes from the iv, and 4 bytes for counter
since aes has a blocksize of 16 bytes.

3. The counter portion of the counter block is stored
in big endian for conformance to rfc 3686.
Signed-off-by: Joy Latten <latten@austin.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

The previous patch fixed spurious read faults from occuring by copying
the data if we happen to have a single block at the end of a page.  It
appears that gcc cannot guarantee 16-byte alignment in the kernel with
__attribute__.  The following report from Torben Viets shows a buffer
that's only 8-byte aligned:

> eneral protection fault: 0000 [#1]
> Modules linked in: xt_TCPMSS xt_tcpmss iptable_mangle ipt_MASQUERADE
> xt_tcpudp xt_mark xt_state iptable_nat nf_nat nf_conntrack_ipv4
> iptable_filter ip_tables x_tables pppoe pppox af_packet ppp_generic slhc
> aes_i586
> CPU:    0
> EIP:    0060:[<c035b828>]    Not tainted VLI
> EFLAGS: 00010292   (2.6.23.12 #7)
> EIP is at aes_crypt_copy+0x28/0x40
> eax: f7639ff0   ebx: f6c24050   ecx: 00000001   edx: f6c24030
> esi: f7e89dc8   edi: f7639ff0   ebp: 00010000   esp: f7e89dc8

Since the hardware must have 16-byte alignment, the following patch fixes
this by open coding the alignment adjustment.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

The xcryptecb instruction always processes an even number of blocks so
we need to ensure th existence of an extra block if we have to process
an odd number of blocks.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

As it is crypto_remove_spawn may try to unregister an instance which is
yet to be registered.  This patch fixes this by checking whether the
instance has been registered before attempting to remove it.

It also removes a bogus cra_destroy check in crypto_register_instance as
1) it's outside the mutex;
2) we have a check in __crypto_register_alg already.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

It seems that newer versions of gcc have regressed in their abilities to
analyse initialisations.  This patch moves the initialisations up to avoid
the warnings.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/x86/linux-2.6-x86:
  x86: simplify "make ARCH=x86" and fix kconfig all.config
  x86: reboot fixup for wrap2c board
  x86: check boundary in count setup resource
  x86: fix reboot with no keyboard attached
  x86: add hpet sanity checks
  x86: on x86_64, correct reading of PC RTC when update in progress in time_64.c
  x86: fix freeze in x86_64 RTC update code in time_64.c
  ntp: fix typo that makes sync_cmos_clock erratic
  Remove x86 merge artifact from top Makefile
  x86: fixup cpu_info array conversion
  x86: show cpuinfo only for online CPUs
  x86: fix cpu-hotplug regression
  x86: ignore the sys_getcpu() tcache parameter
  x86: voyager use correct header file name
  x86: fix smp init sections
  x86: fix voyager_cat_init section
  x86: fix bogus memcpy in es7000_check_dsdt()

Simplify "make ARCH=x86" and fix kconfig so we again can set 64BIT in
all.config.

For a fix the diffstat is nice:
 6 files changed, 3 insertions(+), 36 deletions(-)

The patch reverts these commits:
 - 0f855aa6 ("kconfig: add helper to set
   config symbol from environment variable")
 - 2a113281 ("kconfig: use $K64BIT to
   set 64BIT with all*config targets")

Roman Zippel pointed out that kconfig supported string compares so
the additional complexity introduced by the above two patches were
not needed.

With this patch we have following behaviour:

  # make {allno,allyes,allmod,rand}config [ARCH=...]
  option \ host arch      | 32bit         | 64bit
  =====================================================
  ./.                     | 32bit         | 64bit
  ARCH=x86                | 32bit         | 32bit
  ARCH=i386               | 32bit         | 32bit
  ARCH=x86_64             | 64bit         | 64bit

The general rule are that ARCH= and native architecture takes
precedence over the configuration.

So make ARCH=i386 [whatever] will always build a 32-bit kernel
no matter what the configuration says.  The configuration will
be updated to 32-bit if it was configured to 64-bit and the
other way around.

This behaviour is consistent with previous behaviour so no
suprises here.

make ARCH=x86 will per default result in a 32-bit kernel but as
the only ARCH= value x86 allow the user to select between 32-bit
and 64-bit using menuconfig.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Andreas Herrmann <aherrman@arcor.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Simplify "make ARCH=x86" and fix kconfig so we again
can set 64BIT in all.config.

For a fix the diffstat is nice:
 6 files changed, 3 insertions(+), 36 deletions(-)

The patch reverts these commits:
0f855aa6
-> kconfig: add helper to set config symbol from environment variable

2a113281
-> kconfig: use $K64BIT to set 64BIT with all*config targets

Roman Zippel pointed out that kconfig supported string
compares so the additional complexity introduced by the
above two patches were not needed.

With this patch we have following behaviour:

# make {allno,allyes,allmod,rand}config [ARCH=...]
option \ host arch      | 32bit         | 64bit
=====================================================
./.                     | 32bit         | 64bit
ARCH=x86                | 32bit         | 32bit
ARCH=i386               | 32bit         | 32bit
ARCH=x86_64             | 64bit         | 64bit

The general rule are that ARCH= and native architecture
takes precedence over the configuration.
So make ARCH=i386 [whatever] will always build a 32-bit
kernel no matter what the configuration says.
The configuration will be updated to 32-bit if it was
configured to 64-bit and the other way around.

This behaviour is consistent with previous behaviour so
no suprises here.

make ARCH=x86 will per default result in a 32-bit kernel
but as the only ARCH= value x86 allow the user to select
between 32-bit and 64-bit using menuconfig. 
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Cc: Roman Zippel <zippel@linux-m68k.org>
Cc: Andreas Herrmann <aherrman@arcor.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>

Needed to make the wireless board, WRAP2C reboot.

Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

need to check info->res_num less than PCI_BUS_NUM_RESOURCES, so
info->bus->resource[info->res_num] = res will not beyond of bus resource
array when acpi returns too many resource entries.
Signed-off-by: Yinghai Lu <yinghai.lu@sun.com>
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: Gary Hade <gary.hade@us.ibm.com>
Cc: Len Brown <lenb@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Attempt to fix http://bugzilla.kernel.org/show_bug.cgi?id=8378

Hiroto Shibuya wrote to tell me that he has a VIA EPIA-EK10000 which
suffers from the reboot problem when no keyboard is attached.  My first
patch works for him:

  http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=59f4e7d572980a521b7bdba74ab71b21f5995538

But the latest patch does not work for him :

  http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=8b93789808756bcc1e5c90c99f1b1ef52f839a51

We found that it was necessary to also set the "disable keyboard" flag in
the command byte, as the first patch was doing.  The second patch tries to
minimally modify the command byte, but it is not enough.

Please consider this simple one-line patch to help people with low end VIA
motherboards reboot when no keyboard is attached.  Hiroto Shibuya has
verified that this works for him (as I no longer have an afflicted
machine).


Additional discussion:

Note that original patch from Truxton DOES
disable keyboard and this has been in main tree since 2.6.14, thus it must have
quite a bit of air time already.

http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.14.y.git;a=commit;h=59f4e7d572980a521b7bdba74ab71b21f5995538

Note that he only mention "System flag" in the description and comment, but
in the code, "disable keyboard" flag is set.

  outb(0x14, 0x60);       /* set "System flag" */

In 2.6.23, he made a change to read the current byte and then mask the flags,
but along this change,  he only set the "System flag" and dropped the setting
of "disable keyboard" flag.

http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.23.y.git;a=commit;h=8b93789808756bcc1e5c90c99f1b1ef52f839a51

   outb(cmd | 0x04, 0x60); /* set "System flag" */

So my request is to restore the setting of disable keyboard flag which has been
there since 2.6.14 but disappeared in 2.6.23.

Cc: Lee Garrett <lee-in-berlin@web.de>
Cc: "Hiroto Shibuya" <hiroto.shibuya@gmail.com>
Cc: Natalie Protasevich <protasnb@gmail.com>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Aristeu Rozanski <aris@ruivo.org>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Some BIOSes advertise HPET at 0x0. We really do no want to 
allocate a resource there. Check for it and leave early.

Other BIOSes tell us the HPET is at 0xfed0000000000000 
instead of 0xfed00000. Add a check and fix it up with a warning
on user request.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Correct potentially unstable PC RTC time register reading in time_64.c

Stop the use of an incorrect technique for reading the standard PC RTC
timer, which is documented to "disconnect" time registers from the bus
while updates are in progress.  The use of UIP flag while interrupts
are disabled to protect a 244 microsecond window is one of the
Motorola spec sheet's documented ways to read the RTC time registers
reliably.

tglx: removed locking changes from original patch, as they gain nothing
(read_persistent_clock is only called during boot, suspend, resume - so
no hot path affected) and conflict with the paravirt locking scheme
(see 32bit code), which we do not want to complicate for no benefit.
Signed-off-by: David P. Reed <dpreed@reed.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Fix hard freeze on x86_64 when the ntpd service calls 
update_persistent_clock()

A repeatable but randomly timed freeze has been happening in Fedora 6
and 7 for the last year, whenever I run the ntpd service on my AMD64x2
HP Pavilion dv9000z laptop.  This freeze is due to the use of
spin_lock(&rtc_lock) under the assumption (per a bad comment) that
set_rtc_mmss is called only with interrupts disabled.  The call from
ntp.c to update_persistent_clock is made with interrupts enabled.
Signed-off-by: David P. Reed <dpreed@reed.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Fix a typo in ntp.c that has caused updating of the persistent (RTC)
clock when synced to NTP to behave erratically.

When debugging a freeze that arises on my AMD64 machines when I
run the ntpd service, I added a number of printk's to monitor the
sync_cmos_clock procedure.  I discovered that it was not syncing to
cmos RTC every 11 minutes as documented, but instead would keep trying
every second for hours at a time.  The reason turned out to be a typo
in sync_cmos_clock, where it attempts to ensure that
update_persistent_clock is called very close to 500 msec. after a 1
second boundary (required by the PC RTC's spec). That typo referred to
"xtime" in one spot, rather than "now", which is derived from "xtime"
but not equal to it.  This makes the test erratic, creating a
"coin-flip" that decides when update_persistent_clock is called - when
it is called, which is rarely, it may be at any time during the one
second period, rather than close to 500 msec, so the value written is
needlessly incorrect, too.

Signed-off-by: David P. Reed
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

The x86 merge modified the tags target to handle the two separate
source directories. Remove it now that i386/x86_64 are gone completely.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

92cb7612 sets cpu_info->cpu_index to zero
for no reason. Referencing cpu_info->cpu_index now points always to CPU#0,
which is apparently not what we want.

Remove it.
Spotted-by: Zou Nan hai <nanhai.zou@intel.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Fix regressions introduced with 92cb7612.

It can happen that cpuinfo is displayed for CPUs that are not online or
even worse for CPUs not present at all. As an example, following was
shown for a "second" CPU of a single core K8 variant:

    processor       : 0
    vendor_id       : unknown
    cpu family      : 0
    model           : 0
    model name      : unknown
    stepping        : 0
    cache size      : 0 KB
    fpu             : yes
    fpu_exception   : yes
    cpuid level     : 0
    wp              : yes
    flags           :
    bogomips        : 0.00
    clflush size    : 0
    cache_alignment : 0
    address sizes   : 0 bits physical, 0 bits virtual
    power management:
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Commit d435d862
("cpu hotplug: mce: fix cpu hotplug error handling")
changed the error handling in mce_cpu_callback.

In cases where not all CPUs are brought up during
boot (e.g. using maxcpus and additional_cpus parameters)
mce_cpu_callback now returns NOTFIY_BAD because
for such CPUs cpu_data is not completely filled when
the notifier is called. Thus mce_create_device fails right
at its beginning:

        if (!mce_available(&cpu_data[cpu]))
                return -EIO;

As a quick fix I suggest to check boot_cpu_data for MCE.

To reproduce this regression:

(1) boot with maxcpus=2 addtional_cpus=2 on a 4 CPU x86-64 system
(2) # echo 1 >/sys/devices/system/cpu/cpu2/online
  -bash: echo: write error: Invalid argument

dmesg shows:

_cpu_up: attempt to bring up CPU 2 failed
Signed-off-by: Andreas Herrmann <andreas.herrmann3@amd.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

dont use the vgetcpu tcache - it's causing problems with tasks
migrating, they'll see the old cache up to a jiffy after the
migration, further increasing the costs of the migration.

In the worst case they see a complete bogus information from
the tcache, when a sys_getcpu() call "invalidated" the cache
info by incrementing the jiffies _and_ the cpuid info in the
cache and the following vdso_getcpu() call happens after
vdso_jiffies have been incremented.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Fix header file name for Voyager build.

In file included from arch/x86/kernel/setup_32.c:61:
include/asm-x86/mach-voyager/setup_arch.h:2:26: error: asm/setup_32.h: No such file or directory
make[1]: *** [arch/x86/kernel/setup_32.o] Error 1
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Fix Voyager section mismatch due to using __devinit instead of __cpuinit.

WARNING: vmlinux.o(.text+0xd943): Section mismatch: reference to .init.text:init_gdt (between 'voyager_smp_prepare_boot_cpu' and 'smp_vic_cmn_interrupt')
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Fix Voyager section mismatches:  voyager_cat_init() should be __init.

WARNING: vmlinux.o(.text+0xee83): Section mismatch: reference to .init.data:eprom_buf (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xeea6): Section mismatch: reference to .init.data: (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xeeac): Section mismatch: reference to .init.data: (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xeeb2): Section mismatch: reference to .init.data: (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xef4c): Section mismatch: reference to .init.data: (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xef56): Section mismatch: reference to .init.data: (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xf10f): Section mismatch: reference to .init.data:eprom_buf (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xf13b): Section mismatch: reference to .init.data: (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xf14b): Section mismatch: reference to .init.data: (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xf159): Section mismatch: reference to .init.data: (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xf1b1): Section mismatch: reference to .init.data:eprom_buf (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xf1bb): Section mismatch: reference to .init.data: (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xf1c1): Section mismatch: reference to .init.data:eprom_buf (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xf1c7): Section mismatch: reference to .init.data:eprom_buf (between 'voyager_cat_init' and 'aes_enc_blk')
WARNING: vmlinux.o(.text+0xf1e6): Section mismatch: reference to .init.data: (between 'voyager_cat_init' and 'aes_enc_blk')
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

es7000_check_dst() contains a memcpy from 0, which probably should have been
a memset. Remove it and check the retunr value from acpi_get_table_header.

Noticed by: Joe Perches <joe@perches.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/selinux-2.6:
  SELinux: return EOPNOTSUPP not ENOTSUPP

* 'for-linus' of master.kernel.org:/home/rmk/linux-2.6-arm:
  [ARM] 4638/1: pxa: use PXA3xx specific macros to define clks
  [ARM] remove useless setting of VM_RESERVED

* master.kernel.org:/pub/scm/linux/kernel/git/davej/cpufreq:
  [CPUFREQ] Fix up whitespace in conservative governor.
  [CPUFREQ] Make cpufreq_conservative handle out-of-sync events properly
  [CPUFREQ] architectural pstate driver for powernow-k8

ENOTSUPP is not a valid error code in the kernel (it is defined in some
NFS internal error codes and has been improperly used other places).  In
the !CONFIG_SECURITY_SELINUX case though it is possible that we could
return this from selinux_audit_rule_init().  This patch just returns the
userspace valid EOPNOTSUPP.
Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: James Morris <jmorris@namei.org>

PXA3xx uses its own clk_pxa3xx_cken_ops, modify the code to use the
PXA3xx specific macros to define its clocks
Signed-off-by: eric miao <eric.miao@marvell.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>

This code harks back to the days when we didn't count dirty mapped
pages, which led us to try to balance the number of dirty unmapped pages
by how much unmapped memory there was in the system.

That makes no sense any more, since now the dirty counts include the
mapped pages.  Not to mention that the math doesn't work with HIGHMEM
machines anyway, and causes the unmapped_ratio to potentially turn
negative (which we do catch thanks to clamping it at a minimum value,
but I mention that as an indication of how broken the code is).

The code also was written at a time when the default dirty ratio was
much larger, and the unmapped_ratio logic effectively capped that large
dirty ratio a bit.  Again, we've since lowered the dirty ratio rather
aggressively, further lessening the point of that code.
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>