Currently flush tlb vector allocation is based on below equation:
	sender = smp_processor_id() % 8
This isn't optimal, CPUs from different node can have the same vector, this
causes a lot of lock contention. Instead, we can assign the same vectors to
CPUs from the same node, while different node has different vectors. This has
below advantages:
a. if there is lock contention, the lock contention is between CPUs from one
node. This should be much cheaper than the contention between nodes.
b. completely avoid lock contention between nodes. This especially benefits
kswapd, which is the biggest user of tlb flush, since kswapd sets its affinity
to specific node.

In my test, this could reduce > 20% CPU overhead in extreme case.The test
machine has 4 nodes and each node has 16 CPUs. I then bind each node's kswapd
to the first CPU of the node. I run a workload with 4 sequential mmap file
read thread. The files are empty sparse file. This workload will trigger a
lot of page reclaim and tlbflush. The kswapd bind is to easy trigger the
extreme tlb flush lock contention because otherwise kswapd keeps migrating
between CPUs of a node and I can't get stable result. Sure in real workload,
we can't always see so big tlb flush lock contention, but it's possible.

[ hpa: folded in fix from Eric Dumazet to use this_cpu_read() ]
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
LKML-Reference: <1287544023.4571.8.camel@sli10-conroe.sh.intel.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Add a new readmostly percpu section and API.  This can be used to
avoid dirtying data lines which are generally not written to, which is
especially important for data which may be accessed by processors
other than the one for which the percpu area belongs to.

[ hpa: moved it *after* the page-aligned section, for obvious
  reasons. ]
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
LKML-Reference: <1287544022.4571.7.camel@sli10-conroe.sh.intel.com>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

arch/x86/mm/fault.c: In function 'vmalloc_sync_all':
arch/x86/mm/fault.c:238: warning: assignment makes integer from pointer without a cast

introduced by 617d34d9.
Signed-off-by: NBorislav Petkov <borislav.petkov@amd.com>
LKML-Reference: <20101020103642.GA3135@kryptos.osrc.amd.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Take mm->page_table_lock while syncing the vmalloc region.  This prevents
a race with the Xen pagetable pin/unpin code, which expects that the
page_table_lock is already held.  If this race occurs, then Xen can see
an inconsistent page type (a page can either be read/write or a pagetable
page, and pin/unpin converts it between them), which will cause either
the pin or the set_p[gm]d to fail; either will crash the kernel.

vmalloc_sync_all() should be called rarely, so this extra use of
page_table_lock should not interfere with its normal users.

The mm pointer is stashed in the pgd page's index field, as that won't
be otherwise used for pgds.
Reported-by: NIan Campbell <ian.cambell@eu.citrix.com>
Originally-by: NJan Beulich <jbeulich@novell.com>
LKML-Reference: <4CB88A4C.1080305@goop.org>
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

Whitespace cleanup only.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

On 32-bit non-PAE system, cast to 'phys_addr_t' truncates value
before subtraction. Subtracting before cast produce same result
but remove following warnings from sparse:

 arch/x86/include/asm/pgtable_types.h:255:38: warning: cast truncates bits from constant value (100000000 becomes 0)
 arch/x86/include/asm/pgtable_types.h:270:38: warning: cast truncates bits from constant value (100000000 becomes 0)
 arch/x86/include/asm/pgtable.h:127:32: warning: cast truncates bits from constant value (100000000 becomes 0)
 arch/x86/include/asm/pgtable.h:132:32: warning: cast truncates bits from constant value (100000000 becomes 0)
 arch/x86/include/asm/pgtable.h:344:31: warning: cast truncates bits from constant value (100000000 becomes 0)

64-bit or PAE machines will not be affected by this change.
Signed-off-by: NNamhyung Kim <namhyung@gmail.com>
LKML-Reference: <1285770588-14065-1-git-send-email-namhyung@gmail.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

This is useful when converting static arrays into boot-time brk
allocated objects.
Signed-off-by: NJeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
LKML-Reference: <4C805EEA.1080205@goop.org>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

During the reading of /proc/vmcore the kernel is doing
ioremap()/iounmap() repeatedly. And the buildup of un-flushed
vm_area_struct's is causing a great deal of overhead. (rb_next()
is chewing up most of that time).

This solution is to provide function set_iounmap_nonlazy(). It
causes a subsequent call to iounmap() to immediately purge the
vma area (with try_purge_vmap_area_lazy()).

With this patch we have seen the time for writing a 250MB
compressed dump drop from 71 seconds to 44 seconds.
Signed-off-by: NCliff Wickman <cpw@sgi.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: kexec@lists.infradead.org
Cc: <stable@kernel.org>
LKML-Reference: <E1OwHZ4-0005WK-Tw@eag09.americas.sgi.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The copy of /proc/vmcore to a user buffer proceeds much faster
if the kernel addresses memory as cached.

With this patch we have seen an increase in transfer rate from
less than 15MB/s to 80-460MB/s, depending on size of the
transfer. This makes a big difference in time needed to save a
system dump.
Signed-off-by: NCliff Wickman <cpw@sgi.com>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Cc: kexec@lists.infradead.org
Cc: <stable@kernel.org> # as far back as it would apply
LKML-Reference: <E1OtMLz-0001yp-Ia@eag09.americas.sgi.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This re-adds the lost chunk in commit 9b861528.
Reported-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NWu Fengguang <fengguang.wu@intel.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Haicheng Li <haicheng.li@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
LKML-Reference: <20100903090407.GA19771@localhost>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

The opcodes 0x2e and 0x3e are tested for in the first Group 2
line as well.

The sematic match that finds this problem is as follows:
(http://coccinelle.lip6.fr/)

// <smpl>
@expression@
expression E;
@@

(
* E
  || ... || E
|
* E
  && ... && E
)
// </smpl>
Signed-off-by: NJulia Lawall <julia@diku.dk>
Reviewed-by: NPekka Enberg <penberg@cs.helsinki.fi>
Cc: Vegard Nossum <vegardno@ifi.uio.no>
LKML-Reference: <1283010066-20935-5-git-send-email-julia@diku.dk>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

pte_present() returns true even present bit isn't set but _PAGE_PROTNONE
(global bit) bit is set. While with CONFIG_DEBUG_PAGEALLOC, free pages have
global bit set but present bit clear. This patch makes we could catch
free pages access with CONFIG_DEBUG_PAGEALLOC enabled.

[ hpa: added a comment in the code as a warning to janitors ]
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
LKML-Reference: <1280217988.32400.75.camel@sli10-desk.sh.intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

When memory hotplug-adding happens for a large enough area
that a new PGD entry is needed for the direct mapping, the PGDs
of other processes would not get updated. This leads to some CPUs
oopsing like below when they have to access the unmapped areas.

[ 1139.243192] BUG: soft lockup - CPU#0 stuck for 61s! [bash:6534]
[ 1139.243195] Modules linked in: ipv6 autofs4 rfcomm l2cap crc16 bluetooth rfkill binfmt_misc
dm_mirror dm_region_hash dm_log dm_multipath dm_mod video output sbs sbshc fan battery ac parport_pc
lp parport joydev usbhid processor thermal thermal_sys container button rtc_cmos rtc_core rtc_lib
i2c_i801 i2c_core pcspkr uhci_hcd ohci_hcd ehci_hcd usbcore
[ 1139.243229] irq event stamp: 8538759
[ 1139.243230] hardirqs last  enabled at (8538759): [<ffffffff8100c3fc>] restore_args+0x0/0x30
[ 1139.243236] hardirqs last disabled at (8538757): [<ffffffff810422df>] __do_softirq+0x106/0x146
[ 1139.243240] softirqs last  enabled at (8538758): [<ffffffff81042310>] __do_softirq+0x137/0x146
[ 1139.243245] softirqs last disabled at (8538743): [<ffffffff8100cb5c>] call_softirq+0x1c/0x34
[ 1139.243249] CPU 0:
[ 1139.243250] Modules linked in: ipv6 autofs4 rfcomm l2cap crc16 bluetooth rfkill binfmt_misc
dm_mirror dm_region_hash dm_log dm_multipath dm_mod video output sbs sbshc fan battery ac parport_pc
lp parport joydev usbhid processor thermal thermal_sys container button rtc_cmos rtc_core rtc_lib
i2c_i801 i2c_core pcspkr uhci_hcd ohci_hcd ehci_hcd usbcore
[ 1139.243284] Pid: 6534, comm: bash Tainted: G   M       2.6.32-haicheng-cpuhp #7 QSSC-S4R
[ 1139.243287] RIP: 0010:[<ffffffff810ace35>]  [<ffffffff810ace35>] alloc_arraycache+0x35/0x69
[ 1139.243292] RSP: 0018:ffff8802799f9d78  EFLAGS: 00010286
[ 1139.243295] RAX: ffff8884ffc00000 RBX: ffff8802799f9d98 RCX: 0000000000000000
[ 1139.243297] RDX: 0000000000190018 RSI: 0000000000000001 RDI: ffff8884ffc00010
[ 1139.243300] RBP: ffffffff8100c34e R08: 0000000000000002 R09: 0000000000000000
[ 1139.243303] R10: ffffffff8246dda0 R11: 000000d08246dda0 R12: ffff8802599bfff0
[ 1139.243305] R13: ffff88027904c040 R14: ffff8802799f8000 R15: 0000000000000001
[ 1139.243308] FS:  00007fe81bfe86e0(0000) GS:ffff88000d800000(0000) knlGS:0000000000000000
[ 1139.243311] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 1139.243313] CR2: ffff8884ffc00000 CR3: 000000026cf2d000 CR4: 00000000000006f0
[ 1139.243316] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[ 1139.243318] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
[ 1139.243321] Call Trace:
[ 1139.243324]  [<ffffffff810ace29>] ? alloc_arraycache+0x29/0x69
[ 1139.243328]  [<ffffffff8135004e>] ? cpuup_callback+0x1b0/0x32a
[ 1139.243333]  [<ffffffff8105385d>] ? notifier_call_chain+0x33/0x5b
[ 1139.243337]  [<ffffffff810538a4>] ? __raw_notifier_call_chain+0x9/0xb
[ 1139.243340]  [<ffffffff8134ecfc>] ? cpu_up+0xb3/0x152
[ 1139.243344]  [<ffffffff813388ce>] ? store_online+0x4d/0x75
[ 1139.243348]  [<ffffffff811e53f3>] ? sysdev_store+0x1b/0x1d
[ 1139.243351]  [<ffffffff8110589f>] ? sysfs_write_file+0xe5/0x121
[ 1139.243355]  [<ffffffff810b539d>] ? vfs_write+0xae/0x14a
[ 1139.243358]  [<ffffffff810b587f>] ? sys_write+0x47/0x6f
[ 1139.243362]  [<ffffffff8100b9ab>] ? system_call_fastpath+0x16/0x1b

This patch makes sure to always replicate new direct mapping PGD entries
to the PGDs of all processes, as well as ensures corresponding vmemmap
mapping gets synced.

V1: initial code by Andi Kleen.
V2: fix several issues found in testing.
V3: as suggested by Wu Fengguang, reuse common code of vmalloc_sync_all().

[ hpa: changed pgd_change from int to bool ]
Originally-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NHaicheng Li <haicheng.li@linux.intel.com>
LKML-Reference: <4C6E4FD8.6080100@linux.intel.com>
Reviewed-by: NWu Fengguang <fengguang.wu@intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

No behavior change.

Move some of vmalloc_sync_all() code into a new function
sync_global_pgds() that will be useful for memory hotplug.
Signed-off-by: NHaicheng Li <haicheng.li@linux.intel.com>
LKML-Reference: <4C6E4ECD.1090607@linux.intel.com>
Reviewed-by: NWu Fengguang <fengguang.wu@intel.com>
Reviewed-by: NAndi Kleen <ak@linux.intel.com>
Signed-off-by: NH. Peter Anvin <hpa@linux.intel.com>

In x86, access and dirty bits are set automatically by CPU when CPU accesses
memory. When we go into the code path of below flush_tlb_fix_spurious_fault(),
we already set dirty bit for pte and don't need flush tlb. This might mean
tlb entry in some CPUs hasn't dirty bit set, but this doesn't matter. When
the CPUs do page write, they will automatically check the bit and no software
involved.

On the other hand, flush tlb in below position is harmful. Test creates CPU
number of threads, each thread writes to a same but random address in same vma
range and we measure the total time. Under a 4 socket system, original time is
1.96s, while with the patch, the time is 0.8s. Under a 2 socket system, there is
20% time cut too. perf shows a lot of time are taking to send ipi/handle ipi for
tlb flush.
Signed-off-by: NShaohua Li <shaohua.li@intel.com>
LKML-Reference: <20100816011655.GA362@sli10-desk.sh.intel.com>
Acked-by: NSuresh Siddha <suresh.b.siddha@intel.com>
Cc: Andrea Archangeli <aarcange@redhat.com>
Signed-off-by: NH. Peter Anvin <hpa@zytor.com>

* 'kvm-updates/2.6.36' of git://git.kernel.org/pub/scm/virt/kvm/kvm:
  KVM: PIT: free irq source id in handling error path
  KVM: destroy workqueue on kvm_create_pit() failures
  KVM: fix poison overwritten caused by using wrong xstate size

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/anholt/drm-intel: (58 commits)
  drm/i915,intel_agp: Add support for Sandybridge D0
  drm/i915: fix render pipe control notify on sandybridge
  agp/intel: set 40-bit dma mask on Sandybridge
  drm/i915: Remove the conflicting BUG_ON()
  drm/i915/suspend: s/IS_IRONLAKE/HAS_PCH_SPLIT/
  drm/i915/suspend: Flush register writes before busy-waiting.
  i915: disable DAC on Ironlake also when doing CRT load detection.
  drm/i915: wait for actual vblank, not just 20ms
  drm/i915: make sure eDP PLL is enabled at the right time
  drm/i915: fix VGA plane disable for Ironlake+
  drm/i915: eDP mode set sequence corrections
  drm/i915: add panel reset workaround
  drm/i915: Enable RC6 on Ironlake.
  drm/i915/sdvo: Only set is_lvds if we have a valid fixed mode.
  drm/i915: Set up a render context on Ironlake
  drm/i915 invalidate indirect state pointers at end of ring exec
  drm/i915: Wake-up wait_request() from elapsed hang-check (v2)
  drm/i915: Apply i830 errata for cursor alignment
  drm/i915: Only update i845/i865 CURBASE when disabled (v2)
  drm/i915: FBC is updated within set_base() so remove second call in mode_set()
  ...

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6:
  slab: fix object alignment
  slub: add missing __percpu markup in mm/slub_def.h

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ryusuke/nilfs2:
  nilfs2: wait for discard to finish

Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: NEric Anholt <eric@anholt.net>

This one is missed in last pipe control fix for sandybridge,
that really unmask interrupt bit for notify in render engine IMR.
Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: NEric Anholt <eric@anholt.net>

Signed-off-by: NZhenyu Wang <zhenyuw@linux.intel.com>
Signed-off-by: NEric Anholt <eric@anholt.net>

We now attempt to free "active" objects following a GPU hang as either
the GPU will be reset or the hang is permenant. In either case, the GPU
writes will not be flushed to main memory and it should be safe to
return that memory back to the system.

The BUG_ON(active) is thus overkill and can erroneously fire after a
EIO.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NEric Anholt <eric@anholt.net>

For the shared paths on the next generation chipsets.
Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NEric Anholt <eric@anholt.net>

Signed-off-by: NChris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: NEric Anholt <eric@anholt.net>

Like on Sandybridge, disabling the DAC here when doing CRT load detect
avoids forever hangs waiting on the hardware.

test procedure on HP 2740p:
boot with no VGA plugged in, start X,
plug in VGA monitor (1280x1024)
chvt 3
machine hangs waiting forever.
Signed-off-by: NDave Airlie <airlied@redhat.com>
Signed-off-by: NEric Anholt <eric@anholt.net>

Waiting for a hard coded 20ms isn't always enough to make sure a vblank
period has actually occurred, so add code to make sure we really have
passed through a vblank period (or that the pipe is off when disabling).

This prevents problems with mode setting and link training, and seems to
fix a bug like https://bugs.freedesktop.org/show_bug.cgi?id=29278, but
on an HP 8440p instead.  Hopefully also fixes
https://bugs.freedesktop.org/show_bug.cgi?id=29141.
Signed-off-by: NJesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: NEric Anholt <eric@anholt.net>

With the introduction of the new unified work queue thread pools,
we lost one feature: It's no longer possible to know which worker
is causing the CPU to wake out of idle. The result is that PowerTOP
now reports a lot of "kworker/a:b" instead of more readable results.

This patch adds a pair of tracepoints to the new workqueue code,
similar in style to the timer/hrtimer tracepoints.

With this pair of tracepoints, the next PowerTOP can correctly
report which work item caused the wakeup (and how long it took):

Interrupt (43)            i915      time   3.51ms    wakeups 141
Work      ieee80211_iface_work      time   0.81ms    wakeups  29
Work              do_dbs_timer      time   0.55ms    wakeups  24
Process                   Xorg      time  21.36ms    wakeups   4
Timer    sched_rt_period_timer      time   0.01ms    wakeups   1
Signed-off-by: NArjan van de Ven <arjan@linux.intel.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* git://git.infradead.org/mtd-2.6:
  mtd: nand: Fix probe of Samsung NAND chips
  mtd: nand: Fix regression in BBM detection
  pxa3xx: fix ns2cycle equation

The "Configure" word tends to make user believe they have to say 'yes'
to be able to choose the number of procs/nodes.  "Enable" should be
unambiguous enough.
Signed-off-by: NSamuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Like the mlock() change previously, this makes the stack guard check
code use vma->vm_prev to see what the mapping below the current stack
is, rather than have to look it up with find_vma().

Also, accept an abutting stack segment, since that happens naturally if
you split the stack with mlock or mprotect.
Tested-by: NIan Campbell <ijc@hellion.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If we've split the stack vma, only the lowest one has the guard page.
Now that we have a doubly linked list of vma's, checking this is trivial.
Tested-by: NIan Campbell <ijc@hellion.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

It's a really simple list, and several of the users want to go backwards
in it to find the previous vma.  So rather than have to look up the
previous entry with 'find_vma_prev()' or something similar, just make it
doubly linked instead.
Tested-by: NIan Campbell <ijc@hellion.org.uk>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Apparently, the check for a 6-byte ID string introduced by commit
426c457a ("mtd: nand: extend NAND flash
detection to new MLC chips") is NOT sufficient to determine whether or
not a Samsung chip uses their new MLC detection scheme or the old,
standard scheme. This adds a condition to check cell type.
Signed-off-by: NTilman Sauerbeck <tilman@code-monkey.de>
Signed-off-by: NBrian Norris <norris@broadcom.com>
Signed-off-by: NDavid Woodhouse <David.Woodhouse@intel.com>
Cc: stable@kernel.org

Merge branch 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  x86, apic: Fix apic=debug boot crash
  x86, hotplug: Serialize CPU hotplug to avoid bringup concurrency issues
  x86-32: Fix dummy trampoline-related inline stubs
  x86-32: Separate 1:1 pagetables from swapper_pg_dir
  x86, cpu: Fix regression in AMD errata checking code

This list moved to lists.ozlabs.org quite some time ago.
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

All these lists moved to lists.ozlabs.org quite a while ago.
Signed-off-by: NStephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Chapter 6 is right about mutex_trylock, but chapter 10 wasn't.  This error
was introduced during semaphore-to-mutex conversion of the Unreliable
guide.  :-)

If user context which performs mutex_lock() or mutex_trylock() is
preempted by interrupt context which performs mutex_trylock() on the same
mutex instance, a deadlock occurs.  This is because these functions do not
disable local IRQs when they operate on mutex->wait_lock.
Signed-off-by: NStefan Richter <stefanr@s5r6.in-berlin.de>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

gcc-4.0.2:

  drivers/scsi/qla4xxx/ql4_os.c: In function 'qla4_8xxx_error_recovery':
  drivers/scsi/qla4xxx/ql4_glbl.h:135: sorry, unimplemented: inlining failed in call to 'qla4_8xxx_set_drv_active': function body not available
  drivers/scsi/qla4xxx/ql4_os.c:2377: sorry, unimplemented: called from here
  drivers/scsi/qla4xxx/ql4_glbl.h:135: sorry, unimplemented: inlining failed in call to 'qla4_8xxx_set_drv_active': function body not available
  drivers/scsi/qla4xxx/ql4_os.c:2393: sorry, unimplemented: called from here

Cc: Ravi Anand <ravi.anand@qlogic.com>
Cc: Vikas Chaudhary <vikas.chaudhary@qlogic.com>
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>