There is a race in virtio_net, dealing with disabling/enabling the callback.
I saw the following oops:

kernel BUG at /space/kvm/drivers/virtio/virtio_ring.c:218!
illegal operation: 0001 [#1] SMP
Modules linked in: sunrpc dm_mod
CPU: 2 Not tainted 2.6.25-rc1zlive-host-10623-gd358142-dirty #99
Process swapper (pid: 0, task: 000000000f85a610, ksp: 000000000f873c60)
Krnl PSW : 0404300180000000 00000000002b81a6 (vring_disable_cb+0x16/0x20)
           R:0 T:1 IO:0 EX:0 Key:0 M:1 W:0 P:0 AS:0 CC:3 PM:0 EA:3
Krnl GPRS: 0000000000000001 0000000000000001 0000000010005800 0000000000000001
           000000000f3a0900 000000000f85a610 0000000000000000 0000000000000000
           0000000000000000 000000000f870000 0000000000000000 0000000000001237
           000000000f3a0920 000000000010ff74 00000000002846f6 000000000fa0bcd8
Krnl Code: 00000000002b819a: a7110001           tmll    %r1,1
           00000000002b819e: a7840004           brc     8,2b81a6
           00000000002b81a2: a7f40001           brc     15,2b81a4
          >00000000002b81a6: a51b0001           oill    %r1,1
           00000000002b81aa: 40102000           sth     %r1,0(%r2)
           00000000002b81ae: 07fe               bcr     15,%r14
           00000000002b81b0: eb7ff0380024       stmg    %r7,%r15,56(%r15)
           00000000002b81b6: a7f13e00           tmll    %r15,15872
Call Trace:
([<000000000fa0bcd0>] 0xfa0bcd0)
 [<00000000002b8350>] vring_interrupt+0x5c/0x6c
 [<000000000010ab08>] do_extint+0xb8/0xf0
 [<0000000000110716>] ext_no_vtime+0x16/0x1a
 [<0000000000107e72>] cpu_idle+0x1c2/0x1e0

The problem can be triggered with a high amount of host->guest traffic.
I think its the following race:

poll says netif_rx_complete
poll calls enable_cb
enable_cb opens the interrupt mask
a new packet comes, an interrupt is triggered----\
enable_cb sees that there is more work           |
enable_cb disables the interrupt                 |
       .                                         V
       .                            interrupt is delivered
       .                            skb_recv_done does atomic napi test, ok
 some waiting                       disable_cb is called->check fails->bang!
       .
poll would do napi check
poll would do disable_cb

The fix is to let enable_cb not disable the interrupt again, but expect the
caller to do the cleanup if it returns false. In that case, the interrupt is
only disabled, if the napi test_set_bit was successful.
Signed-off-by: NChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (cleaned up doco)

Add a new poll_controller handler that the netpoll interface needs.

This enables netconsole logging from a kvm guest over the virtio
net interface.
Signed-off-by: NAmit Shah <amitshah@gmx.net>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

If the host asks for a huge target towards_target() can overflow, and
we up oops as we try to release more pages than we have.  The simple
fix is to use a 64-bit value.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

Fix up so that the virtio_blk devices in sysfs link correctly to their
block device.  This then allows them to be detected by hal, etc
Signed-off-by: NJeremy Katz <katzj@redhat.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

virtio-pci acquires its spin lock in an interrupt context so it's necessary
to use spin_lock_irqsave/restore variants.  This patch fixes guest SMP when
using virtio devices in KVM.
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>

* 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6:
  [PARISC] make ptr_to_pide() static
  [PARISC] head.S: section mismatch fixes
  [PARISC] add back Crestone Peak cpu
  [PARISC] futex: special case cmpxchg NULL in kernel space
  [PARISC] clean up show_stack
  [PARISC] add pa8900 CPUs to hardware inventory
  [PARISC] clean up include/asm-parisc/elf.h
  [PARISC] move defconfig to arch/parisc/configs/
  [PARISC] add back AD1889 MAINTAINERS entry
  [PARISC] pdc_console: fix bizarre panic on boot
  [PARISC] dump_stack in show_regs
  [PARISC] pdc_stable: fix compile errors
  [PARISC] remove unused pdc_iodc_printf function
  [PARISC] bump __NR_syscalls
  [PARISC] unbreak pgalloc.h
  [PARISC] move VMALLOC_* definitions to fixmap.h
  [PARISC] wire up timerfd syscalls
  [PARISC] remove old timerfd syscall

Signed-off-by: NFUJITA Tomonori <fujita.tomonori@lab.ntt.co.jp>
Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

- move boot_args[] into the init section
- move $global$ into the read_mostly section
- fix the following two section mismatches:
WARNING: vmlinux.o(.text+0x9c): Section mismatch: reference to .init.text:start_kernel (between '$pgt_fill_loop' and '$is_pa20')
WARNING: vmlinux.o(.text+0xa0): Section mismatch: reference to .init.text:start_kernel (between '$pgt_fill_loop' and '$is_pa20')
Signed-off-by: NHelge Deller <deller@gmx.de>
SIgned-off-by: NKyle McMartin <kyle@mcmartin.ca>

Crestone Peak Slow is the 800MHz PA-8800 cpu in the C8000.
0x88B is probably the Crestone Peak Fast.
Signed-off-by: NKyle McMartin <kyle@mcmartin.ca>

Commit a0c1e907 added code to futex.c
to detect whether futex_atomic_cmpxchg_inatomic was implemented at run
time:

+       curval = cmpxchg_futex_value_locked(NULL, 0, 0);
+       if (curval == -EFAULT)
+               futex_cmpxchg_enabled = 1;

This is bogus on parisc, since page zero in kernel virtual space is the
gateway page for syscall entry, and should not be read from the kernel.
(That, and we really don't like the kernel faulting on its own address
 space...)
Signed-off-by: NKyle McMartin <kyle@mcmartin.ca>

When we show_regs, we obviously have a struct pt_regs of the calling
frame. Use these in show_stack so we don't have the entire bogus call trace
up to the show_stack call.
Signed-off-by: NKyle McMartin <kyle@mcmartin.ca>

This patch adds the known pa8900 CPUs to the inventory list and removes
the Crestone Peak one which apparently never escaped into the wild.
Signed-off-by: NJames Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: NKyle McMartin <kyle@mcmartin.ca>

Cleanup some cruft. No functionality changes.
Signed-off-by: NRandolph Chung <tausq@parisc-linux.org>
Signed-off-by: NKyle McMartin <kyle@mcmartin.ca>

This patch moves the default parisc defconfig to
arch/parisc/configs/generic_defconfig where it belongs and selects it as
the default defconfig through KBUILD_DEFCONFIG.
Signed-off-by: NAdrian Bunk <adrian.bunk@movial.fi>
Signed-off-by: NKyle McMartin <kyle@mcmartin.ca>

Signed-off-by: NThibaut VARENE <T-Bone@parisc-linux.org>
Signed-off-by: NKyle McMartin <kyle@mcmartin.ca>

Commit 721fdf34 introduced a subtle bug
by accidently removing the "static" from iodc_dbuf. This resulted in, what
appeared to be, a trap without *current set to a task. Probably the result of
a trap in real mode while calling firmware.

Also do other misc clean ups. Since the only input from firmware is non
blocking, share iodc_dbuf between input and output, and spinlock the
only callers.
Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

Originally, show_stack was used in BUG() output. However, a recent commit
changed it to print register state (no idea what that's supposed to help,
really...) and parisc was missing a backtrace because of it.
Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

Signed-off-by: NJoel Soete <rubisher@scarlet.be>
Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

oops, forgot this in the previous commit.
Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

Commit 2f569afd broke the compile
rather spectacularly. Fix code errors.
Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

They make way more sense here, really...
Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

Signed-off-by: NKyle McMartin <kyle@parisc-linux.org>

This essentially reverts commit 71fc47a9
("ACPI: basic initramfs DSDT override support"), because the code simply
isn't ready.

It did ugly things to the init sequence to populate the rootfs image
early, but that just ended up showing other problems with the whole
approach.  The fact is, the VFS layer simply isn't initialized this
early, and the relevant ACPI code should either run much later, or this
shouldn't be done at all.

For 2.6.25, we'll just pick the latter option.  We can revisit this
concept later if necessary.

Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Tilman Schmidt <tilman@imap.cc>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Thomas Renninger <trenn@suse.de>
Cc: Eric Piel <eric.piel@tremplin-utc.net>
Cc: Len Brown <len.brown@intel.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Markus Gaugusch <dsdt@gaugusch.at>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

DATA_CARRY is not boolean
Signed-off-by: NRoel Kluin <12o3l@tiscali.nl>
Signed-off-by: NPierre Ossman <drzeus@drzeus.cx>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
  [NET]: Fix tbench regression in 2.6.25-rc1

Use the existing calc_delta_mine() calculation for sched_slice(). This
saves a divide and simplifies the code because we share it with the
other /cfs_rq->load users.

It also improves code size:

      text    data     bss     dec     hex filename
     42659    2740     144   45543    b1e7 sched.o.before
     42093    2740     144   44977    afb1 sched.o.after
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>

Fair sleepers need to scale their latency target down by runqueue
weight. Otherwise busy systems will gain ever larger sleep bonus.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>

Currently we schedule to the leftmost task in the runqueue. When the
runtimes are very short because of some server/client ping-pong,
especially in over-saturated workloads, this will cycle through all
tasks trashing the cache.

Reduce cache trashing by keeping dependent tasks together by running
newly woken tasks first. However, by not running the leftmost task first
we could starve tasks because the wakee can gain unlimited runtime.

Therefore we only run the wakee if its within a small
(wakeup_granularity) window of the leftmost task. This preserves
fairness, but does alternate server/client task groups.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

lw->weight can be 0 for a short time during bootup.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>

Clear the cached inverse value when updating load. This is needed for
calc_delta_mine() to work correctly when using the rq load.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>

Current min_vruntime tracking is incorrect and will cause serious
problems when we don't run the leftmost task for some reason.

min_vruntime does two things; 1) it's used to determine a forward
direction when the u64 vruntime wraps, 2) it's used to track the
leftmost vruntime to position newly enqueued tasks from.

The current logic advances min_vruntime whenever the current task's
vruntime advance. Because the current task may pass the leftmost task
still waiting we're failing the second goal. This causes new tasks to be
placed too far ahead and thus penalizes their runtime.

Fix this by making min_vruntime the min_vruntime of the waiting tasks by
tracking it in enqueue/dequeue, and compare against current's vruntime
to obtain the absolute minimum when placing new tasks.
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Fix a hard to trigger crash seen in the -rt kernel that also affects
the vanilla scheduler.

There is a race condition between schedule() and some dequeue/enqueue
functions; rt_mutex_setprio(), __setscheduler() and sched_move_task().

When scheduling to idle, idle_balance() is called to pull tasks from
other busy processor. It might drop the rq lock. It means that those 3
functions encounter on_rq=0 and running=1. The current task should be
put when running.

Here is a possible scenario:

   CPU0                               CPU1
    |                              schedule()
    |                              ->deactivate_task()
    |                              ->idle_balance()
    |                              -->load_balance_newidle()
rt_mutex_setprio()                     |
    |                              --->double_lock_balance()
    *get lock                          *rel lock
    * on_rq=0, ruuning=1               |
    * sched_class is changed           |
    *rel lock                          *get lock
    :                                  |
                                       :
                                   ->put_prev_task_rt()
                                   ->pick_next_task_fair()
                                       => panic

The current process of CPU1(P1) is scheduling. Deactivated P1, and the
scheduler looks for another process on other CPU's runqueue because CPU1
will be idle. idle_balance(), load_balance_newidle() and
double_lock_balance() are called and double_lock_balance() could drop
the rq lock. On the other hand, CPU0 is trying to boost the priority of
P1. The result of boosting only P1's prio and sched_class are changed to
RT. The sched entities of P1 and P1's group are never put. It makes
cfs_rq invalid, because the cfs_rq has curr and no leaf, but
pick_next_task_fair() is called, then the kernel panics.
Signed-off-by: NHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ieee1394/linux1394-2.6:
  firewire: fw-ohci: shut up false compiler warning on PPC32
  firewire: fw-ohci: use dma_alloc_coherent for ar_buffer
  ieee1394: sbp2: fix for SYM13FW500 bridge (Datafab disk)
  firewire: fw-sbp2: fix for SYM13FW500 bridge (Datafab disk)
  firewire: update Kconfig help text
  firewire: warn on fatal condition in topology code
  firewire: fw-sbp2: set single-phase retry_limit
  firewire: fw-ohci: Apple UniNorth 1st generation support
  firewire: fw-ohci: PPC PMac platform code
  firewire: endianess annotations
  firewire: endianess fix

This bug was always here, but before my commit 6fa02839
("recheck for secure ports in fh_verify"), it could only be triggered by
failure of a kmalloc().  After that commit it could be triggered by a
client making a request from a non-reserved port for access to an export
marked "secure".  (Exports are "secure" by default.)

The result is a struct svc_export with a reference count one too low,
resulting in likely oopses next time the export is accessed.

The reference counting here is not straightforward; a later patch will
clean up fh_verify().

Thanks to Lukas Hejtmanek for the bug report and followup.
Signed-off-by: NJ. Bruce Fields <bfields@citi.umich.edu>
Cc: Lukas Hejtmanek <xhejtman@ics.muni.cz>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The comments in the definition of struct export_operations don't match the
current members.

Add a comment for the 2 new functions and remove 2 comments for unused ones.
Signed-off-by: NMarc Dionne <marc.c.dionne@gmail.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Acked-by: NChristoph Hellwig <hch@lst.de>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Shut up "may be used uninitialised in this function" warnings due to
PPC32's implementation of dma_alloc_coherent().
Signed-off-by: NStefan Richter <stefanr@s5r6.in-berlin.de>

Currently, we do nothing to guarantee we have a consistent DMA buffer for
asynchronous receive packets. Rather than doing several sync's following a
dma_map_single() to get consistent buffers, just switch to using
dma_alloc_coherent().

Resolves constant buffer failures on my own x86_64 laptop w/4GB of RAM and
likely to fix a number of other failures witnessed on x86_64 systems with
4GB of RAM or more.
Signed-off-by: NJarod Wilson <jwilson@redhat.com>
Signed-off-by: NStefan Richter <stefanr@s5r6.in-berlin.de>