When CONFIG_RT_GROUP_SCHED and CONFIG_CGROUP_SCHED are enabled, with:

 echo 10000 > /proc/sys/kernel/sched_rt_period_us

We get this:

 BUG: unable to handle kernel NULL pointer dereference at 0000008c
 [  947.682233] IP: [<c0216b72>] __rt_schedulable+0x12/0x160
 [  947.683123] *pde = 00000000=20
 [  947.683782] Oops: 0000 [#1]
 [  947.684307] Modules linked in:
 [  947.684308]
 [  947.684308] Pid: 2359, comm: bash Not tainted (2.6.26-rc6 #8)
 [  947.684308] EIP: 0060:[<c0216b72>] EFLAGS: 00000246 CPU: 0
 [  947.684308] EIP is at __rt_schedulable+0x12/0x160
 [  947.684308] EAX: 00000000 EBX: 00000000 ECX: 00000000 EDX: 00000001
 [  947.684308] ESI: c0521db4 EDI: 00000001 EBP: c6cc9f00 ESP: c6cc9ed0
 [  947.684308]  DS: 007b ES: 007b FS: 0000 GS: 0033 SS: 0068
 [  947.684308] Process bash (pid: 2359, tiÆcc8000 taskÇa54f00=20 task.tiÆcc8000)
 [  947.684308] Stack: c0222790 00000000 080f8c08 c0521db4 c6cc9f00 00000001 00000000 00000000
 [  947.684308]        c6cc9f9c 00000000 c0521db4 00000001 c6cc9f28 c0216d40 00000000 00000000
 [  947.684308]        c6cc9f9c 000f4240 000e7ef0 ffffffff c0521db4 c79dfb60 c6cc9f58 c02af2cc
 [  947.684308] Call Trace:
 [  947.684308]  [<c0222790>] ? do_proc_dointvec_conv+0x0/0x50
 [  947.684308]  [<c0216d40>] ? sched_rt_handler+0x80/0x110
 [  947.684308]  [<c02af2cc>] ? proc_sys_call_handler+0x9c/0xb0
 [  947.684308]  [<c02af2fa>] ? proc_sys_write+0x1a/0x20
 [  947.684308]  [<c0273c36>] ? vfs_write+0x96/0x160
 [  947.684308]  [<c02af2e0>] ? proc_sys_write+0x0/0x20
 [  947.684308]  [<c027423d>] ? sys_write+0x3d/0x70
 [  947.684308]  [<c0202ef5>] ? sysenter_past_esp+0x6a/0x91
 [  947.684308]  =======================
 [  947.684308] Code: 24 04 e8 62 b1 0e 00 89 c7 89 f8 8b 5d f4 8b 75
 f8 8b 7d fc 89 ec 5d c3 90 55 89 e5 57 56 53 83 ec 24 89 45 ec 89 55 e4
 89 4d e8 <8b> b8 8c 00 00 00 85 ff 0f 84 c9 00 00 00 8b 57 24 39 55 e8
 8b
 [  947.684308] EIP: [<c0216b72>] __rt_schedulable+0x12/0x160 SS:ESP  0068:c6cc9ed0

We think the following patch solves the issue.
Signed-off-by: Dario Faggioli <raistlin@linux.it>
Signed-off-by: Michael Trimarchi <trimarchimichael@yahoo.it>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

Fix this warning, which appears with !CONFIG_SMP:
kernel/sched.c:1216: warning: `init_hrtick' defined but not used
Signed-off-by: Rabin Vincent <rabin@rab.in>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>

* git://git.kernel.org/pub/scm/linux/kernel/git/bart/ide-2.6:
  ide-generic: don't probe all legacy ISA IDE ports by default
  ide-cs: fix releasing I/O resources
  ide-cs: fix probing and add warm-plug support
  ide-pmac: remove bogus comment about pmac_ide_setup_device()
  ide-pmac: add ->cable_detect method
  ide-pmac: bugfix for media-bay support rework
  opti621: add PIO 4 support
  opti621: use pre-calculated PIO timings
  opti621: program devices timings separately in ->set_pio_mode
  opti621: use PCI clock value provided by controller
  opti621: remove DMA support
  opti621: disable read prefetch

lguest (in rusty's use-tun-ringfd patch) assumes that the
guest has updated its feature bits before setting its status
to VIRTIO_CONFIG_S_DRIVER_OK.

That's pretty reasonable, so let's make it so.
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We can't probe all legacy ISA IDE ports by default as the resources may be
occupied by other ISA devices.  Add "probe_mask" module parameter and probe
only first two ISA IDE ports by default leaving the decision about probing
the rest to the user (systems with ISA ide2-6 should be very, very rare).

This fixes a regression caused by:

commit 343a3451
Author: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Date:   Tue Jun 10 20:56:36 2008 +0200

    ide-generic: add missing hwif->chipset setup
...
Reported-by: Mikael Pettersson <mikpe@it.uu.se>
Bisected-by: Mikael Pettersson <mikpe@it.uu.se>
Tested-by: Mikael Pettersson <mikpe@it.uu.se>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

hwif content is already freed after ide_release() call so cache
hwif->io_ports.{data,ctl}_addr in local variables in ide_detach().

This fixes post-2.6.25 regression.
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

* Fix probing by using ide_port_scan() and moving "retry loop"
  from ide_config() to idecs_register().

* Don't fail probe if there are no devices attached to a port.

* Remove (now redundant) error message from ide_config().
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

Add ->cable_detect method and remove no longer needed pmif->cable_80 flag
(there is also no need to mask ->udma_mask now).

This fixes:

- forced ignoring of cable detection (needed for some CF devices & debug)

- cable detection for warm-plug

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

Fix bug introduced by:

commit 2dde7861
Author: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Date:   Fri Apr 18 00:46:23 2008 +0200

    ide: rework PowerMac media-bay support (take 2)
...

[ Yeah, I suck. ]

bay->cd_index shouldn't be changed if IDE devices are not present
or retry operations won't happen.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

* Add PIO 4 support.

While at it:

* Use a single struct ide_port_info instance for OPTi621 and OPTi621X.

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.
Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

* Use pre-calculated PIO timings in ->set_pio_mode.

* Remove no longer needed compute_clocks(), cmpt_clk(), struct pio_clocks_s,
  PIO_* defines and OPTI621_DEBUG define.

There should be no functional changes caused by this patch.

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.
Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

* Set drive->drive_data to 'pio + XFER_PIO_0' instead of 'pio',
  then simplify selecting maximum adress setup timing.

* Remove no longer needed compute_pios() and opti621_port_init_devs().

* Program devices timings separately in ->set_pio_mode.

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.
Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

Use PCI clock value provided by controller instead of depending on
a default (or user supplied) value.

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.
Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

These controllers don't support DMA.

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.
Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Acked-by: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

This fixes 2.6.25 regression (kernel.org bugzilla bug #10723) caused by:

commit 912fb29a
Author: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Date:   Fri Oct 19 00:30:11 2007 +0200

    opti621: always tune PIO
...

Based on a bugreport from Juergen Kosel & inspired by pata_opti.c code.
Bisected-by: Juergen Kosel <juergen.kosel@gmx.de>
Tested-by: Juergen Kosel <juergen.kosel@gmx.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jbarnes/pci-2.6:
  PCI: fixup write combine comment in pci_mmap_resource
  x86: PAT export resource_wc in pci sysfs
  x86, pci-dma.c: don't always add __GFP_NORETRY to gfp
  suspend-vs-iommu: prevent suspend if we could not resume
  x86: pci-dma.c: use __GFP_NO_OOM instead of __GFP_NORETRY
  pci, x86: add workaround for bug in ASUS A7V600 BIOS (rev 1005)
  PCI: use dev_to_node in pci_call_probe
  PCI: Correct last two HP entries in the bfsort whitelist

* git://git.kernel.org/pub/scm/linux/kernel/git/kyle/parisc-2.6:
  parisc: update my email address
  parisc: fix miscompilation of ip_fast_csum with gcc >= 4.3
  parisc: fix off by one in setup_sigcontext32
  parisc: export empty_zero_page
  parisc: export copy_user_page_asm
  parisc: move head.S to head.text section
  Revert "parisc: fix trivial section name warnings"

Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

ip_fast_csum needs an asm "memory" clobber, otherwise the aggressive
optimizations in gcc-4.3 cause it to be miscompiled.
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

Thankfully, the values were irrelevant... Spotted by
newer gcc.
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

Needed by ext4 when built as a module.
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

Needed by fuse (via copy_highpage).
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

And explicitly list it in vmlinux.lds...
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

This reverts commit bd3bb8c1.
Signed-off-by: Kyle McMartin <kyle@mcmartin.ca>

* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
  ahci: Workaround HW bug for SB600/700 SATA controller PMP support
  ahci: workarounds for mcp65

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-2.6:
  tcp: Revert 'process defer accept as established' changes.
  ipv6: Fix duplicate initialization of rawv6_prot.destroy
  bnx2x: Updating the Maintainer
  net: Eliminate flush_scheduled_work() calls while RTNL is held.
  drivers/net/r6040.c: correct bad use of round_jiffies()
  fec_mpc52xx: MPC52xx_MESSAGES_DEFAULT: 2nd NETIF_MSG_IFDOWN => IFUP
  ipg: fix receivemode IPG_RM_RECEIVEMULTICAST{,HASH} in ipg_nic_set_multicast_list()
  netfilter: nf_conntrack: fix ctnetlink related crash in nf_nat_setup_info()
  netfilter: Make nflog quiet when no one listen in userspace.
  ipv6: Fail with appropriate error code when setting not-applicable sockopt.
  ipv6: Check IPV6_MULTICAST_LOOP option value.
  ipv6: Check the hop limit setting in ancillary data.
  ipv6 route: Fix route lifetime in netlink message.
  ipv6 mcast: Check address family of gf_group in getsockopt(MS_FILTER).
  dccp: Bug in initial acknowledgment number assignment
  dccp ccid-3: X truncated due to type conversion
  dccp ccid-3: TFRC reverse-lookup Bug-Fix
  dccp ccid-2: Bug-Fix - Ack Vectors need to be ignored on request sockets
  dccp: Fix sparse warnings
  dccp ccid-3: Bug-Fix - Zero RTT is possible

* git://git.kernel.org/pub/scm/linux/kernel/git/davem/sparc-2.6:
  sparc: get leo framebuffer working

There is one bug in ATI SATA PMP of SB600 and SB700 old revision, which leads
to soft reset failure. This patch can fix the bug.
Signed-off-by: Shane Huang <shane.huang@amd.com>
Acked-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

MCP65 ahci can do NCQ but doesn't set the CAP bit and rev A0 and A1
can't do MSI but have MSI capability.  Implement AHCI_HFLAG_YES_NCQ
and apply appropriate workarounds.
Signed-off-by: Tejun Heo <htejun@gmail.com>
Cc: Peer Chen <pchen@nvidia.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>

* master.kernel.org:/home/rmk/linux-2.6-arm:
  [ARM] 5091/1: Add missing bitfield include to regs-lcd.h
  [ARM] 5090/1: Correct pxafb palette typo error
  [ARM] 5077/1: spi: fix list scan success verification in PXA ssp driver

Ramtron FM3130 is a chip with two separate devices inside, RTC clock and
FRAM.  This driver provides only RTC functionality.

This chip is met in lots of custom boards with AT91SAMXXXX CPU I work
with, is cheap and in no way better or worse than any other RTC on market.
 While it is mostly met on much smaller devices, I think it is great to
have it supported in Linux.
Signed-off-by: Sergey Lapin <slapin@ossfans.org>
Signed-off-by: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

More Kconfig tweaks related to the legacy PC RTC code:

 - Describe the legacy PC RTC driver as such ... it's never quite
   been clear that this driver is for PC RTCs, and now it's fair
   to call this the "legacy" driver.

 - Force it to understand about HPET stealing its IRQs ... kernel
   code does this always when HPET is in use, there should be no
   option for users to goof up the config.

This seems to fix kernel bugzilla #10729.
Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Recently (around 2.6.25) I've noticed that RTC no longer works for me.  It
turned out this is because I use pnpacpi=off kernel option to work around
the parport_pc bugs.  I always did so, but RTC used to work fine in the
past, and now it have regressed.

The patch fixes the problem by creating the platform device for the RTC
when PNP is disabled.  This may also help running the PNP-enabled kernel
on an older PCs.
Signed-off-by: Stas Sergeev <stsp@aknet.ru>
Cc: David Brownell <david-b@pacbell.net>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Bjorn Helgaas <bjorn.helgaas@hp.com>
Cc: Adam Belay <ambx1@neo.rr.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We shrink a radix tree when its root node has only one child, in the left
most slot.  The child becomes the new root node.  To perform this
operation in a manner compatible with concurrent lockless lookups, we
atomically switch the root pointer from the parent to its child.

However a concurrent lockless lookup may now have loaded a pointer to the
parent (and is presently deciding what to do next).  For this reason, we
also have to keep the parent node in a valid state after shrinking the
tree, until the next RCU grace period -- otherwise this lookup with the
parent pointer may not do the right thing.  Notably, we need to keep the
child in the left most slot there in case that is requested by the lookup.

This is all pretty standard RCU stuff.  It is worth repeating because in
my eagerness to obey the radix tree node constructor scheme, I had broken
it by zeroing the radix tree node before the grace period.

What could happen is that a lookup can load the parent pointer, then
decide it wants to follow the left most child slot, only to find the slot
contained NULL due to the concurrent shrinker having zeroed the parent
node before waiting for a grace period.  The lookup would return a false
negative as a result.

Fix it by doing that clearing in the RCU callback.  I would normally want
to rip out the constructor entirely, but radix tree nodes are one of those
places where they make sense (only few cachelines will be touched soon
after allocation).

This was never actually found in any lockless pagecache testing or by the
test harness, but by seeing the odd problem with my scalable vmap rewrite.
 I have not tickled the test harness into reproducing it yet, but I'll
keep working at it.

Fortunately, it is not a problem anywhere lockless pagecache is used in
mainline kernels (pagecache probe is not a guarantee, and brd does not
have concurrent lookups and deletes).
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Several console keyboard maps are broken since

commit 04c71976
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Tue Oct 16 23:27:04 2007 -0700

    unicode diacritics support

because that changeset made k_self consider the value as a latin1
character when in Unicode mode, which is wrong; k_self should still take
the console map into account.
Signed-off-by: Samuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

sysvipc_shm_proc_show() picks between format strings (based on the
expected maximum length of a SHM segment) in a way that prevents gcc from
performing format checks on the seq_printf() parameters.  This hid two
format errors - shp->shm_segsz and shp->shm_nattach are both unsigned
long, but were being printed as unsigned int and signed int respectively.
This leads to 32-bit truncation of SHM segment sizes reported in
/proc/sysvipc/shm.  (And for nattach, but that's less of a problem for
most users).

This patch makes the format string directly visible to gcc's format
specifier checker, and fixes the two broken format specifiers.
Signed-off-by: Paul Menage <menage@google.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We were walking right into huge page areas in the pagemap walker, and
calling the pmds pmd_bad() and clearing them.

That leaked huge pages.  Bad.

This patch at least works around that for now.  It ignores huge pages in
the pagemap walker for the time being, and won't leak those pages.
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

We need this at least for huge page detection for now, because powerpc
needs the vm_area_struct to be able to determine whether a virtual address
is referring to a huge page (its pmd_huge() doesn't work).

It might also come in handy for some of the other users.
Signed-off-by: Dave Hansen <dave@linux.vnet.ibm.com>
Acked-by: Matt Mackall <mpm@selenic.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

The generic nvram driver announces itself as
	'Macintosh non-volatile memory driver'
instead of 'Generic non-volatile memory driver'.  Fix that.
Signed-off-by: Philippe De Muyter <phdm@macqel.be>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Paul Mackerras <paulus@samba.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>