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: NNick Piggin <npiggin@suse.de>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus 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: NSamuel Thibault <samuel.thibault@ens-lyon.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus 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: NPaul 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus 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: NDave Hansen <dave@linux.vnet.ibm.com>
Acked-by: NMatt Mackall <mpm@selenic.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus 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: NDave Hansen <dave@linux.vnet.ibm.com>
Acked-by: NMatt Mackall <mpm@selenic.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus 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: NPhilippe 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: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

In the cirrusfb driver, the RAM address printk has a superfluous 'x' that
could be interpreted as "don't care", while it is actually a typo.  Fix
that.

[akpm@linux-foundation.org: join the two printk strings to make it atomic]
Signed-off-by: NPhilippe De Muyter <phdm@macqel.be>
Cc: Jiri Slaby <jirislaby@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since many distros load this driver by default (throw it against the wall
and see what sticks method).  Change the error message severity level to
avoid alarming users.  Isn't it annoying when users actually read the
error logs...
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Cc: Michael Buesch <mb@bu3sch.de>
Acked-by: NJan Beulich <jbeulich@novell.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

spid has been allocated in this function and so should be freed before
leaving it, as in the other error handling cases.

The semantic match that finds the problem is as follows:
(http://www.emn.fr/x-info/coccinelle/)

@r exists@
expression E,E1;
statement S;
position p1,p2,p3;
@@

E =@p1 \(kmalloc\|kcalloc\|kzalloc\)(...)
... when != E = E1
if (E == NULL || ...) S
... when != E = E1
if@p2 (...) {
 ... when != kfree(E)
 }
... when != E = E1
kfree@p3(E);

@forall@
position r.p2;
expression r.E;
int E1 != 0;
@@

* if@p2 (...) {
 ... when != kfree(E)
     when strict
return E1; }
Signed-off-by: NJulia Lawall <julia@diku.dk>
Cc: Karsten Keil <kkeil@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

With CONFIG_DEBUG_SHIRQ set we will get an interrupt as soon as we
allocate one.  Tasklets may be scheduled in the interrupt handler but they
will be initialized after the handler returns, causing a BUG() in
kernel/softirq.c when they run.

Should fix this Fedora bug report:
https://bugzilla.redhat.com/show_bug.cgi?id=449817Signed-off-by: NChuck Ebbert <cebbert@redhat.com>
Acked-by: NPierre Ossman <drzeus@drzeus.cx>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NEric Miao <eric.miao@marvell.com>
Acked-by: NRussell King <rmk@arm.linux.org.uk>
Acked-by: NNicolas Pitre <nico@marvell.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fedora broke PTRACE_SYSEMU again, and UML crashes as a result when it
doesn't need to.  This patch makes the PTRACE_SYSEMU check fail gracefully
and makes UML fall back to PTRACE_SYSCALL.
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

I allowed an include of asm/user.h to sneak back in.  This patch replaces
it with sys/user.h.
Signed-off-by: NJeff Dike <jdike@linux.intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

alarm->pending indicates whether there's an alarm that has actually been
triggered, not whether we're waiting for it.  alarm->enabled indicates
that.

Also add missing locking around reading the RTC registers.
Signed-off-by: NHaavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: NAlessandro Zummo <a.zummo@towertech.it>
Cc: Hans-Christian Egtvedt <hans-christian.egtvedt@atmel.com>
Cc: David Brownell <david-b@pacbell.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The coldfire timer must be initialised to n - 1 if we want it to count n
cycles between each tick interrupt.  This was already fixed, but has been
lost with the conversion to GENERIC_TIMER.
Signed-off-by: NPhilippe De Muyter <phdm@macqel.be>
Acked-by: NGreg Ungerer <gerg@snapgear.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Fix error checking routine to catch an error which occurs in first
__register_*probe().
Signed-off-by: NMasami Hiramatsu <mhiramat@redhat.com>
Cc: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Cc: Jim Keniston <jkenisto@us.ibm.com>
Cc: David Miller <davem@davemloft.net>
Cc: Anil S Keshavamurthy <anil.s.keshavamurthy@intel.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add support for the next generation of HP Smart Array SAS/SATA
controllers.  Shipping date is late Fall 2008.

Bump the driver version to 3.6.20 to reflect the new hardware support from
patch 1 of this set.
Signed-off-by: NMike Miller <mike.miller@hp.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The dummy module is used by folk that run security conscious code(!?).  A
feature of such code (for example, dhclient) is that it tries to operate
with minimum privilege (dropping unneeded capabilities).  While the dummy
module doesn't restrict code execution based on capability state, the user
code expects the kernel to appear to support it.  This patch adds back
faked support for the PR_SET_KEEPCAPS etc., calls - making the kernel
behave as before 2.6.26.

For details see: http://bugzilla.kernel.org/show_bug.cgi?id=10748Signed-off-by: NAndrew G. Morgan <morgan@kernel.org>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: James Morris <jmorris@namei.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Chris Wright <chrisw@sous-sol.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move the forward-declaration of struct mm_struct a little way up
proc_fs.h.  This fixes a bunch of "'struct mm_struct' declared inside
parameter list" warnings with CONFIG_PROC_FS=n
Signed-off-by: NBen Nizette <bn@niasdigital.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add URL for another CPUSETS web page to the MAINTAINERS file.

This URL provides links to major LGPL user level C libraries supporting
cpuset usage and user level cpu and node masks.
Signed-off-by: NPaul Jackson <pj@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Release ports which are requested during detection which are not freed if
there is no hga card.  Otherwise there is a crash during cat /proc/ioports
command.
Signed-off-by: NKrzysztof Helt <krzysztof.h1@wp.pl>
Cc: <stable@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add ext2_find_{first,next}_bit(), which are needed for ext4.  They're
derived out of the ext2_find_next_zero_bit found in the same file.
Compile tested with crosstools

[Reworked to preserve all symmetry with ext2_find_{first,next}_zero_bit()]

This fixes http://bugzilla.kernel.org/show_bug.cgi?id=10393

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

New chmod() allows only acceptable permission, and if not acceptable, it
returns -EPERM.  Old one allows even if it can't store permission to on
disk inode.  But it seems too strict for users.

E.g.  https://bugzilla.redhat.com/show_bug.cgi?id=449080: With new one,
rsync couldn't create the temporary file.

So, this patch allows like old one, but now it doesn't change the
permission if it can't store, and it returns 0.

Also, this patch fixes missing check.
Signed-off-by: NOGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

"Smarter retry of costly-order allocations" patch series change behaver of
do_try_to_free_pages().  But unfortunately ret variable type was
unchanged.

Thus an overflow is possible.
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: NNishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Addresses https://bugs.edge.launchpad.net/ubuntu/+source/linux-source-2.6.22/+bug/178634Signed-off-by: NAmit Kucheria <amit.kucheria@ubuntu.com>
Signed-off-by: Nmaximilian attems <max@stro.at>
Acked-by: NDave Airlie <airlied@linux.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

.. and a new name, courtesy of Alan.

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: fix pointer type warning in arch/x86/mm/init_64.c:early_memtest
  x86, lockdep: fix "WARNING: at kernel/lockdep.c:2658 check_flags+0x4c/0x128()"
  x86: fix an incompatible pointer type warning on 64-bit compilations
  x86: fix lockdep warning during suspend-to-ram
  x86: fix unused variable 'loops' warning in arch/x86/boot/a20.c
  Revert "x86: fix ioapic bug again"
  x86: fix asm warning in head_32.S
  x86: fix endless page faults in mount_block_root for Linux 2.6
  geode: fix modular build

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

* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
  sched: 64-bit: fix arithmetics overflow
  sched: fair group: fix overflow(was: fix divide by zero)
  sched: fix TASK_WAKEKILL vs SIGKILL race

Changed the call to find_e820_area_size to pass u64 instead of unsigned long.
Signed-off-by: NKevin Winchester <kjwinchester@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Alessandro Suardi reported:
> Recently upgraded my FC6 desktop to Fedora 9; with the
>  latest nautilus RPM updates my VNC session went nuts
>  with nautilus pegging the CPU for everything that breathed.
>
> I now reverted to an earlier nautilus package, but during
>  the peak CPU period my kernel spat this:
>
> [314185.623294] ------------[ cut here ]------------
> [314185.623414] WARNING: at kernel/lockdep.c:2658 check_flags+0x4c/0x128()
> [314185.623514] Modules linked in: iptable_filter ip_tables x_tables
> sunrpc ipv6 fuse snd_via82xx snd_ac97_codec ac97_bus snd_mpu401_uart
> snd_rawmidi via686a hwmon parport_pc sg parport uhci_hcd ehci_hcd
> [314185.623924] Pid: 12314, comm: nautilus Not tainted 2.6.26-rc5-git2 #4
> [314185.624021]  [<c0115b95>] warn_on_slowpath+0x41/0x7b
> [314185.624021]  [<c010de70>] ? do_page_fault+0x2c1/0x5fd
> [314185.624021]  [<c0128396>] ? up_read+0x16/0x28
> [314185.624021]  [<c010de70>] ? do_page_fault+0x2c1/0x5fd
> [314185.624021]  [<c012fa33>] ? __lock_acquire+0xbb4/0xbc3
> [314185.624021]  [<c012d0a0>] check_flags+0x4c/0x128
> [314185.624021]  [<c012fa73>] lock_acquire+0x31/0x7d
> [314185.624021]  [<c0128cf6>] __atomic_notifier_call_chain+0x30/0x80
> [314185.624021]  [<c0128cc6>] ? __atomic_notifier_call_chain+0x0/0x80
> [314185.624021]  [<c0128d52>] atomic_notifier_call_chain+0xc/0xe
> [314185.624021]  [<c0128d81>] notify_die+0x2d/0x2f
> [314185.624021]  [<c01043b0>] do_int3+0x1f/0x4d
> [314185.624021]  [<c02f2d3b>] int3+0x27/0x2c
> [314185.624021]  =======================
> [314185.624021] ---[ end trace 1923f65a2d7bb246 ]---
> [314185.624021] possible reason: unannotated irqs-off.
> [314185.624021] irq event stamp: 488879
> [314185.624021] hardirqs last  enabled at (488879): [<c0102d67>]
> restore_nocheck+0x12/0x15
> [314185.624021] hardirqs last disabled at (488878): [<c0102dca>]
> work_resched+0x19/0x30
> [314185.624021] softirqs last  enabled at (488876): [<c011a1ba>]
> __do_softirq+0xa6/0xac
> [314185.624021] softirqs last disabled at (488865): [<c010476e>]
> do_softirq+0x57/0xa6
>
> I didn't seem to find it with some googling, so here it is.
>
> I was incidentally ltracing that process to try and find out
>  what was gulping down that much CPU (sorry, no idea
>  whether ltrace and the WARNING happened at the same
>  time or which came first) and:

Yeah, this is extremely likely to be the source of the warning.

The warning should be harmless, however.

> Box is my trusty noname K7-800, 512MB RAM; if there's
>  anything else useful I might be able to provide, just ask.

It would be interesting to see where the int3 comes from.  Too bad,
lockdep doesn't provide the register dump. The stacktrace also doesn't
go further than the int3(), I wonder if this int3 came from userspace?
The ltrace readme says "software breakpoints, like gdb", so I guess
this is the case. Yep, seems like it.

This looks relevant:

| commit fb1dac90
| Author: Peter Zijlstra <a.p.zijlstra@chello.nl>
| Date:   Wed Jan 16 09:51:59 2008 +0100
|
|     lockdep: more hardirq annotations for notify_die()

I'm attaching a similarly-looking patch for this case (DO_VM86_ERROR),
though I suspect it might be missing for the other cases
(DO_ERROR/DO_ERROR_INFO) as well.
Reported-by: NAlessandro Suardi <alessandro.suardi@gmail.com>
Signed-off-by: NVegard Nossum <vegard.nossum@gmail.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Fix an incompatible pointer type warning on x86_64 compilations.
early_memtest() is passing a u64* to find_e820_area_size() which is expecting
an unsigned long.  Change t_start and t_size to unsigned long as those are
also 64-bit types on x88_64.
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Andrew Morton wrote:

> I've been seeing the below for a long time during suspend-to-ram on the Vaio.
>
>
> PM: Syncing filesystems ... done.
> PM: Preparing system for mem sleep
> Freezing user space processes ... <4>------------[ cut here ]------------
> WARNING: at kernel/lockdep.c:2658 check_flags+0x4c/0x127()
> Modules linked in: i915 drm ipw2200 sonypi ipv6 autofs4 hidp l2cap bluetooth sunrpc nf_conntrack_netbios_ns ipt_REJECT nf_conntrack_ipv4 xt_state nf_conntrack xt_tcpudp iptable_filter ip_tables x_tables acpi_cpufreq nvram ohci1394 ieee1394 ehci_hcd uhci_hcd sg joydev snd_hda_intel snd_seq_dummy sr_mod snd_seq_oss cdrom snd_seq_midi_event snd_seq snd_seq_device snd_pcm_oss snd_mixer_oss ieee80211 pcspkr ieee80211_crypt snd_pcm i2c_i801 snd_timer i2c_core ide_pci_generic piix snd soundcore snd_page_alloc button ext3 jbd ide_disk ide_core [last unloaded: ipw2200]
> Pid: 3250, comm: zsh Not tainted 2.6.26-rc5 #1
>  [<c011c5f5>] warn_on_slowpath+0x41/0x6d
>  [<c01080e6>] ? native_sched_clock+0x82/0x96
>  [<c013789c>] ? mark_held_locks+0x41/0x5c
>  [<c0315688>] ? _spin_unlock_irqrestore+0x36/0x58
>  [<c0137a29>] ? trace_hardirqs_on+0xe6/0x10d
>  [<c0138637>] ? __lock_acquire+0xae3/0xb2b
>  [<c0313413>] ? schedule+0x39b/0x3b4
>  [<c0135596>] check_flags+0x4c/0x127
>  [<c01386b9>] lock_acquire+0x3a/0x86
>  [<c0315075>] _spin_lock+0x26/0x53
>  [<c0140660>] ? refrigerator+0x13/0xc3
>  [<c0140660>] refrigerator+0x13/0xc3
>  [<c012684a>] get_signal_to_deliver+0x3c/0x31e
>  [<c0102fe7>] do_notify_resume+0x91/0x6ee
>  [<c01359fd>] ? lock_release_holdtime+0x50/0x56
>  [<c0315688>] ? _spin_unlock_irqrestore+0x36/0x58
>  [<c0235d24>] ? read_chan+0x0/0x58c
>  [<c0137a29>] ? trace_hardirqs_on+0xe6/0x10d
>  [<c0315694>] ? _spin_unlock_irqrestore+0x42/0x58
>  [<c0230afa>] ? tty_ldisc_deref+0x5c/0x63
>  [<c0233104>] ? tty_read+0x66/0x98
>  [<c014b3f0>] ? audit_syscall_exit+0x2aa/0x2c5
>  [<c0109430>] ? do_syscall_trace+0x6b/0x16f
>  [<c0103a9c>] work_notifysig+0x13/0x1b
>  =======================
> ---[ end trace 25b49fe59a25afa5 ]---
> possible reason: unannotated irqs-off.
> irq event stamp: 58919
> hardirqs last  enabled at (58919): [<c0103afd>] syscall_exit_work+0x11/0x26

Joy - I so love entry.S

Best I can make of it:

syscall_exit_work
  resume_userspace
    DISABLE_INTERRUPTS
    (no TRACE_IRQS_OFF)
      work_pending
        work_notifysig
          do_notify_resume()
            do_signal()
              get_signal_to_deliver()
                try_to_freeze()
                  refrigerator()
                    task_lock() -> check_flags() -> BANG

The normal path is:

syscall_exit_work
  resume_userspace
    DISABLE_INTERRUPTS
    restore_all
      TRACE_IRQS_IRET
      iret

No idea why that would not warn..
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Following patch fixes the below warning message :
arch/x86/boot/a20.c:118: warning: unused variable 'loops'

Signed-off-by : Manish Katiyar <mkatiyar@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

This reverts commit 6e908947.

Németh Márton reported:

| there is a problem in 2.6.26-rc3 which was not there in case of
| 2.6.25: the CPU wakes up ~90,000 times per sec instead of ~60 per sec.
|
| I also "git bisected" the problem, the result is:
|
| 6e908947 is first bad commit
| commit 6e908947
| Author: Ingo Molnar <mingo@elte.hu>
| Date:   Fri Mar 21 14:32:36 2008 +0100
|
|     x86: fix ioapic bug again

the original problem is fixed by Maciej W. Rozycki in the tip/x86/apic
branch (confirmed by Márton), but those changes are too intrusive for
v2.6.26 so we'll go for the less intrusive (repeated) revert now.
Reported-and-bisected-by: NNémeth Márton <nm127@freemail.hu>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

On Mon, May 19, 2008 at 04:10:02PM -0700, Linus Torvalds wrote:
> It also causes these warnings on 32-bit PAE:
>
> 	  AS      arch/x86/kernel/head_32.o
> 	arch/x86/kernel/head_32.S: Assembler messages:
> 	arch/x86/kernel/head_32.S:225: Warning: left operand is a bignum; integer 0 assumed
> 	arch/x86/kernel/head_32.S:609: Warning: left operand is a bignum; integer 0 assumed
>
> and I do not see why (the end result seems to be identical).

Fix head_32.S gcc bignum warnings when CONFIG_PAE=y.

    arch/x86/kernel/head_32.S: Assembler messages:
    arch/x86/kernel/head_32.S:225: Warning: left operand is a bignum; integer 0 assumed
    arch/x86/kernel/head_32.S:609: Warning: left operand is a bignum; integer 0 assumed

The assembler was stumbling over the 64-bit constant 0x100000000 in the
KPMDS #define.

Testing: a cmp(1) on head_32.o before and after shows the binary is unchanged.

Signed-off-by: Joe Korty <joe.korty@ccur.com
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Theodore Tso <tytso@mit.edu>
Cc: Gabriel C <nix.or.die@googlemail.com>
Cc: Keith Packard <keithp@keithp.com>
Cc: "Pallipadi Venkatesh" <venkatesh.pallipadi@intel.com>
Cc: Eric Anholt <eric@anholt.net>
Cc: "Siddha Suresh B" <suresh.b.siddha@intel.com>
Cc: bugme-daemon@bugzilla.kernel.org
Cc: airlied@linux.ie
Cc: "Barnes Jesse" <jesse.barnes@intel.com>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

Page faults in kernel address space between PAGE_OFFSET up to
VMALLOC_START should not try to map as vmalloc.

Fix rarely endless page faults inside mount_block_root for root
filesystem at boot time.

All 32bit kernels up to 2.6.25 can fail into this hole.
I can not present this under native linux kernel. I see, that the 64bit
has fixed the problem. I copied the same lines into 32bit part.

Recorded debugs are from coLinux kernel 2.6.22.18 (virtualisation):
http://www.henrynestler.com/colinux/testing/pfn-check-0.7.3/20080410-antinx/bug16-recursive-page-fault-endless.txt
The physicaly memory was trimmed down to 192MB to better catch the bug.
More memory gets the bug more rarely.

Details, how every x86 32bit system can fail:

Start from "mount_block_root",
http://lxr.linux.no/linux/init/do_mounts.c#L297
There the variable "fs_names" got one memory page with 4096 bytes.
Variable "p" walks through the existing file system types. The first
string is no problem.
But, with the second loop in mount_block_root the offset of "p" is not
at beginning of page, the offset is for example +9, if "reiserfs" is the
first in list.
Than calls do_mount_root, and lands in sys_mount.
Remember: Variable "type_page" contains now "fs_type+9" and not contains
a full page.
The sys_mount copies 4096 bytes with function "exact_copy_from_user()":
http://lxr.linux.no/linux/fs/namespace.c#L1540

Mostly exist pages after the buffer "fs_names+4096+9" and the page fault
handler was not called. No problem.

In the case, if the page after "fs_names+4096" is not mapped, the page
fault handler was called from http://lxr.linux.no/linux/fs/namespace.c#L1320

The do_page_fault gots an address 0xc03b4000.
It's kernel address, address >= TASK_SIZE, but not from vmalloc! It's
from "__getname()" alias "kmem_cache_alloc".
The "error_code" is 0. "vmalloc_fault" will be call:
http://lxr.linux.no/linux/arch/i386/mm/fault.c#L332

"vmalloc_fault" tryed to find the physical page for a non existing
virtual memory area. The macro "pte_present" in vmalloc_fault()
got a next page fault for 0xc0000ed0 at:
http://lxr.linux.no/linux/arch/i386/mm/fault.c#L282

No PTE exist for such virtual address. The page fault handler was trying
to sync the physical page for the PTE lockup.

This called vmalloc_fault() again for address 0xc000000, and that also
was not existing. The endless began...

In normal case the cpu would still loop with disabled interrrupts. Under
coLinux this was catched by a stack overflow inside printk debugs.
Signed-off-by: NHenry Nestler <henry.nestler@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>

-tip testing found this build bug:

 MODPOST 331 modules
 ERROR: "geode_mfgpt_toggle_event" [drivers/watchdog/geodewdt.ko] undefined!
 ERROR: "geode_mfgpt_alloc_timer" [drivers/watchdog/geodewdt.ko] undefined!
 make[1]: *** [__modpost] Error 1
 make: *** [modules] Error 2

with this config:

  http://redhat.com/~mingo/misc/config-Wed_Jun__4_18_01_59_CEST_2008.bad

export those symbols.
Signed-off-by: NIngo Molnar <mingo@elte.hu>

As we may run relay_reserve from interrupt context we must always disable
IRQs.  This is because a call to relay_reserve may expose previously written
data to use space.

Updated new message code and an old but related comment.
Signed-off-by: NCarl Henrik Lunde <chlunde@ping.uio.no>
Signed-off-by: NJens Axboe <jens.axboe@oracle.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

* git://git.kernel.org/pub/scm/linux/kernel/git/sam/kbuild-fixes:
  kbuild: ignore powerpc specific symbols in modpost

This implements a few changes on top of the recent kobjsize() refactoring
introduced by commit 6cfd53fc.

As Christoph points out:

	virt_to_head_page cannot return NULL. virt_to_page also
	does not return NULL. pfn_valid() needs to be used to
	figure out if a page is valid.  Otherwise the page struct
	reference that was returned may have PageReserved() set
	to indicate that it is not a valid page.

As discussed further in the thread, virt_addr_valid() is the preferable
way to validate the object pointer in this case. In addition to fixing
up the reserved page case, it also has the benefit of encapsulating the
hack introduced by commit 4016a139 on
the impacted platforms, allowing us to get rid of the extra checking in
kobjsize() for the platforms that don't perform this type of bizarre
memory_end abuse (every nommu platform that isn't blackfin). If blackfin
decides to get in line with every other platform and use PageReserved
for the DMA pages in question, kobjsize() will also continue to work
fine.

It also turns out that compound_order() will give us back 0-order for
non-head pages, so we can get rid of the PageCompound check and just
use compound_order() directly. Clean that up while we're at it.
Signed-off-by: NPaul Mundt <lethal@linux-sh.org>
Reviewed-by: NChristoph Lameter <clameter@sgi.com>
Acked-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>