The RCU CPU stall warnings can now be controlled using the
rcu_cpu_stall_suppress boot-time parameter or via the same parameter
from sysfs.  There is therefore no longer any reason to have
kernel config parameters for this feature.  This commit therefore
removes the RCU_CPU_STALL_DETECTOR and RCU_CPU_STALL_DETECTOR_RUNNABLE
kernel config parameters.  The RCU_CPU_STALL_TIMEOUT parameter remains
to allow the timeout to be tuned and the RCU_CPU_STALL_VERBOSE parameter
remains to allow task-stall information to be suppressed if desired.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>

mm/kmemleak-test.c is used to provide an example of how kmemleak
tool works.

Memory is leaked at module unload-time, so building the test
in kernel (Y) makes the leaks impossible and the test useless.

Qualify DEBUG_KMEMLEAK_TEST config symbol with "depends on m",
to restrict module-only building.
Signed-off-by: NDaniel Baluta <dbaluta@ixiacom.com>
Acked-by: NPekka Enberg <penberg@kernel.org>
Acked-by: NCatalin Marinas <catalin.marinas@arm.com>
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

1. simple_strto*() do not contain overflow checks and crufty,
   libc way to indicate failure.
2. strict_strto*() also do not have overflow checks but the name and
   comments pretend they do.
3. Both families have only "long long" and "long" variants,
   but users want strtou8()
4. Both "simple" and "strict" prefixes are wrong:
   Simple doesn't exactly say what's so simple, strict should not exist
   because conversion should be strict by default.

The solution is to use "k" prefix and add convertors for more types.
Enter
	kstrtoull()
	kstrtoll()
	kstrtoul()
	kstrtol()
	kstrtouint()
	kstrtoint()

	kstrtou64()
	kstrtos64()
	kstrtou32()
	kstrtos32()
	kstrtou16()
	kstrtos16()
	kstrtou8()
	kstrtos8()

Include runtime testsuite (somewhat incomplete) as well.

strict_strto*() become deprecated, stubbed to kstrto*() and
eventually will be removed altogether.

Use kstrto*() in code today!

Note: on some archs _kstrtoul() and _kstrtol() are left in tree, even if
      they'll be unused at runtime. This is temporarily solution,
      because I don't want to hardcode list of archs where these
      functions aren't needed. Current solution with sizeof() and
      __alignof__ at least always works.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We've been burned by regressions/bugs which we later realized could have
been triaged quicker if only we'd paid closer attention to dmesg.  To make
it easier to audit dmesg, we'd like to make DEFAULT_MESSAGE_LEVEL
Kconfig-settable.  That way we can set it to KERN_NOTICE and audit any
messages <= KERN_WARNING.
Signed-off-by: NMandeep Singh Baines <msb@chromium.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Joe Perches <joe@perches.com>
Cc: Olof Johansson <olofj@chromium.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When a cpu is considered stuck, instead of limping along and just printing
a warning, it is sometimes preferred to just panic, let kdump capture the
vmcore and reboot.  This gets the machine back into a stable state quickly
while saving the info that got it into a stuck state to begin with.

Add a Kconfig option to allow users to set the hardlockup to panic
by default.  Also add in a 'nmi_watchdog=nopanic' to override this.

[akpm@linux-foundation.org: fix strncmp length]
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Reviewed-by: NWANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

CONFIG_DEBUG_SECTION_MISMATCH has also runtime effects due to the
-fno-inline-functions-called-once compiler flag, so forcing it on
everyone is not a good idea.
Signed-off-by: NMichal Marek <mmarek@suse.cz>

This removes the implementation of the big kernel lock,
at last. A lot of people have worked on this in the
past, I so the credit for this patch should be with
everyone who participated in the hunt.

The names on the Cc list are the people that were the
most active in this, according to the recorded git
history, in alphabetical order.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NAlan Cox <alan@linux.intel.com>
Cc: Alessio Igor Bogani <abogani@texware.it>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Andrew Hendry <andrew.hendry@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Eric W. Biederman <ebiederm@xmission.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Hans Verkuil <hverkuil@xs4all.nl>
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: Jan Blunck <jblunck@infradead.org>
Cc: John Kacur <jkacur@redhat.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Matthew Wilcox <matthew@wil.cx>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: Paul Menage <menage@google.com>
Acked-by: NThomas Gleixner <tglx@linutronix.de>
Cc: Trond Myklebust <Trond.Myklebust@netapp.com>

This was disabled in commit

	e5f95c8b (kbuild: print only total number of section mismatces found)

because there were too many warnings.  Now we're down to a reasonable
number again, so we start scaring people with the details.
Signed-off-by: NUwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: NRandy Dunlap <rdunlap@xenotime.net>
Acked-by: NMike Frysinger <vapier@gentoo.org>
Signed-off-by: NMichal Marek <mmarek@suse.cz>

M68KNOMMU is set nowhere.
Signed-off-by: NGeert Uytterhoeven <geert@linux-m68k.org>
Signed-off-by: NGreg Ungerer <gerg@uclinux.org>

The meaning of CONFIG_EMBEDDED has long since been obsoleted; the option
is used to configure any non-standard kernel with a much larger scope than
only small devices.

This patch renames the option to CONFIG_EXPERT in init/Kconfig and fixes
references to the option throughout the kernel.  A new CONFIG_EMBEDDED
option is added that automatically selects CONFIG_EXPERT when enabled and
can be used in the future to isolate options that should only be
considered for embedded systems (RISC architectures, SLOB, etc).

Calling the option "EXPERT" more accurately represents its intention: only
expert users who understand the impact of the configuration changes they
are making should enable it.
Reviewed-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NDavid Woodhouse <david.woodhouse@intel.com>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Cc: Greg KH <gregkh@suse.de>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Jens Axboe <axboe@kernel.dk>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Robin Holt <holt@sgi.com>
Cc: <linux-arch@vger.kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The x86 arch has shifted its use of the nmi_watchdog from a
local implementation to the global one provide by
kernel/watchdog.c.  This shift has caused a whole bunch of
compile problems under different config options.  I attempt to
simplify things with the patch below.

In order to simplify things, I had to come to terms with the
meaning of two terms ARCH_HAS_NMI_WATCHDOG and
CONFIG_HARDLOCKUP_DETECTOR.  Basically they mean the same thing,
the former on a local level and the latter on a global level.

With the old x86 nmi watchdog gone, there is no need to rely on
defining the ARCH_HAS_NMI_WATCHDOG variable because it doesn't
make sense any more.  x86 will now use the global
implementation.

The changes below do a few things.  First it changes the few
places that relied on ARCH_HAS_NMI_WATCHDOG to use
CONFIG_X86_LOCAL_APIC (the former was an alias for the latter
anyway, so nothing unusual here).  Those pieces of code were
relying more on local apic functionality the nmi watchdog
functionality, so the change should make sense.

Second, I removed the x86 implementation of
touch_nmi_watchdog().  It isn't need now, instead x86 will rely
on kernel/watchdog.c's implementation.

Third, I removed the #define ARCH_HAS_NMI_WATCHDOG itself from
x86.  And tweaked the include/linux/nmi.h file to tell users to
look for an externally defined touch_nmi_watchdog in the case of
ARCH_HAS_NMI_WATCHDOG _or_ CONFIG_HARDLOCKUP_DETECTOR. This
changes removes some of the ugliness in that file.

Finally, I added a Kconfig dependency for
CONFIG_HARDLOCKUP_DETECTOR that said you can't have
ARCH_HAS_NMI_WATCHDOG _and_ CONFIG_HARDLOCKUP_DETECTOR.  You can
only have one nmi_watchdog.

Tested with
ARCH=i386: allnoconfig, defconfig, allyesconfig, (various broken
configs) ARCH=x86_64: allnoconfig, defconfig, allyesconfig,
(various broken configs)

Hopefully, after this patch I won't get any more compile broken
emails. :-)

v3:
  changed a couple of 'linux/nmi.h' -> 'asm/nmi.h' to pick-up correct function
  prototypes when CONFIG_HARDLOCKUP_DETECTOR is not set.
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: fweisbec@gmail.com
LKML-Reference: <1293044403-14117-1-git-send-email-dzickus@redhat.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

While hunting a non-existing bug in 'list_sort()', I've improved the
'list_sort_test()' function which tests the 'list_sort()' library call.
Although at the end I found a bug in my code, but not in 'list_sort()', I
think my clean-ups and improvements are worth merging because they make
the test function better.

This patch:

Make the self-tests selectable via Kconfig rather than by manual enabling
of DEBUG_LIST_SORT.
Signed-off-by: NArtem Bityutskiy <Artem.Bityutskiy@nokia.com>
Cc: Don Mullis <don.mullis@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

All percpu counters are linked to a global list on initialization and
removed from it on destruction.  The list is walked during CPU up/down.
If a percpu counter is freed without being properly destroyed, the system
will oops only on the next CPU up/down making it pretty nasty to track
down.  This patch adds debugobj support for percpu counters so that such
problems can be found easily.

As percpu counters don't make sense on stack and can't be statically
initialized, debugobj support is pretty simple.  It's initialized and
activated on counter initialization, and deactivatd and destroyed on
counter destruction.  With this patch applied, the bug fixed by commit
602586a8 (shmem: put_super must
percpu_counter_destroy) triggers the following warning on tmpfs unmount
and the system won't oops on the next cpu up/down operation.

 ------------[ cut here ]------------
 WARNING: at lib/debugobjects.c:259 debug_print_object+0x5c/0x70()
 Hardware name: Bochs
 ODEBUG: free active (active state 0) object type: percpu_counter
 Modules linked in:
 Pid: 3999, comm: umount Not tainted 2.6.36-rc2-work+ #5
 Call Trace:
  [<ffffffff81083f7f>] warn_slowpath_common+0x7f/0xc0
  [<ffffffff81084076>] warn_slowpath_fmt+0x46/0x50
  [<ffffffff813b45cc>] debug_print_object+0x5c/0x70
  [<ffffffff813b50e5>] debug_check_no_obj_freed+0x125/0x210
  [<ffffffff811577d3>] kfree+0xb3/0x2f0
  [<ffffffff81132edd>] shmem_put_super+0x1d/0x30
  [<ffffffff81162e96>] generic_shutdown_super+0x56/0xe0
  [<ffffffff81162f86>] kill_anon_super+0x16/0x60
  [<ffffffff81162ff7>] kill_litter_super+0x27/0x30
  [<ffffffff81163295>] deactivate_locked_super+0x45/0x60
  [<ffffffff81163cfa>] deactivate_super+0x4a/0x70
  [<ffffffff8117d446>] mntput_no_expire+0x86/0xe0
  [<ffffffff8117df7f>] sys_umount+0x6f/0x360
  [<ffffffff8103f01b>] system_call_fastpath+0x16/0x1b
 ---[ end trace cce2a341ba3611a7 ]---
Signed-off-by: NTejun Heo <tj@kernel.org>
Acked-by: Thomas Gleixner <tglxlinutronix.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

With all the patches we have queued in the BKL removal tree, only a
few dozen modules are left that actually rely on the BKL, and even
there are lots of low-hanging fruit. We need to decide what to do
about them, this patch illustrates one of the options:

Every user of the BKL is marked as 'depends on BKL' in Kconfig,
and the CONFIG_BKL becomes a user-visible option. If it gets
disabled, no BKL using module can be built any more and the BKL
code itself is compiled out.

The one exception is file locking, which is practically always
enabled and does a 'select BKL' instead. This effectively forces
CONFIG_BKL to be enabled until we have solved the fs/lockd
mess and can apply the patch that removes the BKL from fs/locks.c.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>

All the necessary functionality was already there; we just need
to make it possible to select the config option.
Signed-off-by: NChris Metcalf <cmetcalf@tilera.com>

The prompt for "Self test for hardware accelerated raid6 recovery" does not
belong in the top level configuration menu.  All the options in
crypto/async_tx/Kconfig are selected and do not depend on CRYPTO.
Kconfig.debug seems like a reasonable fit.

Cc: Herbert Xu <herbert@gondor.apana.org.au>
Cc: David Woodhouse <David.Woodhouse@intel.com>
Signed-off-by: NDan Williams <dan.j.williams@intel.com>

Currently disabling CONFIG_SLUB_DEBUG also disabled SYSFS support meaning
that the slabs cannot be tuned without DEBUG.

Make SYSFS support independent of CONFIG_SLUB_DEBUG
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

The PROVE_RCU_REPEATEDLY has no "Say Y"/"Say N" advice, so this commit
adds it.
Reported-by: NJohannes Berg <johannes@sipsolutions.net>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>

When CONFIG_IRQSOFF_TRACER is set and CONFIG_PROVE_LOCKING is not, we
get the following error:

$  make oldconfig
scripts/kconfig/conf --oldconfig arch/x86/Kconfig
warning: (IRQSOFF_TRACER && TRACING_SUPPORT && FTRACE && TRACE_IRQFLAGS_SUPPORT && !ARCH_USES_GETTIMEOFFSET) selects TRACE_IRQFLAGS which has unmet direct dependencies (DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && PROVE_LOCKING)
warning: (IRQSOFF_TRACER && TRACING_SUPPORT && FTRACE && TRACE_IRQFLAGS_SUPPORT && !ARCH_USES_GETTIMEOFFSET) selects TRACE_IRQFLAGS which has unmet direct dependencies (DEBUG_KERNEL && TRACE_IRQFLAGS_SUPPORT && PROVE_LOCKING)

This is because IRQSOFF_TRACER selects TRACE_IRQFLAGS but TRACE_IRQFLAGS
has PROVE_LOCKING as a dependency. This code is incorrect, and
this patch changes the TRACE_IRQFLAGS to be just a simple bool that
does not depend or select anything. Instead both IRQSOFF_TRACER and
PROVE_LOCKING select it.
Reported-by: NRichard Kennedy <richard@rsk.demon.co.uk>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>

Currently, if RCU CPU stall warnings are enabled, they are enabled
immediately upon boot.  They can be manually disabled via /sys (and
also re-enabled via /sys), and are automatically disabled upon panic.
However, some users need RCU CPU stalls to be disabled at boot time,
but to be enabled without rebuilding/rebooting.  For example, someone
running a real-time application in production might not want the
additional latency of RCU CPU stall detection in normal operation, but
might need to enable it at any point for fault isolation purposes.

This commit therefore provides a new CONFIG_RCU_CPU_STALL_DETECTOR_RUNNABLE
kernel configuration parameter that maintains the current behavior
(enable at boot) by default, but allows a kernel to be configured
with RCU CPU stall detection built into the kernel, but disabled at
boot time.
Requested-by: NClark Williams <williams@redhat.com>
Requested-by: NJohn Kacur <jkacur@redhat.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>

Also set the default to 60 seconds, up from the previous hard-coded timeout
of 10 seconds.  This allows people who care to set short timeouts, while
avoiding people with unusual configurations (make randconfig!!!) from being
bothered with spurious CPU stall warnings.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>

This commit provides definitions for the __rcu annotation defined earlier.
This annotation permits sparse to check for correct use of RCU-protected
pointers.  If a pointer that is annotated with __rcu is accessed
directly (as opposed to via rcu_dereference(), rcu_assign_pointer(),
or one of their variants), sparse can be made to complain.  To enable
such complaints, use the new default-disabled CONFIG_SPARSE_RCU_POINTER
kernel configuration option.  Please note that these sparse complaints are
intended to be a debugging aid, -not- a code-style-enforcement mechanism.

There are special rcu_dereference_protected() and rcu_access_pointer()
accessors for use when RCU read-side protection is not required, for
example, when no other CPU has access to the data structure in question
or while the current CPU hold the update-side lock.

This patch also updates a number of docbook comments that were showing
their age.
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Christopher Li <sparse@chrisli.org>
Reviewed-by: NJosh Triplett <josh@joshtriplett.org>

warning: (LATENCYTOP && HAVE_LATENCYTOP_SUPPORT) selects
SCHED_DEBUG which has unmet direct dependencies (DEBUG_KERNEL &&
PROC_FS) warning: (LATENCYTOP && HAVE_LATENCYTOP_SUPPORT) selects
SCHEDSTATS which has unmet direct dependencies (DEBUG_KERNEL && PROC_FS)

Add depends on STACKTRACE_SUPPORT for 'select STACKTRACE'.
Add depends on PROC_FS since that is where the output goes.
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Cc: Arjan van de Ven <arjan@linux.intel.com>
LKML-Reference: <20100812123121.a7c99cde.randy.dunlap@oracle.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>

debugfs no longer uses 'kernel_subsys' (which is gone), and other
kernel/ksysfs.c code is always built, so DEBUG_FS does not need
to depend on SYSFS.

Fixes this kconfig warning:

warning: (TREE_RCU_TRACE || AMD_IOMMU_STATS && AMD_IOMMU || MTD_UBI_DEBUG && MTD && SYSFS && MTD_UBI || UBIFS_FS_DEBUG && MISC_FILESYSTEMS && UBIFS_FS || DEBUG_KMEMLEAK && DEBUG_KERNEL && EXPERIMENTAL && !MEMORY_HOTPLUG && (X86 || ARM || PPC || S390 || SPARC64 || SUPERH || MICROBLAZE) && SYSFS || TRACING || X86_PTDUMP && DEBUG_KERNEL || BLK_DEV_IO_TRACE && TRACING_SUPPORT && FTRACE && SYSFS && BLOCK) selects DEBUG_FS which has unmet direct dependencies (SYSFS)
Signed-off-by: NRandy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

Microblaze doesn't support frame pointers. Ftrace code
uses CALLER_ADDR1 which is defined in linux/ftrace.h. For Microblaze
is 0.
Signed-off-by: NMichal Simek <monstr@monstr.eu>

The last 't' of 'fault' is missing in the description of FAIL_IO_TIMEOUT.
Signed-off-by: NTakuya Yoshikawa <yoshikawa.takuya@oss.ntt.co.jp>
Signed-off-by: NJiri Kosina <jkosina@suse.cz>

Introduce a new DEBUG_KMEMLEAK_DEFAULT_OFF config parameter that allows
kmemleak to be disabled by default, but enabled on the command line
via: kmemleak=on. Although a reboot is required to turn it on, its still
useful to not require a re-compile.
Signed-off-by: NJason Baron <jbaron@redhat.com>
Signed-off-by: NCatalin Marinas <catalin.marinas@arm.com>
Acked-by: NPekka Enberg <penberg@cs.helsinki.fi>

Newer gcc has a -femit-struct-debug-baseonly option that dramatically
reduces the size of object files with debug info. What it does
is to only emit type information for structures when the structures
are defined in the same file or in a header file.

This means the type information for most headers are not included.
This is not good when the type information is actually
needed (e.g. with kgdb or systemtap)

But often kernel hackers only care about line numbers and don't
need all the type information anyways. In this case setting
the option can be a big win:

A build dir for a specific x86-64 configuration with gcc 4.5
shrunk from 2.3G to 1.2G. The compilation was also nearly a minute
faster.
Signed-off-by: NAndi Kleen <ak@linux.intel.com>
[mmarek: reformatted help text]
Signed-off-by: NMichal Marek <mmarek@suse.cz>

Helps finding racy users of call_rcu(), which results in hangs because list
entries are overwritten and/or skipped.

Changelog since v4:
- Bissectability is now OK
- Now generate a WARN_ON_ONCE() for non-initialized rcu_head passed to
  call_rcu(). Statically initialized objects are detected with
  object_is_static().
- Rename rcu_head_init_on_stack to init_rcu_head_on_stack.
- Remove init_rcu_head() completely.

Changelog since v3:
- Include comments from Lai Jiangshan

This new patch version is based on the debugobjects with the newly introduced
"active state" tracker.

Non-initialized entries are all considered as "statically initialized". An
activation fixup (triggered by call_rcu()) takes care of performing the debug
object initialization without issuing any warning. Since we cannot increase the
size of struct rcu_head, I don't see much room to put an identifier for
statically initialized rcu_head structures. So for now, we have to live without
"activation without explicit init" detection. But the main purpose of this debug
option is to detect double-activations (double call_rcu() use of a rcu_head
before the callback is executed), which is correctly addressed here.

This also detects potential internal RCU callback corruption, which would cause
the callbacks to be executed twice.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: David S. Miller <davem@davemloft.net>
CC: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
CC: akpm@linux-foundation.org
CC: mingo@elte.hu
CC: laijs@cn.fujitsu.com
CC: dipankar@in.ibm.com
CC: josh@joshtriplett.org
CC: dvhltc@us.ibm.com
CC: niv@us.ibm.com
CC: tglx@linutronix.de
CC: peterz@infradead.org
CC: rostedt@goodmis.org
CC: Valdis.Kletnieks@vt.edu
CC: dhowells@redhat.com
CC: eric.dumazet@gmail.com
CC: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: NLai Jiangshan <laijs@cn.fujitsu.com>

I used this module to test the series of modification to the cpu notifiers
code.

Example1: inject CPU offline error (-1 == -EPERM)

	# modprobe cpu-notifier-error-inject cpu_down_prepare_error=-1
	# echo 0 > /sys/devices/system/cpu/cpu1/online
	bash: echo: write error: Operation not permitted

Example2: inject CPU online error (-2 == -ENOENT)

	# modprobe cpu-notifier-error-inject cpu_up_prepare_error=-2
	# echo 1 > /sys/devices/system/cpu/cpu1/online
	bash: echo: write error: No such file or directory

[akpm@linux-foundation.org: fix Kconfig help text]
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NFlorian Ragwitz <rafl@debian.org>
Cc: Jason Baron <jbaron@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The lockup detector is a new feature that now involves the
nmi watchdog. Drop the default y and let the user choose.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>

This new config is deemed to simplify even more the lockup detector
dependencies and can make it easier to bring a smooth sorting
between archs that support the new generic lockup detector and those
that still have their own, especially for those that are in the
middle of this migration.

Instead of checking whether we have CONFIG_LOCKUP_DETECTOR +
CONFIG_PERF_EVENTS_NMI each time an arch wants to know if it needs
to build its own lockup detector, take a shortcut with this new
config. It is enabled only if the hardlockup detection part of
the whole lockup detector is on.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>

We kept CONFIG_DETECT_SOFTLOCKUP around for compatibility with
older configs. But it was enabled by default if CONFIG_DEBUG_KERNEL.

So if we want to enable CONFIG_LOCKUP_DETECTOR on configs that had
CONFIG_DETECT_SOFTLOCKUP, all we need is to have the same enabling
by default if CONFIG_DEBUG_KERNEL. We can then remove
CONFIG_DETECT_SOFTLOCKUP directly.

So tag CONFIG_LOCKUP_DETECTOR as default y. This is what we want for
most serious kernel debugging anyway.

And also forbid the lockup detector in S390 as it was for the
previous softlockup detector, event though the true reason for that
is not outlined.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>

Panic on softlockups was still depending on the softlockup detector.
But the latter has been merged into the lockup detector now.

Let's update this config dependency.
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>
Cc: Don Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>

The new nmi_watchdog (which uses the perf event subsystem) is very
similar in structure to the softlockup detector.  Using Ingo's
suggestion, I combined the two functionalities into one file:
kernel/watchdog.c.

Now both the nmi_watchdog (or hardlockup detector) and softlockup
detector sit on top of the perf event subsystem, which is run every
60 seconds or so to see if there are any lockups.

To detect hardlockups, cpus not responding to interrupts, I
implemented an hrtimer that runs 5 times for every perf event
overflow event.  If that stops counting on a cpu, then the cpu is
most likely in trouble.

To detect softlockups, tasks not yielding to the scheduler, I used the
previous kthread idea that now gets kicked every time the hrtimer fires.
If the kthread isn't being scheduled neither is anyone else and the
warning is printed to the console.

I tested this on x86_64 and both the softlockup and hardlockup paths
work.

V2:
- cleaned up the Kconfig and softlockup combination
- surrounded hardlockup cases with #ifdef CONFIG_PERF_EVENTS_NMI
- seperated out the softlockup case from perf event subsystem
- re-arranged the enabling/disabling nmi watchdog from proc space
- added cpumasks for hardlockup failure cases
- removed fallback to soft events if no PMU exists for hard events

V3:
- comment cleanups
- drop support for older softlockup code
- per_cpu cleanups
- completely remove software clock base hardlockup detector
- use per_cpu masking on hard/soft lockup detection
- #ifdef cleanups
- rename config option NMI_WATCHDOG to LOCKUP_DETECTOR
- documentation additions

V4:
- documentation fixes
- convert per_cpu to __get_cpu_var
- powerpc compile fixes

V5:
- split apart warn flags for hard and soft lockups

TODO:
- figure out how to make an arch-agnostic clock2cycles call
  (if possible) to feed into perf events as a sample period

[fweisbec: merged conflict patch]
Signed-off-by: NDon Zickus <dzickus@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Cyrill Gorcunov <gorcunov@gmail.com>
Cc: Eric Paris <eparis@redhat.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
LKML-Reference: <1273266711-18706-2-git-send-email-dzickus@redhat.com>
Signed-off-by: NFrederic Weisbecker <fweisbec@gmail.com>

The CPU_STALL_VERBOSE kernel configuration parameter was added to
2.6.34 to identify any preempted/blocked tasks that were preventing
the current grace period from completing when running preemptible
RCU.  As is conventional for new configurations parameters, this
defaulted disabled.  It is now time to enable it by default.
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>

There is no need to disable lockdep after an RCU lockdep splat,
so remove the debug_lockdeps_off() from lockdep_rcu_dereference().
To avoid repeated lockdep splats, use a static variable in the inlined
rcu_dereference_check() and rcu_dereference_protected() macros so that
a given instance splats only once, but so that multiple instances can
be detected per boot.

This is controlled by a new config variable CONFIG_PROVE_RCU_REPEATEDLY,
which is disabled by default.  This provides the normal lockdep behavior
by default, but permits people who want to find multiple RCU-lockdep
splats per boot to easily do so.
Requested-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NLai Jiangshan <laijs@cn.fujitsu.com>
Tested-by: NEric Paris <eparis@redhat.com>
Signed-off-by: NPaul E. McKenney <paulmck@linux.vnet.ibm.com>

Only missing thing was an _sdata marker in vmlinux.lds.S
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

Enable DEBUG_KMEMLEAK for microblaze
Signed-off-by: NMichal Simek <monstr@monstr.eu>