Only works for the generic request timer handling. Allows one to
sporadically ignore request completions, thus exercising the timeout
handling.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
DEBUG_BLOCK_EXT_DEVT shuffles SCSI and IDE device numbers and root
device number set using rdev become meaningless. Root devices should
be explicitly specified using textual names. Warn about it if root
can't be found and DEBUG_BLOCK_EXT_DEVT is enabled. Also, add warning
to the help text.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
It's a debug option that you would explicitly enable to test this
feature, we should default it to 'n' to prevent accidental surprises
for now.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
Extended devt introduces non-contiguos device numbers. This patch
implements a debug option which forces most devt allocations to be
from the extended area and spreads them out. This is enabled by
default if DEBUG_KERNEL is set and achieves...
1. Detects code paths in kernel or userland which expect predetermined
consecutive device numbers.
2. When something goes wrong, avoid corruption as adding to the minor
of earlier partition won't lead to the wrong but valid device.
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
This patch adds stalled-CPU detection to Classic RCU. This capability
is enabled by a new config variable CONFIG_RCU_CPU_STALL_DETECTOR, which
defaults disabled.
This is a debugging feature to detect infinite loops in kernel code, not
something that non-kernel-hackers would be expected to care about.
This feature can detect looping CPUs in !PREEMPT builds and looping CPUs
with preemption disabled in PREEMPT builds. This is essentially a port of
this functionality from the treercu patch, replacing the stall debug patch
that is already in tip/core/rcu (commit 67182ae1c4).
The changes from the patch in tip/core/rcu include making the config
variable name match that in treercu, changing from seconds to jiffies to
avoid spurious warnings, and printing a boot message when this feature
is enabled.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This bug is causing random crashes
(http://bugzilla.kernel.org/show_bug.cgi?id=11414).
-fno-omit-frame-pointer is only needed on powerpc when -pg is also
supplied, and there is a gcc bug that causes incorrect code generation
on 32-bit powerpc when -fno-omit-frame-pointer is used---it uses stack
locations below the stack pointer, which is not allowed by the ABI
because those locations can and sometimes do get corrupted by an
interrupt.
This ensures that CONFIG_FRAME_POINTER is only selected by ftrace.
When CONFIG_FTRACE is enabled we also pass -mno-sched-epilog to work
around the gcc codegen bug.
Patch based on work by:
Andreas Schwab <schwab@suse.de>
Segher Boessenkool <segher@kernel.crashing.org>
Signed-off-by: Tony Breeds <tony@bakeyournoodle.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
I noticed that sysctl_check.o was the largest object file in
a allnoconfig build in kernel/*.
36243 0 0 36243 8d93 kernel/sysctl_check.o
This is because it was default y and && EMBEDDED. But I don't
really see a need for a non kernel developer to have their
sysctls checked all the time.
So move the Kconfig into the kernel debugging section and
also drop the default y and the EMBEDDED check.
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Currently source files in the Documentation/ sub-dir can easily bit-rot
since they are not generally buildable, either because they are hidden in
text files or because there are no Makefile rules for them. This needs to
be fixed so that the source files remain usable and good examples of code
instead of bad examples.
Add the ability to build source files that are in the Documentation/ dir.
Add to Kconfig as "BUILD_DOCSRC" config symbol.
Use "CONFIG_BUILD_DOCSRC=1 make ..." to build objects from the
Documentation/ sources. Or enable BUILD_DOCSRC in the *config system.
However, this symbol depends on HEADERS_CHECK since the header files need
to be installed (for userspace builds).
Built (using cross-tools) for x86-64, i386, alpha, ia64, sparc32,
sparc64, powerpc, sh, m68k, & mips.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
this is a diagnostic patch for Classic RCU.
The approach is to record a timestamp at the beginning
of the grace period (in rcu_start_batch()), then have
rcu_check_callbacks() complain if:
1. it is running on a CPU that has holding up grace periods for
a long time (say one second). This will identify the culprit
assuming that the culprit has not disabled hardware irqs,
instruction execution, or some such.
2. it is running on a CPU that is not holding up grace periods,
but grace periods have been held up for an even longer time
(say two seconds).
It is enabled via the default-off CONFIG_DEBUG_RCU_STALL kernel parameter.
Rather than exponential backoff, it backs off to once per 30 seconds.
My feeling upon thinking on it was that if you have stalled RCU grace
periods for that long, a few extra printk() messages are probably the
least of your worries...
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Yinghai Lu <yhlu.kernel@gmail.com>
Cc: David Witbrodt <dawitbro@sbcglobal.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Boot initialisation is very complex, with significant numbers of
architecture-specific routines, hooks and code ordering. While significant
amounts of the initialisation is architecture-independent, it trusts the data
received from the architecture layer. This is a mistake, and has resulted in
a number of difficult-to-diagnose bugs.
This patchset adds some validation and tracing to memory initialisation. It
also introduces a few basic defensive measures. The validation code can be
explicitly disabled for embedded systems.
This patch:
Add additional debugging and verification code for memory initialisation.
Once enabled, the verification checks are always run and when required
additional debugging information may be outputted via a mminit_loglevel=
command-line parameter.
The verification code is placed in a new file mm/mm_init.c. Ideally other mm
initialisation code will be moved here over time.
Signed-off-by: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Andy Whitcroft <apw@shadowen.org>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This patch adds saved stack-traces to the backtrace suite of self-tests.
Note that we don't depend on or unconditionally enable CONFIG_STACKTRACE
because not all architectures may have it (and we still want to enable the
other tests for those architectures).
Cc: Arjan van de Ven <arjan@infradead.org>
Signed-off-by: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add some (configurable) expensive sanity checking to catch wrong address
translations on x86.
- create linux/mmdebug.h file to be able include this file in
asm headers to not get unsolvable loops in header files
- __phys_addr on x86_32 became a function in ioremap.c since
PAGE_OFFSET, is_vmalloc_addr and VMALLOC_* non-constasts are undefined
if declared in page_32.h
- add __phys_addr_const for initializing doublefault_tss.__cr3
Tested on 386, 386pae, x86_64 and x86_64 numa=fake=2.
Contains Andi's enable numa virtual address debug patch.
Signed-off-by: Jiri Slaby <jirislaby@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch re-institutes the ability to build rcutorture directly into
the Linux kernel. The reason that this capability was removed was that
this could result in your kernel being pretty much useless, as rcutorture
would be running starting from early boot. This problem has been avoided
by (1) making rcutorture run only three seconds of every six by default,
(2) adding a CONFIG_RCU_TORTURE_TEST_RUNNABLE that permits rcutorture
to be quiesced at boot time, and (3) adding a sysctl in /proc named
/proc/sys/kernel/rcutorture_runnable that permits rcutorture to be
quiesced and unquiesced when built into the kernel.
Please note that this /proc file is -not- available when rcutorture
is built as a module. Please also note that to get the earlier
take-no-prisoners behavior, you must use the boot command line to set
rcutorture's "stutter" parameter to zero.
The rcutorture quiescing mechanism is currently quite crude: loops
in each rcutorture process that poll a global variable once per tick.
Suggestions for improvement are welcome. The default action will
be to reduce the polling rate to a few times per second.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This reverts commit 9aaffc898f.
That commit was a very bad idea. RCU_TORTURE found many boot timing
bugs and other sorts of bugs in the past, so excluding it from
boot images is very silly.
The option already depends on DEBUG_KERNEL and is disabled by default.
Even when it runs, the test threads are reniced. If it annoys people
we could add a runtime sysctl.
allow users to configure the softlockup detector to generate a panic
instead of a warning message.
high-availability systems might opt for this strict method (combined
with panic_timeout= boot option/sysctl), instead of generating
softlockup warnings ad infinitum.
also, automated tests work better if the system reboots reliably (into
a safe kernel) in case of a lockup.
The full spectrum of configurability is supported: boot option, sysctl
option and Kconfig option.
it's default-disabled.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
If CONFIG_FTRACE is selected and /proc/sys/kernel/ftrace_enabled is
set to a non-zero value the ftrace routine will be called everytime
we enter a kernel function that is not marked with the "notrace"
attribute.
The ftrace routine will then call a registered function if a function
happens to be registered.
[ This code has been highly hacked by Steven Rostedt and Ingo Molnar,
so don't blame Arnaldo for all of this ;-) ]
Update:
It is now possible to register more than one ftrace function.
If only one ftrace function is registered, that will be the
function that ftrace calls directly. If more than one function
is registered, then ftrace will call a function that will loop
through the functions to call.
Signed-off-by: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add calls to the generic object debugging infrastructure and provide fixup
functions which allow to keep the system alive when recoverable problems have
been detected by the object debugging core code.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We can see an ever repeating problem pattern with objects of any kind in the
kernel:
1) freeing of active objects
2) reinitialization of active objects
Both problems can be hard to debug because the crash happens at a point where
we have no chance to decode the root cause anymore. One problem spot are
kernel timers, where the detection of the problem often happens in interrupt
context and usually causes the machine to panic.
While working on a timer related bug report I had to hack specialized code
into the timer subsystem to get a reasonable hint for the root cause. This
debug hack was fine for temporary use, but far from a mergeable solution due
to the intrusiveness into the timer code.
The code further lacked the ability to detect and report the root cause
instantly and keep the system operational.
Keeping the system operational is important to get hold of the debug
information without special debugging aids like serial consoles and special
knowledge of the bug reporter.
The problems described above are not restricted to timers, but timers tend to
expose it usually in a full system crash. Other objects are less explosive,
but the symptoms caused by such mistakes can be even harder to debug.
Instead of creating specialized debugging code for the timer subsystem a
generic infrastructure is created which allows developers to verify their code
and provides an easy to enable debug facility for users in case of trouble.
The debugobjects core code keeps track of operations on static and dynamic
objects by inserting them into a hashed list and sanity checking them on
object operations and provides additional checks whenever kernel memory is
freed.
The tracked object operations are:
- initializing an object
- adding an object to a subsystem list
- deleting an object from a subsystem list
Each operation is sanity checked before the operation is executed and the
subsystem specific code can provide a fixup function which allows to prevent
the damage of the operation. When the sanity check triggers a warning message
and a stack trace is printed.
The list of operations can be extended if the need arises. For now it's
limited to the requirements of the first user (timers).
The core code enqueues the objects into hash buckets. The hash index is
generated from the address of the object to simplify the lookup for the check
on kfree/vfree. Each bucket has it's own spinlock to avoid contention on a
global lock.
The debug code can be compiled in without being active. The runtime overhead
is minimal and could be optimized by asm alternatives. A kernel command line
option enables the debugging code.
Thanks to Ingo Molnar for review, suggestions and cleanup patches.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add option to enable -Wframe-larger-than= on gcc 4.4
gcc mainline (upcoming 4.4) added a new -Wframe-larger-than=...
option to warn at build time about too large stack frames. Add a config
option to enable this warning, since this very useful for the kernel.
I choose (somewhat arbitarily) 2048 as default warning threshold for 64bit
and 1024 as default for 32bit architectures. With some research and
fixing all the code for smaller values these defaults should be probably
lowered.
With the default allyesconfigs have some new warnings, but I think
that is all code that should be just fixed.
At some point (when gcc 4.4 is released and widely used) this should
obsolete make checkstack
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
There have been a few oopses caused by 'struct file's with NULL f_vfsmnts.
There was also a set of potentially missed mnt_want_write()s from
dentry_open() calls.
This patch provides a very simple debugging framework to catch these kinds of
bugs. It will WARN_ON() them, but should stop us from having any oopses or
mnt_writer count imbalances.
I'm quite convinced that this is a good thing because it found bugs in the
stuff I was working on as soon as I wrote it.
[hch: made it conditional on a debug option.
But it's still a little bit too ugly]
[hch: merged forced remount r/o fix from Dave and akpm's fix for the fix]
Signed-off-by: Dave Hansen <haveblue@us.ibm.com>
Acked-by: Al Viro <viro@ZenIV.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This way firewire-ohci can be used for remote debugging like ohci1394.
Version with amendment from Fri, 11 Apr 2008 00:08:08 +0200.
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de>
Acked-by: Bernhard Kaindl <bk@suse.de>
kgdb core code. Handles the protocol and the arch details.
[ mingo@elte.hu: heavily modified, simplified and cleaned up. ]
[ xemul@openvz.org: use find_task_by_pid_ns ]
Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Alpha and FRV mutexes had an option to print lots of debugging messages
in their semaphore implementation. This feature has not been carried
over to the generic semaphores, so remove the stale Kconfig option.
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
count_partial() is used by both slabinfo and the sysfs proc support. Move
the function directly before the beginning of the sysfs code so that it can
be easily found. Rework the preprocessor conditional to take into account
that slub sysfs support depends on CONFIG_SYSFS *and* CONFIG_SLUB_DEBUG.
Make CONFIG_SLUB_STATS depend on CONFIG_SLUB_DEBUG and CONFIG_SYSFS. There
is no point of keeping statistics if no one can restrive them.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Make LKDTM depend on BLOCK to prevent build failures with certain configs.
Signed-off-by: Chris Snook <csnook@redhat.com>
Acked-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
We started to see patches enabling this - so explain why
it is disabled and the condition to enable it again.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Other than the defconfigs, remove the entry in compiler-gcc4.h,
Kconfig.debug and feature-removal-schedule.txt.
Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Add architecture support for the MN10300/AM33 CPUs produced by MEI to the
kernel.
This patch also adds board support for the ASB2303 with the ASB2308 daughter
board, and the ASB2305. The only processor supported is the MN103E010, which
is an AM33v2 core plus on-chip devices.
[akpm@linux-foundation.org: nuke cvs control strings]
Signed-off-by: Masakazu Urade <urade.masakazu@jp.panasonic.com>
Signed-off-by: Koichi Yasutake <yasutake.koichi@jp.panasonic.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
The statistics provided here allow the monitoring of allocator behavior but
at the cost of some (minimal) loss of performance. Counters are placed in
SLUB's per cpu data structure. The per cpu structure may be extended by the
statistics to grow larger than one cacheline which will increase the cache
footprint of SLUB.
There is a compile option to enable/disable the inclusion of the runtime
statistics and its off by default.
The slabinfo tool is enhanced to support these statistics via two options:
-D Switches the line of information displayed for a slab from size
mode to activity mode.
-A Sorts the slabs displayed by activity. This allows the display of
the slabs most important to the performance of a certain load.
-r Report option will report detailed statistics on
Example (tbench load):
slabinfo -AD ->Shows the most active slabs
Name Objects Alloc Free %Fast
skbuff_fclone_cache 33 111953835 111953835 99 99
:0000192 2666 5283688 5281047 99 99
:0001024 849 5247230 5246389 83 83
vm_area_struct 1349 119642 118355 91 22
:0004096 15 66753 66751 98 98
:0000064 2067 25297 23383 98 78
dentry 10259 28635 18464 91 45
:0000080 11004 18950 8089 98 98
:0000096 1703 12358 10784 99 98
:0000128 762 10582 9875 94 18
:0000512 184 9807 9647 95 81
:0002048 479 9669 9195 83 65
anon_vma 777 9461 9002 99 71
kmalloc-8 6492 9981 5624 99 97
:0000768 258 7174 6931 58 15
So the skbuff_fclone_cache is of highest importance for the tbench load.
Pretty high load on the 192 sized slab. Look for the aliases
slabinfo -a | grep 000192
:0000192 <- xfs_btree_cur filp kmalloc-192 uid_cache tw_sock_TCP
request_sock_TCPv6 tw_sock_TCPv6 skbuff_head_cache xfs_ili
Likely skbuff_head_cache.
Looking into the statistics of the skbuff_fclone_cache is possible through
slabinfo skbuff_fclone_cache ->-r option implied if cache name is mentioned
.... Usual output ...
Slab Perf Counter Alloc Free %Al %Fr
--------------------------------------------------
Fastpath 111953360 111946981 99 99
Slowpath 1044 7423 0 0
Page Alloc 272 264 0 0
Add partial 25 325 0 0
Remove partial 86 264 0 0
RemoteObj/SlabFrozen 350 4832 0 0
Total 111954404 111954404
Flushes 49 Refill 0
Deactivate Full=325(92%) Empty=0(0%) ToHead=24(6%) ToTail=1(0%)
Looks good because the fastpath is overwhelmingly taken.
skbuff_head_cache:
Slab Perf Counter Alloc Free %Al %Fr
--------------------------------------------------
Fastpath 5297262 5259882 99 99
Slowpath 4477 39586 0 0
Page Alloc 937 824 0 0
Add partial 0 2515 0 0
Remove partial 1691 824 0 0
RemoteObj/SlabFrozen 2621 9684 0 0
Total 5301739 5299468
Deactivate Full=2620(100%) Empty=0(0%) ToHead=0(0%) ToTail=0(0%)
Descriptions of the output:
Total: The total number of allocation and frees that occurred for a
slab
Fastpath: The number of allocations/frees that used the fastpath.
Slowpath: Other allocations
Page Alloc: Number of calls to the page allocator as a result of slowpath
processing
Add Partial: Number of slabs added to the partial list through free or
alloc (occurs during cpuslab flushes)
Remove Partial: Number of slabs removed from the partial list as a result of
allocations retrieving a partial slab or by a free freeing
the last object of a slab.
RemoteObj/Froz: How many times were remotely freed object encountered when a
slab was about to be deactivated. Frozen: How many times was
free able to skip list processing because the slab was in use
as the cpuslab of another processor.
Flushes: Number of times the cpuslab was flushed on request
(kmem_cache_shrink, may result from races in __slab_alloc)
Refill: Number of times we were able to refill the cpuslab from
remotely freed objects for the same slab.
Deactivate: Statistics how slabs were deactivated. Shows how they were
put onto the partial list.
In general fastpath is very good. Slowpath without partial list processing is
also desirable. Any touching of partial list uses node specific locks which
may potentially cause list lock contention.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Including additional fixes from Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Geert Uytterhoeven <Geert.Uytterhoeven@sonycom.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
We have too many section mismatches detected at the moment.
So silence modpost and prevent the option from being
set in a typical allyesconfig build.
Tell the user how to see all the deteils in the summary
message from modpost.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Change latencytop Kconfig entry so it doesn't list the archictectures
that support it. Instead introduce HAVE_LATENCY_SUPPORT which any
architecture can set. Should reduce patch conflicts.
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Holger Wolf <wolf@linux.vnet.ibm.com>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch adds a new configuration option, which adds support for a new
early_param which gets checked in arch/x86/kernel/setup_{32,64}.c:setup_arch()
to decide wether OHCI-1394 FireWire controllers should be initialized and
enabled for physical DMA access to allow remote debugging of early problems
like issues ACPI or other subsystems which are executed very early.
If the config option is not enabled, no code is changed, and if the boot
paramenter is not given, no new code is executed, and independent of that,
all new code is freed after boot, so the config option can be even enabled
in standard, non-debug kernels.
With specialized tools, it is then possible to get debugging information
from machines which have no serial ports (notebooks) such as the printk
buffer contents, or any data which can be referenced from global pointers,
if it is stored below the 4GB limit and even memory dumps of of the physical
RAM region below the 4GB limit can be taken without any cooperation from the
CPU of the host, so the machine can be crashed early, it does not matter.
In the extreme, even kernel debuggers can be accessed in this way. I wrote
a small kgdb module and an accompanying gdb stub for FireWire which allows
to gdb to talk to kgdb using remote remory reads and writes over FireWire.
An version of the gdb stub fore FireWire is able to read all global data
from a system which is running a a normal kernel without any kernel debugger,
without any interruption or support of the system's CPU. That way, e.g. the
task struct and so on can be read and even manipulated when the physical DMA
access is granted.
A HOWTO is included in this patch, in Documentation/debugging-via-ohci1394.txt
and I've put a copy online at
ftp://ftp.suse.de/private/bk/firewire/docs/debugging-via-ohci1394.txt
It also has links to all the tools which are available to make use of it
another copy of it is online at:
ftp://ftp.suse.de/private/bk/firewire/kernel/ohci1394_dma_early-v2.diff
Signed-Off-By: Bernhard Kaindl <bk@suse.de>
Tested-By: Thomas Renninger <trenn@suse.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
During the work on the x86 32 and 64 bit backtrace code I found it useful
to have a simple test module to test a process and irq context backtrace.
Since the existing backtrace code was buggy, I figure it might be useful
to have such a test module in the kernel so that maybe we can even
detect such bugs earlier..
[ mingo@elte.hu: build fix ]
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Here is a quick and naive smoke test for kprobes. This is intended to
just verify if some unrelated change broke the *probes subsystem. It is
self contained, architecture agnostic and isn't of any great use by itself.
This needs to be built in the kernel and runs a basic set of tests to
verify if kprobes, jprobes and kretprobes run fine on the kernel. In case
of an error, it'll print out a message with a "BUG" prefix.
This is a start; we intend to add more tests to this bucket over time.
Thanks to Jim Keniston and Masami Hiramatsu for comments and suggestions.
Tested on x86 (32/64) and powerpc.
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Acked-by: Masami Hiramatsu <mhiramat@redhat.com>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
If the config option CONFIG_SECTION_MISMATCH is not set and
we see a Section mismatch present the following to the user:
modpost: Found 1 section mismatch(es).
To see additional details select "Enable full Section mismatch analysis"
in the Kernel Hacking menu (CONFIG_SECTION_MISMATCH).
If the option CONFIG_SECTION_MISMATCH is selected
then be verbose in the Section mismatch reporting from mdopost.
Sample outputs:
WARNING: o-x86_64/vmlinux.o(.text+0x7396): Section mismatch in reference from the function discover_ebda() to the variable .init.data:ebda_addr
The function discover_ebda() references
the variable __initdata ebda_addr.
This is often because discover_ebda lacks a __initdata
annotation or the annotation of ebda_addr is wrong.
WARNING: o-x86_64/vmlinux.o(.data+0x74d58): Section mismatch in reference from the variable pci_serial_quirks to the function .devexit.text:pci_plx9050_exit()
The variable pci_serial_quirks references
the function __devexit pci_plx9050_exit()
If the reference is valid then annotate the
variable with __exit* (see linux/init.h) or name the variable:
*driver, *_template, *_timer, *_sht, *_ops, *_probe, *_probe_one, *_console,
WARNING: o-x86_64/vmlinux.o(__ksymtab+0x630): Section mismatch in reference from the variable __ksymtab_arch_register_cpu to the function .cpuinit.text:arch_register_cpu()
The symbol arch_register_cpu is exported and annotated __cpuinit
Fix this by removing the __cpuinit annotation of arch_register_cpu or drop the export.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Setting the option DEBUG_SECTION_MISMATCH will
report additional section mismatch'es but this
should in the end makes it possible to get rid of
all of them.
See help text in lib/Kconfig.debug for details.
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
LatencyTOP kernel infrastructure; it measures latencies in the
scheduler and tracks it system wide and per process.
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The __deprecated marker is quite useful in highlighting the remnants of
old APIs that want removing.
However, it is quite normal for one or more years to pass, before the
(usually ancient, bitrotten) code in question is either updated or
deleted.
Thus, like __must_check, add a Kconfig option that permits the silencing
of this compiler warning.
This change mimics the ifdef-ery and Kconfig defaults of MUST_CHECK as
closely as possible.
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Begin infrastructure for kernel code samples in the samples/ directory.
Add its Kconfig and Kbuild files.
Source its Kconfig file in all arch/ Kconfigs.
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Optionally add a boot delay after each kernel printk() call, crudely
measured in milliseconds, with a maximum delay of 10 seconds per printk.
Enable CONFIG_BOOT_PRINTK_DELAY=y and then add (e.g.):
"lpj=loops_per_jiffy boot_delay=100"
to the kernel command line.
It has been useful in cases like "during boot, my machine just reboots or the
screen goes black" by slowing down printk, (and adding initcall_debug), we can
usually see the last thing that happened before the lights went out which is
usually a valuable clue.
[akpm@linux-foundation.org: not all architectures implement CONFIG_HZ]
[akpm@linux-foundation.org: fix lots of stuff]
[bunk@stusta.de: kernel/printk.c: make 2 variables static]
[heiko.carstens@de.ibm.com: fix slow down printk on boot compile error]
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Dave Jones <davej@redhat.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Provide some documentation for CONFIG_LOCK_STAT.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: "Randy.Dunlap" <rdunlap@xenotime.net>
Cc: Rob Landley <rob@landley.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Add CONFIG_DEBUG_PREEMPT support to ppc64: it was useful for testing
get_paca() preemption. Cheat a little, just use debug_smp_processor_id()
in the debug version of get_paca(): it contains all the right checks and
reporting, though get_paca() doesn't really use smp_processor_id().
Use local_paca for what might have been called __raw_get_paca().
Silence harmless warnings from io.h and lparcfg.c with local_paca -
it is okay for iseries_lparcfg_data to be referencing shared_proc
with preemption enabled: all cpus should show the same value for
shared_proc.
Why do other architectures need TRACE_IRQFLAGS_SUPPORT for DEBUG_PREEMPT?
I don't know, ppc64 appears to get along fine without it.
Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>
The arm26 port has been in a state where it was far from even compiling
for quite some time.
Ian Molton agreed with the removal.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Cc: Ian Molton <spyro@f2s.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Introduce the core lock statistics code.
Lock statistics provides lock wait-time and hold-time (as well as the count
of corresponding contention and acquisitions events). Also, the first few
call-sites that encounter contention are tracked.
Lock wait-time is the time spent waiting on the lock. This provides insight
into the locking scheme, that is, a heavily contended lock is indicative of
a too coarse locking scheme.
Lock hold-time is the duration the lock was held, this provides a reference for
the wait-time numbers, so they can be put into perspective.
1)
lock
2)
... do stuff ..
unlock
3)
The time between 1 and 2 is the wait-time. The time between 2 and 3 is the
hold-time.
The lockdep held-lock tracking code is reused, because it already collects locks
into meaningful groups (classes), and because it is an existing infrastructure
for lock instrumentation.
Currently lockdep tracks lock acquisition with two hooks:
lock()
lock_acquire()
_lock()
... code protected by lock ...
unlock()
lock_release()
_unlock()
We need to extend this with two more hooks, in order to measure contention.
lock_contended() - used to measure contention events
lock_acquired() - completion of the contention
These are then placed the following way:
lock()
lock_acquire()
if (!_try_lock())
lock_contended()
_lock()
lock_acquired()
... do locked stuff ...
unlock()
lock_release()
_unlock()
(Note: the try_lock() 'trick' is used to avoid instrumenting all platform
dependent lock primitive implementations.)
It is also possible to toggle the two lockdep features at runtime using:
/proc/sys/kernel/prove_locking
/proc/sys/kernel/lock_stat
(esp. turning off the O(n^2) prove_locking functionaliy can help)
[akpm@linux-foundation.org: build fixes]
[akpm@linux-foundation.org: nuke unneeded ifdefs]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jason Baron <jbaron@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Jens Axboe