For some reason nr_chain_hlocks is updated with cmpxchg, but
this is performed inside of the lockdep global "grab_lock()",
which also makes simple modification of this variable atomic.
Remove the cmpxchg logic for updating nr_chain_hlocks and
simplify the code.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110421014300.727863282@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Lockdep output can be pretty cryptic, having nicer output
can save a lot of head scratching. When a simple irq inversion
scenario is detected by lockdep (lock A taken in interrupt
context but also in thread context without disabling interrupts)
we now get the following (hopefully more informative) output:
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(lockA);
<Interrupt>
lock(lockA);
*** DEADLOCK ***
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110421014300.436140880@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The message of "Bad BFS generated tree" is a bit confusing.
Replace it with a more sane error message.
Thanks to Peter Zijlstra for helping me come up with a better
message.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110421014300.135521252@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Irq inversion and irq dependency bugs are only subtly
different. The diffenerence lies where the interrupt occurred.
For irq dependency:
irq_disable
lock(A)
lock(B)
unlock(B)
unlock(A)
irq_enable
lock(B)
unlock(B)
<interrupt>
lock(A)
The interrupt comes in after it has been established that lock A
can be held when taking an irq unsafe lock. Lockdep detects the
problem when taking lock A in interrupt context.
With the irq_inversion the irq happens before it is established
and lockdep detects the problem with the taking of lock B:
<interrupt>
lock(A)
irq_disable
lock(A)
lock(B)
unlock(B)
unlock(A)
irq_enable
lock(B)
unlock(B)
Since the problem with the locking logic for both of these issues
is in actuality the same, they both should report the same scenario.
This patch implements that and prints this:
other info that might help us debug this:
Chain exists of:
&rq->lock --> lockA --> lockC
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(lockC);
local_irq_disable();
lock(&rq->lock);
lock(lockA);
<Interrupt>
lock(&rq->lock);
*** DEADLOCK ***
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110421014259.910720381@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Lockdep output can be pretty cryptic, having nicer output
can save a lot of head scratching. When a simple deadlock
scenario is detected by lockdep (lock A -> lock A) we now
get the following new output:
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0
----
lock(&(lock)->rlock);
lock(&(lock)->rlock);
*** DEADLOCK ***
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110421014259.643930104@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The lockdep output can be pretty cryptic, having nicer output
can save a lot of head scratching. When a normal deadlock
scenario is detected by lockdep (lock A -> lock B and there
exists a place where lock B -> lock A) we now get the following
new output:
other info that might help us debug this:
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(lockB);
lock(lockA);
lock(lockB);
lock(lockA);
*** DEADLOCK ***
On cases where there's a deeper chair, it shows the partial
chain that can cause the issue:
Chain exists of:
lockC --> lockA --> lockB
Possible unsafe locking scenario:
CPU0 CPU1
---- ----
lock(lockB);
lock(lockA);
lock(lockB);
lock(lockC);
*** DEADLOCK ***
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110421014259.380621789@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Locking order inversion due to interrupts is a subtle problem.
When an irq lockiinversion discovered by lockdep it currently
reports something like:
[ INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected ]
... and then prints out the locks that are involved, as back traces.
Judging by lkml feedback developers were routinely confused by what
a HARDIRQ->safe to unsafe issue is all about, and sometimes even
blew it off as a bug in lockdep.
It is not obvious when lockdep prints this message about a lock that
is never taken in interrupt context.
After explaining the problems that lockdep is reporting, I
decided to add a description of the problem in visual form. Now
the following is shown:
---
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(lockA);
local_irq_disable();
lock(&rq->lock);
lock(lockA);
<Interrupt>
lock(&rq->lock);
*** DEADLOCK ***
---
The above is the case when the unsafe lock is taken while
holding a lock taken in irq context. But when a lock is taken
that also grabs a unsafe lock, the call chain is shown:
---
other info that might help us debug this:
Chain exists of:
&rq->lock --> lockA --> lockC
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(lockC);
local_irq_disable();
lock(&rq->lock);
lock(lockA);
<Interrupt>
lock(&rq->lock);
*** DEADLOCK ***
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20110421014259.132728798@goodmis.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
During early boot, local IRQ is disabled until IRQ subsystem is
properly initialized. During this time, no one should enable
local IRQ and some operations which usually are not allowed with
IRQ disabled, e.g. operations which might sleep or require
communications with other processors, are allowed.
lockdep tracked this with early_boot_irqs_off/on() callbacks.
As other subsystems need this information too, move it to
init/main.c and make it generally available. While at it,
toggle the boolean to early_boot_irqs_disabled instead of
enabled so that it can be initialized with %false and %true
indicates the exceptional condition.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110120110635.GB6036@htj.dyndns.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Current look_up_lock_class() doesn't check the parameter "subclass".
This rarely rises problems because the main caller of this function,
register_lock_class(), checks it.
But register_lock_class() is not the only function which calls
look_up_lock_class(). lock_set_class() and its callees also call it.
And lock_set_class() doesn't check this parameter.
This will rise problems when the the value of subclass is larger than
MAX_LOCKDEP_SUBCLASSES. Because the address (used as the key of class)
caliculated with too large subclass has a probability to point
another key in different lock_class_key.
Of course this problem depends on the memory layout and
occurs with really low probability.
Signed-off-by: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Dmitry Torokhov <dtor@mail.ru>
Cc: Vojtech Pavlik <vojtech@ucw.cz>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286958626-986-1-git-send-email-mitake@dcl.info.waseda.ac.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Current lockdep_map only caches one class with subclass == 0,
and looks up hash table of classes when subclass != 0.
It seems that this has no problem because the case of
subclass != 0 is rare. But locks of struct rq are
acquired with subclass == 1 when task migration is executed.
Task migration is high frequent event, so I modified lockdep
to cache subclasses.
I measured the score of perf bench sched messaging.
This patch has slightly but certain (order of milli seconds
or 10 milli seconds) effect when lots of tasks are running.
I'll show the result in the tail of this description.
NR_LOCKDEP_CACHING_CLASSES specifies how many classes can be
cached in the instances of lockdep_map.
I discussed with Peter Zijlstra in LinuxCon Japan about
this approach and he taught me that caching every subclasses(8)
is cleary waste of memory. So number of cached classes
should be configurable.
=== Score comparison of benchmarks ===
# "min" means best score, and "max" means worst score
for i in `seq 1 10`; do ./perf bench -f simple sched messaging; done
before: min: 0.565000, max: 0.583000, avg: 0.572500
after: min: 0.559000, max: 0.568000, avg: 0.563300
# with more processes
for i in `seq 1 10`; do ./perf bench -f simple sched messaging -g 40; done
before: min: 2.274000, max: 2.298000, avg: 2.286300
after: min: 2.242000, max: 2.270000, avg: 2.259700
Signed-off-by: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1286269311-28336-2-git-send-email-mitake@dcl.info.waseda.ac.jp>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
There is no longer any functional difference between
__debug_show_held_locks() and debug_show_held_locks(),
so remove the former.
Signed-off-by: John Kacur <jkacur@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1281021054-4228-1-git-send-email-jkacur@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
For people who otherwise get to write: cpu_clock(smp_processor_id()),
there is now: local_clock().
Also, as per suggestion from Andrew, provide some documentation on
the various clock interfaces, and minimize the unsigned long long vs
u64 mess.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jens Axboe <jaxboe@fusionio.com>
LKML-Reference: <1275052414.1645.52.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The conversion of device->sem to device->mutex resulted in lockdep
warnings. Create a novalidate class for now until the driver folks
come up with separate classes. That way we have at least the basic
mutex debugging coverage.
Add a checkpatch error so the usage is reserved for device->mutex.
[ tglx: checkpatch and compile fix for LOCKDEP=n ]
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
* 'perf-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (311 commits)
perf tools: Add mode to build without newt support
perf symbols: symbol inconsistency message should be done only at verbose=1
perf tui: Add explicit -lslang option
perf options: Type check all the remaining OPT_ variants
perf options: Type check OPT_BOOLEAN and fix the offenders
perf options: Check v type in OPT_U?INTEGER
perf options: Introduce OPT_UINTEGER
perf tui: Add workaround for slang < 2.1.4
perf record: Fix bug mismatch with -c option definition
perf options: Introduce OPT_U64
perf tui: Add help window to show key associations
perf tui: Make <- exit menus too
perf newt: Add single key shortcuts for zoom into DSO and threads
perf newt: Exit browser unconditionally when CTRL+C, q or Q is pressed
perf newt: Fix the 'A'/'a' shortcut for annotate
perf newt: Make <- exit the ui_browser
x86, perf: P4 PMU - fix counters management logic
perf newt: Make <- zoom out filters
perf report: Report number of events, not samples
perf hist: Clarify events_stats fields usage
...
Fix up trivial conflicts in kernel/fork.c and tools/perf/builtin-record.c
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (24 commits)
rcu: remove all rcu head initializations, except on_stack initializations
rcu head introduce rcu head init on stack
Debugobjects transition check
rcu: fix build bug in RCU_FAST_NO_HZ builds
rcu: RCU_FAST_NO_HZ must check RCU dyntick state
rcu: make SRCU usable in modules
rcu: improve the RCU CPU-stall warning documentation
rcu: reduce the number of spurious RCU_SOFTIRQ invocations
rcu: permit discontiguous cpu_possible_mask CPU numbering
rcu: improve RCU CPU stall-warning messages
rcu: print boot-time console messages if RCU configs out of ordinary
rcu: disable CPU stall warnings upon panic
rcu: enable CPU_STALL_VERBOSE by default
rcu: slim down rcutiny by removing rcu_scheduler_active and friends
rcu: refactor RCU's context-switch handling
rcu: rename rcutiny rcu_ctrlblk to rcu_sched_ctrlblk
rcu: shrink rcutiny by making synchronize_rcu_bh() be inline
rcu: fix now-bogus rcu_scheduler_active comments.
rcu: Fix bogus CONFIG_PROVE_LOCKING in comments to reflect reality.
rcu: ignore offline CPUs in last non-dyntick-idle CPU check
...
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: Eric Paris <eparis@redhat.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Tested-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Drop the nested field as we don't use it. Every nested state can
be computed from a state machine on post processing already.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Steven Rostedt <rostedt@goodmis.org>
Drop the waittime field from the lock_acquired event, we can
calculate it by substracting the lock_acquired event timestamp
with the matching lock_acquire one.
It is not needed and takes useless space in the traces.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Steven Rostedt <rostedt@goodmis.org>
When calling check_prevs_add(), if all validations passed
add_lock_to_list() will add new lock to dependency tree and
alloc stack_trace for each list_entry.
But at this time, we are always on the same stack, so stack_trace
for each list_entry has the same value. This is redundant and eats
up lots of memory which could lead to warning on low
MAX_STACK_TRACE_ENTRIES.
Use one copy of stack_trace instead.
V2: As suggested by Peter Zijlstra, move save_trace() from
check_prevs_add() to check_prev_add().
Add tracking for trylock dependence which is also redundant.
Signed-off-by: Yong Zhang <yong.zhang0@windriver.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100504065711.GC10784@windriver.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We forgot to provide a !CONFIG_DEBUG_LOCKDEP case for the
redundant_hardirqs_on stat handling.
Manage that in the headers with a new __debug_atomic_inc() helper.
Fixes:
kernel/lockdep.c:2306: error: 'lockdep_stats' undeclared (first use in this function)
kernel/lockdep.c:2306: error: (Each undeclared identifier is reported only once
kernel/lockdep.c:2306: error: for each function it appears in.)
Reported-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
When a path restore the flags while irqs are already enabled, we
update the per cpu var redundant_hardirqs_on in a racy fashion
and debug_atomic_inc() warns about this situation.
In this particular case, loosing a few hits in a stat is not a big
deal, so increment it without protection.
v2: Don't bother with disabling irq, we can miss one count in
rare situations
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: David Miller <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Locking statistics are implemented using global atomic
variables. This is usually fine unless some path write them very
often.
This is the case for the function and function graph tracers
that disable irqs for each entry saved (except if the function
tracer is in preempt disabled only mode).
And calls to local_irq_save/restore() increment
hardirqs_on_events and hardirqs_off_events stats (or similar
stats for redundant versions).
Incrementing these global vars for each function ends up in too
much cache bouncing if lockstats are enabled.
To solve this, implement the debug_atomic_*() operations using
per cpu vars.
-v2: Use per_cpu() instead of get_cpu_var() to fetch the desired
cpu vars on debug_atomic_read()
-v3: Store the stats in a structure. No need for local_t as we
are NMI/irq safe.
-v4: Fix tons of build errors. I thought I had tested it but I
probably forgot to select the relevant config.
Suggested-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
LKML-Reference: <1270505417-8144-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
* 'slabh' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc:
eeepc-wmi: include slab.h
staging/otus: include slab.h from usbdrv.h
percpu: don't implicitly include slab.h from percpu.h
kmemcheck: Fix build errors due to missing slab.h
include cleanup: Update gfp.h and slab.h includes to prepare for breaking implicit slab.h inclusion from percpu.h
iwlwifi: don't include iwl-dev.h from iwl-devtrace.h
x86: don't include slab.h from arch/x86/include/asm/pgtable_32.h
Fix up trivial conflicts in include/linux/percpu.h due to
is_kernel_percpu_address() having been introduced since the slab.h
cleanup with the percpu_up.c splitup.
percpu.h is included by sched.h and module.h and thus ends up being
included when building most .c files. percpu.h includes slab.h which
in turn includes gfp.h making everything defined by the two files
universally available and complicating inclusion dependencies.
percpu.h -> slab.h dependency is about to be removed. Prepare for
this change by updating users of gfp and slab facilities include those
headers directly instead of assuming availability. As this conversion
needs to touch large number of source files, the following script is
used as the basis of conversion.
http://userweb.kernel.org/~tj/misc/slabh-sweep.py
The script does the followings.
* Scan files for gfp and slab usages and update includes such that
only the necessary includes are there. ie. if only gfp is used,
gfp.h, if slab is used, slab.h.
* When the script inserts a new include, it looks at the include
blocks and try to put the new include such that its order conforms
to its surrounding. It's put in the include block which contains
core kernel includes, in the same order that the rest are ordered -
alphabetical, Christmas tree, rev-Xmas-tree or at the end if there
doesn't seem to be any matching order.
* If the script can't find a place to put a new include (mostly
because the file doesn't have fitting include block), it prints out
an error message indicating which .h file needs to be added to the
file.
The conversion was done in the following steps.
1. The initial automatic conversion of all .c files updated slightly
over 4000 files, deleting around 700 includes and adding ~480 gfp.h
and ~3000 slab.h inclusions. The script emitted errors for ~400
files.
2. Each error was manually checked. Some didn't need the inclusion,
some needed manual addition while adding it to implementation .h or
embedding .c file was more appropriate for others. This step added
inclusions to around 150 files.
3. The script was run again and the output was compared to the edits
from #2 to make sure no file was left behind.
4. Several build tests were done and a couple of problems were fixed.
e.g. lib/decompress_*.c used malloc/free() wrappers around slab
APIs requiring slab.h to be added manually.
5. The script was run on all .h files but without automatically
editing them as sprinkling gfp.h and slab.h inclusions around .h
files could easily lead to inclusion dependency hell. Most gfp.h
inclusion directives were ignored as stuff from gfp.h was usually
wildly available and often used in preprocessor macros. Each
slab.h inclusion directive was examined and added manually as
necessary.
6. percpu.h was updated not to include slab.h.
7. Build test were done on the following configurations and failures
were fixed. CONFIG_GCOV_KERNEL was turned off for all tests (as my
distributed build env didn't work with gcov compiles) and a few
more options had to be turned off depending on archs to make things
build (like ipr on powerpc/64 which failed due to missing writeq).
* x86 and x86_64 UP and SMP allmodconfig and a custom test config.
* powerpc and powerpc64 SMP allmodconfig
* sparc and sparc64 SMP allmodconfig
* ia64 SMP allmodconfig
* s390 SMP allmodconfig
* alpha SMP allmodconfig
* um on x86_64 SMP allmodconfig
8. percpu.h modifications were reverted so that it could be applied as
a separate patch and serve as bisection point.
Given the fact that I had only a couple of failures from tests on step
6, I'm fairly confident about the coverage of this conversion patch.
If there is a breakage, it's likely to be something in one of the arch
headers which should be easily discoverable easily on most builds of
the specific arch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Guess-its-ok-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
lockdep has custom code to check whether a pointer belongs to static
percpu area which is somewhat broken. Implement proper
is_kernel/module_percpu_address() and replace the custom code.
On UP, percpu variables are regular static variables and can't be
distinguished from them. Always return %false on UP.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: (35 commits)
perf: Fix unexported generic perf_arch_fetch_caller_regs
perf record: Don't try to find buildids in a zero sized file
perf: export perf_trace_regs and perf_arch_fetch_caller_regs
perf, x86: Fix hw_perf_enable() event assignment
perf, ppc: Fix compile error due to new cpu notifiers
perf: Make the install relative to DESTDIR if specified
kprobes: Calculate the index correctly when freeing the out-of-line execution slot
perf tools: Fix sparse CPU numbering related bugs
perf_event: Fix oops triggered by cpu offline/online
perf: Drop the obsolete profile naming for trace events
perf: Take a hot regs snapshot for trace events
perf: Introduce new perf_fetch_caller_regs() for hot regs snapshot
perf/x86-64: Use frame pointer to walk on irq and process stacks
lockdep: Move lock events under lockdep recursion protection
perf report: Print the map table just after samples for which no map was found
perf report: Add multiple event support
perf session: Change perf_session post processing functions to take histogram tree
perf session: Add storage for seperating event types in report
perf session: Change add_hist_entry to take the tree root instead of session
perf record: Add ID and to recorded event data when recording multiple events
...
There are rcu locked read side areas in the path where we submit
a trace event. And these rcu_read_(un)lock() trigger lock events,
which create recursive events.
One pair in do_perf_sw_event:
__lock_acquire
|
|--96.11%-- lock_acquire
| |
| |--27.21%-- do_perf_sw_event
| | perf_tp_event
| | |
| | |--49.62%-- ftrace_profile_lock_release
| | | lock_release
| | | |
| | | |--33.85%-- _raw_spin_unlock
Another pair in perf_output_begin/end:
__lock_acquire
|--23.40%-- perf_output_begin
| | __perf_event_overflow
| | perf_swevent_overflow
| | perf_swevent_add
| | perf_swevent_ctx_event
| | do_perf_sw_event
| | perf_tp_event
| | |
| | |--55.37%-- ftrace_profile_lock_acquire
| | | lock_acquire
| | | |
| | | |--37.31%-- _raw_spin_lock
The problem is not that much the trace recursion itself, as we have a
recursion protection already (though it's always wasteful to recurse).
But the trace events are outside the lockdep recursion protection, then
each lockdep event triggers a lock trace, which will trigger two
other lockdep events. Here the recursive lock trace event won't
be taken because of the trace recursion, so the recursion stops there
but lockdep will still analyse these new events:
To sum up, for each lockdep events we have:
lock_*()
|
trace lock_acquire
|
----- rcu_read_lock()
| |
| lock_acquire()
| |
| trace_lock_acquire() (stopped)
| |
| lockdep analyze
|
----- rcu_read_unlock()
|
lock_release
|
trace_lock_release() (stopped)
|
lockdep analyze
And you can repeat the above two times as we have two rcu read side
sections when we submit an event.
This is fixed in this patch by moving the lock trace event under
the lockdep recursion protection.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jens Axboe <jens.axboe@oracle.com>
Lockdep has found the real bug, but the output doesn't look right to me:
> =========================================================
> [ INFO: possible irq lock inversion dependency detected ]
> 2.6.33-rc5 #77
> ---------------------------------------------------------
> emacs/1609 just changed the state of lock:
> (&(&tty->ctrl_lock)->rlock){+.....}, at: [<ffffffff8127c648>] tty_fasync+0xe8/0x190
> but this lock took another, HARDIRQ-unsafe lock in the past:
> (&(&sighand->siglock)->rlock){-.....}
"HARDIRQ-unsafe" and "this lock took another" looks wrong, afaics.
> ... key at: [<ffffffff81c054a4>] __key.46539+0x0/0x8
> ... acquired at:
> [<ffffffff81089af6>] __lock_acquire+0x1056/0x15a0
> [<ffffffff8108a0df>] lock_acquire+0x9f/0x120
> [<ffffffff81423012>] _raw_spin_lock_irqsave+0x52/0x90
> [<ffffffff8127c1be>] __proc_set_tty+0x3e/0x150
> [<ffffffff8127e01d>] tty_open+0x51d/0x5e0
The stack-trace shows that this lock (ctrl_lock) was taken under
->siglock (which is hopefully irq-safe).
This is a clear typo in check_usage_backwards() where we tell the print a
fancy routine we're forwards.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20100126181641.GA10460@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Name space cleanup. No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
Further name space cleanup. No functional change
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
The raw_spin* namespace was taken by lockdep for the architecture
specific implementations. raw_spin_* would be the ideal name space for
the spinlocks which are not converted to sleeping locks in preempt-rt.
Linus suggested to convert the raw_ to arch_ locks and cleanup the
name space instead of using an artifical name like core_spin,
atomic_spin or whatever
No functional change.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Ingo Molnar <mingo@elte.hu>
Cc: linux-arch@vger.kernel.org
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (34 commits)
m68k: rename global variable vmalloc_end to m68k_vmalloc_end
percpu: add missing per_cpu_ptr_to_phys() definition for UP
percpu: Fix kdump failure if booted with percpu_alloc=page
percpu: make misc percpu symbols unique
percpu: make percpu symbols in ia64 unique
percpu: make percpu symbols in powerpc unique
percpu: make percpu symbols in x86 unique
percpu: make percpu symbols in xen unique
percpu: make percpu symbols in cpufreq unique
percpu: make percpu symbols in oprofile unique
percpu: make percpu symbols in tracer unique
percpu: make percpu symbols under kernel/ and mm/ unique
percpu: remove some sparse warnings
percpu: make alloc_percpu() handle array types
vmalloc: fix use of non-existent percpu variable in put_cpu_var()
this_cpu: Use this_cpu_xx in trace_functions_graph.c
this_cpu: Use this_cpu_xx for ftrace
this_cpu: Use this_cpu_xx in nmi handling
this_cpu: Use this_cpu operations in RCU
this_cpu: Use this_cpu ops for VM statistics
...
Fix up trivial (famous last words) global per-cpu naming conflicts in
arch/x86/kvm/svm.c
mm/slab.c
ia64 found this the hard way (because we currently have a stub
for save_stack_trace() that does nothing). But it would be a
good idea to be cautious in case a real save_stack_trace()
bailed out with an error before it set trace->nr_entries.
Signed-off-by: Tony Luck <tony.luck@intel.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: luming.yu@intel.com
LKML-Reference: <4b2024d085302c2a2@agluck-desktop.sc.intel.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Fix min, max times in /proc/lock_stats
(1) When collecting lock hold and wait times, if the current minimum
time is zero, it will be replaced by the next time.
(2) When aggregating minimum and maximum lock hold and wait times
accross cpus, the values are added, instead of selecting the
minimum and maximum.
Signed-off-by: Frank Rowand <frank.rowand@am.sony.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4B05BBAE.2050005@am.sony.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Lockdep events subsystem gathers various locking related events
such as a request, release, contention or acquisition of a lock.
The name of this event subsystem is a bit of a misnomer since
these events are not quite related to lockdep but more generally
to locking, ie: these events are not reporting lock dependencies
or possible deadlock scenario but pure locking events.
Hence this rename.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Hitoshi Mitake <mitake@dcl.info.waseda.ac.jp>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Li Zefan <lizf@cn.fujitsu.com>
LKML-Reference: <1258103194-843-1-git-send-email-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This patch updates percpu related symbols under kernel/ and mm/ such
that percpu symbols are unique and don't clash with local symbols.
This serves two purposes of decreasing the possibility of global
percpu symbol collision and allowing dropping per_cpu__ prefix from
percpu symbols.
* kernel/lockdep.c: s/lock_stats/cpu_lock_stats/
* kernel/sched.c: s/init_rq_rt/init_rt_rq_var/ (any better idea?)
s/sched_group_cpus/sched_groups/
* kernel/softirq.c: s/ksoftirqd/run_ksoftirqd/a
* kernel/softlockup.c: s/(*)_timestamp/softlockup_\1_ts/
s/watchdog_task/softlockup_watchdog/
s/timestamp/ts/ for local variables
* kernel/time/timer_stats: s/lookup_lock/tstats_lookup_lock/
* mm/slab.c: s/reap_work/slab_reap_work/
s/reap_node/slab_reap_node/
* mm/vmstat.c: local variable changed to avoid collision with vmstat_work
Partly based on Rusty Russell's "alloc_percpu: rename percpu vars
which cause name clashes" patch.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: (slab/vmstat) Christoph Lameter <cl@linux-foundation.org>
Reviewed-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Nick Piggin <npiggin@suse.de>
Some tracepoint magic (TRACE_EVENT(lock_acquired)) relies on
the fact that lock hold times are positive and uses div64 on
that. That triggered a build warning on MIPS, and probably
causes bad output in certain circumstances as well.
Make it truly positive.
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1254818502.21044.112.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This allows lockdep to locate symbols that are in arch-specific data
sections (such as data in Blackfin on-chip SRAM regions).
Signed-off-by: Mike Frysinger <vapier@gentoo.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Robin Getz <rgetz@blackfin.uclinux.org>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Since lockdep has introduced BFS to avoid recursion, statistics
for recursion does not make any sense now. So remove them.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Cc: a.p.zijlstra@chello.nl
LKML-Reference: <1251542879-5211-1-git-send-email-tom.leiming@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The unit is KB, so sizeof(struct circular_queue) should be
divided by 1024.
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Cc: akpm@linux-foundation.org
Cc: torvalds@linux-foundation.org
Cc: davem@davemloft.net
Cc: Ming Lei <tom.leiming@gmail.com>
Cc: a.p.zijlstra@chello.nl
LKML-Reference: <1249220616-7190-1-git-send-email-tom.leiming@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
We still can apply DaveM's generation count optimization to
BFS, based on the following idea:
- before doing each BFS, increase the global generation id
by 1
- if one node in the graph has been visited, mark it as
visited by storing the current global generation id into
the node's dep_gen_id field
- so we can decide if one node has been visited already, by
comparing the node's dep_gen_id with the global generation id.
By applying DaveM's generation count optimization to current
implementation of BFS, we gain the following advantages:
- we save MAX_LOCKDEP_ENTRIES/8 bytes memory;
- we remove the bitmap_zero(bfs_accessed, MAX_LOCKDEP_ENTRIES);
in each BFS, which is very time-consuming since
MAX_LOCKDEP_ENTRIES may be very large.(16384UL)
Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: "David S. Miller" <davem@davemloft.net>
LKML-Reference: <1248274089-6358-1-git-send-email-tom.leiming@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
spin_lock_nest_lock() allows to take many instances of the same
class, this can easily lead to overflow of MAX_LOCK_DEPTH.
To avoid this overflow, we'll stop accounting instances but
start reference counting the class in the held_lock structure.
[ We could maintain a list of instances, if we'd move the hlock
stuff into __lock_acquired(), but that would require
significant modifications to the current code. ]
We restrict this mode to spin_lock_nest_lock() only, because it
degrades the lockdep quality due to lost of instance.
For lockstat this means we don't track lock statistics for any
but the first lock in the series.
Currently nesting is limited to 11 bits because that was the
spare space available in held_lock. This yields a 2048
instances maximium.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Marcelo Tosatti <mtosatti@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add a lockdep helper to validate that we indeed are the owner
of a lock.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
fixes a few comments and whitespaces that annoyed me.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
