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2011-12-09clockevents: Set noop handler in clockevents_exchange_device()Thomas Gleixner
commit de28f25e8244c7353abed8de0c7792f5f883588c upstream. If a device is shutdown, then there might be a pending interrupt, which will be processed after we reenable interrupts, which causes the original handler to be run. If the old handler is the (broadcast) periodic handler the shutdown state might hang the kernel completely. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09clocksource: Fix bug with max_deferment margin calculationYang Honggang (Joseph)
commit b1f919664d04a8d0ba29cb76673c7ca3325a2006 upstream. In order to leave a margin of 12.5% we should >> 3 not >> 5. Signed-off-by: Yang Honggang (Joseph) <eagle.rtlinux@gmail.com> [jstultz: Modified commit subject] Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09jump_label: jump_label_inc may return before the code is patchedGleb Natapov
commit bbbf7af4bf8fc69bc751818cf30521080fa47dcb upstream. If cpu A calls jump_label_inc() just after atomic_add_return() is called by cpu B, atomic_inc_not_zero() will return value greater then zero and jump_label_inc() will return to a caller before jump_label_update() finishes its job on cpu B. Link: http://lkml.kernel.org/r/20111018175551.GH17571@redhat.com Cc: Peter Zijlstra <a.p.zijlstra@chello.nl> Acked-by: Jason Baron <jbaron@redhat.com> Signed-off-by: Gleb Natapov <gleb@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09tick-broadcast: Stop active broadcast device when replacing itThomas Gleixner
commit c1be84309c58b1e7c6d626e28fba41a22b364c3d upstream. When a better rated broadcast device is installed, then the current active device is not disabled, which results in two running broadcast devices. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09tracing: fix event_subsystem ref countingIlya Dryomov
commit cb59974742aea24adf6637eb0c4b8e7b48bca6fb upstream. Fix a bug introduced by e9dbfae5, which prevents event_subsystem from ever being released. Ref_count was added to keep track of subsystem users, not for counting events. Subsystem is created with ref_count = 1, so there is no need to increment it for every event, we have nr_events for that. Fix this by touching ref_count only when we actually have a new user - subsystem_open(). Signed-off-by: Ilya Dryomov <idryomov@gmail.com> Link: http://lkml.kernel.org/r/1320052062-7846-1-git-send-email-idryomov@gmail.com Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09trace_events_filter: Use rcu_assign_pointer() when setting ↵Tejun Heo
ftrace_event_call->filter commit d3d9acf646679c1981032b0985b386d12fccc60c upstream. ftrace_event_call->filter is sched RCU protected but didn't use rcu_assign_pointer(). Use it. TODO: Add proper __rcu annotation to call->filter and all its users. -v2: Use RCU_INIT_POINTER() for %NULL clearing as suggested by Eric. Link: http://lkml.kernel.org/r/20111123164949.GA29639@google.com Cc: Eric Dumazet <eric.dumazet@gmail.com> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09ftrace: Remove force undef config value left for testingSteven Rostedt
commit c7c6ec8becaf742b223c7b491f4893014be23a07 upstream. A forced undef of a config value was used for testing and was accidently left in during the final commit. This causes x86 to run slower than needed while running function tracing as well as causes the function graph selftest to fail when DYNMAIC_FTRACE is not set. This is because the code in MCOUNT expects the ftrace code to be processed with the config value set that happened to be forced not set. The forced config option was left in by: commit 6331c28c962561aee59e5a493b7556a4bb585957 ftrace: Fix dynamic selftest failure on some archs Link: http://lkml.kernel.org/r/20111102150255.GA6973@debian Reported-by: Rabin Vincent <rabin@rab.in> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09genirq: Fix race condition when stopping the irq threadIdo Yariv
commit 550acb19269d65f32e9ac4ddb26c2b2070e37f1c upstream. In irq_wait_for_interrupt(), the should_stop member is verified before setting the task's state to TASK_INTERRUPTIBLE and calling schedule(). In case kthread_stop sets should_stop and wakes up the process after should_stop is checked by the irq thread but before the task's state is changed, the irq thread might never exit: kthread_stop irq_wait_for_interrupt ------------ ---------------------- ... ... while (!kthread_should_stop()) { kthread->should_stop = 1; wake_up_process(k); wait_for_completion(&kthread->exited); ... set_current_state(TASK_INTERRUPTIBLE); ... schedule(); } Fix this by checking if the thread should stop after modifying the task's state. [ tglx: Simplified it a bit ] Signed-off-by: Ido Yariv <ido@wizery.com> Link: http://lkml.kernel.org/r/1322740508-22640-1-git-send-email-ido@wizery.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09clocksource: Avoid selecting mult values that might overflow when adjustedJohn Stultz
commit d65670a78cdbfae94f20a9e05ec705871d7cdf2b upstream. For some frequencies, the clocks_calc_mult_shift() function will unfortunately select mult values very close to 0xffffffff. This has the potential to overflow when NTP adjusts the clock, adding to the mult value. This patch adds a clocksource.maxadj value, which provides an approximation of an 11% adjustment(NTP limits adjustments to 500ppm and the tick adjustment is limited to 10%), which could be made to the clocksource.mult value. This is then used to both check that the current mult value won't overflow/underflow, as well as warning us if the timekeeping_adjust() code pushes over that 11% boundary. v2: Fix max_adjustment calculation, and improve WARN_ONCE messages. v3: Don't warn before maxadj has actually been set CC: Yong Zhang <yong.zhang0@gmail.com> CC: David Daney <ddaney.cavm@gmail.com> CC: Thomas Gleixner <tglx@linutronix.de> CC: Chen Jie <chenj@lemote.com> CC: zhangfx <zhangfx@lemote.com> Reported-by: Chen Jie <chenj@lemote.com> Reported-by: zhangfx <zhangfx@lemote.com> Tested-by: Yong Zhang <yong.zhang0@gmail.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09hrtimer: Fix extra wakeups from __remove_hrtimer()Jeff Ohlstein
commit 27c9cd7e601632b3794e1c3344d37b86917ffb43 upstream. __remove_hrtimer() attempts to reprogram the clockevent device when the timer being removed is the next to expire. However, __remove_hrtimer() reprograms the clockevent *before* removing the timer from the timerqueue and thus when hrtimer_force_reprogram() finds the next timer to expire it finds the timer we're trying to remove. This is especially noticeable when the system switches to NOHz mode and the system tick is removed. The timer tick is removed from the system but the clockevent is programmed to wakeup in another HZ anyway. Silence the extra wakeup by removing the timer from the timerqueue before calling hrtimer_force_reprogram() so that we actually program the clockevent for the next timer to expire. This was broken by 998adc3 "hrtimers: Convert hrtimers to use timerlist infrastructure". Signed-off-by: Jeff Ohlstein <johlstei@codeaurora.org> Link: http://lkml.kernel.org/r/1321660030-8520-1-git-send-email-johlstei@codeaurora.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09timekeeping: add arch_offset hook to ktime_get functionsHector Palacios
commit d004e024058a0eaca097513ce62cbcf978913e0a upstream. ktime_get and ktime_get_ts were calling timekeeping_get_ns() but later they were not calling arch_gettimeoffset() so architectures using this mechanism returned 0 ns when calling these functions. This happened for example when running Busybox's ping which calls syscall(__NR_clock_gettime, CLOCK_MONOTONIC, ts) which eventually calls ktime_get. As a result the returned ping travel time was zero. Signed-off-by: Hector Palacios <hector.palacios@digi.com> Signed-off-by: John Stultz <john.stultz@linaro.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09cgroup_freezer: fix freezing groups with stopped tasksMichal Hocko
commit 884a45d964dd395eda945842afff5e16bcaedf56 upstream. 2d3cbf8b (cgroup_freezer: update_freezer_state() does incorrect state transitions) removed is_task_frozen_enough and replaced it with a simple frozen call. This, however, breaks freezing for a group with stopped tasks because those cannot be frozen and so the group remains in CGROUP_FREEZING state (update_if_frozen doesn't count stopped tasks) and never reaches CGROUP_FROZEN. Let's add is_task_frozen_enough back and use it at the original locations (update_if_frozen and try_to_freeze_cgroup). Semantically we consider stopped tasks as frozen enough so we should consider both cases when testing frozen tasks. Testcase: mkdir /dev/freezer mount -t cgroup -o freezer none /dev/freezer mkdir /dev/freezer/foo sleep 1h & pid=$! kill -STOP $pid echo $pid > /dev/freezer/foo/tasks echo FROZEN > /dev/freezer/foo/freezer.state while true do cat /dev/freezer/foo/freezer.state [ "`cat /dev/freezer/foo/freezer.state`" = "FROZEN" ] && break sleep 1 done echo OK Signed-off-by: Michal Hocko <mhocko@suse.cz> Acked-by: Li Zefan <lizf@cn.fujitsu.com> Cc: Tomasz Buchert <tomasz.buchert@inria.fr> Cc: Paul Menage <paul@paulmenage.org> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Tejun Heo <htejun@gmail.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-12-09genirq: fix regression in irqfixup, irqpollEdward Donovan
commit 52553ddffad76ccf192d4dd9ce88d5818f57f62a upstream. Commit fa27271bc8d2("genirq: Fixup poll handling") introduced a regression that broke irqfixup/irqpoll for some hardware configurations. Amidst reorganizing 'try_one_irq', that patch removed a test that checked for 'action->handler' returning IRQ_HANDLED, before acting on the interrupt. Restoring this test back returns the functionality lost since 2.6.39. In the current set of tests, after 'action' is set, it must precede '!action->next' to take effect. With this and my previous patch to irq/spurious.c, c75d720fca8a, all IRQ regressions that I have encountered are fixed. Signed-off-by: Edward Donovan <edward.donovan@numble.net> Reported-and-tested-by: Rogério Brito <rbrito@ime.usp.br> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-11-26genirq: Fix irqfixup, irqpoll regressionEdward Donovan
commit c75d720fca8a91ce99196d33adea383621027bf2 upstream. commit d05c65fff0 ("genirq: spurious: Run only one poller at a time") introduced a regression, leaving the boot options 'irqfixup' and 'irqpoll' non-functional. The patch placed tests in each function, to exit if the function is already running. The test in 'misrouted_irq' exited when it should have proceeded, effectively disabling 'misrouted_irq' and 'poll_spurious_irqs'. The check for an already running poller needs to be "!= 1" not "== 1" as "1" is the value when the first poller starts running. Signed-off-by: Edward Donovan <edward.donovan@numble.net> Cc: maciej.rutecki@gmail.com Link: http://lkml.kernel.org/r/1320175784-6745-1-git-send-email-edward.donovan@numble.net Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-11-11PM / Suspend: Off by one in pm_suspend()Dan Carpenter
commit 528f7ce6e439edeac38f6b3f8561f1be129b5e91 upstream. In enter_state() we use "state" as an offset for the pm_states[] array. The pm_states[] array only has PM_SUSPEND_MAX elements so this test is off by one. Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-11-11genirq: Add IRQF_RESUME_EARLY and resume such IRQs earlierIan Campbell
commit 9bab0b7fbaceec47d32db51cd9e59c82fb071f5a upstream. This adds a mechanism to resume selected IRQs during syscore_resume instead of dpm_resume_noirq. Under Xen we need to resume IRQs associated with IPIs early enough that the resched IPI is unmasked and we can therefore schedule ourselves out of the stop_machine where the suspend/resume takes place. This issue was introduced by 676dc3cf5bc3 "xen: Use IRQF_FORCE_RESUME". Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Cc: Rafael J. Wysocki <rjw@sisk.pl> Cc: Jeremy Fitzhardinge <Jeremy.Fitzhardinge@citrix.com> Cc: xen-devel <xen-devel@lists.xensource.com> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Link: http://lkml.kernel.org/r/1318713254.11016.52.camel@dagon.hellion.org.uk Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-11-11tracing: Fix returning of duplicate data after EOF in trace_pipe_rawSteven Rostedt
commit 436fc280261dcfce5af38f08b89287750dc91cd2 upstream. The trace_pipe_raw handler holds a cached page from the time the file is opened to the time it is closed. The cached page is used to handle the case of the user space buffer being smaller than what was read from the ring buffer. The left over buffer is held in the cache so that the next read will continue where the data left off. After EOF is returned (no more data in the buffer), the index of the cached page is set to zero. If a user app reads the page again after EOF, the check in the buffer will see that the cached page is less than page size and will return the cached page again. This will cause reading the trace_pipe_raw again after EOF to return duplicate data, making the output look like the time went backwards but instead data is just repeated. The fix is to not reset the index right after all data is read from the cache, but to reset it after all data is read and more data exists in the ring buffer. Reported-by: Jeremy Eder <jeder@redhat.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-11-11ftrace/kprobes: Fix not to delete probes if in useMasami Hiramatsu
commit 02ca1521ad404cf566e0075848f80d064c0a0503 upstream. Fix kprobe-tracer not to delete a probe if the probe is in use. In that case, delete operation will return -EBUSY. This bug can cause a kernel panic if enabled probes are deleted during perf record. (Add some probes on functions) sh-4.2# perf probe --del probe:\* sh-4.2# exit (kernel panic) This is originally reported on the fedora bugzilla: https://bugzilla.redhat.com/show_bug.cgi?id=742383 I've also checked that this problem doesn't happen on tracepoints when module removing because perf event locks target module. $ sudo ./perf record -e xfs:\* -aR sh sh-4.2# rmmod xfs ERROR: Module xfs is in use sh-4.2# exit [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.203 MB perf.data (~8862 samples) ] Signed-off-by: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com> Cc: Arnaldo Carvalho de Melo <acme@redhat.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Frederic Weisbecker <fweisbec@gmail.com> Cc: Frank Ch. Eigler <fche@redhat.com> Link: http://lkml.kernel.org/r/20111004104438.14591.6553.stgit@fedora15 Signed-off-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-11-11time: Change jiffies_to_clock_t() argument type to unsigned longhank
commit cbbc719fccdb8cbd87350a05c0d33167c9b79365 upstream. The parameter's origin type is long. On an i386 architecture, it can easily be larger than 0x80000000, causing this function to convert it to a sign-extended u64 type. Change the type to unsigned long so we get the correct result. Signed-off-by: hank <pyu@redhat.com> Cc: John Stultz <john.stultz@linaro.org> [ build fix ] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-11-11kmod: prevent kmod_loop_msg overflow in __request_module()Jiri Kosina
commit 37252db6aa576c34fd794a5a54fb32d7a8b3a07a upstream. Due to post-increment in condition of kmod_loop_msg in __request_module(), the system log can be spammed by much more than 5 instances of the 'runaway loop' message if the number of events triggering it makes the kmod_loop_msg to overflow. Fix that by making sure we never increment it past the threshold. Signed-off-by: Jiri Kosina <jkosina@suse.cz> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
2011-10-18cputimer: Cure lock inversionPeter Zijlstra
There's a lock inversion between the cputimer->lock and rq->lock; notably the two callchains involved are: update_rlimit_cpu() sighand->siglock set_process_cpu_timer() cpu_timer_sample_group() thread_group_cputimer() cputimer->lock thread_group_cputime() task_sched_runtime() ->pi_lock rq->lock scheduler_tick() rq->lock task_tick_fair() update_curr() account_group_exec() cputimer->lock Where the first one is enabling a CLOCK_PROCESS_CPUTIME_ID timer, and the second one is keeping up-to-date. This problem was introduced by e8abccb7193 ("posix-cpu-timers: Cure SMP accounting oddities"). Cure the problem by removing the cputimer->lock and rq->lock nesting, this leaves concurrent enablers doing duplicate work, but the time wasted should be on the same order otherwise wasted spinning on the lock and the greater-than assignment filter should ensure we preserve monotonicity. Reported-by: Dave Jones <davej@redhat.com> Reported-by: Simon Kirby <sim@hostway.ca> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: stable@kernel.org Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Link: http://lkml.kernel.org/r/1318928713.21167.4.camel@twins Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-10-17Avoid using variable-length arrays in kernel/sys.cLinus Torvalds
The size is always valid, but variable-length arrays generate worse code for no good reason (unless the function happens to be inlined and the compiler sees the length for the simple constant it is). Also, there seems to be some code generation problem on POWER, where Henrik Bakken reports that register r28 can get corrupted under some subtle circumstances (interrupt happening at the wrong time?). That all indicates some seriously broken compiler issues, but since variable length arrays are bad regardless, there's little point in trying to chase it down. "Just don't do that, then". Reported-by: Henrik Grindal Bakken <henribak@cisco.com> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> Cc: stable@kernel.org Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-10-01Merge branches 'irq-urgent-for-linus', 'x86-urgent-for-linus' and ↵Linus Torvalds
'sched-urgent-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip * 'irq-urgent-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip: irq: Fix check for already initialized irq_domain in irq_domain_add irq: Add declaration of irq_domain_simple_ops to irqdomain.h * 'x86-urgent-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip: x86/rtc: Don't recursively acquire rtc_lock * 'sched-urgent-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip: posix-cpu-timers: Cure SMP wobbles sched: Fix up wchan borkage sched/rt: Migrate equal priority tasks to available CPUs
2011-09-30posix-cpu-timers: Cure SMP wobblesPeter Zijlstra
David reported: Attached below is a watered-down version of rt/tst-cpuclock2.c from GLIBC. Just build it with "gcc -o test test.c -lpthread -lrt" or similar. Run it several times, and you will see cases where the main thread will measure a process clock difference before and after the nanosleep which is smaller than the cpu-burner thread's individual thread clock difference. This doesn't make any sense since the cpu-burner thread is part of the top-level process's thread group. I've reproduced this on both x86-64 and sparc64 (using both 32-bit and 64-bit binaries). For example: [davem@boricha build-x86_64-linux]$ ./test process: before(0.001221967) after(0.498624371) diff(497402404) thread: before(0.000081692) after(0.498316431) diff(498234739) self: before(0.001223521) after(0.001240219) diff(16698) [davem@boricha build-x86_64-linux]$ The diff of 'process' should always be >= the diff of 'thread'. I make sure to wrap the 'thread' clock measurements the most tightly around the nanosleep() call, and that the 'process' clock measurements are the outer-most ones. --- #include <unistd.h> #include <stdio.h> #include <stdlib.h> #include <time.h> #include <fcntl.h> #include <string.h> #include <errno.h> #include <pthread.h> static pthread_barrier_t barrier; static void *chew_cpu(void *arg) { pthread_barrier_wait(&barrier); while (1) __asm__ __volatile__("" : : : "memory"); return NULL; } int main(void) { clockid_t process_clock, my_thread_clock, th_clock; struct timespec process_before, process_after; struct timespec me_before, me_after; struct timespec th_before, th_after; struct timespec sleeptime; unsigned long diff; pthread_t th; int err; err = clock_getcpuclockid(0, &process_clock); if (err) return 1; err = pthread_getcpuclockid(pthread_self(), &my_thread_clock); if (err) return 1; pthread_barrier_init(&barrier, NULL, 2); err = pthread_create(&th, NULL, chew_cpu, NULL); if (err) return 1; err = pthread_getcpuclockid(th, &th_clock); if (err) return 1; pthread_barrier_wait(&barrier); err = clock_gettime(process_clock, &process_before); if (err) return 1; err = clock_gettime(my_thread_clock, &me_before); if (err) return 1; err = clock_gettime(th_clock, &th_before); if (err) return 1; sleeptime.tv_sec = 0; sleeptime.tv_nsec = 500000000; nanosleep(&sleeptime, NULL); err = clock_gettime(th_clock, &th_after); if (err) return 1; err = clock_gettime(my_thread_clock, &me_after); if (err) return 1; err = clock_gettime(process_clock, &process_after); if (err) return 1; diff = process_after.tv_nsec - process_before.tv_nsec; printf("process: before(%lu.%.9lu) after(%lu.%.9lu) diff(%lu)\n", process_before.tv_sec, process_before.tv_nsec, process_after.tv_sec, process_after.tv_nsec, diff); diff = th_after.tv_nsec - th_before.tv_nsec; printf("thread: before(%lu.%.9lu) after(%lu.%.9lu) diff(%lu)\n", th_before.tv_sec, th_before.tv_nsec, th_after.tv_sec, th_after.tv_nsec, diff); diff = me_after.tv_nsec - me_before.tv_nsec; printf("self: before(%lu.%.9lu) after(%lu.%.9lu) diff(%lu)\n", me_before.tv_sec, me_before.tv_nsec, me_after.tv_sec, me_after.tv_nsec, diff); return 0; } This is due to us using p->se.sum_exec_runtime in thread_group_cputime() where we iterate the thread group and sum all data. This does not take time since the last schedule operation (tick or otherwise) into account. We can cure this by using task_sched_runtime() at the cost of having to take locks. This also means we can (and must) do away with thread_group_sched_runtime() since the modified thread_group_cputime() is now more accurate and would deadlock when called from thread_group_sched_runtime(). Aside of that it makes the function safe on 32 bit systems. The old code added t->se.sum_exec_runtime unprotected. sum_exec_runtime is a 64bit value and could be changed on another cpu at the same time. Reported-by: David Miller <davem@davemloft.net> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: stable@kernel.org Link: http://lkml.kernel.org/r/1314874459.7945.22.camel@twins Tested-by: David Miller <davem@davemloft.net> Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-09-29Resource: fix wrong resource window calculationRam Pai
__find_resource() incorrectly returns a resource window which overlaps an existing allocated window. This happens when the parent's resource-window spans 0x00000000 to 0xffffffff and is entirely allocated to all its children resource-windows. __find_resource() looks for gaps in resource allocation among the children resource windows. When it encounters the last child window it blindly tries the range next to one allocated to the last child. Since the last child's window ends at 0xffffffff the calculation overflows, leading the algorithm to believe that any window in the range 0x0000000 to 0xfffffff is available for allocation. This leads to a conflicting window allocation. Michal Ludvig reported this issue seen on his platform. The following patch fixes the problem and has been verified by Michal. I believe this bug has been there for ages. It got exposed by git commit 2bbc6942273b ("PCI : ability to relocate assigned pci-resources") Signed-off-by: Ram Pai <linuxram@us.ibm.com> Tested-by: Michal Ludvig <mludvig@logix.net.nz> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-26sched: Fix up wchan borkageSimon Kirby
Commit c259e01a1ec ("sched: Separate the scheduler entry for preemption") contained a boo-boo wrecking wchan output. It forgot to put the new schedule() function in the __sched section and thereby doesn't get properly ignored for things like wchan. Tested-by: Simon Kirby <sim@hostway.ca> Cc: stable@kernel.org # 2.6.39+ Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110923000346.GA25425@hostway.ca Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-09-25ptrace: PTRACE_LISTEN forgets to unlock ->siglockOleg Nesterov
If PTRACE_LISTEN fails after lock_task_sighand() it doesn't drop ->siglock. Reported-by: Matt Fleming <matt.fleming@intel.com> Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-20irq: Fix check for already initialized irq_domain in irq_domain_addRob Herring
The sanity check in irq_domain_add() tests desc->irq_data != NULL or irq_data->domain != NULL. This prevents adding an irq_domain to a irq descriptor when irq_data exists, which true when the irq descriptor exists. This went unnoticed so far as the simple domain code did not enter this code path because domain->nr_irqs is always 0 for the simple domains. Split the check for irq_data == NULL out and have a separate warning for it. [ tglx: Made the check for irq_data == NULL separate ] Signed-off-by: Rob Herring <rob.herring@calxeda.com> Cc: Grant Likely <grant.likely@secretlab.ca> Cc: marc.zyngier@arm.com Cc: thomas.abraham@linaro.org Cc: jamie@jamieiles.com Cc: b-cousson@ti.com Cc: shawn.guo@linaro.org Cc: linux-arm-kernel@lists.infradead.org Cc: devicetree-discuss@lists.ozlabs.org Link: http://lkml.kernel.org/r/1316017900-19918-3-git-send-email-robherring2@gmail.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-09-19Merge branch 'irq-fixes-for-linus' of git://tesla.tglx.de/git/linux-2.6-tipLinus Torvalds
* 'irq-fixes-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip: x86, iommu: Mark DMAR IRQ as non-threaded genirq: Make irq_shutdown() symmetric vs. irq_startup again
2011-09-19Make taskstats round statistics down to nearest 1k bytes/eventsLinus Torvalds
Even with just the interface limited to admin, there really is little to reason to give byte-per-byte counts for taskstats. So round it down to something less intrusive. Acked-by: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-19Make TASKSTATS require root accessLinus Torvalds
Ok, this isn't optimal, since it means that 'iotop' needs admin capabilities, and we may have to work on this some more. But at the same time it is very much not acceptable to let anybody just read anybody elses IO statistics quite at this level. Use of the GENL_ADMIN_PERM suggested by Johannes Berg as an alternative to checking the capabilities by hand. Reported-by: Vasiliy Kulikov <segoon@openwall.com> Cc: Johannes Berg <johannes.berg@intel.com> Acked-by: Balbir Singh <bsingharora@gmail.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-18sched/rt: Migrate equal priority tasks to available CPUsShawn Bohrer
Commit 43fa5460fe60dea5c610490a1d263415419c60f6 ("sched: Try not to migrate higher priority RT tasks") also introduced a change in behavior which keeps RT tasks on the same CPU if there is an equal priority RT task currently running even if there are empty CPUs available. This can cause unnecessary wakeup latencies, and can prevent the scheduler from balancing all RT tasks across available CPUs. This change causes an RT task to search for a new CPU if an equal priority RT task is already running on wakeup. Lower priority tasks will still have to wait on higher priority tasks, but the system should still balance out because there is always the possibility that if there are both a high and low priority RT tasks on a given CPU that the high priority task could wakeup while the low priority task is running and force it to search for a better runqueue. Signed-off-by: Shawn Bohrer <sbohrer@rgmadvisors.com> Acked-by: Steven Rostedt <rostedt@goodmis.org> Tested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: stable@kernel.org # 37+ Link: http://lkml.kernel.org/r/1315837684-18733-1-git-send-email-sbohrer@rgmadvisors.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-09-14workqueue: lock cwq access in drain_workqueueThomas Tuttle
Take cwq->gcwq->lock to avoid racing between drain_workqueue checking to make sure the workqueues are empty and cwq_dec_nr_in_flight decrementing and then incrementing nr_active when it activates a delayed work. We discovered this when a corner case in one of our drivers resulted in us trying to destroy a workqueue in which the remaining work would always requeue itself again in the same workqueue. We would hit this race condition and trip the BUG_ON on workqueue.c:3080. Signed-off-by: Thomas Tuttle <ttuttle@chromium.org> Acked-by: Tejun Heo <tj@kernel.org> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-09-12genirq: Make irq_shutdown() symmetric vs. irq_startup againGeert Uytterhoeven
If an irq_chip provides .irq_shutdown(), but neither of .irq_disable() or .irq_mask(), free_irq() crashes when jumping to NULL. Fix this by only trying .irq_disable() and .irq_mask() if there's no .irq_shutdown() provided. This revives the symmetry with irq_startup(), which tries .irq_startup(), .irq_enable(), and irq_unmask(), and makes it consistent with the comment for irq_chip.irq_shutdown() in <linux/irq.h>, which says: * @irq_shutdown: shut down the interrupt (defaults to ->disable if NULL) This is also how __free_irq() behaved before the big overhaul, cfr. e.g. 3b56f0585fd4c02d047dc406668cb40159b2d340 ("genirq: Remove bogus conditional"), where the core interrupt code always overrode .irq_shutdown() to .irq_disable() if .irq_shutdown() was NULL. Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org> Cc: linux-m68k@lists.linux-m68k.org Link: http://lkml.kernel.org/r/1315742394-16036-2-git-send-email-geert@linux-m68k.org Cc: stable@kernel.org Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2011-09-07Merge branch 'timers-fixes-for-linus' of git://tesla.tglx.de/git/linux-2.6-tipLinus Torvalds
* 'timers-fixes-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip: rtc: twl: Fix registration vs. init order rtc: Initialized rtc_time->tm_isdst rtc: Fix RTC PIE frequency limit rtc: rtc-twl: Remove lockdep related local_irq_enable() rtc: rtc-twl: Switch to using threaded irq rtc: ep93xx: Fix 'rtc' may be used uninitialized warning alarmtimers: Avoid possible denial of service with high freq periodic timers alarmtimers: Memset itimerspec passed into alarm_timer_get alarmtimers: Avoid possible null pointer traversal
2011-09-07Merge branch 'sched-fixes-for-linus' of git://tesla.tglx.de/git/linux-2.6-tipLinus Torvalds
* 'sched-fixes-for-linus' of git://tesla.tglx.de/git/linux-2.6-tip: sched: Fix a memory leak in __sdt_free() sched: Move blk_schedule_flush_plug() out of __schedule() sched: Separate the scheduler entry for preemption
2011-08-31perf_event: Fix broken calc_timer_values()Eric B Munson
We detected a serious issue with PERF_SAMPLE_READ and timing information when events were being multiplexing. Samples would have time_running > time_enabled. That was easy to reproduce with a libpfm4 example (ran 3 times to cause multiplexing on Core 2): $ syst_smpl -e uops_retired:freq=1 & $ syst_smpl -e uops_retired:freq=1 & $ syst_smpl -e uops_retired:freq=1 & IIP:0x0000000040062d ... PERIOD:2355332948 ENA=40144625315 RUN=60014875184 syst_smpl: WARNING: time_running > time_enabled 63277537998 uops_retired:freq=1 , scaled The bug was not present in kernel up to (and including) 3.0. It turns out the bug was introduced by the following commit: commit c4794295917ebeda8013b6cb9c8d71ab4f74a1fa events: Move lockless timer calculation into helper function The parameters of the function got reversed yet the call sites were not updated to reflect the change. That lead to time_running and time_enabled being swapped. That had no effect when there was no multiplexing because in that case time_running = time_enabled but it would show up in any other scenario. Signed-off-by: Stephane Eranian <eranian@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110829124112.GA4828@quad Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-29perf events: Fix slow and broken cgroup context switch codeStephane Eranian
The current cgroup context switch code was incorrect leading to bogus counts. Furthermore, as soon as there was an active cgroup event on a CPU, the context switch cost on that CPU would increase by a significant amount as demonstrated by a simple ping/pong example: $ ./pong Both processes pinned to CPU1, running for 10s 10684.51 ctxsw/s Now start a cgroup perf stat: $ perf stat -e cycles,cycles -A -a -G test -C 1 -- sleep 100 $ ./pong Both processes pinned to CPU1, running for 10s 6674.61 ctxsw/s That's a 37% penalty. Note that pong is not even in the monitored cgroup. The results shown by perf stat are bogus: $ perf stat -e cycles,cycles -A -a -G test -C 1 -- sleep 100 Performance counter stats for 'sleep 100': CPU1 <not counted> cycles test CPU1 16,984,189,138 cycles # 0.000 GHz The second 'cycles' event should report a count @ CPU clock (here 2.4GHz) as it is counting across all cgroups. The patch below fixes the bogus accounting and bypasses any cgroup switches in case the outgoing and incoming tasks are in the same cgroup. With this patch the same test now yields: $ ./pong Both processes pinned to CPU1, running for 10s 10775.30 ctxsw/s Start perf stat with cgroup: $ perf stat -e cycles,cycles -A -a -G test -C 1 -- sleep 10 Run pong outside the cgroup: $ /pong Both processes pinned to CPU1, running for 10s 10687.80 ctxsw/s The penalty is now less than 2%. And the results for perf stat are correct: $ perf stat -e cycles,cycles -A -a -G test -C 1 -- sleep 10 Performance counter stats for 'sleep 10': CPU1 <not counted> cycles test # 0.000 GHz CPU1 23,933,981,448 cycles # 0.000 GHz Now perf stat reports the correct counts for for the non cgroup event. If we run pong inside the cgroup, then we also get the correct counts: $ perf stat -e cycles,cycles -A -a -G test -C 1 -- sleep 10 Performance counter stats for 'sleep 10': CPU1 22,297,726,205 cycles test # 0.000 GHz CPU1 23,933,981,448 cycles # 0.000 GHz 10.001457237 seconds time elapsed Signed-off-by: Stephane Eranian <eranian@google.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Link: http://lkml.kernel.org/r/20110825135803.GA4697@quad Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-29sched: Fix a memory leak in __sdt_free()WANG Cong
This patch fixes the following memory leak: unreferenced object 0xffff880107266800 (size 512): comm "sched-powersave", pid 3718, jiffies 4323097853 (age 27495.450s) hex dump (first 32 bytes): 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 ................ backtrace: [<ffffffff81133940>] create_object+0x187/0x28b [<ffffffff814ac103>] kmemleak_alloc+0x73/0x98 [<ffffffff811232ba>] __kmalloc_node+0x104/0x159 [<ffffffff81044b98>] kzalloc_node.clone.97+0x15/0x17 [<ffffffff8104cb90>] build_sched_domains+0xb7/0x7f3 [<ffffffff8104d4df>] partition_sched_domains+0x1db/0x24a [<ffffffff8109ee4a>] do_rebuild_sched_domains+0x3b/0x47 [<ffffffff810a00c7>] rebuild_sched_domains+0x10/0x12 [<ffffffff8104d5ba>] sched_power_savings_store+0x6c/0x7b [<ffffffff8104d5df>] sched_mc_power_savings_store+0x16/0x18 [<ffffffff8131322c>] sysdev_class_store+0x20/0x22 [<ffffffff81193876>] sysfs_write_file+0x108/0x144 [<ffffffff81135b10>] vfs_write+0xaf/0x102 [<ffffffff81135d23>] sys_write+0x4d/0x74 [<ffffffff814c8a42>] system_call_fastpath+0x16/0x1b [<ffffffffffffffff>] 0xffffffffffffffff Signed-off-by: WANG Cong <amwang@redhat.com> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: stable@kernel.org # 3.0 Link: http://lkml.kernel.org/r/1313671017-4112-1-git-send-email-amwang@redhat.com Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-29sched: Move blk_schedule_flush_plug() out of __schedule()Thomas Gleixner
There is no real reason to run blk_schedule_flush_plug() with interrupts and preemption disabled. Move it into schedule() and call it when the task is going voluntarily to sleep. There might be false positives when the task is woken between that call and actually scheduling, but that's not really different from being woken immediately after switching away. This fixes a deadlock in the scheduler where the blk_schedule_flush_plug() callchain enables interrupts and thereby allows a wakeup to happen of the task that's going to sleep. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: stable@kernel.org # 2.6.39+ Link: http://lkml.kernel.org/n/tip-dwfxtra7yg1b5r65m32ywtct@git.kernel.org Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-29sched: Separate the scheduler entry for preemptionThomas Gleixner
Block-IO and workqueues call into notifier functions from the scheduler core code with interrupts and preemption disabled. These calls should be made before entering the scheduler core. To simplify this, separate the scheduler core code into __schedule(). __schedule() is directly called from the places which set PREEMPT_ACTIVE and from schedule(). This allows us to add the work checks into schedule(), so they are only called when a task voluntary goes to sleep. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Tejun Heo <tj@kernel.org> Cc: Jens Axboe <axboe@kernel.dk> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: stable@kernel.org # 2.6.39+ Link: http://lkml.kernel.org/r/20110622174918.813258321@linutronix.de Signed-off-by: Ingo Molnar <mingo@elte.hu>
2011-08-26All Arch: remove linkage for sys_nfsservctl system callNeilBrown
The nfsservctl system call is now gone, so we should remove all linkage for it. Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: J. Bruce Fields <bfields@redhat.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-25kernel/printk: do not turn off bootconsole in printk_late_init() if keep_bootconNishanth Aravamudan
It seems that 7bf693951a8e ("console: allow to retain boot console via boot option keep_bootcon") doesn't always achieve what it aims, as when printk_late_init() runs it unconditionally turns off all boot consoles. With this patch, I am able to see more messages on the boot console in KVM guests than I can without, when keep_bootcon is specified. I think it is appropriate for the relevant -stable trees. However, it's more of an annoyance than a serious bug (ideally you don't need to keep the boot console around as console handover should be working -- I was encountering a situation where the console handover wasn't working and not having the boot console available meant I couldn't see why). Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com> Cc: David S. Miller <davem@davemloft.net> Cc: Alan Cox <alan@lxorguk.ukuu.org.uk> Cc: Greg KH <gregkh@suse.de> Acked-by: Fabio M. Di Nitto <fdinitto@redhat.com> Cc: <stable@kernel.org> [2.6.39.x, 3.0.x] Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-25Add a personality to report 2.6.x version numbersAndi Kleen
I ran into a couple of programs which broke with the new Linux 3.0 version. Some of those were binary only. I tried to use LD_PRELOAD to work around it, but it was quite difficult and in one case impossible because of a mix of 32bit and 64bit executables. For example, all kind of management software from HP doesnt work, unless we pretend to run a 2.6 kernel. $ uname -a Linux svivoipvnx001 3.0.0-08107-g97cd98f #1062 SMP Fri Aug 12 18:11:45 CEST 2011 i686 i686 i386 GNU/Linux $ hpacucli ctrl all show Error: No controllers detected. $ rpm -qf /usr/sbin/hpacucli hpacucli-8.75-12.0 Another notable case is that Python now reports "linux3" from sys.platform(); which in turn can break things that were checking sys.platform() == "linux2": https://bugzilla.mozilla.org/show_bug.cgi?id=664564 It seems pretty clear to me though it's a bug in the apps that are using '==' instead of .startswith(), but this allows us to unbreak broken programs. This patch adds a UNAME26 personality that makes the kernel report a 2.6.40+x version number instead. The x is the x in 3.x. I know this is somewhat ugly, but I didn't find a better workaround, and compatibility to existing programs is important. Some programs also read /proc/sys/kernel/osrelease. This can be worked around in user space with mount --bind (and a mount namespace) To use: wget ftp://ftp.kernel.org/pub/linux/kernel/people/ak/uname26/uname26.c gcc -o uname26 uname26.c ./uname26 program Signed-off-by: Andi Kleen <ak@linux.intel.com> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-23Merge branch 'for-linus' of git://oss.sgi.com/xfs/xfsLinus Torvalds
* 'for-linus' of git://oss.sgi.com/xfs/xfs: xfs: fix tracing builds inside the source tree xfs: remove subdirectories xfs: don't expect xfs headers to be in subdirectories
2011-08-23Revert "irq: Always set IRQF_ONESHOT if no primary handler is specified"Linus Torvalds
This reverts commit f3637a5f2e2eb391ff5757bc83fb5de8f9726464. It turns out that this breaks several drivers, one example being OMAP boards which use the on-board OMAP UARTs and the omap-serial driver that will not boot to userspace after the commit. Paul Walmsley reports that enabling CONFIG_DEBUG_SHIRQ reveals 'IRQ handler type mismatch' errors: IRQ handler type mismatch for IRQ 74 current handler: serial idle ... and the reason is that setting IRQF_ONESHOT will now result in those interrupt handlers having different IRQF flags, and thus being unsharable. So the commit log in the reverted commit: "Since it is required for those users and there is no difference for others it makes sense to add this flag unconditionally." is simply not true: there may not be any difference from a "actions at irq time", but there is a *big* difference wrt this flag testing irq management (see __setup_irq() in kernel/irq/manage.c). One solution may be to stop verifying IRQF_ONESHOT in __setup_irq(), but right now the safe course of action is to revert the change. Let's revisit this in a later merge window. Reported-by: Paul Walmsley <paul@pwsan.com> Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Requested-by: Alan Cox <alan@lxorguk.ukuu.org.uk> Acked-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-19Merge branch 'for-linus' of git://git.kernel.dk/linux-blockLinus Torvalds
* 'for-linus' of git://git.kernel.dk/linux-block: (23 commits) Revert "cfq: Remove special treatment for metadata rqs." block: fix flush machinery for stacking drivers with differring flush flags block: improve rq_affinity placement blktrace: add FLUSH/FUA support Move some REQ flags to the common bio/request area allow blk_flush_policy to return REQ_FSEQ_DATA independent of *FLUSH xen/blkback: Make description more obvious. cfq-iosched: Add documentation about idling block: Make rq_affinity = 1 work as expected block: swim3: fix unterminated of_device_id table block/genhd.c: remove useless cast in diskstats_show() drivers/cdrom/cdrom.c: relax check on dvd manufacturer value drivers/block/drbd/drbd_nl.c: use bitmap_parse instead of __bitmap_parse bsg-lib: add module.h include cfq-iosched: Reduce linked group count upon group destruction blk-throttle: correctly determine sync bio loop: fix deadlock when sysfs and LOOP_CLR_FD race against each other loop: add BLK_DEV_LOOP_MIN_COUNT=%i to allow distros 0 pre-allocated loop devices loop: add management interface for on-demand device allocation loop: replace linked list of allocated devices with an idr index ...
2011-08-18irqdesc: fix new kernel-doc warningRandy Dunlap
Fix kernel-doc warning in irqdesc.c: Warning(kernel/irq/irqdesc.c:353): No description found for parameter 'owner' Signed-off-by: Randy Dunlap <rdunlap@xenotime.net> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2011-08-17Merge branch 'pm-fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm * 'pm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm: PM / Domains: Fix build for CONFIG_PM_RUNTIME unset
2011-08-17Merge branch 'core-fixes-for-linus' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip * 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: lockdep: Fix wrong assumption in match_held_lock