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The current logic which handles clock events programming failures can
increase min_delta_ns unlimited and even can cause overflows.
Sanitize it by:
- prevent zero increase when min_delta_ns == 1
- limiting min_delta_ns to a jiffie
- bail out if the jiffie limit is hit
- add retries stats for /proc/timer_list so we can gather data
Reported-by: Uwe Kleine-Koenig <u.kleine-koenig@pengutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
ring-buffer: Do 8 byte alignment for 64 bit that can not handle 4 byte align
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The ring buffer uses 4 byte alignment while recording events into the
buffer, even on 64bit machines. This saves space when there are lots
of events being recorded at 4 byte boundaries.
The ring buffer has a zero copy method to write into the buffer, with
the reserving of space and then committing it. This may cause problems
when writing an 8 byte word into a 4 byte alignment (not 8). For x86 and
PPC this is not an issue, but on some architectures this would cause an
out-of-alignment exception.
This patch uses CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS to determine
if it is OK to use 4 byte alignments on 64 bit machines. If it is not,
it forces the ring buffer event header to be 8 bytes and not 4,
and will align the length of the data to be 8 byte aligned.
This keeps the data payload at 8 byte alignments and will allow these
machines to run without issue.
The trick to this is that the header can be either 4 bytes or 8 bytes
depending on the length of the data payload. The 4 byte header
has a length field that supports up to 112 bytes. If the length of
the data is more than 112, the length field is set to zero, and the actual
length is stored in the next 4 bytes after the header.
When CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS is not set, the code forces
zero in the 4 byte header forcing the length to be stored in the 4 byte
array, even with a small data load. It also forces the length of the
data load to be 8 byte aligned. The combination of these two guarantee
that the data is always at 8 byte alignment.
Tested-by: Frederic Weisbecker <fweisbec@gmail.com>
(on sparc64)
Reported-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Use proper type in sched_getaffinity()
kernel/sched.c: Suppress unused var warning
sched: sched_getaffinity(): Allow less than NR_CPUS length
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Using the proper type fixes the following compiler warning:
kernel/sched.c:4850: warning: comparison of distinct pointer types lacks a cast
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: torvalds@linux-foundation.org
Cc: travis@sgi.com
Cc: peterz@infradead.org
Cc: drepper@redhat.com
Cc: rja@sgi.com
Cc: sharyath@in.ibm.com
Cc: steiner@sgi.com
LKML-Reference: <20100317090046.4C79.A69D9226@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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On UP:
kernel/sched.c: In function 'wake_up_new_task':
kernel/sched.c:2631: warning: unused variable 'cpu'
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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[ Note, this commit changes the syscall ABI for > 1024 CPUs systems. ]
Recently, some distro decided to use NR_CPUS=4096 for mysterious reasons.
Unfortunately, glibc sched interface has the following definition:
# define __CPU_SETSIZE 1024
# define __NCPUBITS (8 * sizeof (__cpu_mask))
typedef unsigned long int __cpu_mask;
typedef struct
{
__cpu_mask __bits[__CPU_SETSIZE / __NCPUBITS];
} cpu_set_t;
It mean, if NR_CPUS is bigger than 1024, cpu_set_t makes an
ABI issue ...
More recently, Sharyathi Nagesh reported following test program makes
misterious syscall failure:
-----------------------------------------------------------------------
#define _GNU_SOURCE
#include<stdio.h>
#include<errno.h>
#include<sched.h>
int main()
{
cpu_set_t set;
if (sched_getaffinity(0, sizeof(cpu_set_t), &set) < 0)
printf("\n Call is failing with:%d", errno);
}
-----------------------------------------------------------------------
Because the kernel assumes len argument of sched_getaffinity() is bigger
than NR_CPUS. But now it is not correct.
Now we are faced with the following annoying dilemma, due to
the limitations of the glibc interface built in years ago:
(1) if we change glibc's __CPU_SETSIZE definition, we lost
binary compatibility of _all_ application.
(2) if we don't change it, we also lost binary compatibility of
Sharyathi's use case.
Then, I would propse to change the rule of the len argument of
sched_getaffinity().
Old:
len should be bigger than NR_CPUS
New:
len should be bigger than maximum possible cpu id
This creates the following behavior:
(A) In the real 4096 cpus machine, the above test program still
return -EINVAL.
(B) NR_CPUS=4096 but the machine have less than 1024 cpus (almost
all machines in the world), the above can run successfully.
Fortunatelly, BIG SGI machine is mainly used for HPC use case. It means
they can rebuild their programs.
IOW we hope they are not annoyed by this issue ...
Reported-by: Sharyathi Nagesh <sharyath@in.ibm.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Ulrich Drepper <drepper@redhat.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Russ Anderson <rja@sgi.com>
Cc: Mike Travis <travis@sgi.com>
LKML-Reference: <20100312161316.9520.A69D9226@jp.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'irq-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
genirq: Move two IRQ functions from .init.text to .text
genirq: Protect access to irq_desc->action in can_request_irq()
genirq: Prevent oneshot irq thread race
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Both functions should not be marked as __init, since they be called
from modules after the init section is freed.
Signed-off-by: Henrik Kretzschmar <henne@nachtwindheim.de>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Kosina <jkosina@suse.cz>
LKML-Reference: <1269431961-5731-1-git-send-email-henne@nachtwindheim.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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can_request_irq() accesses and dereferences irq_desc->action w/o
holding irq_desc->lock. So action can be freed on another CPU before
it's dereferenced. Unlikely, but ...
Protect it with desc->lock.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Lars-Peter pointed out that the oneshot threaded interrupt handler
code has the following race:
CPU0 CPU1
hande_level_irq(irq X)
mask_ack_irq(irq X)
handle_IRQ_event(irq X)
wake_up(thread_handler)
thread handler(irq X) runs
finalize_oneshot(irq X)
does not unmask due to
!(desc->status & IRQ_MASKED)
return from irq
does not unmask due to
(desc->status & IRQ_ONESHOT)
This leaves the interrupt line masked forever.
The reason for this is the inconsistent handling of the IRQ_MASKED
flag. Instead of setting it in the mask function the oneshot support
sets the flag after waking up the irq thread.
The solution for this is to set/clear the IRQ_MASKED status whenever
we mask/unmask an interrupt line. That's the easy part, but that
cleanup opens another race:
CPU0 CPU1
hande_level_irq(irq)
mask_ack_irq(irq)
handle_IRQ_event(irq)
wake_up(thread_handler)
thread handler(irq) runs
finalize_oneshot_irq(irq)
unmask(irq)
irq triggers again
handle_level_irq(irq)
mask_ack_irq(irq)
return from irq due to IRQ_INPROGRESS
return from irq
does not unmask due to
(desc->status & IRQ_ONESHOT)
This requires that we synchronize finalize_oneshot_irq() with the
primary handler. If IRQ_INPROGESS is set we wait until the primary
handler on the other CPU has returned before unmasking the interrupt
line again.
We probably have never seen that problem because it does not happen on
UP and on SMP the irqbalancer protects us by pinning the primary
handler and the thread to the same CPU.
Reported-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@kernel.org
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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:
x86: Remove excessive early_res debug output
softlockup: Stop spurious softlockup messages due to overflow
rcu: Fix local_irq_disable() CONFIG_PROVE_RCU=y false positives
rcu: Fix tracepoints & lockdep false positive
rcu: Make rcu_read_lock_bh_held() allow for disabled BH
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Ensure additions on touch_ts do not overflow. This can occur
when the top 32 bits of the TSC reach 0xffffffff causing
additions to touch_ts to overflow and this in turn generates
spurious softlockup warnings.
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: <stable@kernel.org>
LKML-Reference: <1268994482.1798.6.camel@lenovo>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Disabling BH can stand in for rcu_read_lock_bh(), and this patch
updates rcu_read_lock_bh_held() to allow for this. In order to
avoid include-file hell, this function is moved out of line to
kernel/rcupdate.c.
This fixes a false positive RCU warning.
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <20100316000343.GA25857@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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cpuset_mem_spread_node() returns an offline node, and causes an oops.
This patch fixes it by initializing task->mems_allowed to
node_states[N_HIGH_MEMORY], and updating task->mems_allowed when doing
memory hotplug.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Reported-by: Nick Piggin <npiggin@suse.de>
Tested-by: Nick Piggin <npiggin@suse.de>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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commit e6a1105b ("cgroups: subsystem module loading interface") and commit
c50cc752 ("sched, cgroups: Fix module export") result in duplicate
including of module.h
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* '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
...
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perf_arch_fetch_caller_regs() is exported for the overriden x86
version, but not for the generic weak version.
As a general rule, weak functions should not have their symbol
exported in the same file they are defined.
So let's export it on trace_event_perf.c as it is used by trace
events only.
This fixes:
ERROR: ".perf_arch_fetch_caller_regs" [fs/xfs/xfs.ko] undefined!
ERROR: ".perf_arch_fetch_caller_regs" [arch/powerpc/platforms/cell/spufs/spufs.ko] undefined!
-v2: And also only build it if trace events are enabled.
-v3: Fix changelog mistake
Reported-by: Stephen Rothwell <sfr@canb.auug.org.au>
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
Cc: Paul Mackerras <paulus@samba.org>
LKML-Reference: <1268697902-9518-1-git-send-regression-fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Export perf_trace_regs and perf_arch_fetch_caller_regs since module will
use these.
Signed-off-by: Xiao Guangrong <xiaoguangrong@cn.fujitsu.com>
[ use EXPORT_PER_CPU_SYMBOL_GPL() ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <4B989C1B.2090407@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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execution slot
From : Ananth N Mavinakayanahalli <ananth@in.ibm.com>
When freeing the instruction slot, the arithmetic to calculate
the index of the slot in the page needs to account for the total
size of the instruction on the various architectures.
Calculate the index correctly when freeing the out-of-line
execution slot.
Reported-by: Sachin Sant <sachinp@in.ibm.com>
Reported-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Ananth N Mavinakayanahalli <ananth@in.ibm.com>
Signed-off-by: Masami Hiramatsu <mhiramat@redhat.com>
LKML-Reference: <4B9667AB.9050507@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Anton Blanchard found that he could reliably make the kernel hit a
BUG_ON in the slab allocator by taking a cpu offline and then online
while a system-wide perf record session was running.
The reason is that when the cpu comes up, we completely reinitialize
the ctx field of the struct perf_cpu_context for the cpu. If there is
a system-wide perf record session running, then there will be a struct
perf_event that has a reference to the context, so its refcount will
be 2. (The perf_event has been removed from the context's group_entry
and event_entry lists by perf_event_exit_cpu(), but that doesn't
remove the perf_event's reference to the context and doesn't decrement
the context's refcount.)
When the cpu comes up, perf_event_init_cpu() gets called, and it calls
__perf_event_init_context() on the cpu's context. That resets the
refcount to 1. Then when the perf record session finishes and the
perf_event is closed, the refcount gets decremented to 0 and the
context gets kfreed after an RCU grace period. Since the context
wasn't kmalloced -- it's part of a per-cpu variable -- bad things
happen.
In fact we don't need to completely reinitialize the context when the
cpu comes up. It's sufficient to initialize the context once at boot,
but we need to do it for all possible cpus.
This moves the context initialization to happen at boot time. With
this, we don't trash the refcount and the context never gets kfreed,
and we don't hit the BUG_ON.
Reported-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
Tested-by: Anton Blanchard <anton@samba.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Drop the obsolete "profile" naming used by perf for trace events.
Perf can now do more than simple events counting, so generalize
the API naming.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
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We are taking a wrong regs snapshot when a trace event triggers.
Either we use get_irq_regs(), which gives us the interrupted
registers if we are in an interrupt, or we use task_pt_regs()
which gives us the state before we entered the kernel, assuming
we are lucky enough to be no kernel thread, in which case
task_pt_regs() returns the initial set of regs when the kernel
thread was started.
What we want is different. We need a hot snapshot of the regs,
so that we can get the instruction pointer to record in the
sample, the frame pointer for the callchain, and some other
things.
Let's use the new perf_fetch_caller_regs() for that.
Comparison with perf record -e lock: -R -a -f -g
Before:
perf [kernel] [k] __do_softirq
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--- __do_softirq
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|--55.16%-- __open
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--44.84%-- __write_nocancel
After:
perf [kernel] [k] perf_tp_event
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--- perf_tp_event
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|--41.07%-- lock_acquire
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| |--39.36%-- _raw_spin_lock
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| | |--7.81%-- hrtimer_interrupt
| | | smp_apic_timer_interrupt
| | | apic_timer_interrupt
The old case was producing unreliable callchains. Now having
right frame and instruction pointers, we have the trace we
want.
Also syscalls and kprobe events already have the right regs,
let's use them instead of wasting a retrieval.
v2: Follow the rename perf_save_regs() -> perf_fetch_caller_regs()
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Archs <linux-arch@vger.kernel.org>
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Events that trigger overflows by interrupting a context can
use get_irq_regs() or task_pt_regs() to retrieve the state
when the event triggered. But this is not the case for some
other class of events like trace events as tracepoints are
executed in the same context than the code that triggered
the event.
It means we need a different api to capture the regs there,
namely we need a hot snapshot to get the most important
informations for perf: the instruction pointer to get the
event origin, the frame pointer for the callchain, the code
segment for user_mode() tests (we always use __KERNEL_CS as
trace events always occur from the kernel) and the eflags
for further purposes.
v2: rename perf_save_regs to perf_fetch_caller_regs as per
Masami's suggestion.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Masami Hiramatsu <mhiramat@redhat.com>
Cc: Jason Baron <jbaron@redhat.com>
Cc: Archs <linux-arch@vger.kernel.org>
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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
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|--96.11%-- lock_acquire
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| |--27.21%-- do_perf_sw_event
| | perf_tp_event
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| | |--49.62%-- ftrace_profile_lock_release
| | | lock_release
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| | | |--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
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| | |--55.37%-- ftrace_profile_lock_acquire
| | | lock_acquire
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| | | |--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_*()
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trace lock_acquire
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----- rcu_read_lock()
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| lock_acquire()
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| trace_lock_acquire() (stopped)
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| lockdep analyze
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----- rcu_read_unlock()
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lock_release
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trace_lock_release() (stopped)
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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>
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Try to avoid useless rotation and PMU disables.
[ Could be improved by keeping a nr_runnable count to better account
for the < PERF_STAT_INACTIVE counters ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
Cc: paulus@samba.org
Cc: eranian@google.com
Cc: robert.richter@amd.com
Cc: fweisbec@gmail.com
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Currently we always call hw_perf_disable(), even if its already disabled,
this seems superflous, esp. since it cannot be made NMI safe (see further
patches).
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: paulus@samba.org
Cc: eranian@google.com
Cc: robert.richter@amd.com
Cc: fweisbec@gmail.com
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Remove the hw_perf_event_*() hotplug hooks in favour of per PMU hotplug
notifiers. This has the advantage of reducing the static weak interface
as well as exposing all hotplug actions to the PMU.
Use this to fix x86 hotplug usage where we did things in ONLINE which
should have been done in UP_PREPARE or STARTING.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: paulus@samba.org
Cc: eranian@google.com
Cc: robert.richter@amd.com
Cc: fweisbec@gmail.com
Cc: Arnaldo Carvalho de Melo <acme@infradead.org>
LKML-Reference: <20100305154128.736225361@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Fix pick_next_highest_task_rt() for cgroups
sched: Cleanup: remove unused variable in try_to_wake_up()
x86: Fix sched_clock_cpu for systems with unsynchronized TSC
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Since pick_next_highest_task_rt() already iterates all the cgroups and
is really only interested in tasks, skip over the !task entries.
Reported-by: Dhaval Giani <dhaval.giani@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Dhaval Giani <dhaval.giani@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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We haven't used the "orig_rq" variable since
055a00865d "Fix/add missing update_rq_clock() calls"
Signed-off-by: Dan Carpenter <error27@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andreas Herrmann <andreas.herrmann3@amd.com>
Cc: Gautham R Shenoy <ego@in.ibm.com>
Cc: efault@gmx.de
LKML-Reference: <20100306111752.GL4958@bicker>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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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:
locking: Make sparse work with inline spinlocks and rwlocks
x86/mce: Fix RCU lockdep splats
rcu: Increase RCU CPU stall timeouts if PROVE_RCU
ftrace: Replace read_barrier_depends() with rcu_dereference_raw()
rcu: Suppress RCU lockdep warnings during early boot
rcu, ftrace: Fix RCU lockdep splat in ftrace_perf_buf_prepare()
rcu: Suppress __mpol_dup() false positive from RCU lockdep
rcu: Make rcu_read_lock_sched_held() handle !PREEMPT
rcu: Add control variables to lockdep_rcu_dereference() diagnostics
rcu, cgroup: Relax the check in task_subsys_state() as early boot is now handled by lockdep-RCU
rcu: Use wrapper function instead of exporting tasklist_lock
sched, rcu: Fix rcu_dereference() for RCU-lockdep
rcu: Make task_subsys_state() RCU-lockdep checks handle boot-time use
rcu: Fix holdoff for accelerated GPs for last non-dynticked CPU
x86/gart: Unexport gart_iommu_aperture
Fix trivial conflicts in kernel/trace/ftrace.c
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CONFIG_PROVE_RCU imposes additional overhead on the kernel, so
increase the RCU CPU stall timeouts in an attempt to allow for
this effect.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1267830207-9474-2-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Replace the calls to read_barrier_depends() in
ftrace_list_func() with rcu_dereference_raw() to improve
readability. The reason that we use rcu_dereference_raw() here
is that removed entries are never freed, instead they are simply
leaked. This is one of a very few cases where use of
rcu_dereference_raw() is the long-term right answer. And I
don't yet know of any others. ;-)
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1267830207-9474-1-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Change the pair of rcu_dereference() calls in
ftrace_perf_buf_prepare() to rcu_dereference_sched().
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1267667418-32233-3-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Add the values of rcu_scheduler_active() and debug_locks() to
the lockdep_rcu_dereference() output to help diagnose RCU
lockdep splats that occur shortly after the scheduler starts.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1267631219-8713-4-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Lockdep-RCU commit d11c563d exported tasklist_lock, which is not
a good thing. This patch instead exports a function that uses
lockdep to check whether tasklist_lock is held.
Suggested-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: Christoph Hellwig <hch@lst.de>
LKML-Reference: <1267631219-8713-1-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Merge reason: Switch from topical split to the stabilization track
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Make rcu_dereference() of runqueue data structures be
rcu_dereference_sched().
Located-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <20100228163218.GD6846@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Merge reason: Backmerge latest upstream to queue up dependent fix in the
scheduler.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Make the holdoff only happen when the full number of attempts
have been made.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1267311188-16603-1-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
tracing: Do not record user stack trace from NMI context
tracing: Disable buffer switching when starting or stopping trace
tracing: Use same local variable when resetting the ring buffer
function-graph: Init curr_ret_stack with ret_stack
ring-buffer: Move disabled check into preempt disable section
function-graph: Add tracing_thresh support to function_graph tracer
tracing: Update the comm field in the right variable in update_max_tr
function-graph: Use comment notation for func names of dangling '}'
function-graph: Fix unused reference to ftrace_set_func()
tracing: Fix warning in s_next of trace file ops
tracing: Include irqflags headers from trace clock
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A bug was found with Li Zefan's ftrace_stress_test that caused applications
to segfault during the test.
Placing a tracing_off() in the segfault code, and examining several
traces, I found that the following was always the case. The lock tracer
was enabled (lockdep being required) and userstack was enabled. Testing
this out, I just enabled the two, but that was not good enough. I needed
to run something else that could trigger it. Running a load like hackbench
did not work, but executing a new program would. The following would
trigger the segfault within seconds:
# echo 1 > /debug/tracing/options/userstacktrace
# echo 1 > /debug/tracing/events/lock/enable
# while :; do ls > /dev/null ; done
Enabling the function graph tracer and looking at what was happening
I finally noticed that all cashes happened just after an NMI.
1) | copy_user_handle_tail() {
1) | bad_area_nosemaphore() {
1) | __bad_area_nosemaphore() {
1) | no_context() {
1) | fixup_exception() {
1) 0.319 us | search_exception_tables();
1) 0.873 us | }
[...]
1) 0.314 us | __rcu_read_unlock();
1) 0.325 us | native_apic_mem_write();
1) 0.943 us | }
1) 0.304 us | rcu_nmi_exit();
[...]
1) 0.479 us | find_vma();
1) | bad_area() {
1) | __bad_area() {
After capturing several traces of failures, all of them happened
after an NMI. Curious about this, I added a trace_printk() to the NMI
handler to read the regs->ip to see where the NMI happened. In which I
found out it was here:
ffffffff8135b660 <page_fault>:
ffffffff8135b660: 48 83 ec 78 sub $0x78,%rsp
ffffffff8135b664: e8 97 01 00 00 callq ffffffff8135b800 <error_entry>
What was happening is that the NMI would happen at the place that a page
fault occurred. It would call rcu_read_lock() which was traced by
the lock events, and the user_stack_trace would run. This would trigger
a page fault inside the NMI. I do not see where the CR2 register is
saved or restored in NMI handling. This means that it would corrupt
the page fault handling that the NMI interrupted.
The reason the while loop of ls helped trigger the bug, was that
each execution of ls would cause lots of pages to be faulted in, and
increase the chances of the race happening.
The simple solution is to not allow user stack traces in NMI context.
After this patch, I ran the above "ls" test for a couple of hours
without any issues. Without this patch, the bug would trigger in less
than a minute.
Cc: stable@kernel.org
Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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When the trace iterator is read, tracing_start() and tracing_stop()
is called to stop tracing while the iterator is processing the trace
output.
These functions disable both the standard buffer and the max latency
buffer. But if the wakeup tracer is running, it can switch these
buffers between the two disables:
buffer = global_trace.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
<<<--------- swap happens here
buffer = max_tr.buffer;
if (buffer)
ring_buffer_record_disable(buffer);
What happens is that we disabled the same buffer twice. On tracing_start()
we can enable the same buffer twice. All ring_buffer_record_disable()
must be matched with a ring_buffer_record_enable() or the buffer
can be disable permanently, or enable prematurely, and cause a bug
where a reset happens while a trace is commiting.
This patch protects these two by taking the ftrace_max_lock to prevent
a switch from occurring.
Found with Li Zefan's ftrace_stress_test.
Cc: stable@kernel.org
Reported-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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In the ftrace code that resets the ring buffer it references the
buffer with a local variable, but then uses the tr->buffer as the
parameter to reset. If the wakeup tracer is running, which can
switch the tr->buffer with the max saved buffer, this can break
the requirement of disabling the buffer before the reset.
buffer = tr->buffer;
ring_buffer_record_disable(buffer);
synchronize_sched();
__tracing_reset(tr->buffer, cpu);
If the tr->buffer is swapped, then the reset is not happening to the
buffer that was disabled. This will cause the ring buffer to fail.
Found with Li Zefan's ftrace_stress_test.
Cc: stable@kernel.org
Reported-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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If the graph tracer is active, and a task is forked but the allocating of
the processes graph stack fails, it can cause crash later on.
This is due to the temporary stack being NULL, but the curr_ret_stack
variable is copied from the parent. If it is not -1, then in
ftrace_graph_probe_sched_switch() the following:
for (index = next->curr_ret_stack; index >= 0; index--)
next->ret_stack[index].calltime += timestamp;
Will cause a kernel OOPS.
Found with Li Zefan's ftrace_stress_test.
Cc: stable@kernel.org
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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The ring buffer resizing and resetting relies on a schedule RCU
action. The buffers are disabled, a synchronize_sched() is called
and then the resize or reset takes place.
But this only works if the disabling of the buffers are within the
preempt disabled section, otherwise a window exists that the buffers
can be written to while a reset or resize takes place.
Cc: stable@kernel.org
Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4B949E43.2010906@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/linux-2.6-trace into tracing/urgent
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Add support for tracing_thresh to the function_graph tracer. This
version of this feature isolates the checks into new entry and
return functions, to avoid adding more conditional code into the
main function_graph paths.
When the tracing_thresh is set and the function graph tracer is
enabled, only the functions that took longer than the time in
microseconds that was set in tracing_thresh are recorded. To do this
efficiently, only the function exits are recorded:
[tracing]# echo 100 > tracing_thresh
[tracing]# echo function_graph > current_tracer
[tracing]# cat trace
# tracer: function_graph
#
# CPU DURATION FUNCTION CALLS
# | | | | | | |
1) ! 119.214 us | } /* smp_apic_timer_interrupt */
1) <========== |
0) ! 101.527 us | } /* __rcu_process_callbacks */
0) ! 126.461 us | } /* rcu_process_callbacks */
0) ! 145.111 us | } /* __do_softirq */
0) ! 149.667 us | } /* do_softirq */
0) ! 168.817 us | } /* irq_exit */
0) ! 248.254 us | } /* smp_apic_timer_interrupt */
Also, add support for specifying tracing_thresh on the kernel
command line. When used like so: "tracing_thresh=200 ftrace=function_graph"
this can be used to analyse system startup. It is important to disable
tracing soon after boot, in order to avoid losing the trace data.
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Tim Bird <tim.bird@am.sony.com>
LKML-Reference: <4B87098B.4040308@am.sony.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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