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git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
* 'fixes-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq:
workqueue: note the nested NOT_RUNNING test in worker_clr_flags() isn't a noop
workqueue: relax lockdep annotation on flush_work()
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The nested NOT_RUNNING test in worker_clr_flags() is slightly
misleading in that if NOT_RUNNING were a single flag the nested test
would be always %true and thus noop. Add a comment noting that the
test isn't a noop.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Hillf Danton <dhillf@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
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Currently, the lockdep annotation in flush_work() requires exclusive
access on the workqueue the target work is queued on and triggers
warning if a work is trying to flush another work on the same
workqueue; however, this is no longer true as workqueues can now
execute multiple works concurrently.
This patch adds lock_map_acquire_read() and make process_one_work()
hold read access to the workqueue while executing a work and
start_flush_work() check for write access if concurrnecy level is one
or the workqueue has a rescuer (as only one execution resource - the
rescuer - is guaranteed to be available under memory pressure), and
read access if higher.
This better represents what's going on and removes spurious lockdep
warnings which are triggered by fake dependency chain created through
flush_work().
* Peter pointed out that flushing another work from a WQ_MEM_RECLAIM
wq breaks forward progress guarantee under memory pressure.
Condition check accordingly updated.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Tested-by: "Rafael J. Wysocki" <rjw@sisk.pl>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@kernel.org
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All architectures are finally converted. Remove the cruft.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Greg Ungerer <gerg@uclinux.org>
Cc: Michal Simek <monstr@monstr.eu>
Acked-by: David Howells <dhowells@redhat.com>
Cc: Kyle McMartin <kyle@mcmartin.ca>
Acked-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Jeff Dike <jdike@addtoit.com>
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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:
smp: Allow on_each_cpu() to be called while early_boot_irqs_disabled status to init/main.c
lockdep: Move early boot local IRQ enable/disable status to init/main.c
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to init/main.c
percpu may end up calling vfree() during early boot which in
turn may call on_each_cpu() for TLB flushes. The function of
on_each_cpu() can be done safely while IRQ is disabled during
early boot but it assumed that the function is always called
with local IRQ enabled which ended up enabling local IRQ
prematurely during boot and triggering a couple of warnings.
This patch updates on_each_cpu() and smp_call_function_many()
such on_each_cpu() can be used safely while
early_boot_irqs_disabled is set.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Pekka Enberg <penberg@kernel.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <20110120110713.GC6036@htj.dyndns.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Reported-by: Ingo Molnar <mingo@elte.hu>
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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>
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* akpm:
kernel/smp.c: consolidate writes in smp_call_function_interrupt()
kernel/smp.c: fix smp_call_function_many() SMP race
memcg: correctly order reading PCG_USED and pc->mem_cgroup
backlight: fix 88pm860x_bl macro collision
drivers/leds/ledtrig-gpio.c: make output match input, tighten input checking
MAINTAINERS: update Atmel AT91 entry
mm: fix truncate_setsize() comment
memcg: fix rmdir, force_empty with THP
memcg: fix LRU accounting with THP
memcg: fix USED bit handling at uncharge in THP
memcg: modify accounting function for supporting THP better
fs/direct-io.c: don't try to allocate more than BIO_MAX_PAGES in a bio
mm: compaction: prevent division-by-zero during user-requested compaction
mm/vmscan.c: remove duplicate include of compaction.h
memblock: fix memblock_is_region_memory()
thp: keep highpte mapped until it is no longer needed
kconfig: rename CONFIG_EMBEDDED to CONFIG_EXPERT
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We have to test the cpu mask in the interrupt handler before checking the
refs, otherwise we can start to follow an entry before its deleted and
find it partially initailzed for the next trip. Presently we also clear
the cpumask bit before executing the called function, which implies
getting write access to the line. After the function is called we then
decrement refs, and if they go to zero we then unlock the structure.
However, this implies getting write access to the call function data
before and after another the function is called. If we can assert that no
smp_call_function execution function is allowed to enable interrupts, then
we can move both writes to after the function is called, hopfully allowing
both writes with one cache line bounce.
On a 256 thread system with a kernel compiled for 1024 threads, the time
to execute testcase in the "smp_call_function_many race" changelog was
reduced by about 30-40ms out of about 545 ms.
I decided to keep this as WARN because its now a buggy function, even
though the stack trace is of no value -- a simple printk would give us the
information needed.
Raw data:
Without patch:
ipi_test startup took 1219366ns complete 539819014ns total 541038380ns
ipi_test startup took 1695754ns complete 543439872ns total 545135626ns
ipi_test startup took 7513568ns complete 539606362ns total 547119930ns
ipi_test startup took 13304064ns complete 533898562ns total 547202626ns
ipi_test startup took 8668192ns complete 544264074ns total 552932266ns
ipi_test startup took 4977626ns complete 548862684ns total 553840310ns
ipi_test startup took 2144486ns complete 541292318ns total 543436804ns
ipi_test startup took 21245824ns complete 530280180ns total 551526004ns
With patch:
ipi_test startup took 5961748ns complete 500859628ns total 506821376ns
ipi_test startup took 8975996ns complete 495098924ns total 504074920ns
ipi_test startup took 19797750ns complete 492204740ns total 512002490ns
ipi_test startup took 14824796ns complete 487495878ns total 502320674ns
ipi_test startup took 11514882ns complete 494439372ns total 505954254ns
ipi_test startup took 8288084ns complete 502570774ns total 510858858ns
ipi_test startup took 6789954ns complete 493388112ns total 500178066ns
#include <linux/module.h>
#include <linux/init.h>
#include <linux/sched.h> /* sched clock */
#define ITERATIONS 100
static void do_nothing_ipi(void *dummy)
{
}
static void do_ipis(struct work_struct *dummy)
{
int i;
for (i = 0; i < ITERATIONS; i++)
smp_call_function(do_nothing_ipi, NULL, 1);
printk(KERN_DEBUG "cpu %d finished\n", smp_processor_id());
}
static struct work_struct work[NR_CPUS];
static int __init testcase_init(void)
{
int cpu;
u64 start, started, done;
start = local_clock();
for_each_online_cpu(cpu) {
INIT_WORK(&work[cpu], do_ipis);
schedule_work_on(cpu, &work[cpu]);
}
started = local_clock();
for_each_online_cpu(cpu)
flush_work(&work[cpu]);
done = local_clock();
pr_info("ipi_test startup took %lldns complete %lldns total %lldns\n",
started-start, done-started, done-start);
return 0;
}
static void __exit testcase_exit(void)
{
}
module_init(testcase_init)
module_exit(testcase_exit)
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Anton Blanchard");
Signed-off-by: Milton Miller <miltonm@bga.com>
Cc: Anton Blanchard <anton@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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I noticed a failure where we hit the following WARN_ON in
generic_smp_call_function_interrupt:
if (!cpumask_test_and_clear_cpu(cpu, data->cpumask))
continue;
data->csd.func(data->csd.info);
refs = atomic_dec_return(&data->refs);
WARN_ON(refs < 0); <-------------------------
We atomically tested and cleared our bit in the cpumask, and yet the
number of cpus left (ie refs) was 0. How can this be?
It turns out commit 54fdade1c3332391948ec43530c02c4794a38172
("generic-ipi: make struct call_function_data lockless") is at fault. It
removes locking from smp_call_function_many and in doing so creates a
rather complicated race.
The problem comes about because:
- The smp_call_function_many interrupt handler walks call_function.queue
without any locking.
- We reuse a percpu data structure in smp_call_function_many.
- We do not wait for any RCU grace period before starting the next
smp_call_function_many.
Imagine a scenario where CPU A does two smp_call_functions back to back,
and CPU B does an smp_call_function in between. We concentrate on how CPU
C handles the calls:
CPU A CPU B CPU C CPU D
smp_call_function
smp_call_function_interrupt
walks
call_function.queue sees
data from CPU A on list
smp_call_function
smp_call_function_interrupt
walks
call_function.queue sees
(stale) CPU A on list
smp_call_function int
clears last ref on A
list_del_rcu, unlock
smp_call_function reuses
percpu *data A
data->cpumask sees and
clears bit in cpumask
might be using old or new fn!
decrements refs below 0
set data->refs (too late!)
The important thing to note is since the interrupt handler walks a
potentially stale call_function.queue without any locking, then another
cpu can view the percpu *data structure at any time, even when the owner
is in the process of initialising it.
The following test case hits the WARN_ON 100% of the time on my PowerPC
box (having 128 threads does help :)
#include <linux/module.h>
#include <linux/init.h>
#define ITERATIONS 100
static void do_nothing_ipi(void *dummy)
{
}
static void do_ipis(struct work_struct *dummy)
{
int i;
for (i = 0; i < ITERATIONS; i++)
smp_call_function(do_nothing_ipi, NULL, 1);
printk(KERN_DEBUG "cpu %d finished\n", smp_processor_id());
}
static struct work_struct work[NR_CPUS];
static int __init testcase_init(void)
{
int cpu;
for_each_online_cpu(cpu) {
INIT_WORK(&work[cpu], do_ipis);
schedule_work_on(cpu, &work[cpu]);
}
return 0;
}
static void __exit testcase_exit(void)
{
}
module_init(testcase_init)
module_exit(testcase_exit)
MODULE_LICENSE("GPL");
MODULE_AUTHOR("Anton Blanchard");
I tried to fix it by ordering the read and the write of ->cpumask and
->refs. In doing so I missed a critical case but Paul McKenney was able
to spot my bug thankfully :) To ensure we arent viewing previous
iterations the interrupt handler needs to read ->refs then ->cpumask then
->refs _again_.
Thanks to Milton Miller and Paul McKenney for helping to debug this issue.
[miltonm@bga.com: add WARN_ON and BUG_ON, remove extra read of refs before initial read of mask that doesn't help (also noted by Peter Zijlstra), adjust comments, hopefully clarify scenario ]
[miltonm@bga.com: remove excess tests]
Signed-off-by: Anton Blanchard <anton@samba.org>
Signed-off-by: Milton Miller <miltonm@bga.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: <stable@kernel.org> [2.6.32+]
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
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched, cgroup: Use exit hook to avoid use-after-free crash
sched: Fix signed unsigned comparison in check_preempt_tick()
sched: Replace rq->bkl_count with rq->rq_sched_info.bkl_count
sched, autogroup: Fix CONFIG_RT_GROUP_SCHED sched_setscheduler() failure
sched: Display autogroup names in /proc/sched_debug
sched: Reinstate group names in /proc/sched_debug
sched: Update effective_load() to use global share weights
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By not notifying the controller of the on-exit move back to
init_css_set, we fail to move the task out of the previous
cgroup's cfs_rq. This leads to an opportunity for a
cgroup-destroy to come in and free the cgroup (there are no
active tasks left in it after all) to which the not-quite dead
task is still enqueued.
Reported-by: Miklos Vajna <vmiklos@frugalware.org>
Fixed-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: <stable@kernel.org>
Cc: Mike Galbraith <efault@gmx.de>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
LKML-Reference: <1293206353.29444.205.camel@laptop>
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Signed unsigned comparison may lead to superfluous resched if leftmost
is right of the current task, wasting a few cycles, and inadvertently
_lengthening_ the current task's slice.
Reported-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1294202477.9384.5.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Now rq->rq_sched_info.bkl_count is not used for rq, scroll
rq->bkl_count into it. Thus we can save some space for rq.
Signed-off-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1294991859-13246-1-git-send-email-yong.zhang0@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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If CONFIG_RT_GROUP_SCHED is set, __sched_setscheduler() fails due to autogroup
not allocating rt_runtime. Free unused/unusable rt_se and rt_rq, redirect RT
tasks to the root task group, and tell __sched_setscheduler() that it's ok.
Reported-and-tested-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Mike Galbraith <efault@gmx.de>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <1294890890.8089.39.camel@marge.simson.net>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Add autogroup name to cfs_rq and tasks information to /proc/sched_debug.
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20110111101257.GF4772@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Displaying of group names in /proc/sched_debug was dropped in autogroup
patches. Add group names while displaying cfs_rq and tasks information.
Signed-off-by: Bharata B Rao <bharata@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20110111101153.GE4772@in.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Previously effective_load would approximate the global load weight present on
a group taking advantage of:
entity_weight = tg->shares ( lw / global_lw ), where entity_weight was provided
by tg_shares_up.
This worked (approximately) for an 'empty' (at tg level) cpu since we would
place boost load representative of what a newly woken task would receive.
However, now that load is instantaneously updated this assumption is no longer
true and the load calculation is rather incorrect in this case.
Fix this (and improve the general case) by re-writing effective_load to take
advantage of the new shares distribution code.
Signed-off-by: Paul Turner <pjt@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20110115015817.069769529@google.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
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
perf: Validate cpu early in perf_event_alloc()
perf: Find_get_context: fix the per-cpu-counter check
perf: Fix contexted inheritance
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Starting from perf_event_alloc()->perf_init_event(), the kernel
assumes that event->cpu is either -1 or the valid CPU number.
Change perf_event_alloc() to validate this argument early. This
also means we can remove the similar check in
find_get_context().
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: gregkh@suse.de
Cc: stable@kernel.org
LKML-Reference: <20110118161032.GC693@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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If task == NULL, find_get_context() should always check that cpu
is correct.
Afaics, the bug was introduced by 38a81da2 "perf events: Clean
up pid passing", but even before that commit "&& cpu != -1" was
not exactly right, -ESRCH from find_task_by_vpid() is not
accurate.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Alan Stern <stern@rowland.harvard.edu>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Prasad <prasad@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: gregkh@suse.de
Cc: stable@kernel.org
LKML-Reference: <20110118161008.GB693@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Linus reported that the RCU lockdep annotation bits triggered for this
rcu_dereference() because we're not holding rcu_read_lock().
Going over the code I cannot convince myself its correct:
- holding a ref on the parent_ctx, doesn't avoid it being uncloned
concurrently (as the comment says), so we can race with a free.
- holding parent_ctx->mutex doesn't avoid the above free from taking
place either, it would at best avoid parent_ctx from being freed.
I.e. the warning is correct. To fix the bug, serialize against the
unclone_ctx() call by extending the reach of the parent_ctx->lock.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
LKML-Reference: <new-submission>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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'timers-fixes-for-linus' and 'perf-fixes-for-linus' of 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:
rcu: avoid pointless blocked-task warnings
rcu: demote SRCU_SYNCHRONIZE_DELAY from kernel-parameter status
rtmutex: Fix comment about why new_owner can be NULL in wake_futex_pi()
* 'x86-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
x86, olpc: Add missing Kconfig dependencies
x86, mrst: Set correct APB timer IRQ affinity for secondary cpu
x86: tsc: Fix calibration refinement conditionals to avoid divide by zero
x86, ia64, acpi: Clean up x86-ism in drivers/acpi/numa.c
* 'timers-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
timekeeping: Make local variables static
time: Rename misnamed minsec argument of clocks_calc_mult_shift()
* 'perf-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
tracing: Remove syscall_exit_fields
tracing: Only process module tracepoints once
perf record: Add "nodelay" mode, disabled by default
perf sched: Fix list of events, dropping unsupported ':r' modifier
Revert "perf tools: Emit clearer message for sys_perf_event_open ENOENT return"
perf top: Fix annotate segv
perf evsel: Fix order of event list deletion
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There is no need for syscall_exit_fields as the syscall
exit event class can already host the fields in its structure,
like most other trace events do by default. Use that
default behavior instead.
Following this scheme, we don't need anymore to override the
get_fields() callback of the syscall exit event class either.
Hence both syscall_exit_fields and syscall_get_exit_fields() can
be removed.
Also changed some indentation to keep the following under 80
characters:
".fields = LIST_HEAD_INIT(event_class_syscall_exit.fields),"
Acked-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
LKML-Reference: <4D301C0E.8090408@cn.fujitsu.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
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Signed-off-by: H Hartley Sweeten <hsweeten@visionengravers.com>
Cc: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <0D753D10438DA54287A00B027084269764CE0E54B7@AUSP01VMBX24.collaborationhost.net>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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The minsec argument to clocks_calc_mult_shift() is misnamed. It is used
to clamp the magnitude of the mult factor so that a multiplication with
any value in the given range won't overflow a 64 bit result. Let's
rename it to match the actual usage.
Signed-off-by: Nicolas Pitre <nicolas.pitre@linaro.org>
Acked-by: John Stultz <johnstul@us.ibm.com>
LKML-Reference: <alpine.LFD.2.00.1101111207140.17086@xanadu.home>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/urgent
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If the RCU callback-processing kthread has nothing to do, it parks in
a wait_event(). If RCU remains idle for more than two minutes, the
kernel complains about this. This commit changes from wait_event()
to wait_event_interruptible() to prevent the kernel from complaining
just because RCU is idle.
Reported-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Thomas Weber <weber@corscience.de>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
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Because the adaptive synchronize_srcu_expedited() approach has
worked very well in testing, remove the kernel parameter and
replace it by a C-preprocessor macro. If someone finds problems
with this approach, a more complex and aggressively adaptive
approach might be required.
Longer term, SRCU will be merged with the other RCU implementations,
at which point synchronize_srcu_expedited() will be event driven,
just as synchronize_sched_expedited() currently is. At that point,
there will be no need for this adaptive approach.
Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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The comment about why rt_mutex_next_owner() can return NULL in
wake_futex_pi() is not the normal case.
Tracing the cause of why this occurs is more likely that waiter
simply timedout. But because it originally caused contention with
the futex, the owner will go into the kernel when it unlocks
the lock. Then it will hit this code path and
rt_mutex_next_owner() will return NULL.
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin
* 'vfs-scale-working' of git://git.kernel.org/pub/scm/linux/kernel/git/npiggin/linux-npiggin:
kernel: fix hlist_bl again
cgroups: Fix a lockdep warning at cgroup removal
fs: namei fix ->put_link on wrong inode in do_filp_open
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Commit 2fd6b7f5 ("fs: dcache scale subdirs") forgot to annotate a dentry
lock, which caused a lockdep warning.
Reported-by: Valdis Kletnieks <Valdis.Kletnieks@vt.edu>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
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cgroup can't use simple_lookup(), since that'd override its desired ->d_op.
Tested-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6
* 'release' of git://git.kernel.org/pub/scm/linux/kernel/git/lenb/linux-acpi-2.6: (59 commits)
ACPI / PM: Fix build problems for !CONFIG_ACPI related to NVS rework
ACPI: fix resource check message
ACPI / Battery: Update information on info notification and resume
ACPI: Drop device flag wake_capable
ACPI: Always check if _PRW is present before trying to evaluate it
ACPI / PM: Check status of power resources under mutexes
ACPI / PM: Rename acpi_power_off_device()
ACPI / PM: Drop acpi_power_nocheck
ACPI / PM: Drop acpi_bus_get_power()
Platform / x86: Make fujitsu_laptop use acpi_bus_update_power()
ACPI / Fan: Rework the handling of power resources
ACPI / PM: Register power resource devices as soon as they are needed
ACPI / PM: Register acpi_power_driver early
ACPI / PM: Add function for updating device power state consistently
ACPI / PM: Add function for device power state initialization
ACPI / PM: Introduce __acpi_bus_get_power()
ACPI / PM: Introduce function for refcounting device power resources
ACPI / PM: Add functions for manipulating lists of power resources
ACPI / PM: Prevent acpi_power_get_inferred_state() from making changes
ACPICA: Update version to 20101209
...
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Generic Hardware Error Source provides a way to report platform
hardware errors (such as that from chipset). It works in so called
"Firmware First" mode, that is, hardware errors are reported to
firmware firstly, then reported to Linux by firmware. This way, some
non-standard hardware error registers or non-standard hardware link
can be checked by firmware to produce more valuable hardware error
information for Linux.
This patch adds POLL/IRQ/NMI notification types support.
Because the memory area used to transfer hardware error information
from BIOS to Linux can be determined only in NMI, IRQ or timer
handler, but general ioremap can not be used in atomic context, so a
special version of atomic ioremap is implemented for that.
Known issue:
- Error information can not be printed for recoverable errors notified
via NMI, because printk is not NMI-safe. Will fix this via delay
printing to IRQ context via irq_work or make printk NMI-safe.
v2:
- adjust printk format per comments.
Signed-off-by: Huang Ying <ying.huang@intel.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>
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The saving of the ACPI NVS area during hibernation and suspend and
restoring it during the subsequent resume is entirely specific to
ACPI, so move it to drivers/acpi and drop the CONFIG_SUSPEND_NVS
configuration option which is redundant.
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>
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When ioremap() fails (which might happen for some reason), we nicely
oops in suspend_nvs_save() due to NULL dereference by memcpy() in there.
Fail gracefully instead.
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Len Brown <len.brown@intel.com>
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Add khugepaged to relocate fragmented pages into hugepages if new
hugepages become available. (this is indipendent of the defrag logic that
will have to make new hugepages available)
The fundamental reason why khugepaged is unavoidable, is that some memory
can be fragmented and not everything can be relocated. So when a virtual
machine quits and releases gigabytes of hugepages, we want to use those
freely available hugepages to create huge-pmd in the other virtual
machines that may be running on fragmented memory, to maximize the CPU
efficiency at all times. The scan is slow, it takes nearly zero cpu time,
except when it copies data (in which case it means we definitely want to
pay for that cpu time) so it seems a good tradeoff.
In addition to the hugepages being released by other process releasing
memory, we have the strong suspicion that the performance impact of
potentially defragmenting hugepages during or before each page fault could
lead to more performance inconsistency than allocating small pages at
first and having them collapsed into large pages later... if they prove
themselfs to be long lived mappings (khugepaged scan is slow so short
lived mappings have low probability to run into khugepaged if compared to
long lived mappings).
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This increase the size of the mm struct a bit but it is needed to
preallocate one pte for each hugepage so that split_huge_page will not
require a fail path. Guarantee of success is a fundamental property of
split_huge_page to avoid decrasing swapping reliability and to avoid
adding -ENOMEM fail paths that would otherwise force the hugepage-unaware
VM code to learn rolling back in the middle of its pte mangling operations
(if something we need it to learn handling pmd_trans_huge natively rather
being capable of rollback). When split_huge_page runs a pte is needed to
succeed the split, to map the newly splitted regular pages with a regular
pte. This way all existing VM code remains backwards compatible by just
adding a split_huge_page* one liner. The memory waste of those
preallocated ptes is negligible and so it is worth it.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Rik van Riel <riel@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Futex code is smarter than most other gup_fast O_DIRECT code and knows
about the compound internals. However now doing a put_page(head_page)
will not release the pin on the tail page taken by gup-fast, leading to
all sort of refcounting bugchecks. Getting a stable head_page is a little
tricky.
page_head = page is there because if this is not a tail page it's also the
page_head. Only in case this is a tail page, compound_head is called,
otherwise it's guaranteed unnecessary. And if it's a tail page
compound_head has to run atomically inside irq disabled section
__get_user_pages_fast before returning. Otherwise ->first_page won't be a
stable pointer.
Disableing irq before __get_user_page_fast and releasing irq after running
compound_head is needed because if __get_user_page_fast returns == 1, it
means the huge pmd is established and cannot go away from under us.
pmdp_splitting_flush_notify in __split_huge_page_splitting will have to
wait for local_irq_enable before the IPI delivery can return. This means
__split_huge_page_refcount can't be running from under us, and in turn
when we run compound_head(page) we're not reading a dangling pointer from
tailpage->first_page. Then after we get to stable head page, we are
always safe to call compound_lock and after taking the compound lock on
head page we can finally re-check if the page returned by gup-fast is
still a tail page. in which case we're set and we didn't need to split
the hugepage in order to take a futex on it.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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We'd like to be able to oom_score_adj a process up/down as it
enters/leaves the foreground. Currently, it is not possible to oom_adj
down without CAP_SYS_RESOURCE. This patch allows a task to decrease its
oom_score_adj back to the value that a CAP_SYS_RESOURCE thread set it to
or its inherited value at fork. Assuming the thread that has forked it
has oom_score_adj of 0, each process could decrease it back from 0 upon
activation unless a CAP_SYS_RESOURCE thread elevated it to something
higher.
Alternative considered:
* a setuid binary
* a daemon with CAP_SYS_RESOURCE
Since you don't wan't all processes to be able to reduce their oom_adj, a
setuid or daemon implementation would be complex. The alternatives also
have much higher overhead.
This patch updated from original patch based on feedback from David
Rientjes.
Signed-off-by: Mandeep Singh Baines <msb@chromium.org>
Acked-by: David Rientjes <rientjes@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Ying Han <yinghan@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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This warning was added in commit bdff746a3915 ("clone: prepare to recycle
CLONE_STOPPED") three years ago. 2.6.26 came and went. As far as I know,
no-one is actually using CLONE_STOPPED.
Signed-off-by: Dave Jones <davej@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Use modern per_cpu API to increment {soft|hard}irq counters, and use
per_cpu allocation for (struct irq_desc)->kstats_irq instead of an array.
This gives better SMP/NUMA locality and saves few instructions per irq.
With small nr_cpuids values (8 for example), kstats_irq was a small array
(less than L1_CACHE_BYTES), potentially source of false sharing.
In the !CONFIG_SPARSE_IRQ case, remove the huge, NUMA/cache unfriendly
kstat_irqs_all[NR_IRQS][NR_CPUS] array.
Note: we still populate kstats_irq for all possible irqs in
early_irq_init(). We probably could use on-demand allocations. (Code
included in alloc_descs()). Problem is not all IRQS are used with a prior
alloc_descs() call.
kstat_irqs_this_cpu() is not used anymore, remove it.
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Reviewed-by: Christoph Lameter <cl@linux.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* 'for-2.6.38/core' of git://git.kernel.dk/linux-2.6-block: (43 commits)
block: ensure that completion error gets properly traced
blktrace: add missing probe argument to block_bio_complete
block cfq: don't use atomic_t for cfq_group
block cfq: don't use atomic_t for cfq_queue
block: trace event block fix unassigned field
block: add internal hd part table references
block: fix accounting bug on cross partition merges
kref: add kref_test_and_get
bio-integrity: mark kintegrityd_wq highpri and CPU intensive
block: make kblockd_workqueue smarter
Revert "sd: implement sd_check_events()"
block: Clean up exit_io_context() source code.
Fix compile warnings due to missing removal of a 'ret' variable
fs/block: type signature of major_to_index(int) to major_to_index(unsigned)
block: convert !IS_ERR(p) && p to !IS_ERR_NOR_NULL(p)
cfq-iosched: don't check cfqg in choose_service_tree()
fs/splice: Pull buf->ops->confirm() from splice_from_pipe actors
cdrom: export cdrom_check_events()
sd: implement sd_check_events()
sr: implement sr_check_events()
...
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We normally just use the BIO_UPTODATE flag to signal 0/-EIO. If
we have more information available, we should pass that along to
the trace output.
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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blktrace.c block bio complete callback needs to gain a new argument to reflect
the newly added "error" tracepoint argument. This is needed to match the new
block_bio_complete TRACE_EVENT as of
commit de983a7bfcb7c020901ca6e2314cf55a4207ab5a.
Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
CC: Jeff Moyer <jmoyer@redhat.com>
CC: Steven Rostedt <rostedt@goodmis.org>
CC: Frederic Weisbecker <fweisbec@gmail.com>
CC: Ingo Molnar <mingo@elte.hu>
CC: Thomas Gleixner <tglx@linutronix.de>
CC: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/tj/misc into for-2.6.38/core
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After recent blkdev_get() modifications, open_by_devnum() and
open_bdev_exclusive() are simple wrappers around blkdev_get().
Replace them with blkdev_get_by_dev() and blkdev_get_by_path().
blkdev_get_by_dev() is identical to open_by_devnum().
blkdev_get_by_path() is slightly different in that it doesn't
automatically add %FMODE_EXCL to @mode.
All users are converted. Most conversions are mechanical and don't
introduce any behavior difference. There are several exceptions.
* btrfs now sets FMODE_EXCL in btrfs_device->mode, so there's no
reason to OR it explicitly on blkdev_put().
* gfs2, nilfs2 and the generic mount_bdev() now set FMODE_EXCL in
sb->s_mode.
* With the above changes, sb->s_mode now always should contain
FMODE_EXCL. WARN_ON_ONCE() added to kill_block_super() to detect
errors.
The new blkdev_get_*() functions are with proper docbook comments.
While at it, add function description to blkdev_get() too.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Neil Brown <neilb@suse.de>
Cc: Mike Snitzer <snitzer@redhat.com>
Cc: Joern Engel <joern@lazybastard.org>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Jan Kara <jack@suse.cz>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: KONISHI Ryusuke <konishi.ryusuke@lab.ntt.co.jp>
Cc: reiserfs-devel@vger.kernel.org
Cc: xfs-masters@oss.sgi.com
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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Over time, block layer has accumulated a set of APIs dealing with bdev
open, close, claim and release.
* blkdev_get/put() are the primary open and close functions.
* bd_claim/release() deal with exclusive open.
* open/close_bdev_exclusive() are combination of open and claim and
the other way around, respectively.
* bd_link/unlink_disk_holder() to create and remove holder/slave
symlinks.
* open_by_devnum() wraps bdget() + blkdev_get().
The interface is a bit confusing and the decoupling of open and claim
makes it impossible to properly guarantee exclusive access as
in-kernel open + claim sequence can disturb the existing exclusive
open even before the block layer knows the current open if for another
exclusive access. Reorganize the interface such that,
* blkdev_get() is extended to include exclusive access management.
@holder argument is added and, if is @FMODE_EXCL specified, it will
gain exclusive access atomically w.r.t. other exclusive accesses.
* blkdev_put() is similarly extended. It now takes @mode argument and
if @FMODE_EXCL is set, it releases an exclusive access. Also, when
the last exclusive claim is released, the holder/slave symlinks are
removed automatically.
* bd_claim/release() and close_bdev_exclusive() are no longer
necessary and either made static or removed.
* bd_link_disk_holder() remains the same but bd_unlink_disk_holder()
is no longer necessary and removed.
* open_bdev_exclusive() becomes a simple wrapper around lookup_bdev()
and blkdev_get(). It also has an unexpected extra bdev_read_only()
test which probably should be moved into blkdev_get().
* open_by_devnum() is modified to take @holder argument and pass it to
blkdev_get().
Most of bdev open/close operations are unified into blkdev_get/put()
and most exclusive accesses are tested atomically at the open time (as
it should). This cleans up code and removes some, both valid and
invalid, but unnecessary all the same, corner cases.
open_bdev_exclusive() and open_by_devnum() can use further cleanup -
rename to blkdev_get_by_path() and blkdev_get_by_devt() and drop
special features. Well, let's leave them for another day.
Most conversions are straight-forward. drbd conversion is a bit more
involved as there was some reordering, but the logic should stay the
same.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Neil Brown <neilb@suse.de>
Acked-by: Ryusuke Konishi <konishi.ryusuke@lab.ntt.co.jp>
Acked-by: Mike Snitzer <snitzer@redhat.com>
Acked-by: Philipp Reisner <philipp.reisner@linbit.com>
Cc: Peter Osterlund <petero2@telia.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Jan Kara <jack@suse.cz>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Cc: Mark Fasheh <mfasheh@suse.com>
Cc: Joel Becker <joel.becker@oracle.com>
Cc: Alex Elder <aelder@sgi.com>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: dm-devel@redhat.com
Cc: drbd-dev@lists.linbit.com
Cc: Leo Chen <leochen@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Steven Whitehouse <swhiteho@redhat.com>
Cc: Dave Kleikamp <shaggy@linux.vnet.ibm.com>
Cc: Joern Engel <joern@logfs.org>
Cc: reiserfs-devel@vger.kernel.org
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
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