Miklos Szeredi 53da1d9456 fix ptrace slowness ...

This patch fixes bug #12208:

  Bug-Entry       : http://bugzilla.kernel.org/show_bug.cgi?id=12208
  Subject         : uml is very slow on 2.6.28 host

This turned out to be not a scheduler regression, but an already
existing problem in ptrace being triggered by subtle scheduler
changes.

The problem is this:

 - task A is ptracing task B
 - task B stops on a trace event
 - task A is woken up and preempts task B
 - task A calls ptrace on task B, which does ptrace_check_attach()
 - this calls wait_task_inactive(), which sees that task B is still on the runq
 - task A goes to sleep for a jiffy
 - ...

Since UML does lots of the above sequences, those jiffies quickly add
up to make it slow as hell.

This patch solves this by not rescheduling in read_unlock() after
ptrace_stop() has woken up the tracer.

Thanks to Oleg Nesterov and Ingo Molnar for the feedback.

Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
CC: stable@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2009-03-23 09:22:31 -07:00

..

irq

Merge branch 'core/xen' into x86/urgent

2009-02-04 14:54:56 +01:00

power

PM: Split up sysdev_[suspend|resume] from device_power_[down|up]

2009-02-22 10:33:44 -08:00

time

hrtimers: allow the hot-unplugging of all cpus

2009-01-30 22:35:29 +01:00

trace

tracing: limit the number of loops the ring buffer self test can make

2009-02-18 22:50:01 -05:00

.gitignore

Update kernel/.gitignore with new auto-generated files

2008-02-09 23:27:01 -08:00

acct.c

[CVE-2009-0029] System call wrappers part 04

2009-01-14 14:15:19 +01:00

async.c

async: use list_move_tail

2009-02-08 10:00:26 -08:00

audit_tree.c

audit: validate comparison operations, store them in sane form

2009-01-04 15:14:42 -05:00

audit.c

[PATCH] fix broken timestamps in AVC generated by kernel threads

2008-12-09 02:27:41 -05:00

audit.h

fixing audit rule ordering mess, part 1

2009-01-04 15:14:41 -05:00

auditfilter.c

audit: validate comparison operations, store them in sane form

2009-01-04 15:14:42 -05:00

auditsc.c

make sure that filterkey of task,always rules is reported

2009-01-04 15:14:42 -05:00

backtracetest.c

backtrace: replace timer with tasklet + completions

2008-06-27 18:09:16 +02:00

bounds.c

Add kbuild.h that contains common definitions for kbuild users

2008-04-29 08:06:29 -07:00

capability.c

[CVE-2009-0029] System call wrappers part 04

2009-01-14 14:15:19 +01:00

cgroup_debug.c

cgroups: fix probable race with put_css_set[_taskexit] and find_css_set

2008-10-20 08:52:38 -07:00

cgroup_freezer.c

freezer_cg: disable writing freezer.state of root cgroup

2008-11-12 17:17:16 -08:00

cgroup.c

cgroups: fix possible use after free

2009-02-18 15:37:54 -08:00

compat.c

Allow times and time system calls to return small negative values

2009-01-06 15:59:13 -08:00

configs.c

kernel/configs.c: remove useless comments

2008-10-20 08:52:34 -07:00

cpu.c

stop_machine/cpu hotplug: fix disable_nonboot_cpus

2009-01-07 11:36:14 -08:00

cpuset.c

cpuset: fix possible deadlock in async_rebuild_sched_domains

2009-01-19 02:44:00 +01:00

cred-internals.h

CRED: Inaugurate COW credentials

2008-11-14 10:39:23 +11:00

cred.c

Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6

2009-01-09 13:59:25 -08:00

delayacct.c

schedstat: consolidate per-task cpu runtime stats

2008-12-18 13:54:01 +01:00

dma-coherent.c

dma-coherent: Restore dma_alloc_from_coherent() large alloc fall back policy.

2009-01-21 18:51:53 +09:00

dma.c

kernel/dma.c: remove a CVS keyword

2008-10-16 11:21:30 -07:00

exec_domain.c

[CVE-2009-0029] System call wrappers part 04

2009-01-14 14:15:19 +01:00

exit.c

signal: re-add dead task accumulation stats.

2009-02-05 13:04:33 +01:00

extable.c

Merge branch 'core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2008-12-30 16:10:19 -08:00

fork.c

copy_process: fix CLONE_PARENT && parent_exec_id interaction

2009-03-09 13:23:25 -07:00

freezer.c

freezer_cg: use thaw_process() in unfreeze_cgroup()

2008-10-30 11:38:45 -07:00

futex_compat.c

CRED: Use RCU to access another task's creds and to release a task's own creds

2008-11-14 10:39:19 +11:00

futex.c

futex: fix reference leak

2009-02-11 18:24:08 +01:00

hrtimer.c

hrtimer: prevent negative expiry value after clock_was_set()

2009-01-30 22:35:34 +01:00

itimer.c

timers: split process wide cpu clocks/timers

2009-02-05 13:04:33 +01:00

kallsyms.c

Revert "kbuild: strip generated symbols from *.ko"

2009-01-14 21:38:20 +01:00

Kconfig.freezer

container freezer: implement freezer cgroup subsystem

2008-10-20 08:52:34 -07:00

Kconfig.hz

sched: fix SCHED_HRTICK dependency

2008-07-28 14:37:38 +02:00

Kconfig.preempt

rcu: provide RCU options on non-preempt architectures too

2008-12-25 09:31:28 +01:00

kexec.c

PM: Split up sysdev_[suspend|resume] from device_power_[down|up]

2009-02-22 10:33:44 -08:00

kfifo.c

is_power_of_2: kernel/kfifo.c

2007-07-16 09:05:50 -07:00

kgdb.c

kgdb: call touch_softlockup_watchdog on resume

2008-10-06 13:50:59 -05:00

kmod.c

kmod: fix varargs kernel-doc

2009-01-06 15:59:27 -08:00

kprobes.c

kprobes: check CONFIG_FREEZER instead of CONFIG_PM

2009-01-16 14:32:17 -05:00

ksysfs.c

kernel/ksysfs.c:fix dependence on CONFIG_NET

2009-01-06 10:44:31 -08:00

kthread.c

tracepoints: add DECLARE_TRACE() and DEFINE_TRACE()

2008-11-16 09:01:36 +01:00

latencytop.c

KSYM_SYMBOL_LEN fixes

2008-12-10 08:01:54 -08:00

lockdep_internals.h

lockdep: build fix

2008-08-13 12:55:10 +02:00

lockdep_proc.c

lockstat: contend with points

2008-10-20 15:43:10 +02:00

lockdep.c

Merge branch 'core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip

2008-12-30 16:10:19 -08:00

Makefile

PM: fix build for CONFIG_PM unset

2009-02-21 14:17:17 -08:00

marker.c

markers/tracpoints: fix non-modular build

2008-11-16 09:52:03 +01:00

module.c

module: fix refptr allocation and release order

2009-03-18 09:31:21 +10:30

mutex-debug.c

mutex-debug: check mutex magic before owner

2008-05-16 16:53:35 +02:00

mutex-debug.h

…

mutex.c

mutex: __used is needed for function referenced only from inline asm

2008-11-24 10:00:28 +01:00

mutex.h

…

notifier.c

Merge commit 'v2.6.28-rc6' into core/debug

2008-11-26 08:22:50 +01:00

ns_cgroup.c

ns_cgroup: remove unused spinlock

2009-01-08 08:31:02 -08:00

nsproxy.c

User namespaces: set of cleanups (v2)

2008-11-24 18:57:41 -05:00

panic.c

oops: increment the oops UUID every time we oops

2009-01-06 15:59:12 -08:00

params.c

Fix compile warning in kernel/params.c

2008-10-23 12:09:00 -07:00

pid_namespace.c

pid_ns: (BUG 11391) change ->child_reaper when init->group_leader exits

2008-09-02 19:21:38 -07:00

pid.c

pid: generalize task_active_pid_ns

2009-01-08 08:31:12 -08:00

pm_qos_params.c

pm_qos_requirement might sleep

2008-09-02 19:21:40 -07:00

posix-cpu-timers.c

timers: more consistently use clock vs timer

2009-02-13 13:04:05 +01:00

posix-timers.c

[CVE-2009-0029] System call wrappers part 05

2009-01-14 14:15:20 +01:00

printk.c

PM: Fix suspend_console and resume_console to use only one semaphore

2009-02-21 14:17:18 -08:00

profile.c

profiling: fix broken profiling regression

2009-02-10 00:50:37 +01:00

ptrace.c

[CVE-2009-0029] System call wrappers part 27

2009-01-14 14:15:29 +01:00

rcuclassic.c

rcu: Teach RCU that idle task is not quiscent state at boot

2009-02-26 04:08:14 +01:00

rcupdate.c

rcu: Teach RCU that idle task is not quiscent state at boot

2009-02-26 04:08:14 +01:00

rcupreempt_trace.c

"Tree RCU": scalable classic RCU implementation

2008-12-18 21:56:04 +01:00

rcupreempt.c

rcu: Teach RCU that idle task is not quiscent state at boot

2009-02-26 04:08:14 +01:00

rcutorture.c

rcu: fix bug in rcutorture system-shutdown code

2009-01-07 23:36:25 +01:00

rcutree_trace.c

"Tree RCU": scalable classic RCU implementation

2008-12-18 21:56:04 +01:00

rcutree.c

rcu: Teach RCU that idle task is not quiscent state at boot

2009-02-26 04:08:14 +01:00

relay.c

relay: fix lock imbalance in relay_late_setup_files

2009-01-18 20:29:35 +01:00

res_counter.c

memcg: memory cgroup resource counters for hierarchy

2009-01-08 08:31:05 -08:00

resource.c

resources: fix parameter name and kernel-doc

2009-01-15 16:39:38 -08:00

rtmutex_common.h

Don't operate with pid_t in rtmutex tester

2008-02-08 09:22:41 -08:00

rtmutex-debug.c

Don't operate with pid_t in rtmutex tester

2008-02-08 09:22:41 -08:00

rtmutex-debug.h

…

rtmutex-tester.c

sysdev: Pass the attribute to the low level sysdev show/store function

2008-07-21 21:55:02 -07:00

rtmutex.c

hrtimer: convert kernel/* to the new hrtimer apis

2008-09-05 21:35:13 -07:00

rtmutex.h

…

rwsem.c

sched: mark rwsem functions as __sched for wchan/profiling

2007-12-18 15:21:13 +01:00

sched_clock.c

sched_clock: prevent scd->clock from moving backwards, take #2

2008-12-31 09:53:21 +01:00

sched_cpupri.c

sched: fix section mismatch

2009-01-06 11:07:15 +01:00

sched_cpupri.h

sched: convert struct cpupri_vec cpumask_var_t.

2008-11-24 17:52:22 +01:00

sched_debug.c

sched: partly revert "sched debug: remove NULL checking in print_cfs_rt_rq()"

2009-01-11 02:40:32 +01:00

sched_fair.c

sched: revert recent sync wakeup changes

2009-02-11 14:43:35 +01:00

sched_features.h

sched: backward looking buddy

2008-11-05 10:30:14 +01:00

sched_idletask.c

sched: add CONFIG_SMP consistency

2008-10-22 10:01:52 +02:00

sched_rt.c

sched_rt: don't use first_cpu on cpumask created with cpumask_and

2009-02-01 10:49:52 +01:00

sched_stats.h

timers: split process wide cpu clocks/timers

2009-02-05 13:04:33 +01:00

sched.c

sched: don't allow setuid to succeed if the user does not have rt bandwidth

2009-02-27 11:11:53 +01:00

seccomp.c

x86-64: seccomp: fix 32/64 syscall hole

2009-03-02 15:41:30 -08:00

semaphore.c

semaphore: __down_common: use signal_pending_state()

2008-08-05 14:33:47 -07:00

signal.c

fix ptrace slowness

2009-03-23 09:22:31 -07:00

smp.c

generic-ipi: use per cpu data for single cpu ipi calls

2009-01-30 18:31:08 +01:00

softirq.c

rcu: increment quiescent state counter in ksoftirqd()

2009-03-04 22:08:45 +01:00

softlockup.c

softlock: fix false panic which can occur if softlockup_thresh is reduced

2009-01-14 11:48:07 +01:00

spinlock.c

lockdep: spin_lock_nest_lock(), checkpatch fixes

2008-08-13 13:56:51 +02:00

srcu.c

make srcu_readers_active() static

2008-02-06 10:41:02 -08:00

stacktrace.c

stacktrace: provide save_stack_trace_tsk() weak alias

2008-12-25 11:44:43 +01:00

stop_machine.c

stop_machine: introduce stop_machine_create/destroy.

2009-01-05 08:40:14 +10:30

sys_ni.c

[CVE-2009-0029] Make sys_syslog a conditional system call

2009-01-14 14:15:16 +01:00

sys.c

sched: don't allow setuid to succeed if the user does not have rt bandwidth

2009-02-27 11:11:53 +01:00

sysctl_check.c

[XFS] remove restricted chown parameter from xfs linux

2008-10-30 18:30:09 +11:00

sysctl.c

mm: fix dirty_bytes/dirty_background_bytes sysctls on 64bit arches

2009-02-11 14:25:35 -08:00

taskstats.c

cpumask: convert rest of files in kernel/

2009-01-01 10:12:28 +10:30

test_kprobes.c

kprobes: add tests for register_kprobes

2009-01-06 15:59:20 -08:00

time.c

[CVE-2009-0029] System call wrappers part 01

2009-01-14 14:15:18 +01:00

timeconst.pl

Make constants in kernel/timeconst.h fixed 64 bits

2008-05-02 16:18:42 -07:00

timer.c

[CVE-2009-0029] System call wrappers part 27

2009-01-14 14:15:29 +01:00

tracepoint.c

markers/tracpoints: fix non-modular build

2008-11-16 09:52:03 +01:00

tsacct.c

Fix fixpoint divide exception in acct_update_integrals

2009-03-09 08:13:35 -07:00

uid16.c

[CVE-2009-0029] System call wrappers part 19

2009-01-14 14:15:26 +01:00

up.c

smp_call_function_single(): be slightly less stupid, fix #2

2009-01-12 16:04:37 +01:00

user_namespace.c

Fix recursive lock in free_uid()/free_user_ns()

2009-02-27 16:26:21 -08:00

user.c

kernel/user.c: fix a memory leak when freeing up non-init usernamespaces users

2009-03-10 15:55:11 -07:00

utsname_sysctl.c

sysctl: simplify ->strategy

2008-10-16 11:21:47 -07:00

utsname.c

removed unused #include <linux/version.h>'s

2008-08-23 12:14:12 -07:00

wait.c

wait: prevent exclusive waiter starvation

2009-02-05 12:56:48 -08:00

workqueue.c

work_on_cpu: Use our own workqueue.

2009-01-19 22:36:07 +01:00