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	…
Kconfig.freezer	…
Kconfig.hz	…
Kconfig.preempt	…
Makefile	PM: fix build for CONFIG_PM unset	2009-02-21 14:17:17 -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.c	…
audit.h	…
audit_tree.c	…
auditfilter.c	…
auditsc.c	…
backtracetest.c	…
bounds.c	…
capability.c	[CVE-2009-0029] System call wrappers part 04	2009-01-14 14:15:19 +01:00
cgroup.c	cgroups: fix possible use after free	2009-02-18 15:37:54 -08:00
cgroup_debug.c	…
cgroup_freezer.c	…
compat.c	…
configs.c	…
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.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	…
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	…
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	…
fork.c	copy_process: fix CLONE_PARENT && parent_exec_id interaction	2009-03-09 13:23:25 -07:00
freezer.c	…
futex.c	futex: fix reference leak	2009-02-11 18:24:08 +01:00
futex_compat.c	…
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
kexec.c	PM: Split up sysdev_[suspend|resume] from device_power_[down|up]	2009-02-22 10:33:44 -08:00
kfifo.c	…
kgdb.c	…
kmod.c	…
kprobes.c	kprobes: check CONFIG_FREEZER instead of CONFIG_PM	2009-01-16 14:32:17 -05:00
ksysfs.c	…
kthread.c	…
latencytop.c	…
lockdep.c	…
lockdep_internals.h	…
lockdep_proc.c	…
marker.c	…
module.c	module: fix refptr allocation and release order	2009-03-18 09:31:21 +10:30
mutex-debug.c	…
mutex-debug.h	…
mutex.c	…
mutex.h	…
notifier.c	…
ns_cgroup.c	ns_cgroup: remove unused spinlock	2009-01-08 08:31:02 -08:00
nsproxy.c	…
panic.c	…
params.c	…
pid.c	pid: generalize task_active_pid_ns	2009-01-08 08:31:12 -08:00
pid_namespace.c	…
pm_qos_params.c	…
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.c	rcu: Teach RCU that idle task is not quiscent state at boot	2009-02-26 04:08:14 +01:00
rcupreempt_trace.c	…
rcutorture.c	rcu: fix bug in rcutorture system-shutdown code	2009-01-07 23:36:25 +01:00
rcutree.c	rcu: Teach RCU that idle task is not quiscent state at boot	2009-02-26 04:08:14 +01:00
rcutree_trace.c	…
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-debug.c	…
rtmutex-debug.h	…
rtmutex-tester.c	…
rtmutex.c	…
rtmutex.h	…
rtmutex_common.h	…
rwsem.c	…
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
sched_clock.c	…
sched_cpupri.c	…
sched_cpupri.h	…
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_idletask.c	…
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
seccomp.c	x86-64: seccomp: fix 32/64 syscall hole	2009-03-02 15:41:30 -08:00
semaphore.c	…
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	…
srcu.c	…
stacktrace.c	…
stop_machine.c	…
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
sys_ni.c	[CVE-2009-0029] Make sys_syslog a conditional system call	2009-01-14 14:15:16 +01:00
sysctl.c	mm: fix dirty_bytes/dirty_background_bytes sysctls on 64bit arches	2009-02-11 14:25:35 -08:00
sysctl_check.c	…
taskstats.c	…
test_kprobes.c	…
time.c	[CVE-2009-0029] System call wrappers part 01	2009-01-14 14:15:18 +01:00
timeconst.pl	…
timer.c	[CVE-2009-0029] System call wrappers part 27	2009-01-14 14:15:29 +01:00
tracepoint.c	…
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.c	kernel/user.c: fix a memory leak when freeing up non-init usernamespaces users	2009-03-10 15:55:11 -07:00
user_namespace.c	Fix recursive lock in free_uid()/free_user_ns()	2009-02-27 16:26:21 -08:00
utsname.c	…
utsname_sysctl.c	…
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