Commit Graph

356 Commits

Author SHA1 Message Date
Roland McGrath
25f407f0b6 [PATCH] Call exit_itimers from do_exit, not __exit_signal
When I originally moved exit_itimers into __exit_signal, that was the only
place where we could reliably know it was the last thread in the group
dying, without races.  Since then we've gotten the signal_struct.live
counter, and do_exit can reliably do group-wide cleanup work.

This patch moves the call to do_exit, where it's made without locks.  This
avoids the deadlock issues that the old __exit_signal code's comment talks
about, and the one that Oleg found recently with process CPU timers.

[ This replaces e03d13e985, which is why
  it was just reverted. ]

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-21 15:38:08 -07:00
Linus Torvalds
9465bee863 Revert "Fix cpu timers exit deadlock and races"
Revert commit e03d13e985, to be replaced
by a much nicer fix from Roland.
2005-10-21 15:36:00 -07:00
Alan Stern
d1209d049b [PATCH] Threads shouldn't inherit PF_NOFREEZE
The PF_NOFREEZE process flag should not be inherited when a thread is
forked.  This patch (as585) removes the flag from the child.

This problem is starting to show up more and more as drivers turn to the
kthread API instead of using kernel_thread().  As a result, their kernel
threads are now children of the kthread worker instead of modprobe, and
they inherit the PF_NOFREEZE flag.  This can cause problems during system
suspend; the kernel threads are not getting frozen as they ought to be.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-19 23:04:31 -07:00
Roland McGrath
e03d13e985 [PATCH] Fix cpu timers exit deadlock and races
Oleg Nesterov reported an SMP deadlock.  If there is a running timer
tracking a different process's CPU time clock when the process owning
the timer exits, we deadlock on tasklist_lock in posix_cpu_timer_del via
exit_itimers.

That code was using tasklist_lock to check for a race with __exit_signal
being called on the timer-target task and clearing its ->signal.
However, there is actually no such race.  __exit_signal will have called
posix_cpu_timers_exit and posix_cpu_timers_exit_group before it does
that.  Those will clear those k_itimer's association with the dying
task, so posix_cpu_timer_del will return early and never reach the code
in question.

In addition, posix_cpu_timer_del called from exit_itimers during execve
or directly from timer_delete in the process owning the timer can race
with an exiting timer-target task to cause a double put on timer-target
task struct.  Make sure we always access cpu_timers lists with sighand
lock held.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Chris Wright <chrisw@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-19 23:02:01 -07:00
Eric Dumazet
5ee832dbc6 [PATCH] rcu: keep rcu callback event counter
This makes call_rcu() keep track of how many events there are on the RCU
list, and cause a reschedule event when the list gets too long.

This helps keep RCU event lists down.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-17 15:27:58 -07:00
Oleg Nesterov
47d6b08334 [PATCH] posix-timers: fix task accounting
Make sure we release the task struct properly when releasing pending
timers.

release_task() does write_lock_irq(&tasklist_lock), so it can't race
with run_posix_cpu_timers() on any cpu.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-17 15:00:00 -07:00
Linus Torvalds
2cc78eb52b Increase default RCU batching sharply
Dipankar made RCU limit the batch size to improve latency, but that
approach is unworkable: it can cause the RCU queues to grow without
bounds, since the batch limiter ended up limiting the callbacks.

So make the limit much higher, and start planning on instead limiting
the batch size by doing RCU callbacks more often if the queue looks like
it might be growing too long.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-17 09:10:15 -07:00
Takashi Iwai
c6ecf7ed31 [PATCH] Add missing export of getnstimeofday()
Adds the missing EXPORT_SYMBOL_GPL for getnstimeofday() when
CONFIG_TIME_INTERPOLATION isn't set.  Needed by drivers/char/mmtimer.c

Signed-off-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-14 17:10:12 -07:00
Harald Welte
46113830a1 [PATCH] Fix signal sending in usbdevio on async URB completion
If a process issues an URB from userspace and (starts to) terminate
before the URB comes back, we run into the issue described above.  This
is because the urb saves a pointer to "current" when it is posted to the
device, but there's no guarantee that this pointer is still valid
afterwards.

In fact, there are three separate issues:

1) the pointer to "current" can become invalid, since the task could be
   completely gone when the URB completion comes back from the device.

2) Even if the saved task pointer is still pointing to a valid task_struct,
   task_struct->sighand could have gone meanwhile.

3) Even if the process is perfectly fine, permissions may have changed,
   and we can no longer send it a signal.

So what we do instead, is to save the PID and uid's of the process, and
introduce a new kill_proc_info_as_uid() function.

Signed-off-by: Harald Welte <laforge@gnumonks.org>
[ Fixed up types and added symbol exports ]
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-10 16:16:33 -07:00
Rafael J. Wysocki
3dd083255d [PATCH] x86_64: Set up safe page tables during resume
The following patch makes swsusp avoid the possible temporary corruption
of page translation tables during resume on x86-64.  This is achieved by
creating a copy of the relevant page tables that will not be modified by
swsusp and can be safely used by it on resume.

The problem is that during resume on x86-64 swsusp may temporarily
corrupt the page tables used for the direct mapping of RAM.  If that
happens, a page fault occurs and cannot be handled properly, which leads
to the solid hang of the affected system.  This leads to the loss of the
system's state from before suspend and may result in the loss of data or
the corruption of filesystems, so it is a serious issue.  Also, it
appears to happen quite often (for me, as often as 50% of the time).

The problem is related to the fact that (at least) one of the PMD
entries used in the direct memory mapping (starting at PAGE_OFFSET)
points to a page table the physical address of which is much greater
than the physical address of the PMD entry itself.  Moreover,
unfortunately, the physical address of the page table before suspend
(i.e.  the one stored in the suspend image) happens to be different to
the physical address of the corresponding page table used during resume
(i.e.  the one that is valid right before swsusp_arch_resume() in
arch/x86_64/kernel/suspend_asm.S is executed).  Thus while the image is
restored, the "offending" PMD entry gets overwritten, so it does not
point to the right physical address any more (i.e.  there's no page
table at the address pointed to by it, because it points to the address
the page table has been at during suspend).  Consequently, if the PMD
entry is used later on, and it _is_ used in the process of copying the
image pages, a page fault occurs, but it cannot be handled in the normal
way and the system hangs.

In principle we can call create_resume_mapping() from
swsusp_arch_resume() (ie.  from suspend_asm.S), but then the memory
allocations in create_resume_mapping(), resume_pud_mapping(), and
resume_pmd_mapping() must be made carefully so that we use _only_
NosaveFree pages in them (the other pages are overwritten by the loop in
swsusp_arch_resume()).  Additionally, we are in atomic context at that
time, so we cannot use GFP_KERNEL.  Moreover, if one of the allocations
fails, we should free all of the allocated pages, so we need to trace
them somehow.

All of this is done in the appended patch, except that the functions
populating the page tables are located in arch/x86_64/kernel/suspend.c
rather than in init.c.  It may be done in a more elegan way in the
future, with the help of some swsusp patches that are in the works now.

[AK: move some externs into headers, renamed a function]

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-10 08:36:46 -07:00
Al Viro
dd0fc66fb3 [PATCH] gfp flags annotations - part 1
- added typedef unsigned int __nocast gfp_t;

 - replaced __nocast uses for gfp flags with gfp_t - it gives exactly
   the same warnings as far as sparse is concerned, doesn't change
   generated code (from gcc point of view we replaced unsigned int with
   typedef) and documents what's going on far better.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-08 15:00:57 -07:00
Oleg Nesterov
788e05a67c [PATCH] fix do_coredump() vs SIGSTOP race
Let's suppose we have 2 threads in thread group:
	A - does coredump
	B - has pending SIGSTOP

thread A						thread B

do_coredump:						get_signal_to_deliver:

  lock(->sighand)
  ->signal->flags = SIGNAL_GROUP_EXIT
  unlock(->sighand)

							lock(->sighand)
							signr = dequeue_signal()
								->signal->flags |= SIGNAL_STOP_DEQUEUED
								return SIGSTOP;

							do_signal_stop:
							    unlock(->sighand)

  coredump_wait:

      zap_threads:
          lock(tasklist_lock)
          send SIGKILL to B
              // signal_wake_up() does nothing
          unlock(tasklist_lock)

							    lock(tasklist_lock)
							    lock(->sighand)
							    re-check sig->flags & SIGNAL_STOP_DEQUEUED, yes
							    set_current_state(TASK_STOPPED);
							    finish_stop:
							        schedule();
							            // ->state == TASK_STOPPED

      wait_for_completion(&startup_done)
         // waits for complete() from B,
         // ->state == TASK_UNINTERRUPTIBLE

We can't wake up 'B' in any way:

	SIGCONT will be ignored because handle_stop_signal() sees
	->signal->flags & SIGNAL_GROUP_EXIT.

	sys_kill(SIGKILL)->__group_complete_signal() will choose
	uninterruptible 'A', so it can't help.

	sys_tkill(B, SIGKILL) will be ignored by specific_send_sig_info()
	because B already has pending SIGKILL.

This scenario is not possbile if 'A' does do_group_exit(), because
it sets sig->flags = SIGNAL_GROUP_EXIT and delivers SIGKILL to
subthreads atomically, holding both tasklist_lock and sighand->lock.
That means that do_signal_stop() will notice !SIGNAL_STOP_DEQUEUED
after re-locking ->sighand. And it is not possible to any other
thread to re-add SIGNAL_STOP_DEQUEUED later, because dequeue_signal()
can only return SIGKILL.

I think it is better to change do_coredump() to do sigaddset(SIGKILL)
and signal_wake_up() under sighand->lock, but this patch is much
simpler.

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-08 14:53:31 -07:00
Linus Torvalds
14bf01bb05 Fix inequality comparison against "task->state"
We should always use bitmask ops, rather than depend on some ordering of
the different states.  With the TASK_NONINTERACTIVE flag, the inequality
doesn't really work.

Oleg Nesterov argues (likely correctly) that this test is unnecessary in
the first place.  However, the minimal fix for now is to at least make
it work in the presense of TASK_NONINTERACTIVE.  Waiting for consensus
from Roland & co on potential bigger cleanups.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-01 11:04:18 -07:00
Al Viro
eacaa1f5aa [PATCH] cpuset crapectomy
Switched cpuset_common_file_read() to simple_read_from_buffer(), killed
a bunch of useless (and not quite correct - e.g.  min(size_t,ssize_t))
code.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-30 08:42:24 -07:00
Roland McGrath
5acbc5cb50 [PATCH] Fix task state testing properly in do_signal_stop()
Any tests using < TASK_STOPPED or the like are left over from the time
when the TASK_ZOMBIE and TASK_DEAD bits were in the same word, and it
served to check for "stopped or dead".  I think this one in
do_signal_stop is the only such case.  It has been buggy ever since
exit_state was separated, and isn't testing the exit_state value.

Signed-off-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-29 15:20:47 -07:00
Paul Jackson
5134fc15b6 [PATCH] cpuset read past eof memory leak fix
Don't leak a page of memory if user reads a cpuset file past eof.

Signed-off-by: KUROSAWA Takahiro <kurosawa@valinux.co.jp>
Signed-off-by: Paul Jackson <pj@sgi.com>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-28 07:58:51 -07:00
Rafael J. Wysocki
0f7347c20c [PATCH] swsusp: avoid problems if there are too many pages to save
The following patch makes swsusp avoid problems during resume if there are
too many pages to save on suspend.  It adds a constant that allows us to
verify if we are going to save too many pages and implements the check
(this is done as early as we can tell that the check will trigger, which is
in swsusp_alloc()).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-28 07:46:41 -07:00
Rusty Russell
f36462f078 [PATCH] Ignore trailing whitespace on kernel parameters correctly
Dave Jones says:

... if the modprobe.conf has trailing whitespace, modules fail to load
with the following helpful message..

	snd_intel8x0: Unknown parameter `'

Previous version truncated last argument.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Dave Jones <davej@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-28 07:46:41 -07:00
Rafael J. Wysocki
f2d613799a [PATCH] swsusp: prevent possible memory leak
Prevent swsusp from leaking some memory in case of an error in
read_pagedir().  It also prevents the BUG_ON() from triggering if there's
an error while reading swap.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-28 07:46:40 -07:00
Rafael J. Wysocki
254b54771c [PATCH] swsusp: remove wrong code from data_free
The following patch removes some wrong code from the data_free() function
in swsusp.

This function could only be called if there's an error while writing the
suspend image to swap, so it is not triggered easily.  However, if
triggered, it would probably corrupt some memory.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-28 07:46:40 -07:00
Linus Torvalds
188a1eafa0 Make sure SIGKILL gets proper respect
Bhavesh P. Davda <bhavesh@avaya.com> noticed that SIGKILL wouldn't
properly kill a process under just the right cicumstances: a stopped
task that already had another signal queued would get the SIGKILL
queued onto the shared queue, and there it would remain until SIGCONT.

This simplifies the signal acceptance logic, and fixes the bug in the
process.

Losely based on an earlier patch by Bhavesh.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-23 13:22:21 -07:00
Pavel Machek
8686bcd0a5 [PATCH] swsusp: fix comments
Fix comments in swsusp.

Signed-off-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-22 22:17:36 -07:00
Rafael J. Wysocki
57487f4376 [PATCH] swsusp: do not trigger BUG_ON() if there is not enough memory
The following patch makes swsusp avoid triggering the BUG_ON() in
swsusp_suspend() if there is not enough memory for suspend.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-22 22:17:35 -07:00
Randy Dunlap
720b9429e8 [PATCH] SOFTWARE_SUSPEND needs HOTPLUG_CPU on SMP
Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Acked-by: Pavel Machek <pavel@ucw.cz>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-22 22:17:34 -07:00
Eric W. Biederman
88d10bbaae [PATCH] suspend: cleanup calling of power off methods.
In the lead up to 2.6.13 I fixed a large number of reboot problems by
making the calling conventions consistent.  Despite checking and double
checking my work it appears I missed an obvious one.

The S4 suspend code for PM_DISK_PLATFORM was also calling device_shutdown
without setting system_state, and was not calling the appropriate
reboot_notifier.

This patch fixes the bug by replacing the call of device_suspend with
kernel_poweroff_prepare.

Various forms of this failure have been fixed and tracked for a while.

Thanks for tracking this down go to: Alexey Starikovskiy, Meelis Roos
<mroos@linux.ee>, Nigel Cunningham <ncunningham@cyclades.com>, Pierre
Ossman <drzeus-list@drzeus.cx>

History of this bug is at:
http://bugme.osdl.org/show_bug.cgi?id=4320

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-22 22:17:33 -07:00
Eric W. Biederman
e4c94330e3 [PATCH] reboot: comment and factor the main reboot functions
In the lead up to 2.6.13 I fixed a large number of reboot problems by
making the calling conventions consistent.  Despite checking and double
checking my work it appears I missed an obvious one.

This first patch simply refactors the reboot routines so all of the
preparation for various kinds of reboots are in their own functions.
Making it very hard to get the various kinds of reboot out of sync.

Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-22 22:17:33 -07:00
Andrew Morton
31f6d9d628 [PATCH] Add printk_clock()
ia64's sched_clock() accesses per-cpu data which isn't set up at boot time.
Hence ia64 cannot use printk timestamping, because printk() will crash in
sched_clock().

So make printk() use printk_clock(), defaulting to sched_clock(), overrideable
by the architecture via attribute(weak).

Cc: "Luck, Tony" <tony.luck@intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-21 10:11:54 -07:00
Dipankar Sarma
4fb3a53860 [PATCH] files: fix preemption issues
With the new fdtable locking rules, you have to protect fdtable with either
->file_lock or rcu_read_lock/unlock().  There are some places where we
aren't doing either.  This patch fixes those places.

Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-17 11:50:02 -07:00
Michael Kerrisk
2030c0fd3d [PATCH] PR_GET_DUMPABLE returns incorrect info
2.6.13 incorporated Alan Cox's patch for /proc/sys/fs/suid_dumpable (one
version of this patch can be found here
http://marc.theaimsgroup.com/?l=linux-kernel&m=109647550421014&w=2 ).

This patch also made corresponding changes in kernel/sys.c to change the
prctl() PR_SET_DUMPABLE operation so that the permitted range of 'arg2' was
modified from 0..1 to 0..2.

However, a corresponding change was not made for PR_GET_DUMPABLE: if the
dumpable flag is non-zero, then PR_GET_DUMPABLE always returns 1, so that
the caller can't determine the true setting of this flag.

Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-17 11:50:01 -07:00
Srivatsa Vaddagiri
26ff6ad978 [PATCH] CPU hotplug breaks wake_up_new_task
Fix a problem wherein a new-born task is added to a dead CPU.

Signed-off-by: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Acked-by: Nick Piggin <nickpiggin@yahoo.com.au>
Acked-by: Shaohua Li <shaohua.li@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-17 11:49:59 -07:00
Ingo Molnar
da04c03503 [PATCH] Fix spinlock owner debugging
fix up the runqueue lock owner only if we truly did a context-switch
with the runqueue lock held. Impacts ia64, mips, sparc64 and arm.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-13 09:59:04 -07:00
Linus Torvalds
5d54e69c68 Merge master.kernel.org:/pub/scm/linux/kernel/git/dwmw2/audit-2.6 2005-09-13 09:47:30 -07:00
Randy Dunlap
9f1583339a [PATCH] use add_taint() for setting tainted bit flags
Use the add_taint() interface for setting tainted bit flags instead of
doing it manually.

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-13 08:22:29 -07:00
Andrew Morton
8a1c17574a [PATCH] schedule_timeout_[un]interruptible() speedup
These functions don't need schedule_timeout()'s barrier.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-13 08:22:29 -07:00
Andi Kleen
3f74478b5f [PATCH] x86-64: Some cleanup and optimization to the processor data area.
- Remove unused irqrsp field
- Remove pda->me
- Optimize set_softirq_pending slightly

Signed-off-by: Andi Kleen <ak@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-12 10:49:58 -07:00
Paul Jackson
b3426599af [PATCH] cpuset semaphore depth check optimize
Optimize the deadlock avoidance check on the global cpuset
semaphore cpuset_sem.  Instead of adding a depth counter to the
task struct of each task, rather just two words are enough, one
to store the depth and the other the current cpuset_sem holder.

Thanks to Nikita Danilov for the idea.

Signed-off-by: Paul Jackson <pj@sgi.com>

[ We may want to change this further, but at least it's now
  a totally internal decision to the cpusets code ]

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-12 09:16:27 -07:00
Linus Torvalds
1df5c10a5b Mark ia64-specific MCA/INIT scheduler hooks as dangerous
..and only enable them for ia64. The functions are only valid
when the whole system has been totally stopped and no scheduler
activity is ongoing on any CPU, and interrupts are globally
disabled.

In other words, they aren't useful for anything else. So make
sure that nobody can use them by mistake.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-12 07:59:21 -07:00
Keith Owens
a2a979821b [PATCH] MCA/INIT: scheduler hooks
Scheduler hooks to see/change which process is deemed to be on a cpu.

Signed-off-by: Keith Owens <kaos@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>
2005-09-11 14:01:30 -07:00
Nishanth Aravamudan
75bcc8c5e1 [PATCH] kernel: fix-up schedule_timeout() usage
Use schedule_timeout_{,un}interruptible() instead of
set_current_state()/schedule_timeout() to reduce kernel size.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:37 -07:00
Nishanth Aravamudan
64ed93a268 [PATCH] add schedule_timeout_{,un}interruptible() interfaces
Add schedule_timeout_{,un}interruptible() interfaces so that
schedule_timeout() callers don't have to worry about forgetting to add the
set_current_state() call beforehand.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:36 -07:00
Randy Dunlap
417ef53141 [PATCH] kernel/acct: add kerneldoc
for kernel/acct.c:
- fix typos
- add kerneldoc for non-static functions

Signed-off-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:26 -07:00
Siddha, Suresh B
0c117f1b4d [PATCH] sched: allow the load to grow upto its cpu_power
Don't pull tasks from a group if that would cause the group's total load to
drop below its total cpu_power (ie.  cause the group to start going idle).

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:24 -07:00
Siddha, Suresh B
fa3b6ddc3f [PATCH] sched: don't kick ALB in the presence of pinned task
Jack Steiner brought this issue at my OLS talk.

Take a scenario where two tasks are pinned to two HT threads in a physical
package.  Idle packages in the system will keep kicking migration_thread on
the busy package with out any success.

We will run into similar scenarios in the presence of CMP/NUMA.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:24 -07:00
Renaud Lienhart
5927ad78ec [PATCH] sched: use cached variable in sys_sched_yield()
In sys_sched_yield(), we cache current->array in the "array" variable, thus
there's no need to dereference "current" again later.

Signed-Off-By: Renaud Lienhart <renaud.lienhart@free.fr>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:23 -07:00
Nick Piggin
5969fe0618 [PATCH] sched: HT optimisation
If an idle sibling of an HT queue encounters a busy sibling, then make
higher level load balancing of the non-idle variety.

Performance of multiprocessor HT systems with low numbers of tasks
(generally < number of virtual CPUs) can be significantly worse than the
exact same workloads when running in non-HT mode.  The reason is largely
due to poor scheduling behaviour.

This patch improves the situation, making the performance gap far less
significant on one problematic test case (tbench).

Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:23 -07:00
Nick Piggin
e17224bf1d [PATCH] sched: less locking
During periodic load balancing, don't hold this runqueue's lock while
scanning remote runqueues, which can take a non trivial amount of time
especially on very large systems.

Holding the runqueue lock will only help to stabilise ->nr_running, however
this doesn't do much to help because tasks being woken will simply get held
up on the runqueue lock, so ->nr_running would not provide a really
accurate picture of runqueue load in that case anyway.

What's more, ->nr_running (and possibly the cpu_load averages) of remote
runqueues won't be stable anyway, so load balancing is always an inexact
operation.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:23 -07:00
Nick Piggin
d6d5cfaf45 [PATCH] sched: less newidle locking
Similarly to the earlier change in load_balance, only lock the runqueue in
load_balance_newidle if the busiest queue found has a nr_running > 1.  This
will reduce frequency of expensive remote runqueue lock aquisitions in the
schedule() path on some workloads.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:23 -07:00
Ingo Molnar
67f9a619e7 [PATCH] sched: fix SMT scheduler latency bug
William Weston reported unusually high scheduling latencies on his x86 HT
box, on the -RT kernel.  I managed to reproduce it on my HT box and the
latency tracer shows the incident in action:

                 _------=> CPU#
                / _-----=> irqs-off
               | / _----=> need-resched
               || / _---=> hardirq/softirq
               ||| / _--=> preempt-depth
               |||| /
               |||||     delay
   cmd     pid ||||| time  |   caller
      \   /    |||||   \   |   /
      du-2803  3Dnh2    0us : __trace_start_sched_wakeup (try_to_wake_up)
        ..............................................................
        ... we are running on CPU#3, PID 2778 gets woken to CPU#1: ...
        ..............................................................
      du-2803  3Dnh2    0us : __trace_start_sched_wakeup <<...>-2778> (73 1)
      du-2803  3Dnh2    0us : _raw_spin_unlock (try_to_wake_up)
        ................................................
        ... still on CPU#3, we send an IPI to CPU#1: ...
        ................................................
      du-2803  3Dnh1    0us : resched_task (try_to_wake_up)
      du-2803  3Dnh1    1us : smp_send_reschedule (try_to_wake_up)
      du-2803  3Dnh1    1us : send_IPI_mask_bitmask (smp_send_reschedule)
      du-2803  3Dnh1    2us : _raw_spin_unlock_irqrestore (try_to_wake_up)
        ...............................................
        ... 1 usec later, the IPI arrives on CPU#1: ...
        ...............................................
  <idle>-0     1Dnh.    2us : smp_reschedule_interrupt (c0100c5a 0 0)

So far so good, this is the normal wakeup/preemption mechanism.  But here
comes the scheduler anomaly on CPU#1:

  <idle>-0     1Dnh.    2us : preempt_schedule_irq (need_resched)
  <idle>-0     1Dnh.    2us : preempt_schedule_irq (need_resched)
  <idle>-0     1Dnh.    3us : __schedule (preempt_schedule_irq)
  <idle>-0     1Dnh.    3us : profile_hit (__schedule)
  <idle>-0     1Dnh1    3us : sched_clock (__schedule)
  <idle>-0     1Dnh1    4us : _raw_spin_lock_irq (__schedule)
  <idle>-0     1Dnh1    4us : _raw_spin_lock_irqsave (__schedule)
  <idle>-0     1Dnh2    5us : _raw_spin_unlock (__schedule)
  <idle>-0     1Dnh1    5us : preempt_schedule (__schedule)
  <idle>-0     1Dnh1    6us : _raw_spin_lock (__schedule)
  <idle>-0     1Dnh2    6us : find_next_bit (__schedule)
  <idle>-0     1Dnh2    6us : _raw_spin_lock (__schedule)
  <idle>-0     1Dnh3    7us : find_next_bit (__schedule)
  <idle>-0     1Dnh3    7us : find_next_bit (__schedule)
  <idle>-0     1Dnh3    8us : _raw_spin_unlock (__schedule)
  <idle>-0     1Dnh2    8us : preempt_schedule (__schedule)
  <idle>-0     1Dnh2    8us : find_next_bit (__schedule)
  <idle>-0     1Dnh2    9us : trace_stop_sched_switched (__schedule)
  <idle>-0     1Dnh2    9us : _raw_spin_lock (trace_stop_sched_switched)
  <idle>-0     1Dnh3   10us : trace_stop_sched_switched <<...>-2778> (73 8c)
  <idle>-0     1Dnh3   10us : _raw_spin_unlock (trace_stop_sched_switched)
  <idle>-0     1Dnh1   10us : _raw_spin_unlock (__schedule)
  <idle>-0     1Dnh.   11us : local_irq_enable_noresched (preempt_schedule_irq)
  <idle>-0     1Dnh.   11us < (0)

we didnt pick up pid 2778! It only gets scheduled much later:

   <...>-2778  1Dnh2  412us : __switch_to (__schedule)
   <...>-2778  1Dnh2  413us : __schedule <<idle>-0> (8c 73)
   <...>-2778  1Dnh2  413us : _raw_spin_unlock (__schedule)
   <...>-2778  1Dnh1  413us : trace_stop_sched_switched (__schedule)
   <...>-2778  1Dnh1  414us : _raw_spin_lock (trace_stop_sched_switched)
   <...>-2778  1Dnh2  414us : trace_stop_sched_switched <<...>-2778> (73 1)
   <...>-2778  1Dnh2  414us : _raw_spin_unlock (trace_stop_sched_switched)
   <...>-2778  1Dnh1  415us : trace_stop_sched_switched (__schedule)

the reason for this anomaly is the following code in dependent_sleeper():

                /*
                 * If a user task with lower static priority than the
                 * running task on the SMT sibling is trying to schedule,
                 * delay it till there is proportionately less timeslice
                 * left of the sibling task to prevent a lower priority
                 * task from using an unfair proportion of the
                 * physical cpu's resources. -ck
                 */
[...]
                        if (((smt_curr->time_slice * (100 - sd->per_cpu_gain) /
                                100) > task_timeslice(p)))
                                        ret = 1;

Note that in contrast to the comment above, we dont actually do the check
based on static priority, we do the check based on timeslices.  But
timeslices go up and down, and even highprio tasks can randomly have very
low timeslices (just before their next refill) and can thus be judged as
'lowprio' by the above piece of code.  This condition is clearly buggy.
The correct test is to check for static_prio _and_ to check for the
preemption priority.  Even on different static priority levels, a
higher-prio interactive task should not be delayed due to a
higher-static-prio CPU hog.

There is a symmetric bug in the 'kick SMT sibling' code of this function as
well, which can be solved in a similar way.

The patch below (against the current scheduler queue in -mm) fixes both
bugs.  I have build and boot-tested this on x86 SMT, and nice +20 tasks
still get properly throttled - so the dependent-sleeper logic is still in
action.

btw., these bugs pessimised the SMT scheduler because the 'delay wakeup'
property was applied too liberally, so this fix is likely a throughput
improvement as well.

I separated out a smt_slice() function to make the code easier to read.

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:23 -07:00
Ingo Molnar
d79fc0fc66 [PATCH] sched: TASK_NONINTERACTIVE
This patch implements a task state bit (TASK_NONINTERACTIVE), which can be
used by blocking points to mark the task's wait as "non-interactive".  This
does not mean the task will be considered a CPU-hog - the wait will simply
not have an effect on the waiting task's priority - positive or negative
alike.  Right now only pipe_wait() will make use of it, because it's a
common source of not-so-interactive waits (kernel compilation jobs, etc.).

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:22 -07:00
Ingo Molnar
95cdf3b799 [PATCH] sched cleanups
whitespace cleanups.

Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:22 -07:00