The bug is ancient.

If we trace the sub-thread of our natural child and this sub-thread exits,
we update parent->signal->cxxx fields.  But we should not do this until
the whole thread-group exits, otherwise we account this thread (and all
other live threads) twice.

Add the task_detached() check.  No need to check thread_group_empty(),
wait_consider_task()->delay_group_leader() already did this.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NRoland McGrath <roland@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Vitaly Mayatskikh <vmayatsk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Enable gcov profiling of the entire kernel on x86_64. Required changes
include disabling profiling for:

* arch/kernel/acpi/realmode and arch/kernel/boot/compressed:
  not linked to main kernel
* arch/vdso, arch/kernel/vsyscall_64 and arch/kernel/hpet:
  profiling causes segfaults during boot (incompatible context)
Signed-off-by: NPeter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Li Wei <W.Li@Sun.COM>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Enable the use of GCC's coverage testing tool gcov [1] with the Linux
kernel.  gcov may be useful for:

 * debugging (has this code been reached at all?)
 * test improvement (how do I change my test to cover these lines?)
 * minimizing kernel configurations (do I need this option if the
   associated code is never run?)

The profiling patch incorporates the following changes:

 * change kbuild to include profiling flags
 * provide functions needed by profiling code
 * present profiling data as files in debugfs

Note that on some architectures, enabling gcc's profiling option
"-fprofile-arcs" for the entire kernel may trigger compile/link/
run-time problems, some of which are caused by toolchain bugs and
others which require adjustment of architecture code.

For this reason profiling the entire kernel is initially restricted
to those architectures for which it is known to work without changes.
This restriction can be lifted once an architecture has been tested
and found compatible with gcc's profiling. Profiling of single files
or directories is still available on all platforms (see config help
text).

[1] http://gcc.gnu.org/onlinedocs/gcc/Gcov.htmlSigned-off-by: NPeter Oberparleiter <oberpar@linux.vnet.ibm.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Li Wei <W.Li@Sun.COM>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: WANG Cong <xiyou.wangcong@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Call constructors (gcc-generated initcall-like functions) during kernel
start and module load.  Constructors are e.g.  used for gcov data
initialization.

Disable constructor support for usermode Linux to prevent conflicts with
host glibc.
Signed-off-by: NPeter Oberparleiter <oberpar@linux.vnet.ibm.com>
Acked-by: NRusty Russell <rusty@rustcorp.com.au>
Acked-by: NWANG Cong <xiyou.wangcong@gmail.com>
Cc: Sam Ravnborg <sam@ravnborg.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Huang Ying <ying.huang@intel.com>
Cc: Li Wei <W.Li@Sun.COM>
Cc: Michael Ellerman <michaele@au1.ibm.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Heiko Carstens <heicars2@linux.vnet.ibm.com>
Cc: Martin Schwidefsky <mschwid2@linux.vnet.ibm.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

clone_nsproxy() does useless copying of old nsproxy -- every pointer will
be rewritten to new ns or to old ns.  Remove copying, rename
clone_nsproxy(), create_nsproxy() will be used by C/R code to create fresh
nsproxy on restart.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

create_uts_ns() will be used by C/R to create fresh uts_ns.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

copy_pid_ns() is a perfect example of a case where unwinding leads to more
code and makes it less clear.  Watch the diffstat.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Reviewed-by: NSerge Hallyn <serue@us.ibm.com>
Acked-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Reviewed-by: NWANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

create_pid_namespace() creates everything, but caller has to assign parent
pidns by hand, which is unnatural.  At the moment of call new ->level has
to be taken from somewhere and parent pidns is already available.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Acked-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Reviewed-by: NWANG Cong <xiyou.wangcong@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

find_task_by_pid_type_ns is only used to implement find_task_by_vpid and
find_task_by_pid_ns, but both of them pass PIDTYPE_PID as first argument.
So just fold find_task_by_pid_type_ns into find_task_by_pid_ns and use
find_task_by_pid_ns to implement find_task_by_vpid.

While we're at it also remove the exports for find_task_by_pid_ns and
find_task_by_vpid - we don't have any modular callers left as the only
modular caller of he old pre pid namespace find_task_by_pid (gfs2) was
switched to pid_task which operates on a struct pid pointer instead of a
pid_t.  Given the confusion about pid_t values vs namespace that's
generally the better option anyway and I think we're better of restricting
modules to do it that way.
Signed-off-by: NChristoph Hellwig <hch@lst.de>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remoce the unused variable 'val' from __do_proc_dointvec()

The integer has been declared and used as 'val = -val' and there is no
reference to it anywhere.
Signed-off-by: NSukanto Ghosh <sukanto.cse.iitb@gmail.com>
Cc: Jaswinder Singh Rajput <jaswinder@kernel.org>
Cc: Sukanto Ghosh <sukanto.cse.iitb@gmail.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Now that kthread_stop() can be used even if the task has already exited,
we can kill the "wait_to_die:" loop in migration_thread().  But we must
pin rq->migration_thread after creation.

Actually, I don't think CPU_UP_CANCELED or CPU_DEAD should wait for
->migration_thread exit.  Perhaps we can simplify this code a bit more.
migration_call() can set ->should_stop and forget about this thread.  But
we need a new helper in kthred.c for that.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Vitaliy Gusev <vgusev@openvz.org
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Based on Eric's patch which in turn was based on my patch.

kthread_stop() has the nasty problems:

- it runs unpredictably long with the global semaphore held.

- it deadlocks if kthread itself does kthread_stop() before it obeys
  the kthread_should_stop() request.

- it is not useable if kthread exits on its own, see for example the
  ugly "wait_to_die:" hack in migration_thread()

- it is not possible to just tell kthread it should stop, we must always
  wait for its exit.

With this patch kthread() allocates all neccesary data (struct kthread) on
its own stack, globals kthread_stop_xxx are deleted.  ->vfork_done is used
as a pointer into "struct kthread", this means kthread_stop() can easily
wait for kthread's exit.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Vitaliy Gusev <vgusev@openvz.org
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We use two completions two create the kernel thread, this is a bit ugly.
kthread() wakes up create_kthread() via ->started, then create_kthread()
wakes up the caller kthread_create() via ->done.  But kthread() does not
need to wait for kthread(), it can just return.  Instead kthread() itself
can wake up the caller of kthread_create().

Kill kthread_create_info->started, ->done is enough.  This improves the
scalability a bit and sijmplifies the code.

The only problem if kernel_thread() fails, in that case create_kthread()
must do complete(&create->done).
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Christoph Hellwig <hch@lst.de>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Vitaliy Gusev <vgusev@openvz.org
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Reorder struct wait_opts to remove 8 bytes of alignment padding on 64 bit
builds.
Signed-off-by: NRichard Kennedy <richard@rsk.demon.co.uk>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

do_wait:

	current->state = TASK_INTERRUPTIBLE;

	read_lock(&tasklist_lock);
	... search for the task to reap ...

In theory, the ->state changing can leak into the critical section.  Since
the child can change its status under read_lock(tasklist) in parallel
(finish_stop/ptrace_stop), we can miss the wakeup if __wake_up_parent()
sees us in TASK_RUNNING state.  Add the barrier.

Also, use __set_current_state() to set TASK_RUNNING.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

do_wait() does BUG_ON(tsk->signal != current->signal), this looks like a
raher obsolete check.  At least, I don't think do_wait() is the best place
to verify that all threads have the same ->signal.  Remove it.

Also, change the code to use while_each_thread().
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Now that we don't pass &retval down to other helpers we can simplify
the code more.

- kill tsk_result, just use retval

- add the "notask" label right after the main loop, and
  s/got end/goto notask/ after the fastpath pid check.

  This way we don't need to initialize retval before this
  check and the code becomes a bit more clean, if this pid
  has no attached tasks we should just skip the list search.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Introduce "struct wait_opts" which holds the parameters for misc helpers
in do_wait() pathes.

This adds 13 lines to kernel/exit.c, but saves 256 bytes from .o and imho
makes the code much more readable.

This patch temporary uglifies rusage/siginfo code a little bit, will be
addressed by further cleanups.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Reviewed-by: NIngo Molnar <mingo@elte.hu>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

No functional changes, preparation for the next patch.

ptrace_do_wait() adds WUNTRACED to options for wait_task_stopped() which
should always accept the stopped tracee, even if do_wait() was called
without WUNTRACED.

Change wait_task_stopped() to check "ptrace || WUNTRACED" instead.  This
makes the code more explicit, and "int options" argument becomes const in
do_wait() pathes.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The forked child can have TIF_SIGPENDING if it was copied from parent's
ti->flags.  But this is harmless and actually almost never happens,
because copy_process() can't succeed if signal_pending() == T.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

There is no reason for thread_group_cputime() in wait_task_zombie(), there
must be no other threads.

This call was previously needed to collect the per-cpu data which we do
not have any longer.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NRoland McGrath <roland@redhat.com>
Cc: Stanislaw Gruszka <sgruszka@redhat.com>
Cc: Vitaly Mayatskikh <vmayatsk@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change ptrace_getsiginfo/ptrace_setsiginfo to use lock_task_sighand()
without tasklist_lock.  Perhaps it makes sense to make a single helper
with "bool rw" argument.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If the non-traced sub-thread calls do_notify_parent_cldstop(), we send the
notification to group_leader->real_parent and we report group_leader's
pid.

But, if group_leader is traced we use the wrong ->parent->nsproxy->pid_ns,
the tracer and parent can live in different namespaces.  Change the code
to use "parent" instead of tsk->parent.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Acked-by: NSukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Change wait_task_zombie() to use ->real_parent instead of ->parent.  We
could even use current afaics, but ->real_parent is more clean.

We know that the child is not ptrace_reparented() and thus they are equal.
 But we should avoid using task_struct->parent, we are going to remove it.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

- Use rcu_read_lock() instead of tasklist_lock to find/get the task
  in ptrace_get_task_struct().

- Make it static, it has no callers outside of ptrace.c.

- The comment doesn't match the reality, this helper does not do
  any checks. Beacuse it is really trivial and static I removed the
  whole comment.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove the "Nasty, nasty" lock dance in ptrace_attach()/ptrace_traceme() -
from now task_lock() has nothing to do with ptrace at all.

With the recent changes nobody uses task_lock() to serialize with ptrace,
but in fact it was never needed and it was never used consistently.

However ptrace_attach() calls __ptrace_may_access() and needs task_lock()
to pin task->mm for get_dumpable().  But we can call __ptrace_may_access()
before we take tasklist_lock, ->cred_exec_mutex protects us against
do_execve() path which can change creds and MMF_DUMP* flags.

(ugly, but we can't use ptrace_may_access() because it hides the error
code, so we have to take task_lock() and use __ptrace_may_access()).

NOTE: this change assumes that LSM hooks, security_ptrace_may_access() and
security_ptrace_traceme(), can be called without task_lock() held.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

ptrace_attach() and ptrace_traceme() are the last functions which look as
if the untraced task can have task->ptrace != 0, this must not be
possible.  Change the code to just check ->ptrace != 0 and s/|=/=/ to set
PT_PTRACED.

Also, a couple of trivial whitespace cleanups in ptrace_attach().

And move ptrace_traceme() up near ptrace_attach() to keep them close to
each other.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

- Add PF_KTHREAD check to prevent attaching to the kernel thread
  with a borrowed ->mm.

  With or without this change we can race with daemonize() which
  can set PF_KTHREAD or clear ->mm after ptrace_attach() does the
  check, but this doesn't matter because reparent_to_kthreadd()
  does ptrace_unlink().

- Kill "!task->mm" check. We don't really care about ->mm != NULL,
  and the task can call exit_mm() right after we drop task_lock().
  What we need is to make sure we can't attach after exit_notify(),
  check task->exit_state != 0 instead.

Also, move the "already traced" check down for cosmetic reasons.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Chris Wright <chrisw@sous-sol.org>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

No functional changes.

- Nobody except ptrace.c & co should use ptrace flags directly, we have
  task_ptrace() for that.

- No need to specially check PT_PTRACED, we must not have other PT_ bits
  set without PT_PTRACED. And no need to know this flag exists.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

"Search in the siblings" should use ->real_parent, not ->parent.  If the
task is traced then ->parent == tracer, while the task's parent is always
->real_parent.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

allow_signal() checks ->mm == NULL.  Not sure why.  Perhaps to make sure
current is the kernel thread.  But this helper must not be used unless we
are the kernel thread, kill this check.

Also, document the fact that the CLONE_SIGHAND kthread must not use
allow_signal(), unless the caller really wants to change the parent's
->sighand->action as well.
Signed-off-by: NOleg Nesterov <oleg@redhat.com>
Acked-by: NRoland McGrath <roland@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We don't have an interface to reset mem.limit or memsw.limit now.

This patch allows to reset mem.limit or memsw.limit when they are being
set to -1.
Signed-off-by: NDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Cc: YAMAMOTO Takashi <yamamoto@valinux.co.jp>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The 'noprefix' option was introduced for backwards-compatibility of
cpuset, but actually it can be used when mounting other subsystems.

This results in possibility of name collision, and now the collision can
really happen, because we have 'stat' file in both memory and cpuacct
subsystem:

	# mount -t cgroup -o noprefix,memory,cpuacct xxx /mnt

Cgroup will happily mount the 2 subsystems, but only 'stat' file of memory
subsys can be seen.

We don't want users to use nopreifx, and also want to avoid name
collision, so we change to allow noprefix only if mounting just the cpuset
subsystem.

[akpm@linux-foundation.org: fix shift for cpuset_subsys_id >= 32]
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Acked-by: NKAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Acked-by: NDhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Statistics for softirq doesn't exist.
It will be helpful like statistics for interrupts.
This patch introduces counting the number of softirq,
which will be exported in /proc/softirqs.

When softirq handler consumes much CPU time,
/proc/stat is like the following.

$ while :; do  cat /proc/stat | head -n1 ; sleep 10 ; done
cpu  88 0 408 739665 583 28 2 0 0
cpu  450 0 1090 740970 594 28 1294 0 0
                              ^^^^
                             softirq

In such a situation,
/proc/softirqs shows us which softirq handler is invoked.
We can see the increase rate of softirqs.

<before>
$ cat /proc/softirqs
                CPU0       CPU1       CPU2       CPU3
HI                 0          0          0          0
TIMER         462850     462805     462782     462718
NET_TX             0          0          0        365
NET_RX          2472          2          2         40
BLOCK              0          0        381       1164
TASKLET            0          0          0        224
SCHED         462654     462689     462698     462427
RCU             3046       2423       3367       3173

<after>
$ cat /proc/softirqs
                CPU0       CPU1       CPU2       CPU3
HI                 0          0          0          0
TIMER         463361     465077     465056     464991
NET_TX            53          0          1        365
NET_RX          3757          2          2         40
BLOCK              0          0        398       1170
TASKLET            0          0          0        224
SCHED         463074     464318     464612     463330
RCU             3505       2948       3947       3673

When CPU TIME of softirq is high,
the rates of increase is the following.
  TIMER  : 220/sec     : CPU1-3
  NET_TX : 5/sec       : CPU0
  NET_RX : 120/sec     : CPU0
  SCHED  : 40-200/sec  : all CPU
  RCU    : 45-58/sec   : all CPU

The rates of increase in an idle mode is the following.
  TIMER  : 250/sec
  SCHED  : 250/sec
  RCU    : 2/sec

It seems many softirqs for receiving packets and rcu are invoked.  This
gives us help for checking system.
Signed-off-by: NKeika Kobayashi <kobayashi.kk@ncos.nec.co.jp>
Reviewed-by: NHiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Round the slow work queue's cull and OOM timeouts to whole second boundary
with round_jiffies().  The slow work queue uses a pair of timers to cull
idle threads and, after OOM, to delay new thread creation.

This patch also extracts the mod_timer() logic for the cull timer into a
separate helper function.

By rounding non-time-critical timers such as these to whole seconds, they
will be batched up to fire at the same time rather than being spread out.
This allows the CPU wake up less, which saves power.
Signed-off-by: NChris Peterson <cpeterso@cpeterso.com>
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Move supplementary groups implementation to kernel/groups.c .
kernel/sys.c already accumulated quite a few random stuff.

Do strictly copy/paste + add required headers to compile.  Compile-tested
on many configs and archs.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NRobert P. J. Day <rpjday@crashcourse.ca>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, nobody wants to turn UNEVICTABLE_LRU off.  Thus this
configurability is unnecessary.
Signed-off-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andi Kleen <andi@firstfloor.org>
Acked-by: NMinchan Kim <minchan.kim@gmail.com>
Cc: David Woodhouse <dwmw2@infradead.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, the following scenario appears to be possible in theory:

* Tasks are frozen for hibernation or suspend.
* Free pages are almost exhausted.
* Certain piece of code in the suspend code path attempts to allocate
  some memory using GFP_KERNEL and allocation order less than or
  equal to PAGE_ALLOC_COSTLY_ORDER.
* __alloc_pages_internal() cannot find a free page so it invokes the
  OOM killer.
* The OOM killer attempts to kill a task, but the task is frozen, so
  it doesn't die immediately.
* __alloc_pages_internal() jumps to 'restart', unsuccessfully tries
  to find a free page and invokes the OOM killer.
* No progress can be made.

Although it is now hard to trigger during hibernation due to the memory
shrinking carried out by the hibernation code, it is theoretically
possible to trigger during suspend after the memory shrinking has been
removed from that code path.  Moreover, since memory allocations are
going to be used for the hibernation memory shrinking, it will be even
more likely to happen during hibernation.

To prevent it from happening, introduce the oom_killer_disabled switch
that will cause __alloc_pages_internal() to fail in the situations in
which the OOM killer would have been called and make the freezer set
this switch after tasks have been successfully frozen.

[akpm@linux-foundation.org: be nicer to the namespace]
Signed-off-by: NRafael J. Wysocki <rjw@sisk.pl>
Cc: Fengguang Wu <fengguang.wu@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Acked-by: NPavel Machek <pavel@ucw.cz>
Cc: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Callers of alloc_pages_node() can optionally specify -1 as a node to mean
"allocate from the current node".  However, a number of the callers in
fast paths know for a fact their node is valid.  To avoid a comparison and
branch, this patch adds alloc_pages_exact_node() that only checks the nid
with VM_BUG_ON().  Callers that know their node is valid are then
converted.
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Reviewed-by: NChristoph Lameter <cl@linux-foundation.org>
Reviewed-by: NKOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: NPekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Paul Mundt <lethal@linux-sh.org>	[for the SLOB NUMA bits]
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Dave Hansen <dave@linux.vnet.ibm.com>
Cc: Lee Schermerhorn <Lee.Schermerhorn@hp.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>