Commit Graph

139711 Commits

Author SHA1 Message Date
Oleg Nesterov
1b0f7ffd0e pids: kill signal_struct-> __pgrp/__session and friends
We are wasting 2 words in signal_struct without any reason to implement
task_pgrp_nr() and task_session_nr().

task_session_nr() has no callers since
2e2ba22ea4, we can remove it.

task_pgrp_nr() is still (I believe wrongly) used in fs/autofsX and
fs/coda.

This patch reimplements task_pgrp_nr() via task_pgrp_nr_ns(), and kills
__pgrp/__session and the related helpers.

The change in drivers/char/tty_io.c is cosmetic, but hopefully makes sense
anyway.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Acked-by: Alan Cox <number6@the-village.bc.nu>		[tty parts]
Cc: Cedric Le Goater <clg@fr.ibm.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Serge Hallyn <serue@us.ibm.com>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:02 -07:00
Oleg Nesterov
52ee2dfdd4 pids: refactor vnr/nr_ns helpers to make them safe
Inho, the safety rules for vnr/nr_ns helpers are horrible and buggy.

task_pid_nr_ns(task) needs rcu/tasklist depending on task == current.

As for "special" pids, vnr/nr_ns helpers always need rcu.  However, if
task != current, they are unsafe even under rcu lock, we can't trust
task->group_leader without the special checks.

And almost every helper has a callsite which needs a fix.

Also, it is a bit annoying that the implementations of, say,
task_pgrp_vnr() and task_pgrp_nr_ns() are not "symmetrical".

This patch introduces the new helper, __task_pid_nr_ns(), which is always
safe to use, and turns all other helpers into the trivial wrappers.

After this I'll send another patch which converts task_tgid_xxx() as well,
they're are a bit special.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:02 -07:00
Oleg Nesterov
2ae448efc8 pids: improve get_task_pid() to fix the unsafe sys_wait4()->task_pgrp()
sys_wait4() does get_pid(task_pgrp(current)), this is not safe.  We can
add rcu lock/unlock around, but we already have get_task_pid() which can
be improved to handle the special pids in more reliable manner.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:02 -07:00
Oleg Nesterov
6dda81f438 pids: document task_pgrp/task_session is not safe without tasklist/rcu
Even if task == current, it is not safe to dereference the result of
task_pgrp/task_session.  We can race with another thread which changes the
special pid via setpgid/setsid.

Document this.  The next 2 patches give an example of the unsafe usage, we
have more bad users.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Louis Rilling <Louis.Rilling@kerlabs.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:02 -07:00
Matthew Wilcox
8e654fba4a sysctl: fix suid_dumpable and lease-break-time sysctls
Arne de Bruijn points out that commit
76fdbb25f9 ("coredump masking: bound
suid_dumpable sysctl") mistakenly limits lease-break-time instead of
suid_dumpable.

Signed-off-by: Matthew Wilcox <matthew@wil.cx>
Reported-by: Arne de Bruijn <kernelbt@arbruijn.dds.nl>
Cc: Kawai, Hidehiro <hidehiro.kawai.ez@hitachi.com>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:01 -07:00
Yasunori Goto
303d379c54 hpet: fix the possibility of insane return value of hpet_calibrate() against SMI
hpet_calibrate() has a possibility of miss-calibration due to SMI.  If SMI
interrupts in the while loop of calibration, then return value will be
big.  This change calibrates until stabilizing by the return value with a
small value.

[akpm@linux-foundation.org: trivial style tweaks]
Signed-off-by: Yasunori Goto <y-goto@jp.fujitsu.com>
Acked-by: Clemens Ladisch <clemens@ladisch.de>
Acked-by: Vojtech Pavlik <vojtech@suse.cz>
Cc: Robert Picco <Robert.Picco@hp.com>
Cc: Venkatesh Pallipadi <venkatesh.pallipadi@intel.com>
Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:01 -07:00
Paul Fulghum
1f80769ffd synclink_gt: add clock options
Add support for x8 asynchronous sample rate and ability to specify base
clock frequency.

Signed-off-by: Paul Fulghum <paulkf@microgate.com>
Acked-by: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:01 -07:00
Kirill A. Shutemov
a50b0aa4bd struct linux_binprm: drop unused fields
Signed-off-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:01 -07:00
Mike Frysinger
ab4ad55512 bin_elf_fdpic: check the return value of clear_user
Signed-off-by: Mike Frysinger <vapier.adi@gmail.com>
Signed-off-by: Bryan Wu <cooloney@kernel.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Greg Ungerer <gerg@snapgear.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:01 -07:00
Serge E. Hallyn
11dea19009 proc_sysctl: use CONFIG_PROC_SYSCTL around ipc and utsname proc_handlers
As pointed out by Cedric Le Goater (in response to Alexey's original
comment wrt mqns), ipc_sysctl.c and utsname_sysctl.c are using
CONFIG_PROC_FS, not CONFIG_PROC_SYSCTL, to determine whether to define
the proc_handlers.  Change that.

Signed-off-by: Serge E. Hallyn <serue@us.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Acked-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:01 -07:00
Tony Battersby
e562aebc6c ipc: make shm_get_stat() more robust
shm_get_stat() assumes idr_find(&shm_ids(ns).ipcs_idr) returns "struct
shmid_kernel *"; all other callers assume that it returns "struct
kern_ipc_perm *".  This works because "struct kern_ipc_perm" is currently
the first member of "struct shmid_kernel", but it would be better to use
container_of() to prevent future breakage.

Signed-off-by: Tony Battersby <tonyb@cybernetics.com>
Cc: Jiri Olsa <olsajiri@gmail.com>
Cc: Jiri Kosina <jkosina@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:01 -07:00
Lai Jiangshan
40e8a10de2 cpu hotplug: remove unused cpuhotplug_mutex_lock()
cpuhotplug_mutex_lock() is not used, remove it.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Acked-by: Gautham R Shenoy <ego@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:00 -07:00
Lai Jiangshan
2355b70fd5 workqueue: avoid recursion in run_workqueue()
1) lockdep will complain when run_workqueue() performs recursion.

2) The recursive implementation of run_workqueue() means that
   flush_workqueue() and its documentation are inconsistent.  This may
   hide deadlocks and other bugs.

3) The recursion in run_workqueue() will poison cwq->current_work, but
   flush_work() and __cancel_work_timer(), etcetera need a reliable
   cwq->current_work.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:00 -07:00
Oleg Nesterov
1ee1184485 ptrace_untrace: fix the SIGNAL_STOP_STOPPED check
This bug is ancient too. ptrace_untrace() must not resume the task
if the group stop in progress, we should set TASK_STOPPED instead.

Unfortunately, we still have problems here:

	- if the process/thread was traced, SIGNAL_STOP_STOPPED
	  does not necessary means this thread group is stopped.

	- ptrace breaks the bookkeeping of ->group_stop_count.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:00 -07:00
Oleg Nesterov
95a3540da9 ptrace_detach: the wrong wakeup breaks the ERESTARTxxx logic
Another ancient bug. Consider this trivial test-case,

	int main(void)
	{
		int pid = fork();

		if (pid) {
			ptrace(PTRACE_ATTACH, pid, NULL, NULL);
			wait(NULL);
			ptrace(PTRACE_DETACH, pid, NULL, NULL);
		} else {
			pause();
			printf("WE HAVE A KERNEL BUG!!!\n");
		}

		return 0;
	}

the child must not "escape" for sys_pause(), but it can and this was seen
in practice.

This is because ptrace_detach does:

	if (!child->exit_state)
		wake_up_process(child);

this wakeup can happen after this child has already restarted sys_pause(),
because it gets another wakeup from ptrace_untrace().

With or without this patch, perhaps sys_pause() needs a fix.  But this
wakeup also breaks the SIGNAL_STOP_STOPPED logic in ptrace_untrace().

Remove this wakeup.  The caller saw this task in TASK_TRACED state, and
unless it was SIGKILL'ed in between __ptrace_unlink()->ptrace_untrace()
should handle this case correctly.  If it was SIGKILL'ed, we don't need to
wakup the dying tracee too.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Roland McGrath <roland@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:00 -07:00
Oleg Nesterov
bb24c679a5 tracehook_notify_death: use task_detached() helper
Now that task_detached() is exported, change tracehook_notify_death() to
use this helper, nobody else checks ->exit_signal == -1 by hand.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Metzger, Markus T" <markus.t.metzger@intel.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:00 -07:00
Oleg Nesterov
5dfc80be73 forget_original_parent: do not abuse child->ptrace_entry
By discussion with Roland.

- Use ->sibling instead of ->ptrace_entry to chain the need to be
  release_task'd childs. Nobody else can use ->sibling, this task
  is EXIT_DEAD and nobody can find it on its own list.

- rename ptrace_dead to dead_childs.

- Now that we don't have the "parallel" untrace code, change back
  reparent_thread() to return void, pass dead_childs as an argument.

Actually, I don't understand why do we notify /sbin/init when we
reparent a zombie, probably it is better to reap it unconditionally.

[akpm@linux-foundation.org: s/childs/children/]
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Metzger, Markus T" <markus.t.metzger@intel.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:00 -07:00
Oleg Nesterov
39c626ae47 forget_original_parent: split out the un-ptrace part
By discussion with Roland.

- Rename ptrace_exit() to exit_ptrace(), and change it to do all the
  necessary work with ->ptraced list by its own.

- Move this code from exit.c to ptrace.c

- Update the comment in ptrace_detach() to explain the rechecking of
  the child->ptrace.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: "Metzger, Markus T" <markus.t.metzger@intel.com>
Cc: Roland McGrath <roland@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:05:00 -07:00
Oleg Nesterov
7f5d3652d4 reparent_thread: fix a zombie leak if /sbin/init ignores SIGCHLD
If /sbin/init ignores SIGCHLD and we re-parent a zombie, it is leaked.
reparent_thread() does do_notify_parent() which sets ->exit_signal = -1 in
this case.  This means that nobody except us can reap it, the detached
task is not visible to do_wait().

Change reparent_thread() to return a boolean (like __pthread_detach) to
indicate that the thread is dead and must be released.  Also change
forget_original_parent() to add the child to ptrace_dead list in this
case.

The naming becomes insane, the next patch does the cleanup.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:59 -07:00
Oleg Nesterov
b1442b055c reparent_thread: fix the "is it traced" check
reparent_thread() uses ptrace_reparented() to check whether this thread is
ptraced, in that case we should not notify the new parent.

But ptrace_reparented() is not exactly correct when the reparented thread
is traced by /sbin/init, because forget_original_parent() has already
changed ->real_parent.

Currently, the only problem is the false notification.  But with the next
patch the kernel crash in this (yes, pathological) case.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:59 -07:00
Oleg Nesterov
0a967a044a reparent_thread: don't call kill_orphaned_pgrp() if task_detached()
If task_detached(p) == T, then either

  a) p is not the main thread, we will find the group leader on the
     ->children list.

or

  b) p is the group leader but its ->exit_state = EXIT_DEAD.  This
     can only happen when the last sub-thread has died, but in that case
     that thread has already called kill_orphaned_pgrp() from
     exit_notify().

In both cases kill_orphaned_pgrp() looks bogus.

Move the task_detached() check up and simplify the code, this is also
right from the "common sense" pov: we should do nothing with the detached
childs, except move them to the new parent's ->children list.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:59 -07:00
Oleg Nesterov
4576145c1e ptrace: fix possible zombie leak on PTRACE_DETACH
When ptrace_detach() takes tasklist, the tracee can be SIGKILL'ed.  If it
has already passed exit_notify() we can leak a zombie, because a) ptracing
disables the auto-reaping logic, and b) ->real_parent was not notified
about the child's death.

ptrace_detach() should follow the ptrace_exit's logic, change the code
accordingly.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Tested-by: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:59 -07:00
Oleg Nesterov
b1b4c6799f ptrace: reintroduce __ptrace_detach() as a callee of ptrace_exit()
No functional changes, preparation for the next patch.

Move the "should we release this child" logic into the separate handler,
__ptrace_detach().

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:59 -07:00
Oleg Nesterov
6d69cb87f0 ptrace: simplify ptrace_exit()->ignoring_children() path
ignoring_children() takes parent->sighand->siglock and checks
k_sigaction[SIGCHLD] atomically.  But this buys nothing, we can't get the
"really" wrong result even if we race with sigaction(SIGCHLD).  If we read
the "stale" sa_handler/sa_flags we can pretend it was changed right after
the check.

Remove spin_lock(->siglock), and kill "int ign" which caches the result of
ignoring_children() which becomes rather trivial.

Perhaps it makes sense to export this helper, do_notify_parent() can use
it too.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:59 -07:00
Oleg Nesterov
95c3eb76dc ptrace: kill __ptrace_detach(), fix ->exit_state check
Move the code from __ptrace_detach() to its single caller and kill this
helper.

Also, fix the ->exit_state check, we shouldn't wake up EXIT_DEAD tasks.
Actually, I think task_is_stopped_or_traced() makes more sense, but this
needs another patch.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:59 -07:00
Sukadev Bhattiprolu
6588c1e3ff signals: SI_USER: Masquerade si_pid when crossing pid ns boundary
When sending a signal to a descendant namespace, set ->si_pid to 0 since
the sender does not have a pid in the receiver's namespace.

Note:
	- If rt_sigqueueinfo() sets si_code to SI_USER when sending a
	  signal across a pid namespace boundary, the value in ->si_pid
	  will be cleared to 0.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:58 -07:00
Sukadev Bhattiprolu
b3bfa0cba8 signals: protect cinit from blocked fatal signals
Normally SIG_DFL signals to global and container-init are dropped early.
But if a signal is blocked when it is posted, we cannot drop the signal
since the receiver may install a handler before unblocking the signal.
Once this signal is queued however, the receiver container-init has no way
of knowing if the signal was sent from an ancestor or descendant
namespace.  This patch ensures that contianer-init drops all SIG_DFL
signals in get_signal_to_deliver() except SIGKILL/SIGSTOP.

If SIGSTOP/SIGKILL originate from a descendant of container-init they are
never queued (i.e dropped in sig_ignored() in an earler patch).

If SIGSTOP/SIGKILL originate from parent namespace, the signal is queued
and container-init processes the signal.

IOW, if get_signal_to_deliver() sees a sig_kernel_only() signal for global
or container-init, the signal must have been generated internally or must
have come from an ancestor ns and we process the signal.

Further, the signal_group_exit() check was needed to cover the case of a
multi-threaded init sending SIGKILL to other threads when doing an exit()
or exec().  But since the new sig_kernel_only() check covers the SIGKILL,
the signal_group_exit() check is no longer needed and can be removed.

Finally, now that we have all pieces in place, set SIGNAL_UNKILLABLE for
container-inits.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:58 -07:00
Sukadev Bhattiprolu
e4da026f98 signals: zap_pid_ns_process() should use force_sig()
send_signal() assumes that signals with SEND_SIG_PRIV are generated from
within the same namespace.  So any nested container-init processes become
immune to the SIGKILL generated by kill_proc_info() in
zap_pid_ns_processes().

Use force_sig() in zap_pid_ns_processes() instead - force_sig() clears the
SIGNAL_UNKILLABLE flag ensuring the signal is processed by
container-inits.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:58 -07:00
Sukadev Bhattiprolu
921cf9f630 signals: protect cinit from unblocked SIG_DFL signals
Drop early any SIG_DFL or SIG_IGN signals to container-init from within
the same container.  But queue SIGSTOP and SIGKILL to the container-init
if they are from an ancestor container.

Blocked, fatal signals (i.e when SIG_DFL is to terminate) from within the
container can still terminate the container-init.  That will be addressed
in the next patch.

Note:	To be bisect-safe, SIGNAL_UNKILLABLE will be set for container-inits
   	in a follow-on patch. Until then, this patch is just a preparatory
	step.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:58 -07:00
Sukadev Bhattiprolu
7978b567d3 signals: add from_ancestor_ns parameter to send_signal()
send_signal() (or its helper) needs to determine the pid namespace of the
sender.  But a signal sent via kill_pid_info_as_uid() comes from within
the kernel and send_signal() does not need to determine the pid namespace
of the sender.  So define a helper for send_signal() which takes an
additional parameter, 'from_ancestor_ns' and have kill_pid_info_as_uid()
use that helper directly.

The 'from_ancestor_ns' parameter will be used in a follow-on patch.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Roland McGrath <roland@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:58 -07:00
Oleg Nesterov
f008faff0e signals: protect init from unwanted signals more
(This is a modified version of the patch submitted by Oleg Nesterov
http://lkml.org/lkml/2008/11/18/249 and tries to address comments that
came up in that discussion)

init ignores the SIG_DFL signals but we queue them anyway, including
SIGKILL.  This is mostly OK, the signal will be dropped silently when
dequeued, but the pending SIGKILL has 2 bad implications:

        - it implies fatal_signal_pending(), so we confuse things
          like wait_for_completion_killable/lock_page_killable.

        - for the sub-namespace inits, the pending SIGKILL can
          mask (legacy_queue) the subsequent SIGKILL from the
          parent namespace which must kill cinit reliably.
          (preparation, cinits don't have SIGNAL_UNKILLABLE yet)

The patch can't help when init is ptraced, but ptracing of init is not
"safe" anyway.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:58 -07:00
Oleg Nesterov
43918f2bf4 signals: remove 'handler' parameter to tracehook functions
Container-init must behave like global-init to processes within the
container and hence it must be immune to unhandled fatal signals from
within the container (i.e SIG_DFL signals that terminate the process).

But the same container-init must behave like a normal process to processes
in ancestor namespaces and so if it receives the same fatal signal from a
process in ancestor namespace, the signal must be processed.

Implementing these semantics requires that send_signal() determine pid
namespace of the sender but since signals can originate from workqueues/
interrupt-handlers, determining pid namespace of sender may not always be
possible or safe.

This patchset implements the design/simplified semantics suggested by
Oleg Nesterov.  The simplified semantics for container-init are:

	- container-init must never be terminated by a signal from a
	  descendant process.

	- container-init must never be immune to SIGKILL from an ancestor
	  namespace (so a process in parent namespace must always be able
	  to terminate a descendant container).

	- container-init may be immune to unhandled fatal signals (like
	  SIGUSR1) even if they are from ancestor namespace. SIGKILL/SIGSTOP
	  are the only reliable signals to a container-init from ancestor
	  namespace.

This patch:

Based on an earlier patch submitted by Oleg Nesterov and comments from
Roland McGrath (http://lkml.org/lkml/2008/11/19/258).

The handler parameter is currently unused in the tracehook functions.
Besides, the tracehook functions are called with siglock held, so the
functions can check the handler if they later need to.

Removing the parameter simiplifies changes to sig_ignored() in a follow-on
patch.

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Acked-by: Roland McGrath <roland@redhat.com>
Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Daniel Lezcano <daniel.lezcano@free.fr>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:58 -07:00
Oleg Nesterov
90bc8d8b1a do_wait: fix waiting for the group stop with the dead leader
do_wait(WSTOPPED) assumes that p->state must be == TASK_STOPPED, this is
not true if the leader is already dead.  Check SIGNAL_STOP_STOPPED instead
and use signal->group_exit_code.

Trivial test-case:

	void *tfunc(void *arg)
	{
		pause();
		return NULL;
	}

	int main(void)
	{
		pthread_t thr;
		pthread_create(&thr, NULL, tfunc, NULL);
		pthread_exit(NULL);
		return 0;
	}

It doesn't react to ^Z (and then to ^C or ^\). The task is stopped, but
bash can't see this.

The bug is very old, and it was reported multiple times. This patch was sent
more than a year ago (http://marc.info/?t=119713920000003) but it was ignored.

This change also fixes other oddities (but not all) in this area.  For
example, before this patch:

	$ sleep 100
	^Z
	[1]+  Stopped                 sleep 100
	$ strace -p `pidof sleep`
	Process 11442 attached - interrupt to quit

strace hangs in do_wait(), because ->exit_code was already consumed by
bash.  After this patch, strace happily proceeds:

	--- SIGTSTP (Stopped) @ 0 (0) ---
	restart_syscall(<... resuming interrupted call ...>

To me, this looks much more "natural" and correct.

Another example.  Let's suppose we have the main thread M and sub-thread
T, the process is stopped, and its parent did wait(WSTOPPED).  Now we can
ptrace T but not M.  This looks at least strange to me.

Imho, do_wait() should not confuse the per-thread ptrace stops with the
per-process job control stops.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Jan Kratochvil <jan.kratochvil@redhat.com>
Cc: Kaz Kylheku <kkylheku@gmail.com>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Roland McGrath <roland@redhat.com>
Cc: Ulrich Drepper <drepper@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:57 -07:00
David Rientjes
6d7b2f5f9e cpusets: prevent PF_THREAD_BOUND tasks from attaching to non-root cpusets
Kthreads that have the PF_THREAD_BOUND bit set in their flags are bound to a
specific cpu.  Thus, their set of allowed cpus shall not change.

This patch prevents such threads from attaching to non-root cpusets.  They do
not have mempolicies that restrict them to a subset of system nodes and, since
their cpumask may never change, they cannot use any of the features of
cpusets.

The tasks will forever be a member of the root cpuset and will be returned
when listing the tasks attached to that cpuset.

Cc: Paul Menage <menage@google.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Dhaval Giani <dhaval@linux.vnet.ibm.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:57 -07:00
Paul Menage
db7f47cf48 cpusets: allow cpusets to be configured/built on non-SMP systems
Allow cpusets to be configured/built on non-SMP systems

Currently it's impossible to build cpusets under UML on x86-64, since
cpusets depends on SMP and x86-64 UML doesn't support SMP.

There's code in cpusets that doesn't depend on SMP.  This patch surrounds
the minimum amount of cpusets code with #ifdef CONFIG_SMP in order to
allow cpusets to build/run on UP systems (for testing purposes under UML).

Reviewed-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Paul Menage <menage@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:57 -07:00
David Rientjes
a1bc5a4eee cpusets: replace zone allowed functions with node allowed
The cpuset_zone_allowed() variants are actually only a function of the
zone's node.

Cc: Paul Menage <menage@google.com>
Acked-by: Christoph Lameter <cl@linux-foundation.org>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:57 -07:00
Li Zefan
7f81b1ae18 cpuset: remove struct cpuset_hotplug_scanner
Use cgroup_scanner.data, instead of introducing cpuset_hotplug_scanner.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:57 -07:00
Li Zefan
010cfac4ca cpuset: avoid changing cpuset's mems when errno returned
When writing to cpuset.mems, cpuset has to update its mems_allowed before
calling update_tasks_nodemask(), but this function might return -ENOMEM.

To avoid this rare case, we allocate the memory before changing
mems_allowed, and then pass to update_tasks_nodemask().  Similar to what
update_cpumask() does.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:57 -07:00
Li Zefan
3b6766fe66 cpuset: rewrite update_tasks_nodemask()
This patch uses cgroup_scan_tasks() to rebind tasks' vmas to new cpuset's
mems_allowed.

Not only simplify the code largely, but also avoid allocating an array to
hold mm pointers of all the tasks in the cpuset.  This array can be big
(size > PAGESIZE) if we have lots of tasks in that cpuset, thus has a
chance to fail the allocation when under memory stress.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:57 -07:00
Li Zefan
bd1a8ab73e cgroups: add 'data' field to struct cgroup_scanner
We need to pass some data to test_task() or process_task() in some cases.
Will be used later.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:56 -07:00
Li Zefan
0b4217b3fd cpuset: fix possible races in cpu/memory hotplug
Change to cpuset->cpus_allowed and cpuset->mems_allowed should be protected
by callback_mutex, otherwise the reader may read wrong cpus/mems. This is
cpuset's lock rule.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:56 -07:00
Daisuke Nishimura
83aae4c737 memcg: cleanup cache_charge
Current mem_cgroup_cache_charge is a bit complicated especially
in the case of shmem's swap-in.

This patch cleans it up by using try_charge_swapin and commit_charge_swapin.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:56 -07:00
KAMEZAWA Hiroyuki
627991a20b memcg: remove redundant message at swapon
It's pointed out that swap_cgroup's message at swapon() is nonsense.
Because

  * It can be calculated very easily if all necessary information is
    written in Kconfig.

  * It's not necessary to annoying people at every swapon().

In other view, now, memory usage per swp_entry is reduced to 2bytes from
8bytes(64bit) and I think it's reasonably small.

Reported-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:56 -07:00
KAMEZAWA Hiroyuki
a3b2d69269 cgroups: use css id in swap cgroup for saving memory v5
Try to use CSS ID for records in swap_cgroup.  By this, on 64bit machine,
size of swap_cgroup goes down to 2 bytes from 8bytes.

This means, when 2GB of swap is equipped, (assume the page size is 4096bytes)

	From size of swap_cgroup = 2G/4k * 8 = 4Mbytes.
	To   size of swap_cgroup = 2G/4k * 2 = 1Mbytes.

Reduction is large.  Of course, there are trade-offs.  This CSS ID will
add overhead to swap-in/swap-out/swap-free.

But in general,
  - swap is a resource which the user tend to avoid use.
  - If swap is never used, swap_cgroup area is not used.
  - Reading traditional manuals, size of swap should be proportional to
    size of memory. Memory size of machine is increasing now.

I think reducing size of swap_cgroup makes sense.

Note:
  - ID->CSS lookup routine has no locks, it's under RCU-Read-Side.
  - memcg can be obsolete at rmdir() but not freed while refcnt from
    swap_cgroup is available.

Changelog v4->v5:
 - reworked on to memcg-charge-swapcache-to-proper-memcg.patch
Changlog ->v4:
 - fixed not configured case.
 - deleted unnecessary comments.
 - fixed NULL pointer bug.
 - fixed message in dmesg.

[nishimura@mxp.nes.nec.co.jp: css_tryget can be called twice in !PageCgroupUsed case]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Menage <menage@google.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:56 -07:00
Daisuke Nishimura
3c776e6466 memcg: charge swapcache to proper memcg
memcg_test.txt says at 4.1:

	This swap-in is one of the most complicated work. In do_swap_page(),
	following events occur when pte is unchanged.

	(1) the page (SwapCache) is looked up.
	(2) lock_page()
	(3) try_charge_swapin()
	(4) reuse_swap_page() (may call delete_swap_cache())
	(5) commit_charge_swapin()
	(6) swap_free().

	Considering following situation for example.

	(A) The page has not been charged before (2) and reuse_swap_page()
	    doesn't call delete_from_swap_cache().
	(B) The page has not been charged before (2) and reuse_swap_page()
	    calls delete_from_swap_cache().
	(C) The page has been charged before (2) and reuse_swap_page() doesn't
	    call delete_from_swap_cache().
	(D) The page has been charged before (2) and reuse_swap_page() calls
	    delete_from_swap_cache().

	    memory.usage/memsw.usage changes to this page/swp_entry will be
	 Case          (A)      (B)       (C)     (D)
         Event
       Before (2)     0/ 1     0/ 1      1/ 1    1/ 1
          ===========================================
          (3)        +1/+1    +1/+1     +1/+1   +1/+1
          (4)          -       0/ 0       -     -1/ 0
          (5)         0/-1     0/ 0     -1/-1    0/ 0
          (6)          -       0/-1       -      0/-1
          ===========================================
       Result         1/ 1     1/ 1      1/ 1    1/ 1

       In any cases, charges to this page should be 1/ 1.

In case of (D), mem_cgroup_try_get_from_swapcache() returns NULL
(because lookup_swap_cgroup() returns NULL), so "+1/+1" at (3) means
charges to the memcg("foo") to which the "current" belongs.
OTOH, "-1/0" at (4) and "0/-1" at (6) means uncharges from the memcg("baa")
to which the page has been charged.

So, if the "foo" and "baa" is different(for example because of task move),
this charge will be moved from "baa" to "foo".

I think this is an unexpected behavior.

This patch fixes this by modifying mem_cgroup_try_get_from_swapcache()
to return the memcg to which the swapcache has been charged if PCG_USED bit
is set.
IIUC, checking PCG_USED bit of swapcache is safe under page lock.

Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:56 -07:00
KOSAKI Motohiro
3918b96e03 memcg: remove mem_cgroup_reclaim_imbalance() remnants
commit 4f98a2fee8 (vmscan: split LRU lists
into anon & file sets) removed mem_cgroup_reclaim_imbalance(), but there
are some leftovers in memcontrol.h.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:56 -07:00
KOSAKI Motohiro
c137b5ece4 memcg: remove mem_cgroup_calc_mapped_ratio()
Currently, mem_cgroup_calc_mapped_ratio() is unused at all.  it can be
removed and KAMEZAWA-san suggested it.

Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:55 -07:00
Balbir Singh
e222432bfa memcg: show memcg information during OOM
Add RSS and swap to OOM output from memcg

Display memcg values like failcnt, usage and limit when an OOM occurs due
to memcg.

Thanks to Johannes Weiner, Li Zefan, David Rientjes, Kamezawa Hiroyuki,
Daisuke Nishimura and KOSAKI Motohiro for review.

Sample output
-------------

Task in /a/x killed as a result of limit of /a
memory: usage 1048576kB, limit 1048576kB, failcnt 4183
memory+swap: usage 1400964kB, limit 9007199254740991kB, failcnt 0

[akpm@linux-foundation.org: compilation fix]
[akpm@linux-foundation.org: fix kerneldoc and whitespace]
[akpm@linux-foundation.org: add printk facility level]
Signed-off-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:55 -07:00
KAMEZAWA Hiroyuki
0b7f569e45 memcg: fix OOM killer under memcg
This patch tries to fix OOM Killer problems caused by hierarchy.
Now, memcg itself has OOM KILL function (in oom_kill.c) and tries to
kill a task in memcg.

But, when hierarchy is used, it's broken and correct task cannot
be killed. For example, in following cgroup

	/groupA/	hierarchy=1, limit=1G,
		01	nolimit
		02	nolimit
All tasks' memory usage under /groupA, /groupA/01, groupA/02 is limited to
groupA's 1Gbytes but OOM Killer just kills tasks in groupA.

This patch provides makes the bad process be selected from all tasks
under hierarchy. BTW, currently, oom_jiffies is updated against groupA
in above case. oom_jiffies of tree should be updated.

To see how oom_jiffies is used, please check mem_cgroup_oom_called()
callers.

[akpm@linux-foundation.org: build fix]
[akpm@linux-foundation.org: const fix]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Li Zefan <lizf@cn.fujitsu.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:55 -07:00
KAMEZAWA Hiroyuki
81d39c20f5 memcg: fix shrinking memory to return -EBUSY by fixing retry algorithm
As pointed out, shrinking memcg's limit should return -EBUSY after
reasonable retries.  This patch tries to fix the current behavior of
shrink_usage.

Before looking into "shrink should return -EBUSY" problem, we should fix
hierarchical reclaim code.  It compares current usage and current limit,
but it only makes sense when the kernel reclaims memory because hit
limits.  This is also a problem.

What this patch does are.

  1. add new argument "shrink" to hierarchical reclaim. If "shrink==true",
     hierarchical reclaim returns immediately and the caller checks the kernel
     should shrink more or not.
     (At shrinking memory, usage is always smaller than limit. So check for
      usage < limit is useless.)

  2. For adjusting to above change, 2 changes in "shrink"'s retry path.
     2-a. retry_count depends on # of children because the kernel visits
	  the children under hierarchy one by one.
     2-b. rather than checking return value of hierarchical_reclaim's progress,
	  compares usage-before-shrink and usage-after-shrink.
	  If usage-before-shrink <= usage-after-shrink, retry_count is
	  decremented.

Reported-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Paul Menage <menage@google.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2009-04-02 19:04:55 -07:00