Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Increase the range of various posix message queue limits.

Posix gives the message queue user the ability to 'trade off' the maximum
size of messages with the number of possible messages that can be 'in
flight'.  Linux currently makes this trade off more restrictive than it
needs to be.

In particular, the maximum message size today can be made no smaller than
8192.  This greatly restricts those applications that would like to have
the ability to post large numbers of very small messages.

So this task lowers the limit that the maximum message size can be set to,
from 8192 to 128.  It also lowers the limit that the maximum #number of
messages in flight can be set to, from 10 to 1.

With these changes the message queue user can make better trade offs
between #messages and message size, in order to get everything to fit
within the setrlimit(RLIMIT_MSGQUEUE) limit for that particular user.

This patch also applies the values in

	/proc/sys/fs/mqueue/msg_max
	/proc/sys/fs/mqueue/msgsize_max

as the defaults for the max #messages allowed and the max message size
allowed, respectively, for those applications that do not supply these.
Previously, the defaults were hardwired to 10 and 8192, respectively.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NJoe Korty <joe.korty@ccur.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Shmem segments locked into memory via shmctl(SHM_LOCKED) should not be
kept on the normal LRU, since scanning them is a waste of time and might
throw off kswapd's balancing algorithms.  Place them on the unevictable
LRU list instead.

Use the AS_UNEVICTABLE flag to mark address_space of SHM_LOCKed shared
memory regions as unevictable.  Then these pages will be culled off the
normal LRU lists during vmscan.

Add new wrapper function to clear the mapping's unevictable state when/if
shared memory segment is munlocked.

Add 'scan_mapping_unevictable_page()' to mm/vmscan.c to scan all pages in
the shmem segment's mapping [struct address_space] for evictability now
that they're no longer locked.  If so, move them to the appropriate zone
lru list.

Changes depend on [CONFIG_]UNEVICTABLE_LRU.

[kosaki.motohiro@jp.fujitsu.com: revert shm change]
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NKosaki Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NAdrian Bunk <bunk@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

name and nlen parameters passed to ->strategy hook are unused, remove
them.  In general ->strategy hook should know what it's doing, and don't
do something tricky for which, say, pointer to original userspace array
may be needed (name).
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Acked-by: David S. Miller <davem@davemloft.net> [ networking bits ]
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Howells <dhowells@redhat.com>
Cc: Matt Mackall <mpm@selenic.com>
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>

Incidentally, the name that gives hundreds of false positives on grep
is not a good idea...
Signed-off-by: NAl Viro <viro@zeniv.linux.org.uk>

Kmem cache passed to constructor is only needed for constructors that are
themselves multiplexeres.  Nobody uses this "feature", nor does anybody uses
passed kmem cache in non-trivial way, so pass only pointer to object.

Non-trivial places are:
	arch/powerpc/mm/init_64.c
	arch/powerpc/mm/hugetlbpage.c

This is flag day, yes.
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Acked-by: NPekka Enberg <penberg@cs.helsinki.fi>
Acked-by: NChristoph Lameter <cl@linux-foundation.org>
Cc: Jon Tollefson <kniht@linux.vnet.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Matt Mackall <mpm@selenic.com>
[akpm@linux-foundation.org: fix arch/powerpc/mm/hugetlbpage.c]
[akpm@linux-foundation.org: fix mm/slab.c]
[akpm@linux-foundation.org: fix ubifs]
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This patch proposes an alternative to the "magical
positive-versus-negative number trick" Andrew complained about last week
in http://lkml.org/lkml/2008/6/24/418.

This had been introduced with the patches that scale msgmni to the amount
of lowmem.  With these patches, msgmni has a registered notification
routine that recomputes msgmni value upon memory add/remove or ipc
namespace creation/ removal.

When msgmni is changed from user space (i.e.  value written to the proc
file), that notification routine is unregistered, and the way to make it
registered back is to write a negative value into the proc file.  This is
the "magical positive-versus-negative number trick".

To fix this, a new proc file is introduced: /proc/sys/kernel/auto_msgmni.
This file acts as ON/OFF for msgmni automatic recomputing.

With this patch, the process is the following:
1) kernel boots in "automatic recomputing mode"
   /proc/sys/kernel/msgmni contains the value that has been computed (depends
                           on lowmem)
   /proc/sys/kernel/automatic_msgmni contains "1"

2) echo <val> > /proc/sys/kernel/msgmni
   . sets msg_ctlmni to <val>
   . de-activates automatic recomputing (i.e. if, say, some memory is added
     msgmni won't be recomputed anymore)
   . /proc/sys/kernel/automatic_msgmni now contains "0"

3) echo "0" > /proc/sys/kernel/automatic_msgmni
   . de-activates msgmni automatic recomputing
     this has the same effect as 2) except that msg_ctlmni's value stays
     blocked at its current value)

3) echo "1" > /proc/sys/kernel/automatic_msgmni
   . recomputes msgmni's value based on the current available memory size
     and number of ipc namespaces
   . re-activates automatic recomputing for msgmni.
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Solofo Ramangalahy <Solofo.Ramangalahy@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Also this patch kills unneccesary trailing NULL character.
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The attached patch:
- reverses the locking order of ulp->lock and sem_lock:
  Previously, it was first ulp->lock, then inside sem_lock.
  Now it's the other way around.
- converts the undo structure to rcu.

Benefits:
- With the old locking order, IPC_RMID could not kfree the undo structures.
  The stale entries remained in the linked lists and were released later.
- The patch fixes a a race in semtimedop(): if both IPC_RMID and a semget() that
  recreates exactly the same id happen between find_alloc_undo() and sem_lock,
  then semtimedop() would access already kfree'd memory.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NManfred Spraul <manfred@colorfullife.com>
Reviewed-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

sem_array.sem_pending is a double linked list, the attached patch converts
it to struct list_head.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NManfred Spraul <manfred@colorfullife.com>
Reviewed-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

sem_queue.sma and sem_queue.id were never used, the attached patch removes
them.
Signed-off-by: NManfred Spraul <manfred@colorfullife.com>
Reviewed-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The undo structures contain two linked lists, the attached patch replaces
them with generic struct list_head lists.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NManfred Spraul <manfred@colorfullife.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Remove the ipc_lock_down() routines: they used to call idr_find() locklessly
(given that the ipc ids lock was already held), so they are not needed
anymore.
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Acked-by: N"Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Jim Houston <jim.houston@comcast.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Call idr_find() locklessly from ipc_lock(), since the idr tree is now RCU
protected.
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Acked-by: N"Paul E. McKenney" <paulmck@us.ibm.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Jim Houston <jim.houston@comcast.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Acked-by: NRik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The goal of this patchset is to support multiple hugetlb page sizes.  This
is achieved by introducing a new struct hstate structure, which
encapsulates the important hugetlb state and constants (eg.  huge page
size, number of huge pages currently allocated, etc).

The hstate structure is then passed around the code which requires these
fields, they will do the right thing regardless of the exact hstate they
are operating on.

This patch adds the hstate structure, with a single global instance of it
(default_hstate), and does the basic work of converting hugetlb to use the
hstate.

Future patches will add more hstate structures to allow for different
hugetlbfs mounts to have different page sizes.

[akpm@linux-foundation.org: coding-style fixes]
Acked-by: NAdam Litke <agl@us.ibm.com>
Acked-by: NNishanth Aravamudan <nacc@us.ibm.com>
Signed-off-by: NAndi Kleen <ak@suse.de>
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

sysvipc_shm_proc_show() picks between format strings (based on the
expected maximum length of a SHM segment) in a way that prevents gcc from
performing format checks on the seq_printf() parameters.  This hid two
format errors - shp->shm_segsz and shp->shm_nattach are both unsigned
long, but were being printed as unsigned int and signed int respectively.
This leads to 32-bit truncation of SHM segment sizes reported in
/proc/sysvipc/shm.  (And for nattach, but that's less of a problem for
most users).

This patch makes the format string directly visible to gcc's format
specifier checker, and fixes the two broken format specifiers.
Signed-off-by: NPaul Menage <menage@google.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Manfred Spraul <manfred@colorfullife.com>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Found a silly double assignment of err is do_shmat.  Silly, but good to
clean up the useless code.
Signed-off-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When posting:
[PATCH 1/8] Scaling msgmni to the amount of lowmem
(see http://lkml.org/lkml/2008/2/11/171), I have added a KERN_INFO message
that is output each time msgmni is recomputed.

In http://lkml.org/lkml/2008/4/29/575 Tony Luck complained that this
message references an ipc namespace address that is useless.

I first thought of using an audit_log instead of a printk, as suggested by
Serge Hallyn.  But unfortunately, we do not have any other information
than the namespace address to provide here too.  So I chose to move the
message and output it only at boot time, removing the reference to the
namespace.
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Cc: Manfred Spraul <manfred@colorfullife.com>
Acked-by: NTony Luck <tony.luck@intel.com>
Cc: "Serge E. Hallyn" <serue@us.ibm.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Signed-off-by: NDenis V. Lunev <den@openvz.org>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

A very small cleanup for mq_open.

We do not have to call set_close_on_exit if we create the file
descriptor right away with the flag set.  We have a function for this
now.  The resulting code is smaller and a tiny bit faster.
Signed-off-by: NUlrich Drepper <drepper@redhat.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Use proc_create_data() to make sure that ->proc_fops and ->data be setup
before gluing PDE to main tree.
Signed-off-by: NDenis V. Lunev <den@openvz.org>
Cc: Alexey Dobriyan <adobriyan@gmail.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

sys_unshare(CLONE_NEWIPC) doesn't handle the undo lists properly, this can
cause a kernel memory corruption.  CLONE_NEWIPC must detach from the existing
undo lists.

Fix, part 1: add support for sys_unshare(CLONE_SYSVSEM)

The original reason to not support it was the potential (inevitable?)
confusion due to the fact that sys_unshare(CLONE_SYSVSEM) has the
inverse meaning of clone(CLONE_SYSVSEM).

Our two most reasonable options then appear to be (1) fully support
CLONE_SYSVSEM, or (2) continue to refuse explicit CLONE_SYSVSEM,
but always do it anyway on unshare(CLONE_SYSVSEM).  This patch does
(1).

Changelog:
	Apr 16: SEH: switch to Manfred's alternative patch which
		removes the unshare_semundo() function which
		always refused CLONE_SYSVSEM.
Signed-off-by: NManfred Spraul <manfred@colorfullife.com>
Signed-off-by: NSerge E. Hallyn <serue@us.ibm.com>
Acked-by: N"Eric W. Biederman" <ebiederm@xmission.com>
Cc: Pavel Emelyanov <xemul@openvz.org>
Cc: Michael Kerrisk <mtk.manpages@googlemail.com>
Cc: Pierre Peiffer <peifferp@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add definitions of USHORT_MAX and others into kernel.  ipc uses it and slub
implementation might also use it.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NZhang Yanmin <yanmin.zhang@intel.com>
Reviewed-by: NChristoph Lameter <clameter@sgi.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Cc: "Pierre Peiffer" <peifferp@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

semctl_down(), msgctl_down() and shmctl_down() are used to handle the same set
of commands for each kind of IPC.  They all start to do the same job (they
retrieve the ipc and do some permission checks) before handling the commands
on their own.

This patch proposes to consolidate this by moving these same pieces of code
into one common function called ipcctl_pre_down().

It simplifies a little these xxxctl_down() functions and increases a little
the maintainability.
Signed-off-by: NPierre Peiffer <pierre.peiffer@bull.net>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The IPC_SET command performs the same permission setting for all IPCs.  This
patch introduces a common ipc_update_perm() function to update these
permissions and makes use of it for all IPCs.
Signed-off-by: NPierre Peiffer <pierre.peiffer@bull.net>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

All IPCs make use of an intermetiate *_setbuf structure to handle the IPC_SET
command.  This is not really needed and, moreover, it complicates a little bit
the code.

This patch gets rid of the use of it and uses directly the semid64_ds/
msgid64_ds/shmid64_ds structure.

In addition of removing one struture declaration, it also simplifies and
improves a little bit the common 64-bits path.
Signed-off-by: NPierre Peiffer <pierre.peiffer@bull.net>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

semctl_down() takes one unused parameter: semnum.  This patch proposes to get
rid of it.
Signed-off-by: NPierre Peiffer <pierre.peiffer@bull.net>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

semctl_down is called with the rwmutex (the one which protects the list of
ipcs) taken in write mode.

This patch moves this rwmutex taken in write-mode inside semctl_down.

This has the advantages of reducing a little bit the window during which this
rwmutex is taken, clarifying sys_semctl, and finally of having a coherent
behaviour with [shm|msg]ctl_down
Signed-off-by: NPierre Peiffer <pierre.peiffer@bull.net>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, sys_msgctl is not easy to read.

This patch tries to improve that by introducing the msgctl_down function to
handle all commands requiring the rwmutex to be taken in write mode (ie
IPC_SET and IPC_RMID for now).  It is the equivalent function of semctl_down
for message queues.

This greatly changes the readability of sys_msgctl and also harmonizes the way
these commands are handled among all IPCs.
Signed-off-by: NPierre Peiffer <pierre.peiffer@bull.net>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently, the way the different commands are handled in sys_shmctl introduces
some duplicated code.

This patch introduces the shmctl_down function to handle all the commands
requiring the rwmutex to be taken in write mode (ie IPC_SET and IPC_RMID for
now).  It is the equivalent function of semctl_down for shared memory.

This removes some duplicated code for handling these both commands and
harmonizes the way they are handled among all IPCs.
Signed-off-by: NPierre Peiffer <pierre.peiffer@bull.net>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Trivial patch which adds some small locking functions and makes use of them to
factorize some part of the code and to make it cleaner.
Signed-off-by: NPierre Peiffer <pierre.peiffer@bull.net>
Acked-by: NSerge Hallyn <serue@us.ibm.com>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The enhancement as asked for by Yasunori: if msgmni is set to a negative
value, register it back into the ipcns notifier chain.

A new interface has been added to the notification mechanism:
notifier_chain_cond_register() registers a notifier block only if not already
registered.  With that new interface we avoid taking care of the states
changes in procfs.
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make msgmni not recomputed anymore upon ipc namespace creation / removal or
memory add/remove, as soon as it has been set from userland.

As soon as msgmni is explicitly set via procfs or sysctl(), the associated
callback routine is unregistered from the ipc namespace notifier chain.
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Introduce a notification mechanism that aims at recomputing msgmni each time
an ipc namespace is created or removed.

The ipc namespace notifier chain already defined for memory hotplug management
is used for that purpose too.

Each time a new ipc namespace is allocated or an existing ipc namespace is
removed, the ipcns notifier chain is notified.  The callback routine for each
registered ipc namespace is then activated in order to recompute msgmni for
that namespace.
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Make the memory hotplug chain's mutex held for a shorter time: when memory is
offlined or onlined a work item is added to the global workqueue.  When the
work item is run, it notifies the ipcns notifier chain with the
IPCNS_MEMCHANGED event.
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Introduce the registration of a callback routine that recomputes msg_ctlmni
upon memory add / remove.

A single notifier block is registered in the hotplug memory chain for all the
ipc namespaces.

Since the ipc namespaces are not linked together, they have their own
notification chain: one notifier_block is defined per ipc namespace.

Each time an ipc namespace is created (removed) it registers (unregisters) its
notifier block in (from) the ipcns chain.  The callback routine registered in
the memory chain invokes the ipcns notifier chain with the IPCNS_LOWMEM event.
 Each callback routine registered in the ipcns namespace, in turn, recomputes
msgmni for the owning namespace.
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since all the namespaces see the same amount of memory (the total one) this
patch introduces a new variable that counts the ipc namespaces and divides
msg_ctlmni by this counter.
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

On large systems we'd like to allow a larger number of message queues.  In
some cases up to 32K.  However simply setting MSGMNI to a larger value may
cause problems for smaller systems.

The first patch of this series introduces a default maximum number of message
queue ids that scales with the amount of lowmem.

Since msgmni is per namespace and there is no amount of memory dedicated to
each namespace so far, the second patch of this series scales msgmni to the
number of ipc namespaces too.

Since msgmni depends on the amount of memory, it becomes necessary to
recompute it upon memory add/remove.  In the 4th patch, memory hotplug
management is added: a notifier block is registered into the memory hotplug
notifier chain for the ipc subsystem.  Since the ipc namespaces are not linked
together, they have their own notification chain: one notifier_block is
defined per ipc namespace.  Each time an ipc namespace is created (removed) it
registers (unregisters) its notifier block in (from) the ipcns chain.  The
callback routine registered in the memory chain invokes the ipcns notifier
chain with the IPCNS_MEMCHANGE event.  Each callback routine registered in the
ipcns namespace, in turn, recomputes msgmni for the owning namespace.

The 5th patch makes it possible to keep the memory hotplug notifier chain's
lock for a lesser amount of time: instead of directly notifying the ipcns
notifier chain upon memory add/remove, a work item is added to the global
workqueue.  When activated, this work item is the one who notifies the ipcns
notifier chain.

Since msgmni depends on the number of ipc namespaces, it becomes necessary to
recompute it upon ipc namespace creation / removal.  The 6th patch uses the
ipc namespace notifier chain for that purpose: that chain is notified each
time an ipc namespace is created or removed.  This makes it possible to
recompute msgmni for all the namespaces each time one of them is created or
removed.

When msgmni is explicitely set from userspace, we should avoid recomputing it
upon memory add/remove or ipcns creation/removal.  This is what the 7th patch
does: it simply unregisters the ipcns callback routine as soon as msgmni has
been changed from procfs or sysctl().

Even if msgmni is set by hand, it should be possible to make it back
automatically recomputed upon memory add/remove or ipcns creation/removal.
This what is achieved in patch 8: if set to a negative value, msgmni is added
back to the ipcns notifier chain, making it automatically recomputed again.

This patch:

Compute msg_ctlmni to make it scale with the amount of lowmem.  msg_ctlmni is
now set to make the message queues occupy 1/32 of the available lowmem.

Some cleaning has also been done for the MSGPOOL constant: the msgctl man page
says it's not used, but it also defines it as a size in bytes (the code
expresses it in Kbytes).
Signed-off-by: NNadia Derbey <Nadia.Derbey@bull.net>
Cc: Yasunori Goto <y-goto@jp.fujitsu.com>
Cc: Matt Helsley <matthltc@us.ibm.com>
Cc: Mingming Cao <cmm@us.ibm.com>
Cc: Pierre Peiffer <pierre.peiffer@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

By continuing to consolidate a little the IPC code, each id can be built
directly in ipc_addid() instead of having it built from each callers of
ipc_addid()

And I also remove shm_addid() in order to have, as much as possible, the
same code for shm/sem/msg.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: NPierre Peiffer <pierre.peiffer@bull.net>
Cc: Nadia Derbey <Nadia.Derbey@bull.net>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>