The 192 byte cache is not necessary if we have a basic alignment of 128
byte. If it would be used then the 192 would be aligned to the next 128 byte
boundary which would result in another 256 byte cache. Two 256 kmalloc caches
cause sysfs to complain about a duplicate entry.

MIPS needs 128 byte aligned kmalloc caches and spits out warnings on boot without
this patch.
Signed-off-by: NChristoph Lameter <cl@linux-foundation.org>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Add a WARN_ON for pages that don't have PageSlab nor PageCompound set to catch
the worst abusers of ksize() in the kernel.
Acked-by: NChristoph Lameter <clameter@sgi.com>
Cc: Matt Mackall <mpm@selenic.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

any_slab_objects() does an atomic_read on an atomic_long_t, this
fixes it to use atomic_long_read instead.
Signed-off-by: NBenjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

If we make SLUB_DEBUG depend on SYSFS then we can simplify some
#ifdefs and avoid others.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Fix some issues with wrapping and use strict_strtoul to make parameter
passing from sysfs safer.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

x86 is the only arch right now, which provides an optimized for
div_long_long_rem and it has the downside that one has to be very careful that
the divide doesn't overflow.

The API is a little akward, as the arguments for the unsigned divide are
signed.  The signed version also doesn't handle a negative divisor and
produces worse code on 64bit archs.

There is little incentive to keep this API alive, so this converts the few
users to the new API.
Signed-off-by: NRoman Zippel <zippel@linux-m68k.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: john stultz <johnstul@us.ibm.com>
Cc: Christoph Lameter <clameter@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

We can see an ever repeating problem pattern with objects of any kind in the
kernel:

1) freeing of active objects
2) reinitialization of active objects

Both problems can be hard to debug because the crash happens at a point where
we have no chance to decode the root cause anymore.  One problem spot are
kernel timers, where the detection of the problem often happens in interrupt
context and usually causes the machine to panic.

While working on a timer related bug report I had to hack specialized code
into the timer subsystem to get a reasonable hint for the root cause.  This
debug hack was fine for temporary use, but far from a mergeable solution due
to the intrusiveness into the timer code.

The code further lacked the ability to detect and report the root cause
instantly and keep the system operational.

Keeping the system operational is important to get hold of the debug
information without special debugging aids like serial consoles and special
knowledge of the bug reporter.

The problems described above are not restricted to timers, but timers tend to
expose it usually in a full system crash.  Other objects are less explosive,
but the symptoms caused by such mistakes can be even harder to debug.

Instead of creating specialized debugging code for the timer subsystem a
generic infrastructure is created which allows developers to verify their code
and provides an easy to enable debug facility for users in case of trouble.

The debugobjects core code keeps track of operations on static and dynamic
objects by inserting them into a hashed list and sanity checking them on
object operations and provides additional checks whenever kernel memory is
freed.

The tracked object operations are:
- initializing an object
- adding an object to a subsystem list
- deleting an object from a subsystem list

Each operation is sanity checked before the operation is executed and the
subsystem specific code can provide a fixup function which allows to prevent
the damage of the operation.  When the sanity check triggers a warning message
and a stack trace is printed.

The list of operations can be extended if the need arises.  For now it's
limited to the requirements of the first user (timers).

The core code enqueues the objects into hash buckets.  The hash index is
generated from the address of the object to simplify the lookup for the check
on kfree/vfree.  Each bucket has it's own spinlock to avoid contention on a
global lock.

The debug code can be compiled in without being active.  The runtime overhead
is minimal and could be optimized by asm alternatives.  A kernel command line
option enables the debugging code.

Thanks to Ingo Molnar for review, suggestions and cleanup patches.
Signed-off-by: NThomas Gleixner <tglx@linutronix.de>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
Cc: Greg KH <greg@kroah.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This is a trivial patch that defines the priority of slab_memory_callback in
the callback chain as a constant.  This is to prepare for next patch in the
series.
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>

Not all architectures define cache_line_size() so as suggested by Andrew move
the private implementations in mm/slab.c and mm/slob.c to <linux/cache.h>.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Reviewed-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Filtering zonelists requires very frequent use of zone_idx().  This is costly
as it involves a lookup of another structure and a substraction operation.  As
the zone_idx is often required, it should be quickly accessible.  The node idx
could also be stored here if it was found that accessing zone->node is
significant which may be the case on workloads where nodemasks are heavily
used.

This patch introduces a struct zoneref to store a zone pointer and a zone
index.  The zonelist then consists of an array of these struct zonerefs which
are looked up as necessary.  Helpers are given for accessing the zone index as
well as the node index.

[kamezawa.hiroyu@jp.fujitsu.com: Suggested struct zoneref instead of embedding information in pointers]
[hugh@veritas.com: mm-have-zonelist: fix memcg ooms]
[hugh@veritas.com: just return do_try_to_free_pages]
[hugh@veritas.com: do_try_to_free_pages gfp_mask redundant]
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Acked-by: NChristoph Lameter <clameter@sgi.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NHugh Dickins <hugh@veritas.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Currently a node has two sets of zonelists, one for each zone type in the
system and a second set for GFP_THISNODE allocations.  Based on the zones
allowed by a gfp mask, one of these zonelists is selected.  All of these
zonelists consume memory and occupy cache lines.

This patch replaces the multiple zonelists per-node with two zonelists.  The
first contains all populated zones in the system, ordered by distance, for
fallback allocations when the target/preferred node has no free pages.  The
second contains all populated zones in the node suitable for GFP_THISNODE
allocations.

An iterator macro is introduced called for_each_zone_zonelist() that interates
through each zone allowed by the GFP flags in the selected zonelist.
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Acked-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Introduce a node_zonelist() helper function.  It is used to lookup the
appropriate zonelist given a node and a GFP mask.  The patch on its own is a
cleanup but it helps clarify parts of the two-zonelist-per-node patchset.  If
necessary, it can be merged with the next patch in this set without problems.
Reviewed-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NMel Gorman <mel@csn.ul.ie>
Signed-off-by: NLee Schermerhorn <lee.schermerhorn@hp.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Since we now have more orders available use a denser packing.
Increase slab order if more than 1/16th of a slab would be wasted.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

The mininum objects per slab is calculated based on the number of processors
that may come online.

Processors    min_objects
---------------------------
1             8
2             12
4             16
8             20
16            24
32            28
64            32
1024          48
4096          56

The higher the number of processors the large the order sizes used for various
slab caches will become. This has been shown to address the performance issues
in hackbench on 16p etc.

The calculation is only performed if slub_min_objects is zero (default). If one
specifies a slub_min_objects on boot then that setting is taken.

As suggested by Zhang Yanmin's performance tests on 16-core Tigerton, use the
formula '4 * (fls(nr_cpu_ids) + 1)':

  ./hackbench 100 process 2000:

  1) 2.6.25-rc6slab: 23.5 seconds
  2) 2.6.25-rc7SLUB+slub_min_objects=20: 31 seconds
  3) 2.6.25-rc7SLUB+slub_min_objects=24: 23.5 seconds
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NZhang Yanmin <yanmin.zhang@intel.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

We can now fallback to order 0 slabs. So set the slub_max_order to
PAGE_CACHE_ORDER_COSTLY but keep the slub_min_objects at 4. This
will mostly preserve the orders used in 2.6.25. F.e. The 2k kmalloc slab
will use order 1 allocs and the 4k kmalloc slab order 2.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Since we now have total_objects counter per node use that to
check for the presence of any objects. The loop over all cpu slabs
is not that useful since any cpu slab would require an object allocation
first. So drop that.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Makes /sys/kernel/slab/<slabname>/order writable. The allocation
order of a slab cache can then be changed dynamically during runtime.
This can be used to override the objects per slabs value establisheed
with the slub_min_objects setting that was manually specified or
calculated on bootup.

The changes of the slab order can occur while allocate_slab() runs.
Allocate slab needs the order and the number of slab objects that
are both changed by the change of order. Both are put into
a single word (struct kmem_cache_order_objects). They can then
be atomically updated and retrieved.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

There is now a generic method of falling back to a slab page of minimal
order. No need anymore for the fallback to kmalloc_large().
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

If any higher order allocation fails then fall back the smallest order
necessary to contain at least one object. This enables fallback for all
allocations to order 0 pages. The fallback will waste more memory (objects
will not fit neatly) and the fallback slabs will be not as efficient as larger
slabs since they contain less objects.

Note that SLAB also depends on order 1 allocations for some slabs that waste
too much memory if forced into PAGE_SIZE'd page. SLUB now can now deal with
failing order 1 allocs which SLAB cannot do.

Add a new field min that will contain the objects for the smallest possible order
for a slab cache.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Change the statistics to consider that slabs of the same slabcache
can have different number of objects in them since they may be of
different order.

Provide a new sysfs field

	total_objects

which shows the total objects that the allocated slabs of a slabcache
could hold.

Add a max field that holds the largest slab order that was ever used
for a slab cache.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Pack the order and the number of objects into a single word.
This saves some memory in the kmem_cache_structure and more importantly
allows us to fetch both values atomically.

Later the slab orders become runtime configurable and we need to fetch these
two items together in order to properly allocate a slab and initialize its
objects.

Fix the race by fetching the order and the number of objects in one word.

[penberg@cs.helsinki.fi: fix memset() page order in new_slab()]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Pass the number of objects to the for_each_object macro. Most of these are
debug related.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Split the inuse field up to be able to store the number of objects in this
page in the page struct as well. Necessary if we want to have pages of
various orders for a slab. Also avoids touching struct kmem_cache cachelines in
__slab_alloc().

Update diagnostic code to check the number of objects and make sure that
the number of objects always stays within the bounds of a 16 bit unsigned
integer.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Dump a list of unfreed objects if a slab cache is closed but
objects still remain.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

free_list looked a bit screwy so here is an attempt to clean it up.

free_list is is only used for freeing partial lists. We do not need to return a
parameter if we decrement nr_partial within the function which allows a
simplification of the whole thing.

The current version modifies nr_partial outside of the list_lock which is
technically not correct. It was only ok because we should be the only user of
this slab cache at this point.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

As pointed out by Ingo, the SLUB warning of calling kmem_cache_destroy()
with cache that still has objects triggers in practice. So turn this
WARN_ON() into a nice SLUB specific error message to avoid people
confusing it to a SLUB bug.

Cc: Ingo Molnar <mingo@elte.hu>
Acked-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

The per node counters are used mainly for showing data through the sysfs API.
If that API is not compiled in then there is no point in keeping track of this
data. Disable counters for the number of slabs and the number of total slabs
if !SLUB_DEBUG. Incrementing the per node counters is also accessing a
potentially contended cacheline so this could actually be a performance
benefit to embedded systems.

SLABINFO support is also affected. It now must depends on SLUB_DEBUG (which
is on by default).

Patch also avoids a check for a NULL kmem_cache_node pointer in new_slab()
if the system is not compiled with NUMA support.

[penberg@cs.helsinki.fi: fix oops and move ->nr_slabs into CONFIG_SLUB_DEBUG]
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

__free_slab does some diagnostics. The resetting of mapcount etc
in discard_slab() can interfere with debug processing. So move
the reset immediately before the page is freed.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Only output per cpu stats if the kernel is build for SMP.

Use a capital "C" as a leading character for the processor number
(same as the numa statistics that also use a capital letter "N").
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

count_partial() is used by both slabinfo and the sysfs proc support. Move
the function directly before the beginning of the sysfs code so that it can
be easily found. Rework the preprocessor conditional to take into account
that slub sysfs support depends on CONFIG_SYSFS *and* CONFIG_SLUB_DEBUG.

Make CONFIG_SLUB_STATS depend on CONFIG_SLUB_DEBUG and CONFIG_SYSFS. There
is no point of keeping statistics if no one can restrive them.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Move the definition of kmalloc_caches_dma() into a later #ifdef CONFIG_ZONE_DMA.
This saves one #ifdef and leaves us with a total of two #ifdefs for dma slab support.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

As spotted by kmemcheck, we need to initialize the per-CPU ->stat array before
using it.

[kmem_cache_cpu structures are usually allocated from arrays defined via
DEFINE_PER_CPU that are zeroed so we have not noticed this so far --cl].
Reported-by: NVegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

Small typo in the patch recently merged to avoid the unused symbol
message for count_partial(). Discussion thread with confirmation of fix at
http://marc.info/?t=120696854400001&r=1&w=2

Typo in the check if we need the count_partial function that was
introduced by 53625b42Signed-off-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

This reverts commit 3811dbf6.

The masking was not at all useless, and it was sensible.  We handle
GFP_ZERO in the caller, and passing it down to any page allocator logic
is buggy and wrong.
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Avoid warnings about unused functions if neither SLUB_DEBUG nor CONFIG_SLABINFO
is defined. This patch will be reversed when slab defrag is merged since slab
defrag requires count_partial() to determine the fragmentation status of
slab caches.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>

The fallback path needs to enable interrupts like done for
the other page allocator calls. This was not necessary with
the alternate fast path since we handled irq enable/disable in
the slow path. The regular fastpath handles irq enable/disable
around calls to the slow path so we need to restore the proper
status before calling the page allocator from the slowpath.
Signed-off-by: NChristoph Lameter <clameter@sgi.com>

SLUB should pack even small objects nicely into cachelines if that is what
has been asked for. Use the same algorithm as SLAB for this.

The effect of this patch for a system with a cacheline size of 64
bytes is that the 24 byte sized slab caches will now put exactly
2 objects into a cacheline instead of 3 with some overlap into
the next cacheline. This reduces the object density in a 4k slab
from 170 to 128 objects (same as SLAB).
Signed-off-by: NNick Piggin <npiggin@suse.de>
Signed-off-by: NChristoph Lameter <clameter@sgi.com>

The remote frees are in the freelist of the page and not in the
percpu freelist.
Reviewed-by: NPekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: NChristoph Lameter <clameter@sgi.com>

This patch fix possible NULL pointer dereference if kzalloc
failed. To be able to return proper error code the function
return type is changed to ssize_t (according to callees and
sysfs definitions).
Signed-off-by: NCyrill Gorcunov <gorcunov@gmail.com>
Signed-off-by: NChristoph Lameter <clameter@sgi.com>