Patch series "slab: make memcg slab destruction scalable", v3.

With kmem cgroup support enabled, kmem_caches can be created and
destroyed frequently and a great number of near empty kmem_caches can
accumulate if there are a lot of transient cgroups and the system is not
under memory pressure.  When memory reclaim starts under such
conditions, it can lead to consecutive deactivation and destruction of
many kmem_caches, easily hundreds of thousands on moderately large
systems, exposing scalability issues in the current slab management
code.

I've seen machines which end up with hundred thousands of caches and
many millions of kernfs_nodes.  The current code is O(N^2) on the total
number of caches and has synchronous rcu_barrier() and
synchronize_sched() in cgroup offline / release path which is executed
while holding cgroup_mutex.  Combined, this leads to very expensive and
slow cache destruction operations which can easily keep running for half
a day.

This also messes up /proc/slabinfo along with other cache iterating
operations.  seq_file operates on 4k chunks and on each 4k boundary
tries to seek to the last position in the list.  With a huge number of
caches on the list, this becomes very slow and very prone to the list
content changing underneath it leading to a lot of missing and/or
duplicate entries.

This patchset addresses the scalability problem.

* Add root and per-memcg lists.  Update each user to use the
  appropriate list.

* Make rcu_barrier() for SLAB_DESTROY_BY_RCU caches globally batched
  and asynchronous.

* For dying empty slub caches, remove the sysfs files after
  deactivation so that we don't end up with millions of sysfs files
  without any useful information on them.

This patchset contains the following nine patches.

 0001-Revert-slub-move-synchronize_sched-out-of-slab_mutex.patch
 0002-slub-separate-out-sysfs_slab_release-from-sysfs_slab.patch
 0003-slab-remove-synchronous-rcu_barrier-call-in-memcg-ca.patch
 0004-slab-reorganize-memcg_cache_params.patch
 0005-slab-link-memcg-kmem_caches-on-their-associated-memo.patch
 0006-slab-implement-slab_root_caches-list.patch
 0007-slab-introduce-__kmemcg_cache_deactivate.patch
 0008-slab-remove-synchronous-synchronize_sched-from-memcg.patch
 0009-slab-remove-slub-sysfs-interface-files-early-for-emp.patch
 0010-slab-use-memcg_kmem_cache_wq-for-slab-destruction-op.patch

0001 reverts an existing optimization to prepare for the following
changes.  0002 is a prep patch.  0003 makes rcu_barrier() in release
path batched and asynchronous.  0004-0006 separate out the lists.
0007-0008 replace synchronize_sched() in slub destruction path with
call_rcu_sched().  0009 removes sysfs files early for empty dying
caches.  0010 makes destruction work items use a workqueue with limited
concurrency.

This patch (of 10):

Revert 89e364db ("slub: move synchronize_sched out of slab_mutex on
shrink").

With kmem cgroup support enabled, kmem_caches can be created and destroyed
frequently and a great number of near empty kmem_caches can accumulate if
there are a lot of transient cgroups and the system is not under memory
pressure.  When memory reclaim starts under such conditions, it can lead
to consecutive deactivation and destruction of many kmem_caches, easily
hundreds of thousands on moderately large systems, exposing scalability
issues in the current slab management code.  This is one of the patches to
address the issue.

Moving synchronize_sched() out of slab_mutex isn't enough as it's still
inside cgroup_mutex.  The whole deactivation / release path will be
updated to avoid all synchronous RCU operations.  Revert this insufficient
optimization in preparation to ease future changes.

Link: http://lkml.kernel.org/r/20170117235411.9408-2-tj@kernel.orgSigned-off-by: NTejun Heo <tj@kernel.org>
Reported-by: NJay Vana <jsvana@fb.com>
Cc: Vladimir Davydov <vdavydov.dev@gmail.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

synchronize_sched() is a heavy operation and calling it per each cache
owned by a memory cgroup being destroyed may take quite some time.  What
is worse, it's currently called under the slab_mutex, stalling all works
doing cache creation/destruction.

Actually, there isn't much point in calling synchronize_sched() for each
cache - it's enough to call it just once - after setting cpu_partial for
all caches and before shrinking them.  This way, we can also move it out
of the slab_mutex, which we have to hold for iterating over the slab
cache list.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=172991
Link: http://lkml.kernel.org/r/0a10d71ecae3db00fb4421bcd3f82bcc911f4be4.1475329751.git.vdavydov.dev@gmail.comSigned-off-by: NVladimir Davydov <vdavydov.dev@gmail.com>
Reported-by: NDoug Smythies <dsmythies@telus.net>
Acked-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When slub_debug alloc_calls_show is enabled we will try to track
location and user of slab object on each online node, kmem_cache_node
structure and cpu_cache/cpu_slub shouldn't be freed till there is the
last reference to sysfs file.

This fixes the following panic:

   BUG: unable to handle kernel NULL pointer dereference at 0000000000000020
   IP:  list_locations+0x169/0x4e0
   PGD 257304067 PUD 438456067 PMD 0
   Oops: 0000 [#1] SMP
   CPU: 3 PID: 973074 Comm: cat ve: 0 Not tainted 3.10.0-229.7.2.ovz.9.30-00007-japdoll-dirty #2 9.30
   Hardware name: DEPO Computers To Be Filled By O.E.M./H67DE3, BIOS L1.60c 07/14/2011
   task: ffff88042a5dc5b0 ti: ffff88037f8d8000 task.ti: ffff88037f8d8000
   RIP: list_locations+0x169/0x4e0
   Call Trace:
     alloc_calls_show+0x1d/0x30
     slab_attr_show+0x1b/0x30
     sysfs_read_file+0x9a/0x1a0
     vfs_read+0x9c/0x170
     SyS_read+0x58/0xb0
     system_call_fastpath+0x16/0x1b
   Code: 5e 07 12 00 b9 00 04 00 00 3d 00 04 00 00 0f 4f c1 3d 00 04 00 00 89 45 b0 0f 84 c3 00 00 00 48 63 45 b0 49 8b 9c c4 f8 00 00 00 <48> 8b 43 20 48 85 c0 74 b6 48 89 df e8 46 37 44 00 48 8b 53 10
   CR2: 0000000000000020

Separated __kmem_cache_release from __kmem_cache_shutdown which now
called on slab_kmem_cache_release (after the last reference to sysfs
file object has dropped).

Reintroduced locking in free_partial as sysfs file might access cache's
partial list after shutdowning - partial revert of the commit
69cb8e6b ("slub: free slabs without holding locks").  Zap
__remove_partial and use remove_partial (w/o underscores) as
free_partial now takes list_lock which s partial revert for commit
1e4dd946 ("slub: do not assert not having lock in removing freed
partial")
Signed-off-by: NDmitry Safonov <dsafonov@virtuozzo.com>
Suggested-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: NVladimir Davydov <vdavydov@virtuozzo.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Adjust kmem_cache_alloc_bulk API before we have any real users.

Adjust API to return type 'int' instead of previously type 'bool'.  This
is done to allow future extension of the bulk alloc API.

A future extension could be to allow SLUB to stop at a page boundary, when
specified by a flag, and then return the number of objects.

The advantage of this approach, would make it easier to make bulk alloc
run without local IRQs disabled.  With an approach of cmpxchg "stealing"
the entire c->freelist or page->freelist.  To avoid overshooting we would
stop processing at a slab-page boundary.  Else we always end up returning
some objects at the cost of another cmpxchg.

To keep compatible with future users of this API linking against an older
kernel when using the new flag, we need to return the number of allocated
objects with this API change.
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

alloc_pages_exact_node() was introduced in commit 6484eb3e ("page
allocator: do not check NUMA node ID when the caller knows the node is
valid") as an optimized variant of alloc_pages_node(), that doesn't
fallback to current node for nid == NUMA_NO_NODE.  Unfortunately the
name of the function can easily suggest that the allocation is
restricted to the given node and fails otherwise.  In truth, the node is
only preferred, unless __GFP_THISNODE is passed among the gfp flags.

The misleading name has lead to mistakes in the past, see for example
commits 5265047a ("mm, thp: really limit transparent hugepage
allocation to local node") and b360edb4 ("mm, mempolicy:
migrate_to_node should only migrate to node").

Another issue with the name is that there's a family of
alloc_pages_exact*() functions where 'exact' means exact size (instead
of page order), which leads to more confusion.

To prevent further mistakes, this patch effectively renames
alloc_pages_exact_node() to __alloc_pages_node() to better convey that
it's an optimized variant of alloc_pages_node() not intended for general
usage.  Both functions get described in comments.

It has been also considered to really provide a convenience function for
allocations restricted to a node, but the major opinion seems to be that
__GFP_THISNODE already provides that functionality and we shouldn't
duplicate the API needlessly.  The number of users would be small
anyway.

Existing callers of alloc_pages_exact_node() are simply converted to
call __alloc_pages_node(), with the exception of sba_alloc_coherent()
which open-codes the check for NUMA_NO_NODE, so it is converted to use
alloc_pages_node() instead.  This means it no longer performs some
VM_BUG_ON checks, and since the current check for nid in
alloc_pages_node() uses a 'nid < 0' comparison (which includes
NUMA_NO_NODE), it may hide wrong values which would be previously
exposed.

Both differences will be rectified by the next patch.

To sum up, this patch makes no functional changes, except temporarily
hiding potentially buggy callers.  Restricting the checks in
alloc_pages_node() is left for the next patch which can in turn expose
more existing buggy callers.
Signed-off-by: NVlastimil Babka <vbabka@suse.cz>
Acked-by: NJohannes Weiner <hannes@cmpxchg.org>
Acked-by: NRobin Holt <robinmholt@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Acked-by: NMichael Ellerman <mpe@ellerman.id.au>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Fenghua Yu <fenghua.yu@intel.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Gleb Natapov <gleb@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Cliff Whickman <cpw@sgi.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Add the basic infrastructure for alloc/free operations on pointer arrays.
It includes a generic function in the common slab code that is used in
this infrastructure patch to create the unoptimized functionality for slab
bulk operations.

Allocators can then provide optimized allocation functions for situations
in which large numbers of objects are needed.  These optimization may
avoid taking locks repeatedly and bypass metadata creation if all objects
in slab pages can be used to provide the objects required.

Allocators can extend the skeletons provided and add their own code to the
bulk alloc and free functions.  They can keep the generic allocation and
freeing and just fall back to those if optimizations would not work (like
for example when debugging is on).
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NJesper Dangaard Brouer <brouer@redhat.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

slob_alloc_node() is only used in slob.c.  Remove the EXPORT_SYMBOL and
make slob_alloc_node() static.
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

To speed up further allocations SLUB may store empty slabs in per cpu/node
partial lists instead of freeing them immediately.  This prevents per
memcg caches destruction, because kmem caches created for a memory cgroup
are only destroyed after the last page charged to the cgroup is freed.

To fix this issue, this patch resurrects approach first proposed in [1].
It forbids SLUB to cache empty slabs after the memory cgroup that the
cache belongs to was destroyed.  It is achieved by setting kmem_cache's
cpu_partial and min_partial constants to 0 and tuning put_cpu_partial() so
that it would drop frozen empty slabs immediately if cpu_partial = 0.

The runtime overhead is minimal.  From all the hot functions, we only
touch relatively cold put_cpu_partial(): we make it call
unfreeze_partials() after freezing a slab that belongs to an offline
memory cgroup.  Since slab freezing exists to avoid moving slabs from/to a
partial list on free/alloc, and there can't be allocations from dead
caches, it shouldn't cause any overhead.  We do have to disable preemption
for put_cpu_partial() to achieve that though.

The original patch was accepted well and even merged to the mm tree.
However, I decided to withdraw it due to changes happening to the memcg
core at that time.  I had an idea of introducing per-memcg shrinkers for
kmem caches, but now, as memcg has finally settled down, I do not see it
as an option, because SLUB shrinker would be too costly to call since SLUB
does not keep free slabs on a separate list.  Besides, we currently do not
even call per-memcg shrinkers for offline memcgs.  Overall, it would
introduce much more complexity to both SLUB and memcg than this small
patch.

Regarding to SLAB, there's no problem with it, because it shrinks
per-cpu/node caches periodically.  Thanks to list_lru reparenting, we no
longer keep entries for offline cgroups in per-memcg arrays (such as
memcg_cache_params->memcg_caches), so we do not have to bother if a
per-memcg cache will be shrunk a bit later than it could be.

[1] http://thread.gmane.org/gmane.linux.kernel.mm/118649/focus=118650Signed-off-by: NVladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Now, we track caller if tracing or slab debugging is enabled.  If they are
disabled, we could save one argument passing overhead by calling
__kmalloc(_node)().  But, I think that it would be marginal.  Furthermore,
default slab allocator, SLUB, doesn't use this technique so I think that
it's okay to change this situation.

After this change, we can turn on/off CONFIG_DEBUG_SLAB without full
kernel build and remove some complicated '#if' defintion.  It looks more
benefitial to me.
Signed-off-by: NJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

When we create a sl[au]b cache, we allocate kmem_cache_node structures
for each online NUMA node.  To handle nodes taken online/offline, we
register memory hotplug notifier and allocate/free kmem_cache_node
corresponding to the node that changes its state for each kmem cache.

To synchronize between the two paths we hold the slab_mutex during both
the cache creationg/destruction path and while tuning per-node parts of
kmem caches in memory hotplug handler, but that's not quite right,
because it does not guarantee that a newly created cache will have all
kmem_cache_nodes initialized in case it races with memory hotplug.  For
instance, in case of slub:

    CPU0                            CPU1
    ----                            ----
    kmem_cache_create:              online_pages:
     __kmem_cache_create:            slab_memory_callback:
                                      slab_mem_going_online_callback:
                                       lock slab_mutex
                                       for each slab_caches list entry
                                           allocate kmem_cache node
                                       unlock slab_mutex
      lock slab_mutex
      init_kmem_cache_nodes:
       for_each_node_state(node, N_NORMAL_MEMORY)
           allocate kmem_cache node
      add kmem_cache to slab_caches list
      unlock slab_mutex
                                    online_pages (continued):
                                     node_states_set_node

As a result we'll get a kmem cache with not all kmem_cache_nodes
allocated.

To avoid issues like that we should hold get/put_online_mems() during
the whole kmem cache creation/destruction/shrink paths, just like we
deal with cpu hotplug.  This patch does the trick.

Note, that after it's applied, there is no need in taking the slab_mutex
for kmem_cache_shrink any more, so it is removed from there.
Signed-off-by: NVladimir Davydov <vdavydov@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Zhang Yanfei <zhangyanfei@cn.fujitsu.com>
Cc: Toshi Kani <toshi.kani@hp.com>
Cc: Xishi Qiu <qiuxishi@huawei.com>
Cc: Jiang Liu <liuj97@gmail.com>
Cc: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Wen Congyang <wency@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

'struct page' has two list_head fields: 'lru' and 'list'.  Conveniently,
they are unioned together.  This means that code can use them
interchangably, which gets horribly confusing like with this nugget from
slab.c:

>	list_del(&page->lru);
>	if (page->active == cachep->num)
>		list_add(&page->list, &n->slabs_full);

This patch makes the slab and slub code use page->lru universally instead
of mixing ->list and ->lru.

So, the new rule is: page->lru is what the you use if you want to keep
your page on a list.  Don't like the fact that it's not called ->list?
Too bad.
Signed-off-by: NDave Hansen <dave.hansen@linux.intel.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Cc: Pekka Enberg <penberg@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

The kmalloc* functions of all slab allcoators are similar now so
lets move them into slab.h. This requires some function naming changes
in slob.

As a results of this patch there is a common set of functions for
all allocators. Also means that kmalloc_large() is now available
in general to perform large order allocations that go directly
via the page allocator. kmalloc_large() can be substituted if
kmalloc() throws warnings because of too large allocations.

kmalloc_large() has exactly the same semantics as kmalloc but
can only used for allocations > PAGE_SIZE.
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

While doing some code inspection, I noticed that the slob constructor
method can be called with a NULL pointer. If memory is tight and slob
fails to allocate with slob_alloc() or slob_new_pages() it still calls
the ctor() method with a NULL pointer. Looking at the first ctor()
method I found, I noticed that it can not handle a NULL pointer (I'm
sure others probably can't either):

static void sighand_ctor(void *data)
{
        struct sighand_struct *sighand = data;

        spin_lock_init(&sighand->siglock);
        init_waitqueue_head(&sighand->signalfd_wqh);
}

The solution is to only call the ctor() method if allocation succeeded.
Acked-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Acked-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NSasha Levin <sasha.levin@oracle.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

The function names page_xchg_last_nid(), page_last_nid() and
reset_page_last_nid() were judged to be inconsistent so rename them to a
struct_field_op style pattern.  As it looked jarring to have
reset_page_mapcount() and page_nid_reset_last() beside each other in
memmap_init_zone(), this patch also renames reset_page_mapcount() to
page_mapcount_reset().  There are others like init_page_count() but as
it is used throughout the arch code a rename would likely cause more
conflicts than it is worth.

[akpm@linux-foundation.org: fix zcache]
Signed-off-by: NMel Gorman <mgorman@suse.de>
Suggested-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

struct page already has this information.  If we start chaining caches,
this information will always be more trustworthy than whatever is passed
into the function.
Signed-off-by: NGlauber Costa <glommer@parallels.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Frederic Weisbecker <fweisbec@redhat.com>
Cc: Greg Thelen <gthelen@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: JoonSoo Kim <js1304@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Rik van Riel <riel@redhat.com>
Cc: Suleiman Souhlal <suleiman@google.com>
Cc: Tejun Heo <tj@kernel.org>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

Extract the code to do object alignment from the allocators.
Do the alignment calculations in slab_common so that the
__kmem_cache_create functions of the allocators do not have
to deal with alignment.
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

The definition of ARCH_SLAB_MINALIGN is architecture dependent
and can be either of type size_t or int. Comparing that value
with ARCH_KMALLOC_MINALIGN can cause harmless warnings on
platforms where they are different. Since both are always
small positive integer numbers, using the size_t type to compare
them is safe and gets rid of the warning.

Without this patch, building ARM collie_defconfig results in:

mm/slob.c: In function '__kmalloc_node':
mm/slob.c:431:152: warning: comparison of distinct pointer types lacks a cast [enabled by default]
mm/slob.c: In function 'kfree':
mm/slob.c:484:153: warning: comparison of distinct pointer types lacks a cast [enabled by default]
mm/slob.c: In function 'ksize':
mm/slob.c:503:153: warning: comparison of distinct pointer types lacks a cast [enabled by default]
Acked-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
[ penberg@kernel.org: updates for master ]
Signed-off-by: NPekka Enberg <penberg@kernel.org>

When freeing objects, the slob allocator currently free empty pages
calling __free_pages(). However, page-size kmallocs are disposed
using put_page() instead.

It makes no sense to call put_page() for kernel pages that are provided
by the object allocator, so we shouldn't be doing this ourselves.

This is based on:
commit d9b7f226
Author: Glauber Costa <glommer@parallels.com>
slub: use free_page instead of put_page for freeing kmalloc allocation

Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Acked-by: NGlauber Costa <glommer@parallels.com>
Signed-off-by: NEzequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

This function is identically defined in all three allocators
and it's trivial to move it to slab.h

Since now it's static, inline, header-defined function
this patch also drops the EXPORT_SYMBOL tag.

Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NEzequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Fields object_size and size are not the same: the latter might include
slab metadata. Return object_size field in kmem_cache_size().
Also, improve trace accuracy by correctly tracing reported size.

Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NEzequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

This field was being used to store size allocation so it could be
retrieved by ksize(). However, it is a bad practice to not mark a page
as a slab page and then use fields for special purposes.
There is no need to store the allocated size and
ksize() can simply return PAGE_SIZE << compound_order(page).

Cc: Pekka Enberg <penberg@kernel.org>
Cc: Matt Mackall <mpm@selenic.com>
Acked-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NEzequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

The definition of ARCH_SLAB_MINALIGN is architecture dependent
and can be either of type size_t or int. Comparing that value
with ARCH_KMALLOC_MINALIGN can cause harmless warnings on
platforms where they are different. Since both are always
small positive integer numbers, using the size_t type to compare
them is safe and gets rid of the warning.

Without this patch, building ARM collie_defconfig results in:

mm/slob.c: In function '__kmalloc_node':
mm/slob.c:431:152: warning: comparison of distinct pointer types lacks a cast [enabled by default]
mm/slob.c: In function 'kfree':
mm/slob.c:484:153: warning: comparison of distinct pointer types lacks a cast [enabled by default]
mm/slob.c: In function 'ksize':
mm/slob.c:503:153: warning: comparison of distinct pointer types lacks a cast [enabled by default]
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NChristoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>

On Sat, 8 Sep 2012, Ezequiel Garcia wrote:

> @@ -454,15 +455,35 @@ void *__kmalloc_node(size_t size, gfp_t gfp, int node)
>  			gfp |= __GFP_COMP;
>  		ret = slob_new_pages(gfp, order, node);
>
> -		trace_kmalloc_node(_RET_IP_, ret,
> +		trace_kmalloc_node(caller, ret,
>  				   size, PAGE_SIZE << order, gfp, node);
>  	}
>
>  	kmemleak_alloc(ret, size, 1, gfp);
>  	return ret;
>  }
> +
> +void *__kmalloc_node(size_t size, gfp_t gfp, int node)
> +{
> +	return __do_kmalloc_node(size, gfp, node, _RET_IP_);
> +}
>  EXPORT_SYMBOL(__kmalloc_node);
>
> +#ifdef CONFIG_TRACING
> +void *__kmalloc_track_caller(size_t size, gfp_t gfp, unsigned long caller)
> +{
> +	return __do_kmalloc_node(size, gfp, NUMA_NO_NODE, caller);
> +}
> +
> +#ifdef CONFIG_NUMA
> +void *__kmalloc_node_track_caller(size_t size, gfp_t gfpflags,
> +					int node, unsigned long caller)
> +{
> +	return __do_kmalloc_node(size, gfp, node, caller);
> +}
> +#endif

This breaks Pekka's slab/next tree with this:

mm/slob.c: In function '__kmalloc_node_track_caller':
mm/slob.c:488: error: 'gfp' undeclared (first use in this function)
mm/slob.c:488: error: (Each undeclared identifier is reported only once
mm/slob.c:488: error: for each function it appears in.)

mm, slob: fix build breakage in __kmalloc_node_track_caller

"mm, slob: Add support for kmalloc_track_caller()" breaks the build
because gfp is undeclared.  Fix it.
Acked-by: NEzequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Currently slob falls back to regular kmalloc for this case.
With this patch kmalloc_track_caller() is correctly implemented,
thus tracing the specified caller.

This is important to trace accurately allocations performed by
krealloc, kstrdup, kmemdup, etc.
Signed-off-by: NEzequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NEzequiel Garcia <elezegarcia@gmail.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Get rid of the refcount stuff in the allocators and do that part of
kmem_cache management in the common code.
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Do the initial settings of the fields in common code. This will allow us
to push more processing into common code later and improve readability.
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Shift the allocations to common code. That way the allocation and
freeing of the kmem_cache structures is handled by common code.
Reviewed-by: NGlauber Costa <glommer@parallels.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

What is done there can be done in __kmem_cache_shutdown.

This affects RCU handling somewhat. On rcu free all slab allocators do
not refer to other management structures than the kmem_cache structure.
Therefore these other structures can be freed before the rcu deferred
free to the page allocator occurs.
Reviewed-by: NJoonsoo Kim <js1304@gmail.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

The freeing action is basically the same in all slab allocators.
Move to the common kmem_cache_destroy() function.
Reviewed-by: NGlauber Costa <glommer@parallels.com>
Reviewed-by: NJoonsoo Kim <js1304@gmail.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Make all allocators use the "kmem_cache" slabname for the "kmem_cache"
structure.
Reviewed-by: NGlauber Costa <glommer@parallels.com>
Reviewed-by: NJoonsoo Kim <js1304@gmail.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

kmem_cache_destroy does basically the same in all allocators.

Extract common code which is easy since we already have common mutex
handling.
Reviewed-by: NGlauber Costa <glommer@parallels.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Move the code to append the new kmem_cache to the list of slab caches to
the kmem_cache_create code in the shared code.

This is possible now since the acquisition of the mutex was moved into
kmem_cache_create().
Acked-by: NDavid Rientjes <rientjes@google.com>
Reviewed-by: NGlauber Costa <glommer@parallels.com>
Reviewed-by: NJoonsoo Kim <js1304@gmail.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Commit fd3142a59af2012a7c5dc72ec97a4935ff1c5fc6 broke
slob since a piece of a change for a later patch slipped into
it.

Fengguang Wu writes:

  The commit crashes the kernel w/o any dmesg output (the attached one is
  created by the script as a summary for that run). This is very
  reproducible in kvm for the attached config.
Reported-by: NFengguang Wu <fengguang.wu@intel.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

All allocators have some sort of support for the bootstrap status.

Setup a common definition for the boot states and make all slab
allocators use that definition.
Reviewed-by: NGlauber Costa <glommer@parallels.com>
Reviewed-by: NJoonsoo Kim <js1304@gmail.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Kmem_cache_create() does a variety of sanity checks but those
vary depending on the allocator. Use the strictest tests and put them into
a slab_common file. Make the tests conditional on CONFIG_DEBUG_VM.

This patch has the effect of adding sanity checks for SLUB and SLOB
under CONFIG_DEBUG_VM and removes the checks in SLAB for !CONFIG_DEBUG_VM.
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Define a struct that describes common fields used in all slab allocators.
A slab allocator either uses the common definition (like SLOB) or is
required to provide members of kmem_cache with the definition given.

After that it will be possible to share code that
only operates on those fields of kmem_cache.

The patch basically takes the slob definition of kmem cache and
uses the field namees for the other allocators.

It also standardizes the names used for basic object lengths in
allocators:

object_size	Struct size specified at kmem_cache_create. Basically
		the payload expected to be used by the subsystem.

size		The size of memory allocator for each object. This size
		is larger than object_size and includes padding, alignment
		and extra metadata for each object (f.e. for debugging
		and rcu).
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Those have become so simple that they are no longer needed.
Reviewed-by: NJoonsoo Kim <js1304@gmail.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>

Reviewed-by: NJoonsoo Kim <js1304@gmail.com>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NChristoph Lameter <cl@linux.com>
Signed-off-by: NPekka Enberg <penberg@kernel.org>