slab: destroy a slab without holding any alien cache lock

I haven't heard that this alien cache lock is contended, but to reduce
chance of contention would be better generally.  And with this change,
we can simplify complex lockdep annotation in slab code.  In the
following patch, it will be implemented.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
slab: remove a useless lockdep annotation

Now, there is no code to hold two lock simultaneously, since we don't
call slab_destroy() with holding any lock.  So, lockdep annotation is
useless now.  Remove it.

v2: don't remove BAD_ALIEN_MAGIC in this patch. It will be removed
    in the following patch.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
slab: remove BAD_ALIEN_MAGIC

BAD_ALIEN_MAGIC value isn't used anymore. So remove it.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
slab: change int to size_t for representing allocation size

It is better to represent allocation size in size_t rather than int.  So
change it.

Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Christoph Lameter <cl@linux.com>
Reviewed-by: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
slub: avoid duplicate creation on the first object

When a kmem_cache is created with ctor, each object in the kmem_cache
will be initialized before ready to use.  While in slub implementation,
the first object will be initialized twice.

This patch reduces the duplication of initialization of the first
object.

Fix commit 7656c72b ("SLUB: add macros for scanning objects in a slab").

Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: move slab related stuff from util.c to slab_common.c

Functions krealloc(), __krealloc(), kzfree() belongs to slab API, so
should be placed in slab_common.c

Also move slab allocator's tracepoints defenitions to slab_common.c No
functional changes here.

Signed-off-by: Andrey Ryabinin <a.ryabinin@samsung.com>
Acked-by: 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/slab.c: fix comments

Current struct kmem_cache has no 'lock' field, and slab page is managed by
struct kmem_cache_node, which has 'list_lock' field.

Clean up the related comment.

Signed-off-by: Wang Sheng-Hui <shhuiw@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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm, slub: fix some indenting in cmpxchg_double_slab()

The return statement goes with the cmpxchg_double() condition so it needs
to be indented another tab.

Also these days the fashion is to line function parameters up, and it
looks nicer that way because then the "freelist_new" is not at the same
indent level as the "return 1;".

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
slab: fix the alias count (via sysfs) of slab cache

We mark some slab caches (e.g.  kmem_cache_node) as unmergeable by
setting refcount to -1, and their alias should be 0, not refcount-1, so
correct it here.

Signed-off-by: Gu Zheng <guz.fnst@cn.fujitsu.com>
Acked-by: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
slab: convert last use of __FUNCTION__ to __func__

Just about all of these have been converted to __func__, so convert the
last use.

Signed-off-by: Joe Perches <joe@perches.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/readahead.c: remove unused file_ra_state from count_history_pages

count_history_pages does only call page_cache_prev_hole in rcu_lock
context using address_space mapping.  There's no need to have
file_ra_state here.

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Acked-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memory_hotplug.c: add __meminit to grow_zone_span/grow_pgdat_span

grow_zone_span and grow_pgdat_span are only called by
__meminit __add_zone

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Toshi Kani <toshi.kani@hp.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/page_alloc.c: add __meminit to alloc_pages_exact_nid()

alloc_pages_exact_nid() is only called by __meminit alloc_page_cgroup()

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Cc: Mel Gorman <mgorman@suse.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/page_alloc.c: unexport alloc_pages_exact_nid()

It is only called by mm/page_cgroup.c whcih cannot be modular.

Reported-by: David Rientjes <rientjes@google.com>
Cc: Fabian Frederick <fabf@skynet.be>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
include/linux/memblock.h: add __init to memblock_set_bottom_up()

memblock_set_bottom_up() is only called by __init
cmdline_parse_movable_node() and __init numa_init().

Signed-off-by: Fabian Frederick <fabf@skynet.be>
Reviewed-by: Tang Chen <tangchen@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
vmalloc: use rcu list iterator to reduce vmap_area_lock contention

Richard Yao reported a month ago that his system have a trouble with
vmap_area_lock contention during performance analysis by /proc/meminfo.
Andrew asked why his analysis checks /proc/meminfo stressfully, but he
didn't answer it.

  https://lkml.org/lkml/2014/4/10/416

Although I'm not sure that this is right usage or not, there is a
solution reducing vmap_area_lock contention with no side-effect.  That
is just to use rcu list iterator in get_vmalloc_info().

rcu can be used in this function because all RCU protocol is already
respected by writers, since Nick Piggin commit db64fe02258f1 ("mm:
rewrite vmap layer") back in linux-2.6.28

Specifically :
   insertions use list_add_rcu(),
   deletions use list_del_rcu() and kfree_rcu().

Note the rb tree is not used from rcu reader (it would not be safe),
only the vmap_area_list has full RCU protection.

Note that __purge_vmap_area_lazy() already uses this rcu protection.

        rcu_read_lock();
        list_for_each_entry_rcu(va, &vmap_area_list, list) {
                if (va->flags & VM_LAZY_FREE) {
                        if (va->va_start < *start)
                                *start = va->va_start;
                        if (va->va_end > *end)
                                *end = va->va_end;
                        nr += (va->va_end - va->va_start) >> PAGE_SHIFT;
                        list_add_tail(&va->purge_list, &valist);
                        va->flags |= VM_LAZY_FREEING;
                        va->flags &= ~VM_LAZY_FREE;
                }
        }
        rcu_read_unlock();

Peter:

: While rcu list traversal over the vmap_area_list is safe, this may
: arrive at different results than the spinlocked version. The rcu list
: traversal version will not be a 'snapshot' of a single, valid instant
: of the entire vmap_area_list, but rather a potential amalgam of
: different list states.

Joonsoo:

: Yes, you are right, but I don't think that we should be strict here.
: Meminfo is already not a 'snapshot' at specific time.  While we try to get
: certain stats, the other stats can change.  And, although we may arrive at
: different results than the spinlocked version, the difference would not be
: large and would not make serious side-effect.

[edumazet@google.com: add more commit description]
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Reported-by: Richard Yao <ryao@gentoo.org>
Acked-by: Eric Dumazet <edumazet@google.com>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: Zhang Yanfei <zhangyanfei.yes@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andi Kleen <andi@firstfloor.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm/memory.c: use entry = ACCESS_ONCE(*pte) in handle_pte_fault()

Use ACCESS_ONCE() in handle_pte_fault() when getting the entry or
orig_pte upon which all subsequent decisions and pte_same() tests will
be made.

I have no evidence that its lack is responsible for the mm/filemap.c:202
BUG_ON(page_mapped(page)) in __delete_from_page_cache() found by
trinity, and I am not optimistic that it will fix it.  But I have found
no other explanation, and ACCESS_ONCE() here will surely not hurt.

If gcc does re-access the pte before passing it down, then that would be
disastrous for correct page fault handling, and certainly could explain
the page_mapped() BUGs seen (concurrent fault causing page to be mapped
in a second time on top of itself: mapcount 2 for a single pte).

Signed-off-by: Hugh Dickins <hughd@google.com>
Cc: Sasha Levin <sasha.levin@oracle.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mem-hotplug: avoid illegal state prefixed with legal state when changing state of memory_block

We use the following command to online a memory_block:

    echo online|online_kernel|online_movable > /sys/devices/system/memory/memoryXXX/state

But, if we do the following:

    echo online_fhsjkghfkd > /sys/devices/system/memory/memoryXXX/state

the block will also be onlined.

This is because the following code in store_mem_state() does not compare
the whole string, but only the prefix of the string.

  store_mem_state()
  {
       ......
   328         if (!strncmp(buf, "online_kernel", min_t(int, count, 13)))

Here, only compare the first 13 letters of the string. If we give "online_kernelXXXXXX",
it will be recognized as online_kernel, which is incorrect.

   329                 online_type = ONLINE_KERNEL;
   330         else if (!strncmp(buf, "online_movable", min_t(int, count, 14)))

We have the same problem here,

   331                 online_type = ONLINE_MOVABLE;
   332         else if (!strncmp(buf, "online", min_t(int, count, 6)))

here,

(Here is more problematic.  If we give online_movalbe, which is a typo
of online_movable, it will be recognized as online without noticing the
author.)

   333                 online_type = ONLINE_KEEP;
   334         else if (!strncmp(buf, "offline", min_t(int, count, 7)))

and here.

   335                 online_type = -1;
   336         else {
   337                 ret = -EINVAL;
   338                 goto err;
   339         }
       ......
  }

This patch fixes this problem by using sysfs_streq() to compare the
whole string.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Reported-by: Hu Tao <hutao@cn.fujitsu.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Acked-by: Toshi Kani <toshi.kani@hp.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mem-hotplug: introduce MMOP_OFFLINE to replace the hard coding -1

In store_mem_state(), we have:

  ...
  334         else if (!strncmp(buf, "offline", min_t(int, count, 7)))
  335                 online_type = -1;
  ...
  355         case -1:
  356                 ret = device_offline(&mem->dev);
  357                 break;
  ...

Here, "offline" is hard coded as -1.

This patch does the following renaming:

 ONLINE_KEEP     ->  MMOP_ONLINE_KEEP
 ONLINE_KERNEL   ->  MMOP_ONLINE_KERNEL
 ONLINE_MOVABLE  ->  MMOP_ONLINE_MOVABLE

and introduces MMOP_OFFLINE = -1 to avoid hard coding.

Signed-off-by: Tang Chen <tangchen@cn.fujitsu.com>
Cc: Hu Tao <hutao@cn.fujitsu.com>
Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: Yasuaki Ishimatsu <isimatu.yasuaki@jp.fujitsu.com>
Cc: Gu Zheng <guz.fnst@cn.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: page_alloc: simplify drain_zone_pages by using min()

Instead of open-coding getting minimal value of two, just use min macro.
That is why it is there for.  While changing the function also change
type of batch local variable to match type of per_cpu_pages::batch
(which is int).

Signed-off-by: Michal Nazarewicz <mina86@mina86.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>