mm: vmscan: drop nr_force_scan[] from get_scan_count

//With minor adjustment to gel with previous commit - Noob-X //
The nr_force_scan[] tuple holds the effective scan numbers for anon and
file pages in case the situation called for a forced scan and the
regularly calculated scan numbers turned out zero.

However, the effective scan number can always be assumed to be
SWAP_CLUSTER_MAX right before the division into anon and file.  The
numerators and denominator are properly set up for all cases, be it force
scan for just file, just anon, or both, to do the right thing.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Ying Han <yinghan@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: vmscan: clarify how swappiness, highest priority, memcg interact

//Adapted for WCS - Noob-X //
A swappiness of 0 has a slightly different meaning for global reclaim
(may swap if file cache really low) and memory cgroup reclaim (never
swap, ever).

In addition, global reclaim at highest priority will scan all LRU lists
equal to their size and ignore other balancing heuristics.  UNLESS
swappiness forbids swapping, then the lists are balanced based on recent
reclaim effectiveness.  UNLESS file cache is running low, then anonymous
pages are force-scanned.

This (total mess of a) behaviour is implicit and not obvious from the
way the code is organized.  At least make it apparent in the code flow
and document the conditions.  It will be it easier to come up with sane
semantics later.

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Rik van Riel <riel@redhat.com>
Reviewed-by: Satoru Moriya <satoru.moriya@hds.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Hugh Dickins <hughd@google.com>
Cc: Simon Jeons <simon.jeons@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg: fix oom schedule_timeout()

Before calling schedule_timeout(), task state should be changed.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg: do not expose uninitialized mem_cgroup_per_node to world

If somebody is touching data too early, it might be easier to diagnose a
problem when dereferencing NULL at mem->info.nodeinfo[node] than trying to
understand why mem_cgroup_per_zone is [un|partly]initialized.

Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg: close race between charge and putback

There is a potential race between a thread charging a page and another
thread putting it back to the LRU list:

  charge:                         putback:
  SetPageCgroupUsed               SetPageLRU
  PageLRU && add to memcg LRU     PageCgroupUsed && add to memcg LRU

The order of setting one flag and checking the other is crucial, otherwise
the charge may observe !PageLRU while the putback observes !PageCgroupUsed
and the page is not linked to the memcg LRU at all.

Global memory pressure may fix this by trying to isolate and putback the
page for reclaim, where that putback would link it to the memcg LRU again.
 Without that, the memory cgroup is undeletable due to a charge whose
physical page can not be found and moved out.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Cc: Ying Han <yinghan@google.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg: Fix race condition in memcg_check_events() with this_cpu usage

Various code in memcontrol.c () calls this_cpu_read() on the calculations
to be done from two different percpu variables, or does an open-coded
read-modify-write on a single percpu variable.

Disable preemption throughout these operations so that the writes go to
the correct palces.

[hannes@cmpxchg.org: added this_cpu to __this_cpu conversion]
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Cc: Greg Thelen <gthelen@google.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg: make mem_cgroup_split_huge_fixup() more efficient

In split_huge_page(), mem_cgroup_split_huge_fixup() is called to handle
page_cgroup modifcations.  It takes move_lock_page_cgroup() and modifies
page_cgroup and LRU accounting jobs and called HPAGE_PMD_SIZE - 1 times.

But thinking again,
  - compound_lock() is held at move_accout...then, it's not necessary
    to take move_lock_page_cgroup().
  - LRU is locked and all tail pages will go into the same LRU as
    head is now on.
  - page_cgroup is contiguous in huge page range.

This patch fixes mem_cgroup_split_huge_fixup() as to be called once per
hugepage and reduce costs for spliting.

[akpm@linux-foundation.org: fix typo, per Michal]
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: memcg: clean up fault accounting

The fault accounting functions have a single, memcg-internal user, so they
don't need to be global.  In fact, their one-line bodies can be directly
folded into the caller.  And since faults happen one at a time, use
this_cpu_inc() directly instead of this_cpu_add(foo, 1).

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Balbir Singh <bsingharora@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: memcg: lookup_page_cgroup (almost) never returns NULL

Pages have their corresponding page_cgroup descriptors set up before
they are used in userspace, and thus managed by a memory cgroup.

The only time where lookup_page_cgroup() can return NULL is in the
CONFIG_DEBUG_VM-only page sanity checking code that executes while
feeding pages into the page allocator for the first time.

Remove the NULL checks against lookup_page_cgroup() results from all
callsites where we know that corresponding page_cgroup descriptors must
be allocated, and add a comment to the callsite that actually does have
to check the return value.

[hughd@google.com: stop oops in mem_cgroup_update_page_stat()]
Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Signed-off-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: memcg: remove unneeded checks from newpage_charge()

All callsites pass in freshly allocated pages and a valid mm.  As a
result, all checks pertaining to the page's mapcount, page->mapping or the
fallback to init_mm are unneeded.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: David Rientjes <rientjes@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: memcg: remove unneeded checks from uncharge_page()

mem_cgroup_uncharge_page() is only called on either freshly allocated
pages without page->mapping or on rmapped PageAnon() pages.  There is no
need to check for a page->mapping that is not an anon_vma.

Signed-off-by: Johannes Weiner <jweiner@redhat.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
page_cgroup: add helper function to get swap_cgroup

There are multiple places which need to get the swap_cgroup address, so
add a helper function:

  static struct swap_cgroup *swap_cgroup_getsc(swp_entry_t ent,
                                struct swap_cgroup_ctrl **ctrl);

to simplify the code.

Signed-off-by: Bob Liu <lliubbo@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Johannes Weiner <jweiner@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg: free entries in soft_limit_tree if allocation fails

If we are not able to allocate tree nodes for all NUMA nodes then we
should release those that were allocated.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Hugh Dickins <hughd@google.com>
Cc: Balbir Singh <bsingharora@gmail.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
oom, memcg: fix exclusion of memcg threads after they have detached their mm

The oom killer relies on logic that identifies threads that have already
been oom killed when scanning the tasklist and, if found, deferring
until such threads have exited.  This is done by checking for any
candidate threads that have the TIF_MEMDIE bit set.

For memcg ooms, candidate threads are first found by calling
task_in_mem_cgroup() since the oom killer should not defer if there's an
oom killed thread in another memcg.

Unfortunately, task_in_mem_cgroup() excludes threads if they have
detached their mm in the process of exiting so TIF_MEMDIE is never
detected for such conditions.  This is different for global, mempolicy,
and cpuset oom conditions where a detached mm is only excluded after
checking for TIF_MEMDIE and deferring, if necessary, in
select_bad_process().

The fix is to return true if a task has a detached mm but is still in
the memcg or its hierarchy that is currently oom.  This will allow the
oom killer to appropriately defer rather than kill unnecessarily or, in
the worst case, panic the machine if nothing else is available to kill.

Signed-off-by: David Rientjes <rientjes@google.com>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Balbir Singh <bsingharora@gmail.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg: simplify page cache charging

This patch is a clean up. No functional/logical changes.

Because of commit ef6a3c6311 ("mm: add replace_page_cache_page()
function") , FUSE uses replace_page_cache() instead of
add_to_page_cache().  Then, mem_cgroup_cache_charge() is not called
against FUSE's pages from splice.

So now, mem_cgroup_cache_charge() gets pages that are not on the LRU
with the exception of PageSwapCache pages.  For checking,
WARN_ON_ONCE(PageLRU(page)) is added.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Miklos Szeredi <mszeredi@suse.cz>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Ying Han <yinghan@google.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
cpusets: randomize node rotor used in cpuset_mem_spread_node()

[ This patch has already been accepted as commit 0ac0c0d0f837 but later
  reverted (commit 35926ff5fba8) because it itroduced arch specific
  __node_random which was defined only for x86 code so it broke other
  archs.  This is a followup without any arch specific code.  Other than
  that there are no functional changes.]

Some workloads that create a large number of small files tend to assign
too many pages to node 0 (multi-node systems).  Part of the reason is
that the rotor (in cpuset_mem_spread_node()) used to assign nodes starts
at node 0 for newly created tasks.

This patch changes the rotor to be initialized to a random node number
of the cpuset.

[akpm@linux-foundation.org: fix layout]
[Lee.Schermerhorn@hp.com: Define stub numa_random() for !NUMA configuration]
[mhocko@suse.cz: Make it arch independent]
[akpm@linux-foundation.org: fix CONFIG_NUMA=y, MAX_NUMNODES>1 build]
Signed-off-by: Jack Steiner <steiner@sgi.com>
Signed-off-by: Lee Schermerhorn <lee.schermerhorn@hp.com>
Signed-off-by: Michal Hocko <mhocko@suse.cz>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Paul Menage <menage@google.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: Robin Holt <holt@sgi.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Jack Steiner <steiner@sgi.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Paul Menage <menage@google.com>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: Robin Holt <holt@sgi.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg: cleanup for_each_node_state()

We already have for_each_node(node) define in nodemask.h, better to use it.

Signed-off-by: Bob Liu <lliubbo@gmail.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
mm: memcg: update the correct soft limit tree during migration

end_migration() passes the old page instead of the new page to commit
the charge.  This page descriptor is not used for committing itself,
though, since we also pass the (correct) page_cgroup descriptor.  But
it's used to find the soft limit tree through the page's zone, so the
soft limit tree of the old page's zone is updated instead of that of the
new page's, which might get slightly out of date until the next charge
reaches the ratelimit point.

This glitch has been present since 5564e88 ("memcg: condense
page_cgroup-to-page lookup points").

This fixes a bug that I introduced in 2.6.38.  It's benign enough (to my
knowledge) that we probably don't want this for stable.

Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Acked-by: Kirill A. Shutemov <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
memcg: oom: fix totalpages calculation for memory.swappiness==0

//Adapted for WCS - Noob-X //
oom_badness() takes a totalpages argument which says how many pages are
available and it uses it as a base for the score calculation.  The value
is calculated by mem_cgroup_get_limit which considers both limit and
total_swap_pages (resp.  memsw portion of it).

This is usually correct but since fe35004fbf9e ("mm: avoid swapping out
with swappiness==0") we do not swap when swappiness is 0 which means
that we cannot really use up all the totalpages pages.  This in turn
confuses oom score calculation if the memcg limit is much smaller than
the available swap because the used memory (capped by the limit) is
negligible comparing to totalpages so the resulting score is too small
if adj!=0 (typically task with CAP_SYS_ADMIN or non zero oom_score_adj).
A wrong process might be selected as result.

The problem can be worked around by checking mem_cgroup_swappiness==0
and not considering swap at all in such a case.

Signed-off-by: Michal Hocko <mhocko@suse.cz>
Acked-by: David Rientjes <rientjes@google.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>