linux-stable.git/mm, branch v3.18.17

mm, numa: really disable NUMA balancing by default on single node machines

2015-06-10T17:42:34+00:00

[ Upstream commit b0dc2b9bb4ab782115b964310518ee0b17784277 ]

NUMA balancing is meant to be disabled by default on UMA machines but
the check is using nr_node_ids (highest node) instead of
num_online_nodes (online nodes).

The consequences are that a UMA machine with a node ID of 1 or higher
will enable NUMA balancing.  This will incur useless overhead due to
minor faults with the impact depending on the workload.  These are the
impact on the stats when running a kernel build on a single node machine
whose node ID happened to be 1:

  			       vanilla     patched
  NUMA base PTE updates          5113158           0
  NUMA huge PMD updates              643           0
  NUMA page range updates        5442374           0
  NUMA hint faults               2109622           0
  NUMA hint local faults         2109622           0
  NUMA hint local percent            100         100
  NUMA pages migrated                  0           0

Signed-off-by: Mel Gorman 
Reviewed-by: Rik van Riel 
Cc: 	[3.8+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm: soft-offline: fix num_poisoned_pages counting on concurrent events

2015-05-23T19:52:07+00:00

[ Upstream commit 602498f9aa43d4951eece3fd6ad95a6d0a78d537 ]

If multiple soft offline events hit one free page/hugepage concurrently,
soft_offline_page() can handle the free page/hugepage multiple times,
which makes num_poisoned_pages counter increased more than once.  This
patch fixes this wrong counting by checking TestSetPageHWPoison for normal
papes and by checking the return value of dequeue_hwpoisoned_huge_page()
for hugepages.

Signed-off-by: Naoya Horiguchi 
Acked-by: Dean Nelson 
Cc: Andi Kleen 
Cc: 	[3.14+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

writeback: use |1 instead of +1 to protect against div by zero

2015-05-23T19:52:00+00:00

[ Upstream commit 464d1387acb94dc43ba772b35242345e3d2ead1b ]

mm/page-writeback.c has several places where 1 is added to the divisor
to prevent division by zero exceptions; however, if the original
divisor is equivalent to -1, adding 1 leads to division by zero.

There are three places where +1 is used for this purpose - one in
pos_ratio_polynom() and two in bdi_position_ratio().  The second one
in bdi_position_ratio() actually triggered div-by-zero oops on a
machine running a 3.10 kernel.  The divisor is

  x_intercept - bdi_setpoint + 1 == span + 1

span is confirmed to be (u32)-1.  It isn't clear how it ended up that
but it could be from write bandwidth calculation underflow fixed by
c72efb658f7c ("writeback: fix possible underflow in write bandwidth
calculation").

At any rate, +1 isn't a proper protection against div-by-zero.  This
patch converts all +1 protections to |1.  Note that
bdi_update_dirty_ratelimit() was already using |1 before this patch.

Signed-off-by: Tejun Heo 
Cc: stable@vger.kernel.org
Reviewed-by: Jan Kara 
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

mm/memory-failure: call shake_page() when error hits thp tail page

2015-05-23T19:43:34+00:00

[ Upstream commit 09789e5de18e4e442870b2d700831f5cb802eb05 ]

Currently memory_failure() calls shake_page() to sweep pages out from
pcplists only when the victim page is 4kB LRU page or thp head page.
But we should do this for a thp tail page too.

Consider that a memory error hits a thp tail page whose head page is on
a pcplist when memory_failure() runs.  Then, the current kernel skips
shake_pages() part, so hwpoison_user_mappings() returns without calling
split_huge_page() nor try_to_unmap() because PageLRU of the thp head is
still cleared due to the skip of shake_page().

As a result, me_huge_page() runs for the thp, which is broken behavior.

One effect is a leak of the thp.  And another is to fail to isolate the
memory error, so later access to the error address causes another MCE,
which kills the processes which used the thp.

This patch fixes this problem by calling shake_page() for thp tail case.

Fixes: 385de35722c9 ("thp: allow a hwpoisoned head page to be put back to LRU")
Signed-off-by: Naoya Horiguchi 
Reviewed-by: Andi Kleen 
Acked-by: Dean Nelson 
Cc: Andrea Arcangeli 
Cc: Hidetoshi Seto 
Cc: Jin Dongming 
Cc: 	[3.4+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm/hugetlb: take page table lock in follow_huge_pmd()

2015-05-17T23:12:31+00:00

[ Upstream commit e66f17ff71772b209eed39de35aaa99ba819c93d ]

We have a race condition between move_pages() and freeing hugepages, where
move_pages() calls follow_page(FOLL_GET) for hugepages internally and
tries to get its refcount without preventing concurrent freeing.  This
race crashes the kernel, so this patch fixes it by moving FOLL_GET code
for hugepages into follow_huge_pmd() with taking the page table lock.

This patch intentionally removes page==NULL check after pte_page.
This is justified because pte_page() never returns NULL for any
architectures or configurations.

This patch changes the behavior of follow_huge_pmd() for tail pages and
then tail pages can be pinned/returned.  So the caller must be changed to
properly handle the returned tail pages.

We could have a choice to add the similar locking to
follow_huge_(addr|pud) for consistency, but it's not necessary because
currently these functions don't support FOLL_GET flag, so let's leave it
for future development.

Here is the reproducer:

  $ cat movepages.c
  #include 
  #include 
  #include 

  #define ADDR_INPUT      0x700000000000UL
  #define HPS             0x200000
  #define PS              0x1000

  int main(int argc, char *argv[]) {
          int i;
          int nr_hp = strtol(argv[1], NULL, 0);
          int nr_p  = nr_hp * HPS / PS;
          int ret;
          void **addrs;
          int *status;
          int *nodes;
          pid_t pid;

          pid = strtol(argv[2], NULL, 0);
          addrs  = malloc(sizeof(char *) * nr_p + 1);
          status = malloc(sizeof(char *) * nr_p + 1);
          nodes  = malloc(sizeof(char *) * nr_p + 1);

          while (1) {
                  for (i = 0; i < nr_p; i++) {
                          addrs[i] = (void *)ADDR_INPUT + i * PS;
                          nodes[i] = 1;
                          status[i] = 0;
                  }
                  ret = numa_move_pages(pid, nr_p, addrs, nodes, status,
                                        MPOL_MF_MOVE_ALL);
                  if (ret == -1)
                          err("move_pages");

                  for (i = 0; i < nr_p; i++) {
                          addrs[i] = (void *)ADDR_INPUT + i * PS;
                          nodes[i] = 0;
                          status[i] = 0;
                  }
                  ret = numa_move_pages(pid, nr_p, addrs, nodes, status,
                                        MPOL_MF_MOVE_ALL);
                  if (ret == -1)
                          err("move_pages");
          }
          return 0;
  }

  $ cat hugepage.c
  #include 
  #include 
  #include 

  #define ADDR_INPUT      0x700000000000UL
  #define HPS             0x200000

  int main(int argc, char *argv[]) {
          int nr_hp = strtol(argv[1], NULL, 0);
          char *p;

          while (1) {
                  p = mmap((void *)ADDR_INPUT, nr_hp * HPS, PROT_READ | PROT_WRITE,
                           MAP_PRIVATE | MAP_ANONYMOUS | MAP_HUGETLB, -1, 0);
                  if (p != (void *)ADDR_INPUT) {
                          perror("mmap");
                          break;
                  }
                  memset(p, 0, nr_hp * HPS);
                  munmap(p, nr_hp * HPS);
          }
  }

  $ sysctl vm.nr_hugepages=40
  $ ./hugepage 10 &
  $ ./movepages 10 $(pgrep -f hugepage)

Fixes: e632a938d914 ("mm: migrate: add hugepage migration code to move_pages()")
Signed-off-by: Naoya Horiguchi 
Reported-by: Hugh Dickins 
Cc: James Hogan 
Cc: David Rientjes 
Cc: Mel Gorman 
Cc: Johannes Weiner 
Cc: Michal Hocko 
Cc: Rik van Riel 
Cc: Andrea Arcangeli 
Cc: Luiz Capitulino 
Cc: Nishanth Aravamudan 
Cc: Lee Schermerhorn 
Cc: Steve Capper 
Cc: 	[3.12+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm/hugetlb: use pmd_page() in follow_huge_pmd()

2015-05-17T23:12:31+00:00

[ Upstream commit 97534127012f0e396eddea4691f4c9b170aed74b ]

Commit 61f77eda9bbf ("mm/hugetlb: reduce arch dependent code around
follow_huge_*") broke follow_huge_pmd() on s390, where pmd and pte
layout differ and using pte_page() on a huge pmd will return wrong
results.  Using pmd_page() instead fixes this.

All architectures that were touched by that commit have pmd_page()
defined, so this should not break anything on other architectures.

Fixes: 61f77eda "mm/hugetlb: reduce arch dependent code around follow_huge_*"
Signed-off-by: Gerald Schaefer 
Acked-by: Naoya Horiguchi 
Cc: Hugh Dickins 
Cc: Michal Hocko , Andrea Arcangeli 
Cc: Martin Schwidefsky 
Acked-by: David Rientjes 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

mm: hwpoison: drop lru_add_drain_all() in __soft_offline_page()

2015-04-28T14:48:53+00:00

[ Upstream commit 9ab3b598d2dfbdb0153ffa7e4b1456bbff59a25d ]

A race condition starts to be visible in recent mmotm, where a PG_hwpoison
flag is set on a migration source page *before* it's back in buddy page
poo= l.

This is problematic because no page flag is supposed to be set when
freeing (see __free_one_page().) So the user-visible effect of this race
is that it could trigger the BUG_ON() when soft-offlining is called.

The root cause is that we call lru_add_drain_all() to make sure that the
page is in buddy, but that doesn't work because this function just
schedule= s a work item and doesn't wait its completion.
drain_all_pages() does drainin= g directly, so simply dropping
lru_add_drain_all() solves this problem.

Fixes: f15bdfa802bf ("mm/memory-failure.c: fix memory leak in successful soft offlining")
Signed-off-by: Naoya Horiguchi 
Cc: Andi Kleen 
Cc: Tony Luck 
Cc: Chen Gong 
Cc: 	[3.11+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin

writeback: fix possible underflow in write bandwidth calculation

2015-04-24T21:13:46+00:00

[ Upstream commit c72efb658f7c8b27ca3d0efb5cfd5ded9fcac89e ]

From 1ebf33901ecc75d9496862dceb1ef0377980587c Mon Sep 17 00:00:00 2001
From: Tejun Heo 
Date: Mon, 23 Mar 2015 00:08:19 -0400

2f800fbd777b ("writeback: fix dirtied pages accounting on redirty")
introduced account_page_redirty() which reverts stat updates for a
redirtied page, making BDI_DIRTIED no longer monotonically increasing.

bdi_update_write_bandwidth() uses the delta in BDI_DIRTIED as the
basis for bandwidth calculation.  While unlikely, since the above
patch, the newer value may be lower than the recorded past value and
underflow the bandwidth calculation leading to a wild result.

Fix it by subtracing min of the old and new values when calculating
delta.  AFAIK, there hasn't been any report of it happening but the
resulting erratic behavior would be non-critical and temporary, so
it's possible that the issue is happening without being reported.  The
risk of the fix is very low, so tagged for -stable.

Signed-off-by: Tejun Heo 
Cc: Jens Axboe 
Cc: Jan Kara 
Cc: Wu Fengguang 
Cc: Greg Thelen 
Fixes: 2f800fbd777b ("writeback: fix dirtied pages accounting on redirty")
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

writeback: add missing INITIAL_JIFFIES init in global_update_bandwidth()

2015-04-24T21:13:45+00:00

[ Upstream commit 7d70e15480c0450d2bfafaad338a32e884fc215e ]

global_update_bandwidth() uses static variable update_time as the
timestamp for the last update but forgets to initialize it to
INITIALIZE_JIFFIES.

This means that global_dirty_limit will be 5 mins into the future on
32bit and some large amount jiffies into the past on 64bit.  This
isn't critical as the only effect is that global_dirty_limit won't be
updated for the first 5 mins after booting on 32bit machines,
especially given the auxiliary nature of global_dirty_limit's role -
protecting against global dirty threshold's sudden dips; however, it
does lead to unintended suboptimal behavior.  Fix it.

Fixes: c42843f2f0bb ("writeback: introduce smoothed global dirty limit")
Signed-off-by: Tejun Heo 
Acked-by: Jan Kara 
Cc: Wu Fengguang 
Cc: Jens Axboe 
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe 
Signed-off-by: Sasha Levin

mm/page_alloc.c: call kernel_map_pages in unset_migrateype_isolate

2015-04-24T21:13:43+00:00

[ Upstream commit cfa869438282be84ad4110bba5027ef1fbbe71e4 ]

Commit 3c605096d315 ("mm/page_alloc: restrict max order of merging on
isolated pageblock") changed the logic of unset_migratetype_isolate to
check the buddy allocator and explicitly call __free_pages to merge.

The page that is being freed in this path never had prep_new_page called
so set_page_refcounted is called explicitly but there is no call to
kernel_map_pages.  With the default kernel_map_pages this is mostly
harmless but if kernel_map_pages does any manipulation of the page
tables (unmapping or setting pages to read only) this may trigger a
fault:

    alloc_contig_range test_pages_isolated(ceb00, ced00) failed
    Unable to handle kernel paging request at virtual address ffffffc0cec00000
    pgd = ffffffc045fc4000
    [ffffffc0cec00000] *pgd=0000000000000000
    Internal error: Oops: 9600004f [#1] PREEMPT SMP
    Modules linked in: exfatfs
    CPU: 1 PID: 23237 Comm: TimedEventQueue Not tainted 3.10.49-gc72ad36-dirty #1
    task: ffffffc03de52100 ti: ffffffc015388000 task.ti: ffffffc015388000
    PC is at memset+0xc8/0x1c0
    LR is at kernel_map_pages+0x1ec/0x244

Fix this by calling kernel_map_pages to ensure the page is set in the
page table properly

Fixes: 3c605096d315 ("mm/page_alloc: restrict max order of merging on isolated pageblock")
Signed-off-by: Laura Abbott 
Cc: Naoya Horiguchi 
Cc: Mel Gorman 
Acked-by: Rik van Riel 
Cc: Yasuaki Ishimatsu 
Cc: Zhang Yanfei 
Cc: Xishi Qiu 
Cc: Vladimir Davydov 
Acked-by: Joonsoo Kim 
Cc: Gioh Kim 
Cc: Michal Nazarewicz 
Cc: Marek Szyprowski 
Cc: Vlastimil Babka 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Sasha Levin