linux-toradex.git/mm, branch v3.4.1

mm: mempolicy: Let vma_merge and vma_split handle vma->vm_policy linkages

2012-06-01T07:18:19+00:00

commit 05f144a0d5c2207a0349348127f996e104ad7404 upstream.

Dave Jones' system call fuzz testing tool "trinity" triggered the
following bug error with slab debugging enabled

    =============================================================================
    BUG numa_policy (Not tainted): Poison overwritten
    -----------------------------------------------------------------------------

    INFO: 0xffff880146498250-0xffff880146498250. First byte 0x6a instead of 0x6b
    INFO: Allocated in mpol_new+0xa3/0x140 age=46310 cpu=6 pid=32154
     __slab_alloc+0x3d3/0x445
     kmem_cache_alloc+0x29d/0x2b0
     mpol_new+0xa3/0x140
     sys_mbind+0x142/0x620
     system_call_fastpath+0x16/0x1b
    INFO: Freed in __mpol_put+0x27/0x30 age=46268 cpu=6 pid=32154
     __slab_free+0x2e/0x1de
     kmem_cache_free+0x25a/0x260
     __mpol_put+0x27/0x30
     remove_vma+0x68/0x90
     exit_mmap+0x118/0x140
     mmput+0x73/0x110
     exit_mm+0x108/0x130
     do_exit+0x162/0xb90
     do_group_exit+0x4f/0xc0
     sys_exit_group+0x17/0x20
     system_call_fastpath+0x16/0x1b
    INFO: Slab 0xffffea0005192600 objects=27 used=27 fp=0x          (null) flags=0x20000000004080
    INFO: Object 0xffff880146498250 @offset=592 fp=0xffff88014649b9d0

This implied a reference counting bug and the problem happened during
mbind().

mbind() applies a new memory policy to a range and uses mbind_range() to
merge existing VMAs or split them as necessary.  In the event of splits,
mpol_dup() will allocate a new struct mempolicy and maintain existing
reference counts whose rules are documented in
Documentation/vm/numa_memory_policy.txt .

The problem occurs with shared memory policies.  The vm_op->set_policy
increments the reference count if necessary and split_vma() and
vma_merge() have already handled the existing reference counts.
However, policy_vma() screws it up by replacing an existing
vma->vm_policy with one that potentially has the wrong reference count
leading to a premature free.  This patch removes the damage caused by
policy_vma().

With this patch applied Dave's trinity tool runs an mbind test for 5
minutes without error.  /proc/slabinfo reported that there are no
numa_policy or shared_policy_node objects allocated after the test
completed and the shared memory region was deleted.

Signed-off-by: Mel Gorman 
Cc: Dave Jones 
Cc: KOSAKI Motohiro 
Cc: Stephen Wilson 
Cc: Christoph Lameter 
Cc: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

memcg,thp: fix res_counter:96 regression

2012-05-19T17:10:27+00:00

Occasionally, testing memcg's move_charge_at_immigrate on rc7 shows
a flurry of hundreds of warnings at kernel/res_counter.c:96, where
res_counter_uncharge_locked() does WARN_ON(counter->usage < val).

The first trace of each flurry implicates __mem_cgroup_cancel_charge()
of mc.precharge, and an audit of mc.precharge handling points to
mem_cgroup_move_charge_pte_range()'s THP handling in commit 12724850e806
("memcg: avoid THP split in task migration").

Checking !mc.precharge is good everywhere else, when a single page is to
be charged; but here the "mc.precharge -= HPAGE_PMD_NR" likely to
follow, is liable to result in underflow (a lot can change since the
precharge was estimated).

Simply check against HPAGE_PMD_NR: there's probably a better
alternative, trying precharge for more, splitting if unsuccessful; but
this one-liner is safer for now - no kernel/res_counter.c:96 warnings
seen in 26 hours.

Signed-off-by: Hugh Dickins 
Signed-off-by: Linus Torvalds

slub: missing test for partial pages flush work in flush_all()

2012-05-18T01:00:51+00:00

I found some kernel messages such as:

    SLUB raid5-md127: kmem_cache_destroy called for cache that still has objects.
    Pid: 6143, comm: mdadm Tainted: G           O 3.4.0-rc6+        #75
    Call Trace:
    kmem_cache_destroy+0x328/0x400
    free_conf+0x2d/0xf0 [raid456]
    stop+0x41/0x60 [raid456]
    md_stop+0x1a/0x60 [md_mod]
    do_md_stop+0x74/0x470 [md_mod]
    md_ioctl+0xff/0x11f0 [md_mod]
    blkdev_ioctl+0xd8/0x7a0
    block_ioctl+0x3b/0x40
    do_vfs_ioctl+0x96/0x560
    sys_ioctl+0x91/0xa0
    system_call_fastpath+0x16/0x1b

Then using kmemleak I found these messages:

    unreferenced object 0xffff8800b6db7380 (size 112):
      comm "mdadm", pid 5783, jiffies 4294810749 (age 90.589s)
      hex dump (first 32 bytes):
        01 01 db b6 ad 4e ad de ff ff ff ff ff ff ff ff  .....N..........
        ff ff ff ff ff ff ff ff 98 40 4a 82 ff ff ff ff  .........@J.....
      backtrace:
        kmemleak_alloc+0x21/0x50
        kmem_cache_alloc+0xeb/0x1b0
        kmem_cache_open+0x2f1/0x430
        kmem_cache_create+0x158/0x320
        setup_conf+0x649/0x770 [raid456]
        run+0x68b/0x840 [raid456]
        md_run+0x529/0x940 [md_mod]
        do_md_run+0x18/0xc0 [md_mod]
        md_ioctl+0xba8/0x11f0 [md_mod]
        blkdev_ioctl+0xd8/0x7a0
        block_ioctl+0x3b/0x40
        do_vfs_ioctl+0x96/0x560
        sys_ioctl+0x91/0xa0
        system_call_fastpath+0x16/0x1b

This bug was introduced by commit a8364d5555b ("slub: only IPI CPUs that
have per cpu obj to flush"), which did not include checks for per cpu
partial pages being present on a cpu.

Signed-off-by: majianpeng 
Cc: Gilad Ben-Yossef 
Acked-by: Christoph Lameter 
Cc: Pekka Enberg 
Tested-by: Jeff Layton 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: raise MemFree by reverting percpu_pagelist_fraction to 0

2012-05-11T16:23:39+00:00

Why is there less MemFree than there used to be?  It perturbed a test,
so I've just been bisecting linux-next, and now find the offender went
upstream yesterday.

Commit 93278814d359 "mm: fix division by 0 in percpu_pagelist_fraction()"
mistakenly initialized percpu_pagelist_fraction to the sysctl's minimum 8,
which leaves 1/8th of memory on percpu lists (on each cpu??); but most of
us expect it to be left unset at 0 (and it's not then used as a divisor).

  MemTotal: 8061476kB  8061476kB  8061476kB  8061476kB  8061476kB  8061476kB
  Repetitive test with percpu_pagelist_fraction 8:
  MemFree:  6948420kB  6237172kB  6949696kB  6840692kB  6949048kB  6862984kB
  Same test with percpu_pagelist_fraction back to 0:
  MemFree:  7945000kB  7944908kB  7948568kB  7949060kB  7948796kB  7948812kB

Signed-off-by: Hugh Dickins 
[ We really should fix the crazy sysctl interface too, but that's a
  separate thing - Linus ]
Signed-off-by: Linus Torvalds

Merge branch 'akpm' (Andrew's patch-bomb)

2012-05-10T22:17:24+00:00

Merge misc fixes from Andrew Morton.

* emailed from Andrew Morton : (8 patches)
  MAINTAINERS: add maintainer for LED subsystem
  mm: nobootmem: fix sign extend problem in __free_pages_memory()
  drivers/leds: correct __devexit annotations
  memcg: free spare array to avoid memory leak
  namespaces, pid_ns: fix leakage on fork() failure
  hugetlb: prevent BUG_ON in hugetlb_fault() -> hugetlb_cow()
  mm: fix division by 0 in percpu_pagelist_fraction()
  proc/pid/pagemap: correctly report non-present ptes and holes between vmas

mm: nobootmem: fix sign extend problem in __free_pages_memory()

2012-05-10T22:06:44+00:00

Systems with 8 TBytes of memory or greater can hit a problem where only
the the first 8 TB of memory shows up.  This is due to "int i" being
smaller than "unsigned long start_aligned", causing the high bits to be
dropped.

The fix is to change `i' to unsigned long to match start_aligned
and end_aligned.

Thanks to Jack Steiner for assistance tracking this down.

Signed-off-by: Russ Anderson 
Cc: Jack Steiner 
Cc: Johannes Weiner 
Cc: Tejun Heo 
Cc: David S. Miller 
Cc: Yinghai Lu 
Cc: Gavin Shan 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: free spare array to avoid memory leak

2012-05-10T22:06:44+00:00

When the last event is unregistered, there is no need to keep the spare
array anymore.  So free it to avoid memory leak.

Signed-off-by: Sha Zhengju 
Acked-by: KAMEZAWA Hiroyuki 
Reviewed-by: Kirill A. Shutemov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

hugetlb: prevent BUG_ON in hugetlb_fault() -> hugetlb_cow()

2012-05-10T22:06:44+00:00

Commit 66aebce747eaf ("hugetlb: fix race condition in hugetlb_fault()")
added code to avoid a race condition by elevating the page refcount in
hugetlb_fault() while calling hugetlb_cow().

However, one code path in hugetlb_cow() includes an assertion that the
page count is 1, whereas it may now also have the value 2 in this path.

The consensus is that this BUG_ON has served its purpose, so rather than
extending it to cover both cases, we just remove it.

Signed-off-by: Chris Metcalf 
Acked-by: Mel Gorman 
Acked-by: Hillf Danton 
Acked-by: Hugh Dickins 
Cc: Michal Hocko 
Cc: KAMEZAWA Hiroyuki 
Cc: 	[3.0.29+, 3.2.16+, 3.3.3+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: fix division by 0 in percpu_pagelist_fraction()

2012-05-10T22:06:44+00:00

percpu_pagelist_fraction_sysctl_handler() has only considered -EINVAL as
a possible error from proc_dointvec_minmax().

If any other error is returned, it would proceed to divide by zero since
percpu_pagelist_fraction wasn't getting initialized at any point.  For
example, writing 0 bytes into the proc file would trigger the issue.

Signed-off-by: Sasha Levin 
Reviewed-by: Minchan Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

kmemleak: Fix the kmemleak tracking of the percpu areas with !SMP

2012-05-09T17:13:29+00:00

Kmemleak tracks the percpu allocations via a specific API and the
originally allocated areas must be removed from kmemleak (via
kmemleak_free). The code was already doing this for SMP systems.

Reported-by: Sami Liedes 
Cc: Tejun Heo 
Cc: Christoph Lameter 
Signed-off-by: Catalin Marinas 
Signed-off-by: Tejun Heo