linux-toradex.git/mm, branch v3.2-rc6

Merge branch 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux

2011-12-13T22:58:56+00:00

* 'writeback-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/wfg/linux:
  writeback: set max_pause to lowest value on zero bdi_dirty
  writeback: permit through good bdi even when global dirty exceeded
  writeback: comment on the bdi dirty threshold
  fs: Make write(2) interruptible by a fatal signal
  writeback: Fix issue on make htmldocs

mm: vmalloc: check for page allocation failure before vmlist insertion

2011-12-09T15:50:29+00:00

Commit f5252e00 ("mm: avoid null pointer access in vm_struct via
/proc/vmallocinfo") adds newly allocated vm_structs to the vmlist after
it is fully initialised.  Unfortunately, it did not check that
__vmalloc_area_node() successfully populated the area.  In the event of
allocation failure, the vmalloc area is freed but the pointer to freed
memory is inserted into the vmlist leading to a a crash later in
get_vmalloc_info().

This patch adds a check for ____vmalloc_area_node() failure within
__vmalloc_node_range.  It does not use "goto fail" as in the previous
error path as a warning was already displayed by __vmalloc_area_node()
before it called vfree in its failure path.

Credit goes to Luciano Chavez for doing all the real work of identifying
exactly where the problem was.

Signed-off-by: Mel Gorman 
Reported-by: Luciano Chavez 
Tested-by: Luciano Chavez 
Reviewed-by: Rik van Riel 
Acked-by: David Rientjes 
Cc: 		[3.1.x+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: Ensure that pfn_valid() is called once per pageblock when reserving pageblocks

2011-12-09T15:50:28+00:00

setup_zone_migrate_reserve() expects that zone->start_pfn starts at
pageblock_nr_pages aligned pfn otherwise we could access beyond an
existing memblock resulting in the following panic if
CONFIG_HOLES_IN_ZONE is not configured and we do not check pfn_valid:

  IP: [] setup_zone_migrate_reserve+0xcd/0x180
  *pdpt = 0000000000000000 *pde = f000ff53f000ff53
  Oops: 0000 [#1] SMP
  Pid: 1, comm: swapper Not tainted 3.0.7-0.7-pae #1 VMware, Inc. VMware Virtual Platform/440BX Desktop Reference Platform
  EIP: 0060:[] EFLAGS: 00010006 CPU: 0
  EIP is at setup_zone_migrate_reserve+0xcd/0x180
  EAX: 000c0000 EBX: f5801fc0 ECX: 000c0000 EDX: 00000000
  ESI: 000c01fe EDI: 000c01fe EBP: 00140000 ESP: f2475f58
  DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068
  Process swapper (pid: 1, ti=f2474000 task=f2472cd0 task.ti=f2474000)
  Call Trace:
  [] __setup_per_zone_wmarks+0xec/0x160
  [] setup_per_zone_wmarks+0xf/0x20
  [] init_per_zone_wmark_min+0x27/0x86
  [] do_one_initcall+0x2b/0x160
  [] kernel_init+0xbe/0x157
  [] kernel_thread_helper+0x6/0xd
  Code: a5 39 f5 89 f7 0f 46 fd 39 cf 76 40 8b 03 f6 c4 08 74 32 eb 91 90 89 c8 c1 e8 0e 0f be 80 80 2f 86 c0 8b 14 85 60 2f 86 c0 89 c8 <2b> 82 b4 12 00 00 c1 e0 05 03 82 ac 12 00 00 8b 00 f6 c4 08 0f
  EIP: [] setup_zone_migrate_reserve+0xcd/0x180 SS:ESP 0068:f2475f58
  CR2: 00000000000012b4

We crashed in pageblock_is_reserved() when accessing pfn 0xc0000 because
highstart_pfn = 0x36ffe.

The issue was introduced in 3.0-rc1 by 6d3163ce ("mm: check if any page
in a pageblock is reserved before marking it MIGRATE_RESERVE").

Make sure that start_pfn is always aligned to pageblock_nr_pages to
ensure that pfn_valid s always called at the start of each pageblock.
Architectures with holes in pageblocks will be correctly handled by
pfn_valid_within in pageblock_is_reserved.

Signed-off-by: Michal Hocko 
Signed-off-by: Mel Gorman 
Tested-by: Dang Bo 
Reviewed-by: KAMEZAWA Hiroyuki 
Cc: Andrea Arcangeli 
Cc: David Rientjes 
Cc: Arve Hjnnevg 
Cc: KOSAKI Motohiro 
Cc: John Stultz 
Cc: Dave Hansen 
Cc: 	[3.0+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/migrate.c: pair unlock_page() and lock_page() when migrating huge pages

2011-12-09T15:50:28+00:00

Avoid unlocking and unlocked page if we failed to lock it.

Signed-off-by: Hillf Danton 
Cc: Naoya Horiguchi 
Cc: Andrea Arcangeli 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

thp: set compound tail page _count to zero

2011-12-09T15:50:28+00:00

Commit 70b50f94f1644 ("mm: thp: tail page refcounting fix") keeps all
page_tail->_count zero at all times.  But the current kernel does not
set page_tail->_count to zero if a 1GB page is utilized.  So when an
IOMMU 1GB page is used by KVM, it wil result in a kernel oops because a
tail page's _count does not equal zero.

  kernel BUG at include/linux/mm.h:386!
  invalid opcode: 0000 [#1] SMP
  Call Trace:
    gup_pud_range+0xb8/0x19d
    get_user_pages_fast+0xcb/0x192
    ? trace_hardirqs_off+0xd/0xf
    hva_to_pfn+0x119/0x2f2
    gfn_to_pfn_memslot+0x2c/0x2e
    kvm_iommu_map_pages+0xfd/0x1c1
    kvm_iommu_map_memslots+0x7c/0xbd
    kvm_iommu_map_guest+0xaa/0xbf
    kvm_vm_ioctl_assigned_device+0x2ef/0xa47
    kvm_vm_ioctl+0x36c/0x3a2
    do_vfs_ioctl+0x49e/0x4e4
    sys_ioctl+0x5a/0x7c
    system_call_fastpath+0x16/0x1b
  RIP  gup_huge_pud+0xf2/0x159

Signed-off-by: Youquan Song 
Reviewed-by: Andrea Arcangeli 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

thp: reduce khugepaged freezing latency

2011-12-09T15:50:28+00:00

khugepaged can sometimes cause suspend to fail, requiring that the user
retry the suspend operation.

Use wait_event_freezable_timeout() instead of
schedule_timeout_interruptible() to avoid missing freezer wakeups.  A
try_to_freeze() would have been needed in the khugepaged_alloc_hugepage
tight loop too in case of the allocation failing repeatedly, and
wait_event_freezable_timeout will provide it too.

khugepaged would still freeze just fine by trying again the next minute
but it's better if it freezes immediately.

Reported-by: Jiri Slaby 
Signed-off-by: Andrea Arcangeli 
Tested-by: Jiri Slaby 
Cc: Tejun Heo 
Cc: Oleg Nesterov 
Cc: "Srivatsa S. Bhat" 
Cc: "Rafael J. Wysocki" 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vmscan: use atomic-long for shrinker batching

2011-12-09T15:50:27+00:00

Use atomic-long operations instead of looping around cmpxchg().

[akpm@linux-foundation.org: massage atomic.h inclusions]
Signed-off-by: Konstantin Khlebnikov 
Cc: Dave Chinner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vmscan: fix initial shrinker size handling

2011-12-09T15:50:27+00:00

A shrinker function can return -1, means that it cannot do anything
without a risk of deadlock.  For example prune_super() does this if it
cannot grab a superblock refrence, even if nr_to_scan=0.  Currently we
interpret this -1 as a ULONG_MAX size shrinker and evaluate `total_scan'
according to this.  So the next time around this shrinker can cause
really big pressure.  Let's skip such shrinkers instead.

Also make total_scan signed, otherwise the check (total_scan < 0) below
never works.

Signed-off-by: Konstantin Khlebnikov 
Cc: Dave Chinner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

writeback: set max_pause to lowest value on zero bdi_dirty

2011-12-08T02:49:29+00:00

Some trace shows lots of bdi_dirty=0 lines where it's actually some
small value if w/o the accounting errors in the per-cpu bdi stats.

In this case the max pause time should really be set to the smallest
(non-zero) value to avoid IO queue underrun and improve throughput.

Signed-off-by: Wu Fengguang

writeback: permit through good bdi even when global dirty exceeded

2011-12-08T02:49:27+00:00

On a system with 1 local mount and 1 NFS mount, if the NFS server
becomes not responding when dd to the NFS mount, the NFS dirty pages may
exceed the global dirty limit and _every_ task involving writing will be
blocked. The whole system appears unresponsive.

The workaround is to permit through the bdi's that only has a small
number of dirty pages. The number chosen (bdi_stat_error pages) is not
enough to enable the local disk to run in optimal throughput, however is
enough to make the system responsive on a broken NFS mount. The user can
then kill the dirtiers on the NFS mount and increase the global dirty
limit to bring up the local disk's throughput.

It risks allowing dirty pages to grow much larger than the global dirty
limit when there are 1000+ mounts, however that's very unlikely to happen,
especially in low memory profiles.

Signed-off-by: Wu Fengguang