linux.git/mm, branch v3.18-rc3

mm/balloon_compaction: fix deflation when compaction is disabled

2014-10-29T23:33:15+00:00

If CONFIG_BALLOON_COMPACTION=n balloon_page_insert() does not link pages
with balloon and doesn't set PagePrivate flag, as a result
balloon_page_dequeue() cannot get any pages because it thinks that all
of them are isolated.  Without balloon compaction nobody can isolate
ballooned pages.  It's safe to remove this check.

Fixes: d6d86c0a7f8d ("mm/balloon_compaction: redesign ballooned pages management").
Signed-off-by: Konstantin Khlebnikov 
Reported-by: Matt Mullins 
Cc: 	[3.17]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/slab_common: don't check for duplicate cache names

2014-10-29T23:33:15+00:00

The SLUB cache merges caches with the same size and alignment and there
was long standing bug with this behavior:

 - create the cache named "foo"
 - create the cache named "bar" (which is merged with "foo")
 - delete the cache named "foo" (but it stays allocated because "bar"
   uses it)
 - create the cache named "foo" again - it fails because the name "foo"
   is already used

That bug was fixed in commit 694617474e33 ("slab_common: fix the check
for duplicate slab names") by not warning on duplicate cache names when
the SLUB subsystem is used.

Recently, cache merging was implemented the with SLAB subsystem too, in
12220dea07f1 ("mm/slab: support slab merge")).  Therefore we need stop
checking for duplicate names even for the SLAB subsystem.

This patch fixes the bug by removing the check.

Signed-off-by: Mikulas Patocka 
Acked-by: Christoph Lameter 
Cc: Pekka Enberg 
Cc: David Rientjes 
Cc: Joonsoo Kim 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: rmap: split out page_remove_file_rmap()

2014-10-29T23:33:15+00:00

page_remove_rmap() has too many branches on PageAnon() and is hard to
follow.  Move the file part into a separate function.

Signed-off-by: Johannes Weiner 
Reviewed-by: Michal Hocko 
Cc: Vladimir Davydov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: memcontrol: fix missed end-writeback page accounting

2014-10-29T23:33:15+00:00

Commit 0a31bc97c80c ("mm: memcontrol: rewrite uncharge API") changed
page migration to uncharge the old page right away.  The page is locked,
unmapped, truncated, and off the LRU, but it could race with writeback
ending, which then doesn't unaccount the page properly:

test_clear_page_writeback()              migration
                                           wait_on_page_writeback()
  TestClearPageWriteback()
                                           mem_cgroup_migrate()
                                             clear PCG_USED
  mem_cgroup_update_page_stat()
    if (PageCgroupUsed(pc))
      decrease memcg pages under writeback

  release pc->mem_cgroup->move_lock

The per-page statistics interface is heavily optimized to avoid a
function call and a lookup_page_cgroup() in the file unmap fast path,
which means it doesn't verify whether a page is still charged before
clearing PageWriteback() and it has to do it in the stat update later.

Rework it so that it looks up the page's memcg once at the beginning of
the transaction and then uses it throughout.  The charge will be
verified before clearing PageWriteback() and migration can't uncharge
the page as long as that is still set.  The RCU lock will protect the
memcg past uncharge.

As far as losing the optimization goes, the following test results are
from a microbenchmark that maps, faults, and unmaps a 4GB sparse file
three times in a nested fashion, so that there are two negative passes
that don't account but still go through the new transaction overhead.
There is no actual difference:

 old:     33.195102545 seconds time elapsed       ( +-  0.01% )
 new:     33.199231369 seconds time elapsed       ( +-  0.03% )

The time spent in page_remove_rmap()'s callees still adds up to the
same, but the time spent in the function itself seems reduced:

     # Children      Self  Command        Shared Object       Symbol
 old:     0.12%     0.11%  filemapstress  [kernel.kallsyms]   [k] page_remove_rmap
 new:     0.12%     0.08%  filemapstress  [kernel.kallsyms]   [k] page_remove_rmap

Signed-off-by: Johannes Weiner 
Acked-by: Michal Hocko 
Cc: Vladimir Davydov 
Cc: 	[3.17.x]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: page-writeback: inline account_page_dirtied() into single caller

2014-10-29T23:33:14+00:00

A follow-up patch would have changed the call signature.  To save the
trouble, just fold it instead.

Signed-off-by: Johannes Weiner 
Acked-by: Michal Hocko 
Cc: Vladimir Davydov 
Cc: 	[3.17.x]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memory-hotplug: clear pgdat which is allocated by bootmem in try_offline_node()

2014-10-29T23:33:14+00:00

When hot adding the same memory after hot removal, the following
messages are shown:

  WARNING: CPU: 20 PID: 6 at mm/page_alloc.c:4968 free_area_init_node+0x3fe/0x426()
  ...
  Call Trace:
    dump_stack+0x46/0x58
    warn_slowpath_common+0x81/0xa0
    warn_slowpath_null+0x1a/0x20
    free_area_init_node+0x3fe/0x426
    hotadd_new_pgdat+0x90/0x110
    add_memory+0xd4/0x200
    acpi_memory_device_add+0x1aa/0x289
    acpi_bus_attach+0xfd/0x204
    acpi_bus_attach+0x178/0x204
    acpi_bus_scan+0x6a/0x90
    acpi_device_hotplug+0xe8/0x418
    acpi_hotplug_work_fn+0x1f/0x2b
    process_one_work+0x14e/0x3f0
    worker_thread+0x11b/0x510
    kthread+0xe1/0x100
    ret_from_fork+0x7c/0xb0

The detaled explanation is as follows:

When hot removing memory, pgdat is set to 0 in try_offline_node().  But
if the pgdat is allocated by bootmem allocator, the clearing step is
skipped.

And when hot adding the same memory, the uninitialized pgdat is reused.
But free_area_init_node() checks wether pgdat is set to zero.  As a
result, free_area_init_node() hits WARN_ON().

This patch clears pgdat which is allocated by bootmem allocator in
try_offline_node().

Signed-off-by: Yasuaki Ishimatsu 
Cc: Zhang Zhen 
Cc: Wang Nan 
Cc: Tang Chen 
Reviewed-by: Toshi Kani 
Cc: Dave Hansen 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm, thp: fix collapsing of hugepages on madvise

2014-10-29T23:33:14+00:00

If an anonymous mapping is not allowed to fault thp memory and then
madvise(MADV_HUGEPAGE) is used after fault, khugepaged will never
collapse this memory into thp memory.

This occurs because the madvise(2) handler for thp, hugepage_madvise(),
clears VM_NOHUGEPAGE on the stack and it isn't stored in vma->vm_flags
until the final action of madvise_behavior().  This causes the
khugepaged_enter_vma_merge() to be a no-op in hugepage_madvise() when
the vma had previously had VM_NOHUGEPAGE set.

Fix this by passing the correct vma flags to the khugepaged mm slot
handler.  There's no chance khugepaged can run on this vma until after
madvise_behavior() returns since we hold mm->mmap_sem.

It would be possible to clear VM_NOHUGEPAGE directly from vma->vm_flags
in hugepage_advise(), but I didn't want to introduce special case
behavior into madvise_behavior().  I think it's best to just let it
always set vma->vm_flags itself.

Signed-off-by: David Rientjes 
Reported-by: Suleiman Souhlal 
Cc: "Kirill A. Shutemov" 
Cc: Andrea Arcangeli 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: free compound page with correct order

2014-10-29T23:33:14+00:00

Compound page should be freed by put_page() or free_pages() with correct
order.  Not doing so will cause tail pages leaked.

The compound order can be obtained by compound_order() or use
HPAGE_PMD_ORDER in our case.  Some people would argue the latter is
faster but I prefer the former which is more general.

This bug was observed not just on our servers (the worst case we saw is
11G leaked on a 48G machine) but also on our workstations running Ubuntu
based distro.

  $ cat /proc/vmstat  | grep thp_zero_page_alloc
  thp_zero_page_alloc 55
  thp_zero_page_alloc_failed 0

This means there is (thp_zero_page_alloc - 1) * (2M - 4K) memory leaked.

Fixes: 97ae17497e99 ("thp: implement refcounting for huge zero page")
Signed-off-by: Yu Zhao 
Acked-by: Kirill A. Shutemov 
Cc: Andrea Arcangeli 
Cc: Mel Gorman 
Cc: David Rientjes 
Cc: Bob Liu 
Cc: 	[3.8+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/compaction.c: avoid premature range skip in isolate_migratepages_range

2014-10-29T23:33:13+00:00

Commit edc2ca612496 ("mm, compaction: move pageblock checks up from
isolate_migratepages_range()") commonizes isolate_migratepages variants
and make them use isolate_migratepages_block().

isolate_migratepages_block() could stop the execution when enough pages
are isolated, but, there is no code in isolate_migratepages_range() to
handle this case.  In the result, even if isolate_migratepages_block()
returns prematurely without checking all pages in the range,

isolate_migratepages_block() is called repeately on the following
pageblock and some pages in the previous range are skipped to check.
Then, CMA is failed frequently due to this fact.

To fix this problem, this patch let isolate_migratepages_range() know
the situation that enough pages are isolated and stop the isolation in
that case.

Note that isolate_migratepages() has no such problem, because, it always
stops the isolation after just one call of isolate_migratepages_block().

Signed-off-by: Joonsoo Kim 
Acked-by: Vlastimil Babka 
Cc: David Rientjes 
Cc: Minchan Kim 
Cc: Michal Nazarewicz 
Cc: Naoya Horiguchi 
Cc: Christoph Lameter 
Cc: Rik van Riel 
Cc: Mel Gorman 
Cc: Zhang Yanfei 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cgroup/kmemleak: add kmemleak_free() for cgroup deallocations.

2014-10-29T23:33:13+00:00

Commit ff7ee93f4715 ("cgroup/kmemleak: Annotate alloc_page() for cgroup
allocations") introduces kmemleak_alloc() for alloc_page_cgroup(), but
corresponding kmemleak_free() is missing, which makes kmemleak be
wrongly disabled after memory offlining.  Log is pasted at the end of
this commit message.

This patch add kmemleak_free() into free_page_cgroup().  During page
offlining, this patch removes corresponding entries in kmemleak rbtree.
After that, the freed memory can be allocated again by other subsystems
without killing kmemleak.

  bash # for x in 1 2 3 4; do echo offline > /sys/devices/system/memory/memory$x/state ; sleep 1; done ; dmesg | grep leak

  Offlined Pages 32768
  kmemleak: Cannot insert 0xffff880016969000 into the object search tree (overlaps existing)
  CPU: 0 PID: 412 Comm: sleep Not tainted 3.17.0-rc5+ #86
  Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
  Call Trace:
    dump_stack+0x46/0x58
    create_object+0x266/0x2c0
    kmemleak_alloc+0x26/0x50
    kmem_cache_alloc+0xd3/0x160
    __sigqueue_alloc+0x49/0xd0
    __send_signal+0xcb/0x410
    send_signal+0x45/0x90
    __group_send_sig_info+0x13/0x20
    do_notify_parent+0x1bb/0x260
    do_exit+0x767/0xa40
    do_group_exit+0x44/0xa0
    SyS_exit_group+0x17/0x20
    system_call_fastpath+0x16/0x1b

  kmemleak: Kernel memory leak detector disabled
  kmemleak: Object 0xffff880016900000 (size 524288):
  kmemleak:   comm "swapper/0", pid 0, jiffies 4294667296
  kmemleak:   min_count = 0
  kmemleak:   count = 0
  kmemleak:   flags = 0x1
  kmemleak:   checksum = 0
  kmemleak:   backtrace:
        log_early+0x63/0x77
        kmemleak_alloc+0x4b/0x50
        init_section_page_cgroup+0x7f/0xf5
        page_cgroup_init+0xc5/0xd0
        start_kernel+0x333/0x408
        x86_64_start_reservations+0x2a/0x2c
        x86_64_start_kernel+0xf5/0xfc

Fixes: ff7ee93f4715 (cgroup/kmemleak: Annotate alloc_page() for cgroup allocations)
Signed-off-by: Wang Nan 
Acked-by: Johannes Weiner 
Acked-by: Michal Hocko 
Cc: Steven Rostedt 
Cc: 	[3.2+]
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds