linux-toradex.git/mm/page-writeback.c, branch v3.16.5

mm/page-writeback.c: fix divide by zero in bdi_dirty_limits()

2014-07-31T00:16:13+00:00

Under memory pressure, it is possible for dirty_thresh, calculated by
global_dirty_limits() in balance_dirty_pages(), to equal zero.  Then, if
strictlimit is true, bdi_dirty_limits() tries to resolve the proportion:

  bdi_bg_thresh : bdi_thresh = background_thresh : dirty_thresh

by dividing by zero.

Signed-off-by: Maxim Patlasov 
Acked-by: Rik van Riel 
Cc: Michal Hocko 
Cc: KOSAKI Motohiro 
Cc: Wu Fengguang 
Cc: Johannes Weiner 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4

2014-06-08T20:03:35+00:00

Pull ext4 updates from Ted Ts'o:
 "Clean ups and miscellaneous bug fixes, in particular for the new
  collapse_range and zero_range fallocate functions.  In addition,
  improve the scalability of adding and remove inodes from the orphan
  list"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (25 commits)
  ext4: handle symlink properly with inline_data
  ext4: fix wrong assert in ext4_mb_normalize_request()
  ext4: fix zeroing of page during writeback
  ext4: remove unused local variable "stored" from ext4_readdir(...)
  ext4: fix ZERO_RANGE test failure in data journalling
  ext4: reduce contention on s_orphan_lock
  ext4: use sbi in ext4_orphan_{add|del}()
  ext4: use EXT_MAX_BLOCKS in ext4_es_can_be_merged()
  ext4: add missing BUFFER_TRACE before ext4_journal_get_write_access
  ext4: remove unnecessary double parentheses
  ext4: do not destroy ext4_groupinfo_caches if ext4_mb_init() fails
  ext4: make local functions static
  ext4: fix block bitmap validation when bigalloc, ^flex_bg
  ext4: fix block bitmap initialization under sparse_super2
  ext4: find the group descriptors on a 1k-block bigalloc,meta_bg filesystem
  ext4: avoid unneeded lookup when xattr name is invalid
  ext4: fix data integrity sync in ordered mode
  ext4: remove obsoleted check
  ext4: add a new spinlock i_raw_lock to protect the ext4's raw inode
  ext4: fix locking for O_APPEND writes
  ...

mm: convert use of typedef ctl_table to struct ctl_table

2014-06-06T23:08:16+00:00

This typedef is unnecessary and should just be removed.

Signed-off-by: Joe Perches 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/page-writeback.c: remove outdated comment

2014-06-04T23:54:13+00:00

There is an orphaned prehistoric comment , which used to be against
get_dirty_limits(), the dawn of global_dirtyable_memory().

Back then, the implementation of get_dirty_limits() is complicated and
full of magic numbers, so this comment is necessary.  But we now use the
clear and neat global_dirtyable_memory(), which renders this comment
ambiguous and useless.  Remove it.

Signed-off-by: Jianyu Zhan 
Acked-by: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: replace __get_cpu_var uses with this_cpu_ptr

2014-06-04T23:54:03+00:00

Replace places where __get_cpu_var() is used for an address calculation
with this_cpu_ptr().

Signed-off-by: Christoph Lameter 
Cc: Tejun Heo 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

ext4: fix data integrity sync in ordered mode

2014-05-12T12:12:25+00:00

When we perform a data integrity sync we tag all the dirty pages with
PAGECACHE_TAG_TOWRITE at start of ext4_da_writepages.  Later we check
for this tag in write_cache_pages_da and creates a struct
mpage_da_data containing contiguously indexed pages tagged with this
tag and sync these pages with a call to mpage_da_map_and_submit.  This
process is done in while loop until all the PAGECACHE_TAG_TOWRITE
pages are synced. We also do journal start and stop in each iteration.
journal_stop could initiate journal commit which would call
ext4_writepage which in turn will call ext4_bio_write_page even for
delayed OR unwritten buffers. When ext4_bio_write_page is called for
such buffers, even though it does not sync them but it clears the
PAGECACHE_TAG_TOWRITE of the corresponding page and hence these pages
are also not synced by the currently running data integrity sync. We
will end up with dirty pages although sync is completed.

This could cause a potential data loss when the sync call is followed
by a truncate_pagecache call, which is exactly the case in
collapse_range.  (It will cause generic/127 failure in xfstests)

To avoid this issue, we can use set_page_writeback_keepwrite instead of
set_page_writeback, which doesn't clear TOWRITE tag.

Cc: stable@vger.kernel.org
Signed-off-by: Namjae Jeon 
Signed-off-by: Ashish Sangwan 
Signed-off-by: "Theodore Ts'o" 
Reviewed-by: Jan Kara

mm/page-writeback.c: fix divide by zero in pos_ratio_polynom

2014-05-06T20:04:58+00:00

It is possible for "limit - setpoint + 1" to equal zero, after getting
truncated to a 32 bit variable, and resulting in a divide by zero error.

Using the fully 64 bit divide functions avoids this problem.  It also
will cause pos_ratio_polynom() to return the correct value when
(setpoint - limit) exceeds 2^32.

Also uninline pos_ratio_polynom, at Andrew's request.

Signed-off-by: Rik van Riel 
Reviewed-by: Michal Hocko 
Cc: Aneesh Kumar K.V 
Cc: Mel Gorman 
Cc: Nishanth Aravamudan 
Cc: Luiz Capitulino 
Cc: Masayoshi Mizuma 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: remove unused arg of set_page_dirty_balance()

2014-04-07T23:35:57+00:00

There's only one caller of set_page_dirty_balance() and that will call it
with page_mkwrite == 0.

The page_mkwrite argument was unused since commit b827e496c893 "mm: close
page_mkwrite races".

Signed-off-by: Miklos Szeredi 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: __set_page_dirty_nobuffers() uses spin_lock_irqsave() instead of spin_lock_irq()

2014-02-06T21:48:51+00:00

During aio stress test, we observed the following lockdep warning.  This
mean AIO+numa_balancing is currently deadlockable.

The problem is, aio_migratepage disable interrupt, but
__set_page_dirty_nobuffers unintentionally enable it again.

Generally, all helper function should use spin_lock_irqsave() instead of
spin_lock_irq() because they don't know caller at all.

   other info that might help us debug this:
    Possible unsafe locking scenario:

          CPU0
          ----
     lock(&(&ctx->completion_lock)->rlock);
     
       lock(&(&ctx->completion_lock)->rlock);

    *** DEADLOCK ***

      dump_stack+0x19/0x1b
      print_usage_bug+0x1f7/0x208
      mark_lock+0x21d/0x2a0
      mark_held_locks+0xb9/0x140
      trace_hardirqs_on_caller+0x105/0x1d0
      trace_hardirqs_on+0xd/0x10
      _raw_spin_unlock_irq+0x2c/0x50
      __set_page_dirty_nobuffers+0x8c/0xf0
      migrate_page_copy+0x434/0x540
      aio_migratepage+0xb1/0x140
      move_to_new_page+0x7d/0x230
      migrate_pages+0x5e5/0x700
      migrate_misplaced_page+0xbc/0xf0
      do_numa_page+0x102/0x190
      handle_pte_fault+0x241/0x970
      handle_mm_fault+0x265/0x370
      __do_page_fault+0x172/0x5a0
      do_page_fault+0x1a/0x70
      page_fault+0x28/0x30

Signed-off-by: KOSAKI Motohiro 
Cc: Larry Woodman 
Cc: Rik van Riel 
Cc: Johannes Weiner 
Acked-by: David Rientjes 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/page-writeback.c: do not count anon pages as dirtyable memory

2014-01-30T00:22:39+00:00

The VM is currently heavily tuned to avoid swapping.  Whether that is
good or bad is a separate discussion, but as long as the VM won't swap
to make room for dirty cache, we can not consider anonymous pages when
calculating the amount of dirtyable memory, the baseline to which
dirty_background_ratio and dirty_ratio are applied.

A simple workload that occupies a significant size (40+%, depending on
memory layout, storage speeds etc.) of memory with anon/tmpfs pages and
uses the remainder for a streaming writer demonstrates this problem.  In
that case, the actual cache pages are a small fraction of what is
considered dirtyable overall, which results in an relatively large
portion of the cache pages to be dirtied.  As kswapd starts rotating
these, random tasks enter direct reclaim and stall on IO.

Only consider free pages and file pages dirtyable.

Signed-off-by: Johannes Weiner 
Reported-by: Tejun Heo 
Tested-by: Tejun Heo 
Reviewed-by: Rik van Riel 
Cc: Mel Gorman 
Cc: Wu Fengguang 
Reviewed-by: Michal Hocko 
Cc: 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds