linux-stable.git/mm, branch v3.4-rc2

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

2012-03-29T00:19:28+00:00

Merge third batch of patches from Andrew Morton:
 - Some MM stragglers
 - core SMP library cleanups (on_each_cpu_mask)
 - Some IPI optimisations
 - kexec
 - kdump
 - IPMI
 - the radix-tree iterator work
 - various other misc bits.

 "That'll do for -rc1.  I still have ~10 patches for 3.4, will send
  those along when they've baked a little more."

* emailed from Andrew Morton : (35 commits)
  backlight: fix typo in tosa_lcd.c
  crc32: add help text for the algorithm select option
  mm: move hugepage test examples to tools/testing/selftests/vm
  mm: move slabinfo.c to tools/vm
  mm: move page-types.c from Documentation to tools/vm
  selftests/Makefile: make `run_tests' depend on `all'
  selftests: launch individual selftests from the main Makefile
  radix-tree: use iterators in find_get_pages* functions
  radix-tree: rewrite gang lookup using iterator
  radix-tree: introduce bit-optimized iterator
  fs/proc/namespaces.c: prevent crash when ns_entries[] is empty
  nbd: rename the nbd_device variable from lo to nbd
  pidns: add reboot_pid_ns() to handle the reboot syscall
  sysctl: use bitmap library functions
  ipmi: use locks on watchdog timeout set on reboot
  ipmi: simplify locking
  ipmi: fix message handling during panics
  ipmi: use a tasklet for handling received messages
  ipmi: increase KCS timeouts
  ipmi: decrease the IPMI message transaction time in interrupt mode
  ...

radix-tree: use iterators in find_get_pages* functions

2012-03-29T00:14:37+00:00

Replace radix_tree_gang_lookup_slot() and
radix_tree_gang_lookup_tag_slot() in page-cache lookup functions with
brand-new radix-tree direct iterating.  This avoids the double-scanning
and pointer copying.

Iterator don't stop after nr_pages page-get fails in a row, it continue
lookup till the radix-tree end.  Thus we can safely remove these restart
conditions.

Unfortunately, old implementation didn't forbid nr_pages == 0, this corner
case does not fit into new code, so the patch adds an extra check at the
beginning.

Signed-off-by: Konstantin Khlebnikov 
Tested-by: Hugh Dickins 
Cc: Christoph Hellwig 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: only IPI CPUs to drain local pages if they exist

2012-03-29T00:14:35+00:00

Calculate a cpumask of CPUs with per-cpu pages in any zone and only send
an IPI requesting CPUs to drain these pages to the buddy allocator if they
actually have pages when asked to flush.

This patch saves 85%+ of IPIs asking to drain per-cpu pages in case of
severe memory pressure that leads to OOM since in these cases multiple,
possibly concurrent, allocation requests end up in the direct reclaim code
path so when the per-cpu pages end up reclaimed on first allocation
failure for most of the proceeding allocation attempts until the memory
pressure is off (possibly via the OOM killer) there are no per-cpu pages
on most CPUs (and there can easily be hundreds of them).

This also has the side effect of shortening the average latency of direct
reclaim by 1 or more order of magnitude since waiting for all the CPUs to
ACK the IPI takes a long time.

Tested by running "hackbench 400" on a 8 CPU x86 VM and observing the
difference between the number of direct reclaim attempts that end up in
drain_all_pages() and those were more then 1/2 of the online CPU had any
per-cpu page in them, using the vmstat counters introduced in the next
patch in the series and using proc/interrupts.

In the test sceanrio, this was seen to save around 3600 global
IPIs after trigerring an OOM on a concurrent workload:

$ cat /proc/vmstat | tail -n 2
pcp_global_drain 0
pcp_global_ipi_saved 0

$ cat /proc/interrupts | grep CAL
CAL:          1          2          1          2
          2          2          2          2   Function call interrupts

$ hackbench 400
[OOM messages snipped]

$ cat /proc/vmstat | tail -n 2
pcp_global_drain 3647
pcp_global_ipi_saved 3642

$ cat /proc/interrupts | grep CAL
CAL:          6         13          6          3
          3          3         1 2          7   Function call interrupts

Please note that if the global drain is removed from the direct reclaim
path as a patch from Mel Gorman currently suggests this should be replaced
with an on_each_cpu_cond invocation.

Signed-off-by: Gilad Ben-Yossef 
Acked-by: Mel Gorman 
Cc: KOSAKI Motohiro 
Acked-by: Christoph Lameter 
Acked-by: Peter Zijlstra 
Cc: Pekka Enberg 
Cc: Rik van Riel 
Cc: Andi Kleen 
Acked-by: Michal Nazarewicz 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

slub: only IPI CPUs that have per cpu obj to flush

2012-03-29T00:14:35+00:00

flush_all() is called for each kmem_cache_destroy().  So every cache being
destroyed dynamically ends up sending an IPI to each CPU in the system,
regardless if the cache has ever been used there.

For example, if you close the Infinband ipath driver char device file, the
close file ops calls kmem_cache_destroy().  So running some infiniband
config tool on one a single CPU dedicated to system tasks might interrupt
the rest of the 127 CPUs dedicated to some CPU intensive or latency
sensitive task.

I suspect there is a good chance that every line in the output of "git
grep kmem_cache_destroy linux/ | grep '\->'" has a similar scenario.

This patch attempts to rectify this issue by sending an IPI to flush the
per cpu objects back to the free lists only to CPUs that seem to have such
objects.

The check which CPU to IPI is racy but we don't care since asking a CPU
without per cpu objects to flush does no damage and as far as I can tell
the flush_all by itself is racy against allocs on remote CPUs anyway, so
if you required the flush_all to be determinstic, you had to arrange for
locking regardless.

Without this patch the following artificial test case:

$ cd /sys/kernel/slab
$ for DIR in *; do cat $DIR/alloc_calls > /dev/null; done

produces 166 IPIs on an cpuset isolated CPU. With it it produces none.

The code path of memory allocation failure for CPUMASK_OFFSTACK=y
config was tested using fault injection framework.

Signed-off-by: Gilad Ben-Yossef 
Acked-by: Christoph Lameter 
Cc: Chris Metcalf 
Acked-by: Peter Zijlstra 
Cc: Frederic Weisbecker 
Cc: Russell King 
Cc: Pekka Enberg 
Cc: Matt Mackall 
Cc: Sasha Levin 
Cc: Rik van Riel 
Cc: Andi Kleen 
Cc: Mel Gorman 
Cc: Alexander Viro 
Cc: Avi Kivity 
Cc: Michal Nazarewicz 
Cc: Kosaki Motohiro 
Cc: Milton Miller 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

swapon: check validity of swap_flags

2012-03-29T00:14:35+00:00

Most system calls taking flags first check that the flags passed in are
valid, and that helps userspace to detect when new flags are supported.

But swapon never did so: start checking now, to help if we ever want to
support more swap_flags in future.

It's difficult to get stray bits set in an int, and swapon is not widely
used, so this is most unlikely to break any userspace; but we can just
revert if it turns out to do so.

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

mm, coredump: fail allocations when coredumping instead of oom killing

2012-03-29T00:14:35+00:00

The size of coredump files is limited by RLIMIT_CORE, however, allocating
large amounts of memory results in three negative consequences:

 - the coredumping process may be chosen for oom kill and quickly deplete
   all memory reserves in oom conditions preventing further progress from
   being made or tasks from exiting,

 - the coredumping process may cause other processes to be oom killed
   without fault of their own as the result of a SIGSEGV, for example, in
   the coredumping process, or

 - the coredumping process may result in a livelock while writing to the
   dump file if it needs memory to allocate while other threads are in
   the exit path waiting on the coredumper to complete.

This is fixed by implying __GFP_NORETRY in the page allocator for
coredumping processes when reclaim has failed so the allocations fail and
the process continues to exit.

Signed-off-by: David Rientjes 
Cc: Mel Gorman 
Cc: KAMEZAWA Hiroyuki 
Cc: Minchan Kim 
Cc: Oleg Nesterov 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: thp: fix up pmd_trans_unstable() locations

2012-03-29T00:14:35+00:00

pmd_trans_unstable() should be called before pmd_offset_map() in the
locations where the mmap_sem is held for reading.

Signed-off-by: Andrea Arcangeli 
Cc: Mel Gorman 
Cc: Hugh Dickins 
Cc: Larry Woodman 
Cc: Ulrich Obergfell 
Cc: Rik van Riel 
Cc: Mark Salter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm for fs: add truncate_pagecache_range()

2012-03-29T00:14:35+00:00

Holepunching filesystems ext4 and xfs are using truncate_inode_pages_range
but forgetting to unmap pages first (ocfs2 remembers).  This is not really
a bug, since races already require truncate_inode_page() to handle that
case once the page is locked; but it can be very inefficient if the file
being punched happens to be mapped into many vmas.

Provide a drop-in replacement truncate_pagecache_range() which does the
unmapping pass first, handling the awkward mismatch between arguments to
truncate_inode_pages_range() and arguments to unmap_mapping_range().

Note that holepunching does not unmap privately COWed pages in the range:
POSIX requires that we do so when truncating, but it's hard to justify,
difficult to implement without an i_size cutoff, and no filesystem is
attempting to implement it.

Signed-off-by: Hugh Dickins 
Cc: "Theodore Ts'o" 
Cc: Andreas Dilger 
Cc: Mark Fasheh 
Cc: Joel Becker 
Cc: Ben Myers 
Cc: Alex Elder 
Cc: Christoph Hellwig 
Cc: Dave Chinner 
Cc: Al Viro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

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

2012-03-28T22:04:26+00:00

Pull SLAB changes from Pekka Enberg:
 "There's the new kmalloc_array() API, minor fixes and performance
  improvements, but quite honestly, nothing terribly exciting."

* 'slab/for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/penberg/linux:
  mm: SLAB Out-of-memory diagnostics
  slab: introduce kmalloc_array()
  slub: per cpu partial statistics change
  slub: include include for prefetch
  slub: Do not hold slub_lock when calling sysfs_slab_add()
  slub: prefetch next freelist pointer in slab_alloc()
  slab, cleanup: remove unneeded return

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

2012-03-28T17:02:55+00:00

Pull ext4 updates for 3.4 from Ted Ts'o:
 "Ext4 commits for 3.3 merge window; mostly cleanups and bug fixes

  The changes to export dirty_writeback_interval are from Artem's s_dirt
  cleanup patch series.  The same is true of the change to remove the
  s_dirt helper functions which never got used by anyone in-tree.  I've
  run these changes by Al Viro, and am carrying them so that Artem can
  more easily fix up the rest of the file systems during the next merge
  window.  (Originally we had hopped to remove the use of s_dirt from
  ext4 during this merge window, but his patches had some bugs, so I
  ultimately ended dropping them from the ext4 tree.)"

* tag 'ext4_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tytso/ext4: (66 commits)
  vfs: remove unused superblock helpers
  mm: export dirty_writeback_interval
  ext4: remove useless s_dirt assignment
  ext4: write superblock only once on unmount
  ext4: do not mark superblock as dirty unnecessarily
  ext4: correct ext4_punch_hole return codes
  ext4: remove restrictive checks for EOFBLOCKS_FL
  ext4: always set then trimmed blocks count into len
  ext4: fix trimmed block count accunting
  ext4: fix start and len arguments handling in ext4_trim_fs()
  ext4: update s_free_{inodes,blocks}_count during online resize
  ext4: change some printk() calls to use ext4_msg() instead
  ext4: avoid output message interleaving in ext4_error_()
  ext4: remove trailing newlines from ext4_msg() and ext4_error() messages
  ext4: add no_printk argument validation, fix fallout
  ext4: remove redundant "EXT4-fs: " from uses of ext4_msg
  ext4: give more helpful error message in ext4_ext_rm_leaf()
  ext4: remove unused code from ext4_ext_map_blocks()
  ext4: rewrite punch hole to use ext4_ext_remove_space()
  jbd2: cleanup journal tail after transaction commit
  ...