linux.git/Documentation/sysctl/vm.txt, branch v2.6.28

Documentation cleanup: trivial misspelling, punctuation, and grammar corrections.

2008-07-26T19:00:06+00:00

Cc: Randy Dunlap 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

oom: add sysctl to enable task memory dump

2008-02-07T16:42:19+00:00

Adds a new sysctl, 'oom_dump_tasks', that enables the kernel to produce a
dump of all system tasks (excluding kernel threads) when performing an
OOM-killing.  Information includes pid, uid, tgid, vm size, rss, cpu,
oom_adj score, and name.

This is helpful for determining why there was an OOM condition and which
rogue task caused it.

It is configurable so that large systems, such as those with several
thousand tasks, do not incur a performance penalty associated with dumping
data they may not desire.

If an OOM was triggered as a result of a memory controller, the tasklist
shall be filtered to exclude tasks that are not a member of the same
cgroup.

Cc: Andrea Arcangeli 
Cc: Christoph Lameter 
Cc: Balbir Singh 
Signed-off-by: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm/page-writeback: highmem_is_dirtyable option

2008-02-05T17:44:18+00:00

Add vm.highmem_is_dirtyable toggle

A 32 bit machine with HIGHMEM64 enabled running DCC has an MMAPed file of
approximately 2Gb size which contains a hash format that is written
randomly by the dbclean process.  On 2.6.16 this process took a few
minutes.  With lowmem only accounting of dirty ratios, this takes about 12
hours of 100% disk IO, all random writes.

Include a toggle in /proc/sys/vm/highmem_is_dirtyable which can be set to 1 to
add the highmem back to the total available memory count.

[akpm@linux-foundation.org: Fix the CONFIG_DETECT_SOFTLOCKUP=y build]
Signed-off-by: Bron Gondwana 
Cc: Ethan Solomita 
Cc: Peter Zijlstra 
Cc: WU Fengguang 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Documentation: update hugetlb information

2007-12-18T03:28:17+00:00

The hugetlb documentation has gotten a bit out of sync with the current code.
Updated the sysctl file to refer to Documentation/vm/hugetlbpage.txt.  Update
that file to contain the current state of affairs (with the newer named sysctl
in place).

Signed-off-by: Nishanth Aravamudan 
Acked-by: Adam Litke 
Cc: William Lee Irwin III 
Cc: Dave Hansen 
Cc: David Gibson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

vm.txt: document min_free_pages as critical for correctness

2007-10-17T15:43:06+00:00

min_free_pages is critical for correctness, document it as such.

Signed-off-by: Pavel Machek 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

oom: add oom_kill_allocating_task sysctl

2007-10-17T15:42:46+00:00

Adds a new sysctl, 'oom_kill_allocating_task', which will automatically kill
the OOM-triggering task instead of scanning through the tasklist to find a
memory-hogging target.  This is helpful for systems with an insanely large
number of tasks where scanning the tasklist significantly degrades
performance.

Cc: Andrea Arcangeli 
Acked-by: Christoph Lameter 
Signed-off-by: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

handle kernelcore=: generic

2007-07-17T17:22:59+00:00

This patch adds the kernelcore= parameter for x86.

Once all patches are applied, a new command-line parameter exist and a new
sysctl.  This patch adds the necessary documentation.

From: Yasunori Goto 

  When "kernelcore" boot option is specified, kernel can't boot up on ia64
  because of an infinite loop.  In addition, the parsing code can be handled
  in an architecture-independent manner.

  This patch uses common code to handle the kernelcore= parameter.  It is
  only available to architectures that support arch-independent zone-sizing
  (i.e.  define CONFIG_ARCH_POPULATES_NODE_MAP).  Other architectures will
  ignore the boot parameter.

[bunk@stusta.de: make cmdline_parse_kernelcore() static]
Signed-off-by: Mel Gorman 
Signed-off-by: Yasunori Goto 
Acked-by: Andy Whitcroft 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

change zonelist order: zonelist order selection logic

2007-07-16T16:05:35+00:00

Make zonelist creation policy selectable from sysctl/boot option v6.

This patch makes NUMA's zonelist (of pgdat) order selectable.
Available order are Default(automatic)/ Node-based / Zone-based.

[Default Order]
The kernel selects Node-based or Zone-based order automatically.

[Node-based Order]
This policy treats the locality of memory as the most important parameter.
Zonelist order is created by each zone's locality. This means lower zones
(ex. ZONE_DMA) can be used before higher zone (ex. ZONE_NORMAL) exhausion.
IOW. ZONE_DMA will be in the middle of zonelist.
current 2.6.21 kernel uses this.

Pros.
 * A user can expect local memory as much as possible.
Cons.
 * lower zone will be exhansted before higher zone. This may cause OOM_KILL.

Maybe suitable if ZONE_DMA is relatively big and you never see OOM_KILL
because of ZONE_DMA exhaution and you need the best locality.

(example)
assume 2 node NUMA. node(0) has ZONE_DMA/ZONE_NORMAL, node(1) has ZONE_NORMAL.

*node(0)'s memory allocation order:

 node(0)'s NORMAL -> node(0)'s DMA -> node(1)'s NORMAL.

*node(1)'s memory allocation order:

 node(1)'s NORMAL -> node(0)'s NORMAL -> node(0)'s DMA.

[Zone-based order]
This policy treats the zone type as the most important parameter.
Zonelist order is created by zone-type order. This means lower zone
never be used bofere higher zone exhaustion.
IOW. ZONE_DMA will be always at the tail of zonelist.

Pros.
 * OOM_KILL(bacause of lower zone) occurs only if the whole zones are exhausted.
Cons.
 * memory locality may not be best.

(example)
assume 2 node NUMA. node(0) has ZONE_DMA/ZONE_NORMAL, node(1) has ZONE_NORMAL.

*node(0)'s memory allocation order:

 node(0)'s NORMAL -> node(1)'s NORMAL -> node(0)'s DMA.

*node(1)'s memory allocation order:

 node(1)'s NORMAL -> node(0)'s NORMAL -> node(0)'s DMA.

bootoption "numa_zonelist_order=" and proc/sysctl is supporetd.

command:
%echo N > /proc/sys/vm/numa_zonelist_order

Will rebuild zonelist in Node-based order.

command:
%echo Z > /proc/sys/vm/numa_zonelist_order

Will rebuild zonelist in Zone-based order.

Thanks to Lee Schermerhorn, he gives me much help and codes.

[Lee.Schermerhorn@hp.com: add check_highest_zone to build_zonelists_in_zone_order]
[akpm@linux-foundation.org: build fix]
Signed-off-by: KAMEZAWA Hiroyuki 
Cc: Lee Schermerhorn 
Cc: Christoph Lameter 
Cc: Andi Kleen 
Cc: "jesse.barnes@intel.com" 
Signed-off-by: Lee Schermerhorn 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

security: Protection for exploiting null dereference using mmap

2007-07-12T02:52:29+00:00

Add a new security check on mmap operations to see if the user is attempting
to mmap to low area of the address space.  The amount of space protected is
indicated by the new proc tunable /proc/sys/vm/mmap_min_addr and defaults to
0, preserving existing behavior.

This patch uses a new SELinux security class "memprotect."  Policy already
contains a number of allow rules like a_t self:process * (unconfined_t being
one of them) which mean that putting this check in the process class (its
best current fit) would make it useless as all user processes, which we also
want to protect against, would be allowed. By taking the memprotect name of
the new class it will also make it possible for us to move some of the other
memory protect permissions out of 'process' and into the new class next time
we bump the policy version number (which I also think is a good future idea)

Acked-by: Stephen Smalley 
Acked-by: Chris Wright 
Signed-off-by: Eric Paris 
Signed-off-by: James Morris

mm: fix handling of panic_on_oom when cpusets are in use

2007-05-07T19:12:55+00:00

The current panic_on_oom may not work if there is a process using
cpusets/mempolicy, because other nodes' memory may remain.  But some people
want failover by panic ASAP even if they are used.  This patch makes new
setting for its request.

This is tested on my ia64 box which has 3 nodes.

Signed-off-by: Yasunori Goto 
Signed-off-by: Benjamin LaHaise 
Cc: Christoph Lameter 
Cc: Paul Jackson 
Cc: Ethan Solomita 
Cc: David Rientjes 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds