linux-stable.git/include/linux/swap.h, branch linux-2.6.17.y

[PATCH] fix can_share_swap_page() when !CONFIG_SWAP

2006-05-15T18:20:56+00:00

can_share_swap_page() is used to check if the page has the last reference.
This avoids allocating a new page for COW if it's the last page.

However, if CONFIG_SWAP is not set, can_share_swap_page() is defined as 0,
thus always causes a copy for the last COW page.  The below simple patch
fixes it.

Signed-off-by: Hua Zhong 
Cc: David Howells 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] overcommit: add calculate_totalreserve_pages()

2006-04-11T13:18:32+00:00

These patches are an enhancement of OVERCOMMIT_GUESS algorithm in
__vm_enough_memory().

- why the kernel needed patching

  When the kernel can't allocate anonymous pages in practice, currnet
  OVERCOMMIT_GUESS could return success. This implementation might be
  the cause of oom kill in memory pressure situation.

  If the Linux runs with page reservation features like
  /proc/sys/vm/lowmem_reserve_ratio and without swap region, I think
  the oom kill occurs easily.

- the overall design approach in the patch

  When the OVERCOMMET_GUESS algorithm calculates number of free pages,
  the reserved free pages are regarded as non-free pages.

  This change helps to avoid the pitfall that the number of free pages
  become less than the number which the kernel tries to keep free.

- testing results

  I tested the patches using my test kernel module.

  If the patches aren't applied to the kernel, __vm_enough_memory()
  returns success in the situation but autual page allocation is
  failed.

  On the other hand, if the patches are applied to the kernel, memory
  allocation failure is avoided since __vm_enough_memory() returns
  failure in the situation.

  I checked that on i386 SMP 16GB memory machine. I haven't tested on
  nommu environment currently.

This patch adds totalreserve_pages for __vm_enough_memory().

Calculate_totalreserve_pages() checks maximum lowmem_reserve pages and
pages_high in each zone. Finally, the function stores the sum of each
zone to totalreserve_pages.

The totalreserve_pages is calculated when the VM is initilized.
And the variable is updated when /proc/sys/vm/lowmem_reserve_raito
or /proc/sys/vm/min_free_kbytes are changed.

Signed-off-by: Hideo Aoki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] swsusp: low level interface

2006-03-23T15:38:07+00:00

Introduce the low level interface that can be used for handling the
snapshot of the system memory by the in-kernel swap-writing/reading code of
swsusp and the userland interface code (to be introduced shortly).

Also change the way in which swsusp records the allocated swap pages and,
consequently, simplifies the in-kernel swap-writing/reading code (this is
necessary for the userland interface too).  To this end, it introduces two
helper functions in mm/swapfile.c, so that the swsusp code does not refer
directly to the swap internals.

Signed-off-by: Rafael J. Wysocki 
Acked-by: Pavel Machek 
Signed-off-by: Adrian Bunk 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] page migration reorg

2006-03-22T15:54:06+00:00

Centralize the page migration functions in anticipation of additional
tinkering.  Creates a new file mm/migrate.c

1. Extract buffer_migrate_page() from fs/buffer.c

2. Extract central migration code from vmscan.c

3. Extract some components from mempolicy.c

4. Export pageout() and remove_from_swap() from vmscan.c

5. Make it possible to configure NUMA systems without page migration
   and non-NUMA systems with page migration.

I had to so some #ifdeffing in mempolicy.c that may need a cleanup.

Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] vmscan: use unsigned longs

2006-03-22T15:54:00+00:00

Turn basically everything in vmscan.c into `unsigned long'.  This is to avoid
the possibility that some piece of code in there might decide to operate upon
more than 4G (or even 2G) of pages in one hit.

This might be silly, but we'll need it one day.

Cc: Christoph Lameter 
Cc: Nick Piggin 
Signed-off-by: Rafael J. Wysocki 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Terminate process that fails on a constrained allocation

2006-02-21T04:00:09+00:00

Some allocations are restricted to a limited set of nodes (due to memory
policies or cpuset constraints).  If the page allocator is not able to find
enough memory then that does not mean that overall system memory is low.

In particular going postal and more or less randomly shooting at processes
is not likely going to help the situation but may just lead to suicide (the
whole system coming down).

It is better to signal to the process that no memory exists given the
constraints that the process (or the configuration of the process) has
placed on the allocation behavior.  The process may be killed but then the
sysadmin or developer can investigate the situation.  The solution is
similar to what we do when running out of hugepages.

This patch adds a check before we kill processes.  At that point
performance considerations do not matter much so we just scan the zonelist
and reconstruct a list of nodes.  If the list of nodes does not contain all
online nodes then this is a constrained allocation and we should kill the
current process.

Signed-off-by: Christoph Lameter 
Cc: Nick Piggin 
Cc: Andi Kleen 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Direct Migration V9: Avoid writeback / page_migrate() method

2006-02-01T16:53:17+00:00

Migrate a page with buffers without requiring writeback

This introduces a new address space operation migratepage() that may be used
by a filesystem to implement its own version of page migration.

A version is provided that migrates buffers attached to pages.  Some
filesystems (ext2, ext3, xfs) are modified to utilize this feature.

The swapper address space operation are modified so that a regular
migrate_page() will occur for anonymous pages without writeback (migrate_pages
forces every anonymous page to have a swap entry).

Signed-off-by: Mike Kravetz 
Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Direct Migration V9: remove_from_swap() to remove swap ptes

2006-02-01T16:53:16+00:00

Add remove_from_swap

remove_from_swap() allows the restoration of the pte entries that existed
before page migration occurred for anonymous pages by walking the reverse
maps.  This reduces swap use and establishes regular pte's without the need
for page faults.

Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] Direct Migration V9: migrate_pages() extension

2006-02-01T16:53:16+00:00

Add direct migration support with fall back to swap.

Direct migration support on top of the swap based page migration facility.

This allows the direct migration of anonymous pages and the migration of file
backed pages by dropping the associated buffers (requires writeout).

Fall back to swap out if necessary.

The patch is based on lots of patches from the hotplug project but the code
was restructured, documented and simplified as much as possible.

Note that an additional patch that defines the migrate_page() method for
filesystems is necessary in order to avoid writeback for anonymous and file
backed pages.

Signed-off-by: KAMEZAWA Hiroyuki 
Signed-off-by: Mike Kravetz 
Signed-off-by: Christoph Lameter 
Signed-off-by: Alexey Dobriyan 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[PATCH] zone_reclaim: configurable off node allocation period.

2006-02-01T16:53:16+00:00

Currently the zone_reclaim code has a fixed window of 30 seconds of off node
allocations should a local zone have no unused pagecache pages left.  Reclaim
will be attempted again after this timeout period to avoid repeated useless
scans for memory.  This is also useful to established sufficiently large off
node allocation chunks to relieve the local node.

It may be beneficial to adjust that time period for some special situations.
For example if memory use was exceeding node capacity one may want to give up
for longer periods of time.  If memory spikes intermittendly then one may want
to shorten the time period to reduce the number of off node allocations.

This patch allows just that....

Signed-off-by: Christoph Lameter 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds