linux.git/mm/migrate.c, branch v2.6.29

migration: migrate_vmas should check "vma"

2009-02-11T22:25:34+00:00

migrate_vmas() should check "vma" not "vma->vm_next" for for-loop condition.

Signed-off-by: Daisuke Nishimura 
Cc: Christoph Lameter 
Cc: Johannes Weiner 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

[CVE-2009-0029] System call wrappers part 28

2009-01-14T13:15:30+00:00

Signed-off-by: Heiko Carstens

memcg: simple migration handling

2009-01-08T16:31:04+00:00

Now, management of "charge" under page migration is done under following
manner. (Assume migrate page contents from oldpage to newpage)

 before
  - "newpage" is charged before migration.
 at success.
  - "oldpage" is uncharged at somewhere(unmap, radix-tree-replace)
 at failure
  - "newpage" is uncharged.
  - "oldpage" is charged if necessary (*1)

But (*1) is not reliable....because of GFP_ATOMIC.

This patch tries to change behavior as following by charge/commit/cancel ops.

 before
  - charge PAGE_SIZE (no target page)
 success
  - commit charge against "newpage".
 failure
  - commit charge against "oldpage".
    (PCG_USED bit works effectively to avoid double-counting)
  - if "oldpage" is obsolete, cancel charge of PAGE_SIZE.

Signed-off-by: KAMEZAWA Hiroyuki 
Reviewed-by: Daisuke Nishimura 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

memcg: introduce charge-commit-cancel style of functions

2009-01-08T16:31:04+00:00

There is a small race in do_swap_page().  When the page swapped-in is
charged, the mapcount can be greater than 0.  But, at the same time some
process (shares it ) call unmap and make mapcount 1->0 and the page is
uncharged.

      CPUA 			CPUB
       mapcount == 1.
   (1) charge if mapcount==0     zap_pte_range()
                                (2) mapcount 1 => 0.
			        (3) uncharge(). (success)
   (4) set page's rmap()
       mapcount 0=>1

Then, this swap page's account is leaked.

For fixing this, I added a new interface.
  - charge
   account to res_counter by PAGE_SIZE and try to free pages if necessary.
  - commit
   register page_cgroup and add to LRU if necessary.
  - cancel
   uncharge PAGE_SIZE because of do_swap_page failure.

     CPUA
  (1) charge (always)
  (2) set page's rmap (mapcount > 0)
  (3) commit charge was necessary or not after set_pte().

This protocol uses PCG_USED bit on page_cgroup for avoiding over accounting.
Usual mem_cgroup_charge_common() does charge -> commit at a time.

And this patch also adds following function to clarify all charges.

  - mem_cgroup_newpage_charge() ....replacement for mem_cgroup_charge()
	called against newly allocated anon pages.

  - mem_cgroup_charge_migrate_fixup()
        called only from remove_migration_ptes().
	we'll have to rewrite this later.(this patch just keeps old behavior)
	This function will be removed by additional patch to make migration
	clearer.

Good for clarifying "what we do"

Then, we have 4 following charge points.
  - newpage
  - swap-in
  - add-to-cache.
  - migration.

[akpm@linux-foundation.org: add missing inline directives to stubs]
Signed-off-by: KAMEZAWA Hiroyuki 
Reviewed-by: Daisuke Nishimura 
Cc: Balbir Singh 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: add Set,ClearPageSwapCache stubs

2009-01-06T23:59:02+00:00

If we add NOOP stubs for SetPageSwapCache() and ClearPageSwapCache(), then
we can remove the #ifdef CONFIG_SWAPs from mm/migrate.c.

Signed-off-by: Hugh Dickins 
Acked-by: Christoph Lameter 
Cc: Nick Piggin 
Cc: Mel Gorman 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: move_pages: no need to set pp->page to ZERO_PAGE(0) by default

2009-01-06T23:58:58+00:00

pp->page is never used when not set to the right page, so there is no need
to set it to ZERO_PAGE(0) by default.

Signed-off-by: Brice Goglin 
Acked-by: Christoph Lameter 
Cc: Nick Piggin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

mm: rework do_pages_move() to work on page_sized chunks

2009-01-06T23:58:58+00:00

Rework do_pages_move() to work by page-sized chunks of struct page_to_node
that are passed to do_move_page_to_node_array().  We now only have to
allocate a single page instead a possibly very large vmalloc area to store
all page_to_node entries.

As a result, new_page_node() will now have a very small lookup, hidding
much of the overall sys_move_pages() overhead.

Signed-off-by: Brice Goglin 
Signed-off-by: Nathalie Furmento 
Acked-by: Christoph Lameter 
Cc: Nick Piggin 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

Merge branch 'next' into for-linus

2008-12-25T00:40:09+00:00

mm: Don't touch uninitialized variable in do_pages_stat_array()

2008-12-16T16:19:23+00:00

Commit 80bba1290ab5122c60cdb73332b26d288dc8aedd removed one necessary
variable initialization.  As a result following warning happened:

    CC      mm/migrate.o
  mm/migrate.c: In function 'sys_move_pages':
  mm/migrate.c:1001: warning: 'err' may be used uninitialized in this function

More unfortunately, if find_vma() failed, kernel read uninitialized
memory.

Signed-off-by: KOSAKI Motohiro 
CC: Brice Goglin 
Cc: Christoph Lameter 
Cc: KAMEZAWA Hiroyuki 
Cc: Nick Piggin 
Cc: Hugh Dickins 
Signed-off-by: Linus Torvalds

mm: no get_user/put_user while holding mmap_sem in do_pages_stat?

2008-12-10T16:01:53+00:00

Since commit 2f007e74bb85b9fc4eab28524052161703300f1a, do_pages_stat()
gets the page address from user-space and puts the corresponding status
back while holding the mmap_sem for read.  There is no need to hold
mmap_sem there while some page-faults may occur.

This patch adds a temporary address and status buffer so as to only
hold mmap_sem while working on these kernel buffers.  This is
implemented by extracting do_pages_stat_array() out of do_pages_stat().

Signed-off-by: Brice Goglin 
Cc: Christoph Lameter 
Cc: KAMEZAWA Hiroyuki 
Cc: Nick Piggin 
Cc: Hugh Dickins 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds