linux.git/mm/rmap.c, branch v2.6.36

ksm: fix page_address_in_vma anon_vma oops

2010-10-04T18:09:53+00:00

2.6.36-rc1 commit 21d0d443cdc1658a8c1484fdcece4803f0f96d0e "rmap:
resurrect page_address_in_vma anon_vma check" was right to resurrect
that check; but now that it's comparing anon_vma->roots instead of
just anon_vmas, there's a danger of oopsing on a NULL anon_vma.

In most cases no NULL anon_vma ever gets here; but it turns out that
occasionally KSM, when enabled on a forked or forking process, will
itself call page_address_in_vma() on a "half-KSM" page left over from
an earlier failed attempt to merge - whose page_anon_vma() is NULL.

It's my bug that those should be getting here at all: I thought they
were already dealt with, this oops proves me wrong, I'll fix it in
the next release - such pages are effectively pinned until their
process exits, since rmap cannot find their ptes (though swapoff can).

For now just work around it by making page_address_in_vma() safe (and
add a comment on why that check is wanted anyway).  A similar check
in __page_check_anon_rmap() is safe because do_page_add_anon_rmap()
already excluded KSM pages.

Signed-off-by: Hugh Dickins 
Cc: Andrew Morton 
Cc: Andrea Arcangeli 
Cc: Rik van Riel 
Signed-off-by: Linus Torvalds

hugetlb, rmap: add BUG_ON(!PageLocked) in hugetlb_add_anon_rmap()

2010-09-24T00:29:19+00:00

Confirming page lock is held in hugetlb_add_anon_rmap() may be useful
to detect possible future problems.

Signed-off-by: Naoya Horiguchi 
Acked-by: Rik van Riel 
Acked-by: Andrea Arcangeli 
Signed-off-by: Linus Torvalds

hugetlb, rmap: always use anon_vma root pointer

2010-09-24T00:29:18+00:00

This patch applies Andrea's fix given by the following patch into hugepage
rmapping code:

  commit 288468c334e98aacbb7e2fb8bde6bc1adcd55e05
  Author: Andrea Arcangeli 
  Date:   Mon Aug 9 17:19:09 2010 -0700

This patch uses anon_vma->root and avoids unnecessary overwriting when
anon_vma is already set up.

Signed-off-by: Naoya Horiguchi 
Acked-by: Andrea Arcangeli 
Reviewed-by: Rik van Riel 
Signed-off-by: Linus Torvalds

mm: fix hang on anon_vma->root->lock

2010-08-28T20:54:12+00:00

After several hours, kbuild tests hang with anon_vma_prepare() spinning on
a newly allocated anon_vma's lock - on a box with CONFIG_TREE_PREEMPT_RCU=y
(which makes this very much more likely, but it could happen without).

The ever-subtle page_lock_anon_vma() now needs a further twist: since
anon_vma_prepare() and anon_vma_fork() are liable to change the ->root
of a reused anon_vma structure at any moment, page_lock_anon_vma()
needs to check page_mapped() again before succeeding, otherwise
page_unlock_anon_vma() might address a different root->lock.

Signed-off-by: Hugh Dickins 
Reviewed-by: Rik van Riel 
Cc: Christoph Lameter 
Cc: Peter Zijlstra 
Cc: Andrea Arcangeli 
Signed-off-by: Linus Torvalds

Merge branch 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6

2010-08-12T17:15:10+00:00

* 'hwpoison' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-mce-2.6:
  hugetlb: add missing unlock in avoidcopy path in hugetlb_cow()
  hwpoison: rename CONFIG
  HWPOISON, hugetlb: support hwpoison injection for hugepage
  HWPOISON, hugetlb: detect hwpoison in hugetlb code
  HWPOISON, hugetlb: isolate corrupted hugepage
  HWPOISON, hugetlb: maintain mce_bad_pages in handling hugepage error
  HWPOISON, hugetlb: set/clear PG_hwpoison bits on hugepage
  HWPOISON, hugetlb: enable error handling path for hugepage
  hugetlb, rmap: add reverse mapping for hugepage
  hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h

Fix up trivial conflicts in mm/memory-failure.c

hwpoison: rename CONFIG

2010-08-11T07:23:22+00:00

CONFIG_HUGETLBFS controls hugetlbfs interface code.
OTOH, CONFIG_HUGETLB_PAGE controls hugepage management code.
So we should use CONFIG_HUGETLB_PAGE here.

Signed-off-by: Naoya Horiguchi 
Signed-off-by: Andi Kleen

hugetlb, rmap: add reverse mapping for hugepage

2010-08-11T07:21:15+00:00

This patch adds reverse mapping feature for hugepage by introducing
mapcount for shared/private-mapped hugepage and anon_vma for
private-mapped hugepage.

While hugepage is not currently swappable, reverse mapping can be useful
for memory error handler.

Without this patch, memory error handler cannot identify processes
using the bad hugepage nor unmap it from them. That is:
- for shared hugepage:
  we can collect processes using a hugepage through pagecache,
  but can not unmap the hugepage because of the lack of mapcount.
- for privately mapped hugepage:
  we can neither collect processes nor unmap the hugepage.
This patch solves these problems.

This patch include the bug fix given by commit 23be7468e8, so reverts it.

Dependency:
  "hugetlb: move definition of is_vm_hugetlb_page() to hugepage_inline.h"

ChangeLog since May 24.
- create hugetlb_inline.h and move is_vm_hugetlb_index() in it.
- move functions setting up anon_vma for hugepage into mm/rmap.c.

ChangeLog since May 13.
- rebased to 2.6.34
- fix logic error (in case that private mapping and shared mapping coexist)
- move is_vm_hugetlb_page() into include/linux/mm.h to use this function
  from linear_page_index()
- define and use linear_hugepage_index() instead of compound_order()
- use page_move_anon_rmap() in hugetlb_cow()
- copy exclusive switch of __set_page_anon_rmap() into hugepage counterpart.
- revert commit 24be7468 completely

Signed-off-by: Naoya Horiguchi 
Cc: Andi Kleen 
Cc: Andrew Morton 
Cc: Mel Gorman 
Cc: Andrea Arcangeli 
Cc: Larry Woodman 
Cc: Lee Schermerhorn 
Acked-by: Fengguang Wu 
Acked-by: Mel Gorman 
Signed-off-by: Andi Kleen

rmap: add exclusive page to private anon_vma on swapin

2010-08-10T03:45:02+00:00

On swapin it is fairly common for a page to be owned exclusively by one
process.  In that case we want to add the page to the anon_vma of that
process's VMA, instead of to the root anon_vma.

This will reduce the amount of rmap searching that the swapout code needs
to do.

Signed-off-by: Rik van Riel 
Cc: Andrea Arcangeli 
Cc: KOSAKI Motohiro 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rmap: add anon_vma bug checks

2010-08-10T03:44:59+00:00

Verify the refcounting doesn't go wrong, and resurrect the check in
__page_check_anon_rmap as in old anon-vma code.

Signed-off-by: Andrea Arcangeli 
Signed-off-by: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

rmap: resurrect page_address_in_vma anon_vma check

2010-08-10T03:44:59+00:00

With root anon-vma it's trivial to keep doing the usual check as in
old-anon-vma code.

Signed-off-by: Andrea Arcangeli 
Signed-off-by: Rik van Riel 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds