diff options
| author | Hugh Dickins <hugh.dickins@tiscali.co.uk> | 2009-09-21 17:01:59 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2009-09-22 07:17:31 -0700 |
| commit | 21333b2b66b805a360641568588e5a0bb06d9d1f (patch) | |
| tree | c0ce4d31e31ae2d2b1ef975b00c0611a3099c7a3 /mm/rmap.c | |
| parent | f8af4da3b4c14e7267c4ffb952079af3912c51c5 (diff) | |
| download | lwn-21333b2b66b805a360641568588e5a0bb06d9d1f.tar.gz lwn-21333b2b66b805a360641568588e5a0bb06d9d1f.zip | |
ksm: no debug in page_dup_rmap()
page_dup_rmap(), used on each mapped page when forking, was originally
just an inline atomic_inc of mapcount. 2.6.22 added CONFIG_DEBUG_VM
out-of-line checks to it, which would need to be ever-so-slightly
complicated to allow for the PageKsm() we're about to define.
But I think these checks never caught anything. And if it's coding errors
we're worried about, such checks should be in page_remove_rmap() too, not
just when forking; whereas if it's pagetable corruption we're worried
about, then they shouldn't be limited to CONFIG_DEBUG_VM.
Oh, just revert page_dup_rmap() to an inline atomic_inc of mapcount.
Signed-off-by: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Signed-off-by: Chris Wright <chrisw@redhat.com>
Signed-off-by: Izik Eidus <ieidus@redhat.com>
Cc: Nick Piggin <npiggin@suse.de>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Avi Kivity <avi@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/rmap.c')
| -rw-r--r-- | mm/rmap.c | 21 |
1 files changed, 0 insertions, 21 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index 1406e67f9613..720fc03a7bc4 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -710,27 +710,6 @@ void page_add_file_rmap(struct page *page) } } -#ifdef CONFIG_DEBUG_VM -/** - * page_dup_rmap - duplicate pte mapping to a page - * @page: the page to add the mapping to - * @vma: the vm area being duplicated - * @address: the user virtual address mapped - * - * For copy_page_range only: minimal extract from page_add_file_rmap / - * page_add_anon_rmap, avoiding unnecessary tests (already checked) so it's - * quicker. - * - * The caller needs to hold the pte lock. - */ -void page_dup_rmap(struct page *page, struct vm_area_struct *vma, unsigned long address) -{ - if (PageAnon(page)) - __page_check_anon_rmap(page, vma, address); - atomic_inc(&page->_mapcount); -} -#endif - /** * page_remove_rmap - take down pte mapping from a page * @page: page to remove mapping from |