diff options
author | Andrea Arcangeli <aarcange@redhat.com> | 2010-08-10 02:19:09 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-10 05:44:58 +0200 |
commit | 288468c334e98aacbb7e2fb8bde6bc1adcd55e05 (patch) | |
tree | f64cfebd7fedfd4e53fd5d4474048d5475a339b9 /mm/rmap.c | |
parent | ksm: fix ksm swapin time optimization (diff) | |
download | linux-288468c334e98aacbb7e2fb8bde6bc1adcd55e05.tar.xz linux-288468c334e98aacbb7e2fb8bde6bc1adcd55e05.zip |
rmap: always use anon_vma root pointer
Always use anon_vma->root pointer instead of anon_vma_chain.prev.
Also optimize the map-paths, if a mapping is already established no need
to overwrite it with root anon-vma list, we can keep the more finegrined
anon-vma and skip the overwrite: see the PageAnon check in !exclusive
case. This is also the optimization that hidden the ksm bug as this tends
to make ksm_might_need_to_copy skip the copy, but only the proper fix to
ksm_might_need_to_copy guarantees not triggering the ksm bug unless ksm is
in use. this is an optimization only...
[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
[kamezawa.hiroyu@jp.fujitsu.com: fix false positive BUG_ON in __page_set_anon_rmap]
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 | 18 |
1 files changed, 12 insertions, 6 deletions
diff --git a/mm/rmap.c b/mm/rmap.c index dce74a9efdd6..f5d6799b8a74 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -767,14 +767,20 @@ static void __page_set_anon_rmap(struct page *page, * If the page isn't exclusively mapped into this vma, * we must use the _oldest_ possible anon_vma for the * page mapping! - * - * So take the last AVC chain entry in the vma, which is - * the deepest ancestor, and use the anon_vma from that. */ if (!exclusive) { - struct anon_vma_chain *avc; - avc = list_entry(vma->anon_vma_chain.prev, struct anon_vma_chain, same_vma); - anon_vma = avc->anon_vma; + if (PageAnon(page)) + return; + anon_vma = anon_vma->root; + } else { + /* + * In this case, swapped-out-but-not-discarded swap-cache + * is remapped. So, no need to update page->mapping here. + * We convice anon_vma poitned by page->mapping is not obsolete + * because vma->anon_vma is necessary to be a family of it. + */ + if (PageAnon(page)) + return; } anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON; |