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| author | Andrea Arcangeli <aarcange@redhat.com> | 2010-08-09 17:19:08 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-09 20:44:58 -0700 |
| commit | ba6f0ff3981e6263ab81ac512f04cca55b85ec81 (patch) | |
| tree | 0052d4551de72731be503c8d78949a330ba865ed /include/linux/ksm.h | |
| parent | 26ba0cb63cb8df4e45394227f33c938920b11b88 (diff) | |
| download | lwn-ba6f0ff3981e6263ab81ac512f04cca55b85ec81.tar.gz lwn-ba6f0ff3981e6263ab81ac512f04cca55b85ec81.zip | |
ksm: fix ksm swapin time optimization
The new anon-vma code, was suboptimal and it lead to erratic invocation of
ksm_does_need_to_copy. That leads to host hangs or guest vnc lockup, or
weird behavior. It's unclear why ksm_does_need_to_copy is unstable but
the point is that when KSM is not in use, ksm_does_need_to_copy must never
run or we bounce pages for no good reason. I suspect the same hangs will
happen with KVM swaps. But this at least fixes the regression in the
new-anon-vma code and it only let KSM bugs triggers when KSM is in use.
The code in do_swap_page likely doesn't cope well with a not-swapcache,
especially the memcg code.
Signed-off-by: Andrea Arcangeli <aarcange@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Cc: Izik Eidus <ieidus@yahoo.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 'include/linux/ksm.h')
| -rw-r--r-- | include/linux/ksm.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/ksm.h b/include/linux/ksm.h index 43bdab769fc3..74d691ee9121 100644 --- a/include/linux/ksm.h +++ b/include/linux/ksm.h @@ -78,7 +78,7 @@ static inline struct page *ksm_might_need_to_copy(struct page *page, struct anon_vma *anon_vma = page_anon_vma(page); if (!anon_vma || - (anon_vma == vma->anon_vma && + (anon_vma->root == vma->anon_vma->root && page->index == linear_page_index(vma, address))) return page; |