The patch titled
ksm: fix ksm swapin time optimization
has been added to the -mm tree. Its filename is
ksm-fix-ksm-swapin-time-optimization.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find
out what to do about this
The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/
------------------------------------------------------
Subject: ksm: fix ksm swapin time optimization
From: Andrea Arcangeli <aarcange@xxxxxxxxxx>
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@xxxxxxxxxx>
Signed-off-by: Rik van Riel <riel@xxxxxxxxxx>
Cc: Izik Eidus <ieidus@xxxxxxxxx>
Cc: Avi Kivity <avi@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/ksm.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN include/linux/ksm.h~ksm-fix-ksm-swapin-time-optimization include/linux/ksm.h
--- a/include/linux/ksm.h~ksm-fix-ksm-swapin-time-optimization
+++ a/include/linux/ksm.h
@@ -78,7 +78,7 @@ static inline struct page *ksm_might_nee
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;
_
Patches currently in -mm which might be from aarcange@xxxxxxxxxx are
linux-next.patch
hugetlb-call-mmu-notifiers-on-hugepage-cow.patch
define-madv_hugepage.patch
mmap-remove-unnecessary-lock-from-__vma_link.patch
rmap-always-add-new-vmas-at-the-end.patch
ksm-fix-ksm-swapin-time-optimization.patch
rmap-always-use-anon_vma-root-pointer.patch
rmap-resurrect-page_address_in_vma-anon_vma-check.patch
add-anon_vma-bug-checks.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
