From: Andrea Arcangeli <aarcange@xxxxxxxxxx> Subject: 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@xxxxxxxxxx> Signed-off-by: Rik van Riel <riel@xxxxxxxxxx> --- diff --git a/include/linux/ksm.h b/include/linux/ksm.h --- a/include/linux/ksm.h +++ b/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; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>