The patch titled
Subject: mm/ksm.c: fix inconsistent accounting of zero pages
has been added to the -mm tree. Its filename is
mm-ksm-fix-inconsistent-accounting-of-zero-pages.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-ksm-fix-inconsistent-accounting-of-zero-pages.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-ksm-fix-inconsistent-accounting-of-zero-pages.patch
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From: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxxxxxxx>
Subject: mm/ksm.c: fix inconsistent accounting of zero pages
When using KSM with use_zero_pages, we replace anonymous pages containing
only zeroes with actual zero pages, which are not anonymous. We need to
do proper accounting of the mm counters, otherwise we will get wrong
values in /proc and a BUG message in dmesg when tearing down the mm.
Link: http://lkml.kernel.org/r/1522931274-15552-1-git-send-email-imbrenda@xxxxxxxxxxxxxxxxxx
Fixes: e86c59b1b1 ("mm/ksm: improve deduplication of zero pages with colouring")
Signed-off-by: Claudio Imbrenda <imbrenda@xxxxxxxxxxxxxxxxxx>
Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Andrea Arcangeli <aarcange@xxxxxxxxxx>
Cc: Minchan Kim <minchan@xxxxxxxxxx>
Cc: Kirill A. Shutemov <kirill.shutemov@xxxxxxxxxxxxxxx>
Cc: Hugh Dickins <hughd@xxxxxxxxxx>
Cc: Christian Borntraeger <borntraeger@xxxxxxxxxx>
Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxx>
Cc: <stable@xxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/ksm.c | 7 +++++++
1 file changed, 7 insertions(+)
diff -puN mm/ksm.c~mm-ksm-fix-inconsistent-accounting-of-zero-pages mm/ksm.c
--- a/mm/ksm.c~mm-ksm-fix-inconsistent-accounting-of-zero-pages
+++ a/mm/ksm.c
@@ -1131,6 +1131,13 @@ static int replace_page(struct vm_area_s
} else {
newpte = pte_mkspecial(pfn_pte(page_to_pfn(kpage),
vma->vm_page_prot));
+ /*
+ * We're replacing an anonymous page with a zero page, which is
+ * not anonymous. We need to do proper accounting otherwise we
+ * will get wrong values in /proc, and a BUG message in dmesg
+ * when tearing down the mm.
+ */
+ dec_mm_counter(mm, MM_ANONPAGES);
}
flush_cache_page(vma, addr, pte_pfn(*ptep));
_
Patches currently in -mm which might be from imbrenda@xxxxxxxxxxxxxxxxxx are
mm-ksm-fix-interaction-with-thp.patch
mm-ksm-fix-inconsistent-accounting-of-zero-pages.patch