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authorClaudio Imbrenda <imbrenda@linux.vnet.ibm.com>2018-04-10 16:29:41 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2018-04-11 10:28:31 -0700
commita38c015f3156895b07e71d4e4414289f8a3b2745 (patch)
tree845bd96b416036708a3481da6e0880f372898973
parent8a97ea546bb6532f77a0efe165012ee0d0c4b903 (diff)
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@linux.vnet.ibm.com Fixes: e86c59b1b1 ("mm/ksm: improve deduplication of zero pages with colouring") Signed-off-by: Claudio Imbrenda <imbrenda@linux.vnet.ibm.com> Reviewed-by: Andrew Morton <akpm@linux-foundation.org> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Minchan Kim <minchan@kernel.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Hugh Dickins <hughd@google.com> Cc: Christian Borntraeger <borntraeger@de.ibm.com> Cc: Gerald Schaefer <gerald.schaefer@de.ibm.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/ksm.c7
1 files changed, 7 insertions, 0 deletions
diff --git a/mm/ksm.c b/mm/ksm.c
index e8d6c6210b80..e3cbf9a92f3c 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -1131,6 +1131,13 @@ static int replace_page(struct vm_area_struct *vma, struct page *page,
} 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));