4.14-stable review patch. If anyone has any objections, please let me know.
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From: Claudio Imbrenda imbrenda@linux.vnet.ibm.com
commit a38c015f3156895b07e71d4e4414289f8a3b2745 upstream.
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.vn... 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 Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- mm/ksm.c | 7 +++++++ 1 file changed, 7 insertions(+)
--- a/mm/ksm.c +++ b/mm/ksm.c @@ -1133,6 +1133,13 @@ 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));