mm: Ignore madvise(MADV_MERGEABLE) request for VM_CDM marked VMAs

ascend inclusion
category: feature
bugzilla: https://gitee.com/openeuler/kernel/issues/I4JMLR
CVE: NA
-------------------

VMA containing CDM memory should be excluded from KSM merging. This change
makes madvise(MADV_MERGEABLE) request on target VMA to be ignored.
Signed-off-by: NAnshuman Khandual <khandual@linux.vnet.ibm.com>
Signed-off-by: NLijun Fang <fanglijun3@huawei.com>
Reviewed-by: NWeilong Chen <chenweilong@huawei.com>
Signed-off-by: NZheng Zengkai <zhengzengkai@huawei.com>

mm/ksm.c

@@ -38,6 +38,7 @@
 #include <linux/freezer.h>
 #include <linux/oom.h>
 #include <linux/numa.h>
+#include <linux/mempolicy.h>
 
 #include <asm/tlbflush.h>
 #include "internal.h"
@@ -2454,6 +2455,11 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
 		if (vma_is_dax(vma))
 			return 0;
 
+#ifdef CONFIG_COHERENT_DEVICE
+		if (is_cdm_vma(vma))
+			return 0;
+#endif
+
 #ifdef VM_SAO
 		if (*vm_flags & VM_SAO)
 			return 0;