diff --git a/arch/s390/mm/gmap.c b/arch/s390/mm/gmap.c
index 5a716bdcba05..9d85e5589474 100644
--- a/arch/s390/mm/gmap.c
+++ b/arch/s390/mm/gmap.c
@@ -2591,6 +2591,7 @@ int gmap_mark_unmergeable(void)
 	int ret;
 	VMA_ITERATOR(vmi, mm, 0);
 
+	clear_bit(MMF_VM_MERGE_ANY, &mm->flags);
 	for_each_vma(vmi, vma) {
 		/* Copy vm_flags to avoid partial modifications in ksm_madvise */
 		vm_flags = vma->vm_flags;
diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 7e232ba59b86..c65455bf124c 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -18,20 +18,29 @@
 #ifdef CONFIG_KSM
 int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
 		unsigned long end, int advice, unsigned long *vm_flags);
-int __ksm_enter(struct mm_struct *mm);
-void __ksm_exit(struct mm_struct *mm);
+
+int ksm_add_mm(struct mm_struct *mm);
+void ksm_add_vma(struct vm_area_struct *vma);
+void ksm_add_vmas(struct mm_struct *mm);
+
+int __ksm_enter(struct mm_struct *mm, int flag);
+void __ksm_exit(struct mm_struct *mm, int flag);
 
 static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
 {
+	if (test_bit(MMF_VM_MERGE_ANY, &oldmm->flags))
+		return ksm_add_mm(mm);
 	if (test_bit(MMF_VM_MERGEABLE, &oldmm->flags))
-		return __ksm_enter(mm);
+		return __ksm_enter(mm, MMF_VM_MERGEABLE);
 	return 0;
 }
 
 static inline void ksm_exit(struct mm_struct *mm)
 {
-	if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
-		__ksm_exit(mm);
+	if (test_bit(MMF_VM_MERGE_ANY, &mm->flags))
+		__ksm_exit(mm, MMF_VM_MERGE_ANY);
+	else if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
+		__ksm_exit(mm, MMF_VM_MERGEABLE);
 }
 
 /*
@@ -53,6 +62,18 @@ void folio_migrate_ksm(struct folio *newfolio, struct folio *folio);
 
 #else  /* !CONFIG_KSM */
 
+static inline int ksm_add_mm(struct mm_struct *mm)
+{
+}
+
+static inline void ksm_add_vma(struct vm_area_struct *vma)
+{
+}
+
+static inline void ksm_add_vmas(struct mm_struct *mm)
+{
+}
+
 static inline int ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
 {
 	return 0;
diff --git a/include/linux/sched/coredump.h b/include/linux/sched/coredump.h
index 0e17ae7fbfd3..0ee96ea7a0e9 100644
--- a/include/linux/sched/coredump.h
+++ b/include/linux/sched/coredump.h
@@ -90,4 +90,5 @@ static inline int get_dumpable(struct mm_struct *mm)
 #define MMF_INIT_MASK		(MMF_DUMPABLE_MASK | MMF_DUMP_FILTER_MASK |\
 				 MMF_DISABLE_THP_MASK | MMF_HAS_MDWE_MASK)
 
+#define MMF_VM_MERGE_ANY	29
 #endif /* _LINUX_SCHED_COREDUMP_H */
diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h
index 1312a137f7fb..759b3f53e53f 100644
--- a/include/uapi/linux/prctl.h
+++ b/include/uapi/linux/prctl.h
@@ -290,4 +290,6 @@ struct prctl_mm_map {
 #define PR_SET_VMA		0x53564d41
 # define PR_SET_VMA_ANON_NAME		0
 
+#define PR_SET_MEMORY_MERGE		67
+#define PR_GET_MEMORY_MERGE		68
 #endif /* _LINUX_PRCTL_H */
diff --git a/kernel/fork.c b/kernel/fork.c
index f68954d05e89..1520697cf6c7 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -686,6 +686,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
 		if (vma_iter_bulk_store(&vmi, tmp))
 			goto fail_nomem_vmi_store;
 
+		ksm_add_vma(tmp);
 		mm->map_count++;
 		if (!(tmp->vm_flags & VM_WIPEONFORK))
 			retval = copy_page_range(tmp, mpnt);
diff --git a/kernel/sys.c b/kernel/sys.c
index 495cd87d9bf4..3e6918a10259 100644
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -15,6 +15,7 @@
 #include <linux/highuid.h>
 #include <linux/fs.h>
 #include <linux/kmod.h>
+#include <linux/ksm.h>
 #include <linux/perf_event.h>
 #include <linux/resource.h>
 #include <linux/kernel.h>
@@ -2661,6 +2662,29 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3,
 	case PR_SET_VMA:
 		error = prctl_set_vma(arg2, arg3, arg4, arg5);
 		break;
+#ifdef CONFIG_KSM
+	case PR_SET_MEMORY_MERGE:
+		if (mmap_write_lock_killable(me->mm))
+			return -EINTR;
+
+		if (arg2) {
+			int err = ksm_add_mm(me->mm);
+			if (err)
+				return err;
+
+			ksm_add_vmas(me->mm);
+		} else {
+			clear_bit(MMF_VM_MERGE_ANY, &me->mm->flags);
+		}
+		mmap_write_unlock(me->mm);
+		break;
+	case PR_GET_MEMORY_MERGE:
+		if (arg2 || arg3 || arg4 || arg5)
+			return -EINVAL;
+
+		error = !!test_bit(MMF_VM_MERGE_ANY, &me->mm->flags);
+		break;
+#endif
 	default:
 		error = -EINVAL;
 		break;
diff --git a/mm/ksm.c b/mm/ksm.c
index d7bd28199f6c..ab95ae0f9def 100644
--- a/mm/ksm.c
+++ b/mm/ksm.c
@@ -534,10 +534,33 @@ static int break_ksm(struct vm_area_struct *vma, unsigned long addr,
 	return (ret & VM_FAULT_OOM) ? -ENOMEM : 0;
 }
 
+static bool vma_ksm_compatible(struct vm_area_struct *vma)
+{
+	if (vma->vm_flags & (VM_SHARED  | VM_MAYSHARE   | VM_PFNMAP  |
+			     VM_IO      | VM_DONTEXPAND | VM_HUGETLB |
+			     VM_MIXEDMAP))
+		return false;		/* just ignore the advice */
+
+	if (vma_is_dax(vma))
+		return false;
+
+#ifdef VM_SAO
+	if (vma->vm_flags & VM_SAO)
+		return false;
+#endif
+#ifdef VM_SPARC_ADI
+	if (vma->vm_flags & VM_SPARC_ADI)
+		return false;
+#endif
+
+	return true;
+}
+
 static struct vm_area_struct *find_mergeable_vma(struct mm_struct *mm,
 		unsigned long addr)
 {
 	struct vm_area_struct *vma;
+
 	if (ksm_test_exit(mm))
 		return NULL;
 	vma = vma_lookup(mm, addr);
@@ -1065,6 +1088,7 @@ static int unmerge_and_remove_all_rmap_items(void)
 
 			mm_slot_free(mm_slot_cache, mm_slot);
 			clear_bit(MMF_VM_MERGEABLE, &mm->flags);
+			clear_bit(MMF_VM_MERGE_ANY, &mm->flags);
 			mmdrop(mm);
 		} else
 			spin_unlock(&ksm_mmlist_lock);
@@ -2495,6 +2519,7 @@ static struct ksm_rmap_item *scan_get_next_rmap_item(struct page **page)
 
 		mm_slot_free(mm_slot_cache, mm_slot);
 		clear_bit(MMF_VM_MERGEABLE, &mm->flags);
+		clear_bit(MMF_VM_MERGE_ANY, &mm->flags);
 		mmap_read_unlock(mm);
 		mmdrop(mm);
 	} else {
@@ -2571,6 +2596,63 @@ static int ksm_scan_thread(void *nothing)
 	return 0;
 }
 
+static void __ksm_add_vma(struct vm_area_struct *vma)
+{
+	unsigned long vm_flags = vma->vm_flags;
+
+	if (vm_flags & VM_MERGEABLE)
+		return;
+
+	if (vma_ksm_compatible(vma)) {
+		vm_flags |= VM_MERGEABLE;
+		vm_flags_reset(vma, vm_flags);
+	}
+}
+
+/**
+ * ksm_add_vma - Mark vma as mergeable
+ *
+ * @vma:  Pointer to vma
+ */
+void ksm_add_vma(struct vm_area_struct *vma)
+{
+	struct mm_struct *mm = vma->vm_mm;
+
+	if (test_bit(MMF_VM_MERGE_ANY, &mm->flags))
+		__ksm_add_vma(vma);
+}
+
+/**
+ * ksm_add_vmas - Mark all vma's of a process as mergeable
+ *
+ * @mm:  Pointer to mm
+ */
+void ksm_add_vmas(struct mm_struct *mm)
+{
+	struct vm_area_struct *vma;
+
+	VMA_ITERATOR(vmi, mm, 0);
+	for_each_vma(vmi, vma)
+		__ksm_add_vma(vma);
+}
+
+/**
+ * ksm_add_mm - Add mm to mm ksm list
+ *
+ * @mm:  Pointer to mm
+ *
+ * Returns 0 on success, otherwise error code
+ */
+int ksm_add_mm(struct mm_struct *mm)
+{
+	if (test_bit(MMF_VM_MERGE_ANY, &mm->flags))
+		return -EINVAL;
+	if (test_bit(MMF_VM_MERGEABLE, &mm->flags))
+		return -EINVAL;
+
+	return __ksm_enter(mm, MMF_VM_MERGE_ANY);
+}
+
 int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
 		unsigned long end, int advice, unsigned long *vm_flags)
 {
@@ -2579,28 +2661,13 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
 
 	switch (advice) {
 	case MADV_MERGEABLE:
-		/*
-		 * Be somewhat over-protective for now!
-		 */
-		if (*vm_flags & (VM_MERGEABLE | VM_SHARED  | VM_MAYSHARE   |
-				 VM_PFNMAP    | VM_IO      | VM_DONTEXPAND |
-				 VM_HUGETLB | VM_MIXEDMAP))
-			return 0;		/* just ignore the advice */
-
-		if (vma_is_dax(vma))
+		if (vma->vm_flags & VM_MERGEABLE)
 			return 0;
-
-#ifdef VM_SAO
-		if (*vm_flags & VM_SAO)
+		if (!vma_ksm_compatible(vma))
 			return 0;
-#endif
-#ifdef VM_SPARC_ADI
-		if (*vm_flags & VM_SPARC_ADI)
-			return 0;
-#endif
 
 		if (!test_bit(MMF_VM_MERGEABLE, &mm->flags)) {
-			err = __ksm_enter(mm);
+			err = __ksm_enter(mm, MMF_VM_MERGEABLE);
 			if (err)
 				return err;
 		}
@@ -2626,7 +2693,7 @@ int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
 }
 EXPORT_SYMBOL_GPL(ksm_madvise);
 
-int __ksm_enter(struct mm_struct *mm)
+int __ksm_enter(struct mm_struct *mm, int flag)
 {
 	struct ksm_mm_slot *mm_slot;
 	struct mm_slot *slot;
@@ -2659,7 +2726,7 @@ int __ksm_enter(struct mm_struct *mm)
 		list_add_tail(&slot->mm_node, &ksm_scan.mm_slot->slot.mm_node);
 	spin_unlock(&ksm_mmlist_lock);
 
-	set_bit(MMF_VM_MERGEABLE, &mm->flags);
+	set_bit(flag, &mm->flags);
 	mmgrab(mm);
 
 	if (needs_wakeup)
@@ -2668,7 +2735,7 @@ int __ksm_enter(struct mm_struct *mm)
 	return 0;
 }
 
-void __ksm_exit(struct mm_struct *mm)
+void __ksm_exit(struct mm_struct *mm, int flag)
 {
 	struct ksm_mm_slot *mm_slot;
 	struct mm_slot *slot;
@@ -2700,7 +2767,7 @@ void __ksm_exit(struct mm_struct *mm)
 
 	if (easy_to_free) {
 		mm_slot_free(mm_slot_cache, mm_slot);
-		clear_bit(MMF_VM_MERGEABLE, &mm->flags);
+		clear_bit(flag, &mm->flags);
 		mmdrop(mm);
 	} else if (mm_slot) {
 		mmap_write_lock(mm);
diff --git a/mm/mmap.c b/mm/mmap.c
index 740b54be3ed4..483e182e0b9d 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -46,6 +46,7 @@
 #include <linux/pkeys.h>
 #include <linux/oom.h>
 #include <linux/sched/mm.h>
+#include <linux/ksm.h>
 
 #include <linux/uaccess.h>
 #include <asm/cacheflush.h>
@@ -2213,6 +2214,8 @@ int __split_vma(struct vma_iterator *vmi, struct vm_area_struct *vma,
 	/* vma_complete stores the new vma */
 	vma_complete(&vp, vmi, vma->vm_mm);
 
+	ksm_add_vma(new);
+
 	/* Success. */
 	if (new_below)
 		vma_next(vmi);
@@ -2664,6 +2667,7 @@ unsigned long mmap_region(struct file *file, unsigned long addr,
 	if (file && vm_flags & VM_SHARED)
 		mapping_unmap_writable(file->f_mapping);
 	file = vma->vm_file;
+	ksm_add_vma(vma);
 expanded:
 	perf_event_mmap(vma);
 
@@ -2936,6 +2940,7 @@ static int do_brk_flags(struct vma_iterator *vmi, struct vm_area_struct *vma,
 		goto mas_store_fail;
 
 	mm->map_count++;
+	ksm_add_vma(vma);
 out:
 	perf_event_mmap(vma);
 	mm->total_vm += len >> PAGE_SHIFT;
@@ -3180,6 +3185,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 		if (vma_link(mm, new_vma))
 			goto out_vma_link;
 		*need_rmap_locks = false;
+		ksm_add_vma(new_vma);
 	}
 	validate_mm_mt(mm);
 	return new_vma;
@@ -3356,6 +3362,7 @@ static struct vm_area_struct *__install_special_mapping(
 	vm_stat_account(mm, vma->vm_flags, len >> PAGE_SHIFT);
 
 	perf_event_mmap(vma);
+	ksm_add_vma(vma);
 
 	validate_mm_mt(mm);
 	return vma;
