[PATCH 1/2] mm/ksm: Reset KSM counters in mm_struct during fork

[Donet Tom <donettom@linux.ibm.com>]

Currently, the KSM-related counters in `mm_struct` such as
`ksm_merging_pages`, `ksm_rmap_items`, and `ksm_zero_pages` are
inherited by the child process during fork. This results in
incorrect accounting, since the child has not performed any
KSM page merging.

To fix this, reset these counters to 0 in the newly created
`mm_struct` during fork. This ensures that KSM statistics
remain accurate and only reflect the activity of each process.

Signed-off-by: Donet Tom <donettom@linux.ibm.com>
---
 include/linux/ksm.h | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/include/linux/ksm.h b/include/linux/ksm.h
index 22e67ca7cba3..61b8892c632b 100644
--- a/include/linux/ksm.h
+++ b/include/linux/ksm.h
@@ -56,8 +56,12 @@ static inline long mm_ksm_zero_pages(struct mm_struct *mm)
 static inline void ksm_fork(struct mm_struct *mm, struct mm_struct *oldmm)
 {
 	/* Adding mm to ksm is best effort on fork. */
-	if (mm_flags_test(MMF_VM_MERGEABLE, oldmm))
+	if (mm_flags_test(MMF_VM_MERGEABLE, oldmm)) {
+		mm->ksm_merging_pages = 0;
+		mm->ksm_rmap_items = 0;
+		atomic_long_set(&mm->ksm_zero_pages, 0);
 		__ksm_enter(mm);
+	}
 }
 
 static inline int ksm_execve(struct mm_struct *mm)
-- 
2.51.0