[to-be-updated] mm-ksm-avoid-missing-ksmd-wakeups-in-ksm_enter.patch removed from -mm tree

The quilt patch titled
     Subject: mm/ksm: avoid missing ksmd wakeups in ksm_enter
has been removed from the -mm tree.  Its filename was
     mm-ksm-avoid-missing-ksmd-wakeups-in-ksm_enter.patch

This patch was dropped because an updated version will be issued

------------------------------------------------------
From: Longlong Xia <[email protected]>
Subject: mm/ksm: avoid missing ksmd wakeups in ksm_enter
Date: Mon, 3 Aug 2026 23:21:15 +0800

__ksm_enter() decides whether ksmd needs a wakeup by checking if the mm
slot list is empty before inserting the new slot.

The empty check is currently outside ksm_mmlist_lock.  Another CPU can
remove the last slot and let ksmd go back to sleep after the unlocked
check, while this CPU inserts a new slot and skips the wakeup based on the
stale result.

Take ksm_mmlist_lock before checking the list so the empty-to-nonempty
transition and the insertion are observed as one critical section.

Link: https://lore.kernel.org/[email protected]
Link: https://lore.kernel.org/[email protected]
Fixes: 6e15838425ac ("ksm: keep quiet while list empty")
Signed-off-by: Longlong Xia <[email protected]>
Reviewed-by: Andrew Morton <[email protected]>
Acked-by: David Hildenbrand (Arm) <[email protected]>
Cc: Chengming Zhou <[email protected]>
Cc: Izik Eidus <[email protected]>
Cc: Xu Xin <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---

 mm/ksm.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

--- a/mm/ksm.c~mm-ksm-avoid-missing-ksmd-wakeups-in-ksm_enter
+++ a/mm/ksm.c
@@ -3053,7 +3053,7 @@ int __ksm_enter(struct mm_struct *mm)
 {
 	struct ksm_mm_slot *mm_slot;
 	struct mm_slot *slot;
-	int needs_wakeup;
+	bool needs_wakeup;
 
 	mm_slot = mm_slot_alloc(mm_slot_cache);
 	if (!mm_slot)
@@ -3061,10 +3061,9 @@ int __ksm_enter(struct mm_struct *mm)
 
 	slot = &mm_slot->slot;
 
+	spin_lock(&ksm_mmlist_lock);
 	/* Check ksm_run too?  Would need tighter locking */
 	needs_wakeup = list_empty(&ksm_mm_head.slot.mm_node);
-
-	spin_lock(&ksm_mmlist_lock);
 	mm_slot_insert(mm_slots_hash, mm, slot);
 	/*
 	 * When KSM_RUN_MERGE (or KSM_RUN_STOP),
_

Patches currently in -mm which might be from [email protected] are

zram-fix-out-of-bounds-access-in-writeback_store.patch
zram-fix-out-of-bounds-access-in-read_block_state.patch