Re: [stable-6.6.y] mm: khugepaged refuses to freeze
From: Baolin Wang
Date: Tue Feb 10 2026 - 20:04:09 EST
On 2/10/26 6:21 PM, David Hildenbrand (Arm) wrote:
On 2/10/26 11:07, Baolin Wang wrote:
On 2/10/26 11:21 AM, Sergey Senozhatsky wrote:
On (26/02/06 10:00), David Hildenbrand (Arm) wrote:
Right, mimicking what kswapd does sound reasonable!
I may be missing something, as I'm not seeing dev_pm_ops in vmscan code.
Would something like this work?
---
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index fa6a018b20a8..c5d89ec223d3 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -394,8 +394,12 @@ static inline int hpage_collapse_test_exit(struct mm_struct *mm)
static inline int hpage_collapse_test_exit_or_disable(struct mm_struct *mm)
{
+ bool was_frozen;
+ int ret = kthread_freezable_should_stop(&was_frozen);
+
return hpage_collapse_test_exit(mm) ||
- mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm);
+ mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm) ||
+ was_frozen || ret;
}
Since the hpage_collapse_test_exit_or_disable() can be called by madvise_callapse(), which is not a kernel thread.
Which raises the question whether we should forward that context (khugepaged vs. madvise) to hpage_collapse_test_exit_or_disable().
Passing in the 'cc' pointer looks fine to me. Something like:
static inline int hpage_collapse_test_exit_or_disable(struct mm_struct *mm,
struct collapse_control *cc)
{
bool was_frozen = false;
if (cc->is_khugepaged && unlikely(kthread_freezable_should_stop(&was_frozen)))
return 1;
return hpage_collapse_test_exit(mm) ||
mm_flags_test(MMF_DISABLE_THP_COMPLETELY, mm) ||
was_frozen;
}
Sergey, could you submit a formal patch for review?