From: "Kiryl Shutsemau (Meta)" madvise_collapse() holds an mmgrab() reference across its work. It is redundant. Every caller already holds mm_users: - madvise(2) works on current->mm, which lives as long as the task is in the syscall; - process_madvise(2) reaches a remote mm through mm_access(), which takes an mm_users reference and holds it until the syscall returns; - io_uring passes current->mm; - DAMON takes one with get_task_mm() and drops it after the call. Drop the mmgrab()/mmdrop() pair. Assisted-by: LLM Reviewed-by: Zi Yan Reviewed-by: Baolin Wang Signed-off-by: Kiryl Shutsemau (Meta) --- mm/khugepaged.c | 2 -- 1 file changed, 2 deletions(-) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index e13d233b9967..75c876acf527 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -3229,7 +3229,6 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, cc->is_khugepaged = false; cc->progress = 0; - mmgrab(mm); lru_add_drain_all(); for (addr = hstart; addr < hend; addr += HPAGE_PMD_SIZE) { @@ -3285,7 +3284,6 @@ int madvise_collapse(struct vm_area_struct *vma, unsigned long start, } out_nolock: mmap_assert_locked(mm); - mmdrop(mm); kfree(cc); return thps == ((hend - hstart) >> HPAGE_PMD_SHIFT) ? 0 -- 2.54.0