mm/khugepaged: keep mm in mm_slot without MMF_DISABLE_THP check

Previously, we removed the mm from mm_slot and dropped mm_count
if the MMF_THP_DISABLE flag was set. However, we didn't re-add
the mm back after clearing the MMF_THP_DISABLE flag. Additionally,
We add a check for the MMF_THP_DISABLE flag in hugepage_vma_revalidate().

Link: https://lkml.kernel.org/r/20240227035135.54593-1-ioworker0@gmail.com
Fixes: 879c6000e191 ("mm/khugepaged: bypassing unnecessary scans with MMF_DISABLE_THP check")
Signed-off-by: Lance Yang <ioworker0@gmail.com>
Suggested-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: Yang Shi <shy828301@gmail.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Muchun Song <songmuchun@bytedance.com>
Cc: Peter Xu <peterx@redhat.com>
Cc: Zach O'Keefe <zokeefe@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 2771fc043b3b8b7b9397f51b69801b52187b0604..1c0073daad828ec0a6e69d13a99d33043cf83e59 100644 (file)
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -920,7 +920,7 @@ static int hugepage_vma_revalidate(struct mm_struct *mm, unsigned long address,
 {
        struct vm_area_struct *vma;
 
-       if (unlikely(hpage_collapse_test_exit(mm)))
+       if (unlikely(hpage_collapse_test_exit_or_disable(mm)))
                return SCAN_ANY_PROCESS;
 
        *vmap = vma = find_vma(mm, address);
@@ -1428,7 +1428,7 @@ static void collect_mm_slot(struct khugepaged_mm_slot *mm_slot)
 
        lockdep_assert_held(&khugepaged_mm_lock);
 
-       if (hpage_collapse_test_exit_or_disable(mm)) {
+       if (hpage_collapse_test_exit(mm)) {
                /* free mm_slot */
                hash_del(&slot->hash);
                list_del(&slot->mm_node);
@@ -2456,7 +2456,7 @@ breakouterloop_mmap_lock:
         * Release the current mm_slot if this mm is about to die, or
         * if we scanned all vmas of this mm.
         */
-       if (hpage_collapse_test_exit_or_disable(mm) || !vma) {
+       if (hpage_collapse_test_exit(mm) || !vma) {
                /*
                 * Make sure that if mm_users is reaching zero while
                 * khugepaged runs here, khugepaged_exit will find