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-rw-r--r--mm/khugepaged.c10
1 files changed, 6 insertions, 4 deletions
diff --git a/mm/khugepaged.c b/mm/khugepaged.c
index 01f71786d530..70b7ac66411c 100644
--- a/mm/khugepaged.c
+++ b/mm/khugepaged.c
@@ -1083,10 +1083,12 @@ static void collapse_huge_page(struct mm_struct *mm,
pmd_ptl = pmd_lock(mm, pmd); /* probably unnecessary */
/*
- * After this gup_fast can't run anymore. This also removes
- * any huge TLB entry from the CPU so we won't allow
- * huge and small TLB entries for the same virtual address
- * to avoid the risk of CPU bugs in that area.
+ * This removes any huge TLB entry from the CPU so we won't allow
+ * huge and small TLB entries for the same virtual address to
+ * avoid the risk of CPU bugs in that area.
+ *
+ * Parallel fast GUP is fine since fast GUP will back off when
+ * it detects PMD is changed.
*/
_pmd = pmdp_collapse_flush(vma, address, pmd);
spin_unlock(pmd_ptl);