hugetlb: do not allow pagesize >= MAX_ORDER pool adjustment

[~andy/linux] / mm / huge_memory.c

diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index fce667c0281d5ac87ec5b38e6eeddfa46dfaaeae..004c9c2aac788ebca9c7de0edb95244396b880f1 100644 (file)
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1389,7 +1389,8 @@ out:
        return ret;
 }
 
-int hugepage_madvise(unsigned long *vm_flags, int advice)
+int hugepage_madvise(struct vm_area_struct *vma,
+                    unsigned long *vm_flags, int advice)
 {
        switch (advice) {
        case MADV_HUGEPAGE:
@@ -1404,6 +1405,13 @@ int hugepage_madvise(unsigned long *vm_flags, int advice)
                        return -EINVAL;
                *vm_flags &= ~VM_NOHUGEPAGE;
                *vm_flags |= VM_HUGEPAGE;
+               /*
+                * If the vma become good for khugepaged to scan,
+                * register it here without waiting a page fault that
+                * may not happen any time soon.
+                */
+               if (unlikely(khugepaged_enter_vma_merge(vma)))
+                       return -ENOMEM;
                break;
        case MADV_NOHUGEPAGE:
                /*
@@ -1417,6 +1425,11 @@ int hugepage_madvise(unsigned long *vm_flags, int advice)
                        return -EINVAL;
                *vm_flags &= ~VM_HUGEPAGE;
                *vm_flags |= VM_NOHUGEPAGE;
+               /*
+                * Setting VM_NOHUGEPAGE will prevent khugepaged from scanning
+                * this vma even if we leave the mm registered in khugepaged if
+                * it got registered before VM_NOHUGEPAGE was set.
+                */
                break;
        }
 
@@ -1784,7 +1797,8 @@ static void collapse_huge_page(struct mm_struct *mm,
        if (address < hstart || address + HPAGE_PMD_SIZE > hend)
                goto out;
 
-       if (!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always())
+       if ((!(vma->vm_flags & VM_HUGEPAGE) && !khugepaged_always()) ||
+           (vma->vm_flags & VM_NOHUGEPAGE))
                goto out;
 
        /* VM_PFNMAP vmas may have vm_ops null but vm_file set */
@@ -2007,8 +2021,9 @@ static unsigned int khugepaged_scan_mm_slot(unsigned int pages,
                        break;
                }
 
-               if (!(vma->vm_flags & VM_HUGEPAGE) &&
-                   !khugepaged_always()) {
+               if ((!(vma->vm_flags & VM_HUGEPAGE) &&
+                    !khugepaged_always()) ||
+                   (vma->vm_flags & VM_NOHUGEPAGE)) {
                        progress++;
                        continue;
                }