SAFE public projects git trees. - safe/jmp/linux-2.6/blob - mm/ksm.c

   1 /*
   2  * Initial dummy version just to illustrate KSM's interface to other files.
   3  */
   4
   5 #include <linux/errno.h>
   6 #include <linux/mman.h>
   7 #include <linux/ksm.h>
   8
   9 int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
  10                 unsigned long end, int advice, unsigned long *vm_flags)
  11 {
  12         struct mm_struct *mm = vma->vm_mm;
  13
  14         switch (advice) {
  15         case MADV_MERGEABLE:
  16                 /*
  17                  * Be somewhat over-protective for now!
  18                  */
  19                 if (*vm_flags & (VM_MERGEABLE | VM_SHARED  | VM_MAYSHARE   |
  20                                  VM_PFNMAP    | VM_IO      | VM_DONTEXPAND |
  21                                  VM_RESERVED  | VM_HUGETLB | VM_INSERTPAGE |
  22                                  VM_MIXEDMAP  | VM_SAO))
  23                         return 0;               /* just ignore the advice */
  24
  25                 if (!test_bit(MMF_VM_MERGEABLE, &mm->flags))
  26                         if (__ksm_enter(mm) < 0)
  27                                 return -EAGAIN;
  28
  29                 *vm_flags |= VM_MERGEABLE;
  30                 break;
  31
  32         case MADV_UNMERGEABLE:
  33                 if (!(*vm_flags & VM_MERGEABLE))
  34                         return 0;               /* just ignore the advice */
  35
  36                 /* Unmerge any merged pages here */
  37
  38                 *vm_flags &= ~VM_MERGEABLE;
  39                 break;
  40         }
  41
  42         return 0;
  43 }
  44
  45 int __ksm_enter(struct mm_struct *mm)
  46 {
  47         /* Allocate a structure to track mm and link it into KSM's list */
  48         set_bit(MMF_VM_MERGEABLE, &mm->flags);
  49         return 0;
  50 }
  51
  52 void __ksm_exit(struct mm_struct *mm)
  53 {
  54         /* Unlink and free all KSM's structures which track this mm */
  55         clear_bit(MMF_VM_MERGEABLE, &mm->flags);
  56 }