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/*
* Initial dummy version just to illustrate KSM's interface to other files.
*/
#include <linux/errno.h>
#include <linux/mman.h>
#include <linux/ksm.h>
int ksm_madvise(struct vm_area_struct *vma, unsigned long start,
unsigned long end, int advice, unsigned long *vm_flags)
{
struct mm_struct *mm = vma->vm_mm;
switch (advice) {
case MADV_MERGEABLE:
/*
* Be somewhat over-protective for now!
*/
if (*vm_flags & (VM_MERGEABLE | VM_SHARED | VM_MAYSHARE |
VM_PFNMAP | VM_IO | VM_DONTEXPAND |
VM_RESERVED | VM_HUGETLB | VM_INSERTPAGE |
VM_MIXEDMAP | VM_SAO))
return 0; /* just ignore the advice */
if (!test_bit(MMF_VM_MERGEABLE, &mm->flags))
if (__ksm_enter(mm) < 0)
return -EAGAIN;
*vm_flags |= VM_MERGEABLE;
break;
case MADV_UNMERGEABLE:
if (!(*vm_flags & VM_MERGEABLE))
return 0; /* just ignore the advice */
/* Unmerge any merged pages here */
*vm_flags &= ~VM_MERGEABLE;
break;
}
return 0;
}
int __ksm_enter(struct mm_struct *mm)
{
/* Allocate a structure to track mm and link it into KSM's list */
set_bit(MMF_VM_MERGEABLE, &mm->flags);
return 0;
}
void __ksm_exit(struct mm_struct *mm)
{
/* Unlink and free all KSM's structures which track this mm */
clear_bit(MMF_VM_MERGEABLE, &mm->flags);
}
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