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