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mm/hugetlb: simplify hugetlb unmap

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For hugetlb like THP (and unlike regular page), we do tlb flush after
dropping ptl.  Because of the above, we don't need to track force_flush
like we do now.  Instead we can simply call tlb_remove_page() which will
do the flush if needed.

No functionality change in this patch.

Link: http://lkml.kernel.org/r/1465049193-22197-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com
Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Aneesh Kumar K.V 2016-07-26 15:24:06 -07:00 committed by Linus Torvalds
parent 337d9abf1c
commit 31d49da5ad
1 changed files with 21 additions and 33 deletions
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54
mm/hugetlb.c
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@ -3177,7 +3177,6 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
unsigned long start, unsigned long end,
struct page *ref_page)
{
int force_flush = 0;
struct mm_struct *mm = vma->vm_mm;
unsigned long address;
pte_t *ptep;
@ -3196,19 +3195,22 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
tlb_start_vma(tlb, vma);
mmu_notifier_invalidate_range_start(mm, mmun_start, mmun_end);
address = start;
again:
for (; address < end; address += sz) {
ptep = huge_pte_offset(mm, address);
if (!ptep)
continue;
ptl = huge_pte_lock(h, mm, ptep);
if (huge_pmd_unshare(mm, &address, ptep))
goto unlock;
if (huge_pmd_unshare(mm, &address, ptep)) {
spin_unlock(ptl);
continue;
}
pte = huge_ptep_get(ptep);
if (huge_pte_none(pte))
goto unlock;
if (huge_pte_none(pte)) {
spin_unlock(ptl);
continue;
}
/*
* Migrating hugepage or HWPoisoned hugepage is already
@ -3216,7 +3218,8 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
*/
if (unlikely(!pte_present(pte))) {
huge_pte_clear(mm, address, ptep);
goto unlock;
spin_unlock(ptl);
continue;
}
page = pte_page(pte);
@ -3226,9 +3229,10 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
* are about to unmap is the actual page of interest.
*/
if (ref_page) {
if (page != ref_page)
goto unlock;
if (page != ref_page) {
spin_unlock(ptl);
continue;
}
/*
* Mark the VMA as having unmapped its page so that
* future faults in this VMA will fail rather than
@ -3244,30 +3248,14 @@ void __unmap_hugepage_range(struct mmu_gather *tlb, struct vm_area_struct *vma,
hugetlb_count_sub(pages_per_huge_page(h), mm);
page_remove_rmap(page, true);
force_flush = !__tlb_remove_page(tlb, page);
if (force_flush) {
address += sz;
spin_unlock(ptl);
break;
}
/* Bail out after unmapping reference page if supplied */
if (ref_page) {
spin_unlock(ptl);
break;
}
unlock:
spin_unlock(ptl);
}
/*
* mmu_gather ran out of room to batch pages, we break out of
* the PTE lock to avoid doing the potential expensive TLB invalidate
* and page-free while holding it.
*/
if (force_flush) {
force_flush = 0;
tlb_flush_mmu(tlb);
if (address < end && !ref_page)
goto again;
tlb_remove_page(tlb, page);
/*
* Bail out after unmapping reference page if supplied
*/
if (ref_page)
break;
}
mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);
tlb_end_vma(tlb, vma);