Commit 31d49da5 authored by Aneesh Kumar K.V's avatar Aneesh Kumar K.V Committed by Linus Torvalds
Browse files

mm/hugetlb: simplify hugetlb unmap 

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: default avatarAneesh 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 337d9abf

mm/hugetlb.c

+21 −33
Original line number Diff line number Diff line
@@ -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 @@ again: 
		 */

		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 @@ again: 
		 * 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 @@ again: 


		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);

	}

		tlb_remove_page(tlb, page);

		/*

	 * 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.

		 * Bail out after unmapping reference page if supplied

		 */

	if (force_flush) {

		force_flush = 0;

		tlb_flush_mmu(tlb);

		if (address < end && !ref_page)

			goto again;

		if (ref_page)

			break;

	}

	mmu_notifier_invalidate_range_end(mm, mmun_start, mmun_end);

	tlb_end_vma(tlb, vma);

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