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Commit 86c2ad19 authored by Michel Lespinasse's avatar Michel Lespinasse Committed by Linus Torvalds
Browse files

mm rmap: remove vma_address check for address inside vma 



In file and anon rmap, we use interval trees to find potentially relevant
vmas and then call vma_address() to find the virtual address the given
page might be found at in these vmas.  vma_address() used to include a
check that the returned address falls within the limits of the vma, but
this check isn't necessary now that we always use interval trees in rmap:
the interval tree just doesn't return any vmas which this check would find
to be irrelevant.  As a result, we can replace the use of -EFAULT error
code (which then needed to be checked in every call site) with a
VM_BUG_ON().

Signed-off-by: default avatarMichel Lespinasse <walken@google.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Daniel Santos <daniel.santos@pobox.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent bf181b9f

mm/huge_memory.c

+0 −4
Original line number Diff line number Diff line
@@ -1386,8 +1386,6 @@ static void __split_huge_page(struct page *page, 
		struct vm_area_struct *vma = avc->vma;

		unsigned long addr = vma_address(page, vma);

		BUG_ON(is_vma_temporary_stack(vma));

		if (addr == -EFAULT)

			continue;

		mapcount += __split_huge_page_splitting(page, vma, addr);

	}

	/*
@@ -1412,8 +1410,6 @@ static void __split_huge_page(struct page *page, 
		struct vm_area_struct *vma = avc->vma;

		unsigned long addr = vma_address(page, vma);

		BUG_ON(is_vma_temporary_stack(vma));

		if (addr == -EFAULT)

			continue;

		mapcount2 += __split_huge_page_map(page, vma, addr);

	}

	if (mapcount != mapcount2)

mm/rmap.c

+21 −27
Original line number Diff line number Diff line
@@ -510,22 +510,26 @@ void page_unlock_anon_vma(struct anon_vma *anon_vma) 


/*

 * At what user virtual address is page expected in @vma?

 * Returns virtual address or -EFAULT if page's index/offset is not

 * within the range mapped the @vma.

 */

inline unsigned long

vma_address(struct page *page, struct vm_area_struct *vma)

static inline unsigned long

__vma_address(struct page *page, struct vm_area_struct *vma)

{

	pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);

	unsigned long address;



	if (unlikely(is_vm_hugetlb_page(vma)))

		pgoff = page->index << huge_page_order(page_hstate(page));

	address = vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);

	if (unlikely(address < vma->vm_start || address >= vma->vm_end)) {

		/* page should be within @vma mapping range */

		return -EFAULT;



	return vma->vm_start + ((pgoff - vma->vm_pgoff) << PAGE_SHIFT);

}



inline unsigned long

vma_address(struct page *page, struct vm_area_struct *vma)

{

	unsigned long address = __vma_address(page, vma);



	/* page should be within @vma mapping range */

	VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);



	return address;

}
@@ -535,6 +539,7 @@ vma_address(struct page *page, struct vm_area_struct *vma) 
 */

unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma)

{

	unsigned long address;

	if (PageAnon(page)) {

		struct anon_vma *page__anon_vma = page_anon_vma(page);

		/*
@@ -550,7 +555,10 @@ unsigned long page_address_in_vma(struct page *page, struct vm_area_struct *vma) 
			return -EFAULT;

	} else

		return -EFAULT;

	return vma_address(page, vma);

	address = __vma_address(page, vma);

	if (unlikely(address < vma->vm_start || address >= vma->vm_end))

		return -EFAULT;

	return address;

}



/*
@@ -624,8 +632,8 @@ int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma) 
	pte_t *pte;

	spinlock_t *ptl;



	address = vma_address(page, vma);

	if (address == -EFAULT)		/* out of vma range */

	address = __vma_address(page, vma);

	if (unlikely(address < vma->vm_start || address >= vma->vm_end))

		return 0;

	pte = page_check_address(page, vma->vm_mm, address, &ptl, 1);

	if (!pte)			/* the page is not in this mm */
@@ -732,8 +740,6 @@ static int page_referenced_anon(struct page *page, 
	anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {

		struct vm_area_struct *vma = avc->vma;

		unsigned long address = vma_address(page, vma);

		if (address == -EFAULT)

			continue;

		/*

		 * If we are reclaiming on behalf of a cgroup, skip

		 * counting on behalf of references from different
@@ -799,8 +805,6 @@ static int page_referenced_file(struct page *page, 


	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {

		unsigned long address = vma_address(page, vma);

		if (address == -EFAULT)

			continue;

		/*

		 * If we are reclaiming on behalf of a cgroup, skip

		 * counting on behalf of references from different
@@ -904,8 +908,6 @@ static int page_mkclean_file(struct address_space *mapping, struct page *page) 
	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {

		if (vma->vm_flags & VM_SHARED) {

			unsigned long address = vma_address(page, vma);

			if (address == -EFAULT)

				continue;

			ret += page_mkclean_one(page, vma, address);

		}

	}
@@ -1468,8 +1470,6 @@ static int try_to_unmap_anon(struct page *page, enum ttu_flags flags) 
			continue;



		address = vma_address(page, vma);

		if (address == -EFAULT)

			continue;

		ret = try_to_unmap_one(page, vma, address, flags);

		if (ret != SWAP_AGAIN || !page_mapped(page))

			break;
@@ -1508,8 +1508,6 @@ static int try_to_unmap_file(struct page *page, enum ttu_flags flags) 
	mutex_lock(&mapping->i_mmap_mutex);

	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {

		unsigned long address = vma_address(page, vma);

		if (address == -EFAULT)

			continue;

		ret = try_to_unmap_one(page, vma, address, flags);

		if (ret != SWAP_AGAIN || !page_mapped(page))

			goto out;
@@ -1684,8 +1682,6 @@ static int rmap_walk_anon(struct page *page, int (*rmap_one)(struct page *, 
	anon_vma_interval_tree_foreach(avc, &anon_vma->rb_root, pgoff, pgoff) {

		struct vm_area_struct *vma = avc->vma;

		unsigned long address = vma_address(page, vma);

		if (address == -EFAULT)

			continue;

		ret = rmap_one(page, vma, address, arg);

		if (ret != SWAP_AGAIN)

			break;
@@ -1707,8 +1703,6 @@ static int rmap_walk_file(struct page *page, int (*rmap_one)(struct page *, 
	mutex_lock(&mapping->i_mmap_mutex);

	vma_interval_tree_foreach(vma, &mapping->i_mmap, pgoff, pgoff) {

		unsigned long address = vma_address(page, vma);

		if (address == -EFAULT)

			continue;

		ret = rmap_one(page, vma, address, arg);

		if (ret != SWAP_AGAIN)

			break;