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Date: Tue, 4 Sep 2012 02:20:55 -0700
From: Michel Lespinasse <walken@...gle.com>
To: linux-mm@...ck.org, riel@...hat.com, peterz@...radead.org,
aarcange@...hat.com, hughd@...gle.com, daniel.santos@...ox.com
Cc: linux-kernel@...r.kernel.org, akpm@...ux-foundation.org
Subject: [PATCH 5/7] 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: Michel Lespinasse <walken@...gle.com>
---
mm/huge_memory.c | 4 ----
mm/rmap.c | 48 +++++++++++++++++++++---------------------------
2 files changed, 21 insertions(+), 31 deletions(-)
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index fe119cb71b41..91b65f962320 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1432,8 +1432,6 @@ 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);
}
/*
@@ -1458,8 +1456,6 @@ 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)
diff --git a/mm/rmap.c b/mm/rmap.c
index 9c61bf387fd1..28777412de62 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -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;
--
1.7.7.3
--
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