From 628b60f82d796a58df98b8cb81e855b68bc25021 Mon Sep 17 00:00:00 2001 From: Michel Lespinasse Date: Wed, 26 Sep 2012 11:33:39 +1000 Subject: [PATCH] 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 Cc: Andrea Arcangeli Cc: Rik van Riel Cc: Peter Zijlstra Cc: Daniel Santos Cc: Hugh Dickins Signed-off-by: Andrew Morton --- 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 afc92d2bcf8c..9390917ec19c 100644 --- a/mm/huge_memory.c +++ b/mm/huge_memory.c @@ -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) 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; -- 2.39.5