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authorAdam Litke <agl@us.ibm.com>2007-11-14 16:59:42 -0800
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-11-14 18:45:40 -0800
commit90d8b7e6129e8f4e5b3bc1a2cfbe585372ce8646 (patch)
tree7a078249e1a468dc3ec5973c14f8f6a95cb0620f
parent9a119c056dc2a9970901954a6d561d50a95e528d (diff)
hugetlb: enforce quotas during reservation for shared mappings
When a MAP_SHARED mmap of a hugetlbfs file succeeds, huge pages are reserved to guarantee no problems will occur later when instantiating pages. If quotas are in force, page instantiation could fail due to a race with another process or an oversized (but approved) shared mapping. To prevent these scenarios, debit the quota for the full reservation amount up front and credit the unused quota when the reservation is released. Signed-off-by: Adam Litke <agl@us.ibm.com> Cc: Ken Chen <kenchen@google.com> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Dave Hansen <haveblue@us.ibm.com> Cc: David Gibson <hermes@gibson.dropbear.id.au> Cc: William Lee Irwin III <wli@holomorphy.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--mm/hugetlb.c23
1 files changed, 13 insertions, 10 deletions
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 1e317465ecd..b52b6ddd6c1 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -367,7 +367,7 @@ static struct page *alloc_huge_page_shared(struct vm_area_struct *vma,
spin_lock(&hugetlb_lock);
page = dequeue_huge_page(vma, addr);
spin_unlock(&hugetlb_lock);
- return page;
+ return page ? page : ERR_PTR(-VM_FAULT_OOM);
}
static struct page *alloc_huge_page_private(struct vm_area_struct *vma,
@@ -375,13 +375,16 @@ static struct page *alloc_huge_page_private(struct vm_area_struct *vma,
{
struct page *page = NULL;
+ if (hugetlb_get_quota(vma->vm_file->f_mapping, 1))
+ return ERR_PTR(-VM_FAULT_SIGBUS);
+
spin_lock(&hugetlb_lock);
if (free_huge_pages > resv_huge_pages)
page = dequeue_huge_page(vma, addr);
spin_unlock(&hugetlb_lock);
if (!page)
page = alloc_buddy_huge_page(vma, addr);
- return page;
+ return page ? page : ERR_PTR(-VM_FAULT_OOM);
}
static struct page *alloc_huge_page(struct vm_area_struct *vma,
@@ -390,19 +393,16 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma,
struct page *page;
struct address_space *mapping = vma->vm_file->f_mapping;
- if (hugetlb_get_quota(mapping, 1))
- return ERR_PTR(-VM_FAULT_SIGBUS);
-
if (vma->vm_flags & VM_MAYSHARE)
page = alloc_huge_page_shared(vma, addr);
else
page = alloc_huge_page_private(vma, addr);
- if (page) {
+
+ if (!IS_ERR(page)) {
set_page_refcounted(page);
set_page_private(page, (unsigned long) mapping);
- return page;
- } else
- return ERR_PTR(-VM_FAULT_OOM);
+ }
+ return page;
}
static int __init hugetlb_init(void)
@@ -1148,6 +1148,8 @@ int hugetlb_reserve_pages(struct inode *inode, long from, long to)
if (chg < 0)
return chg;
+ if (hugetlb_get_quota(inode->i_mapping, chg))
+ return -ENOSPC;
ret = hugetlb_acct_memory(chg);
if (ret < 0)
return ret;
@@ -1158,5 +1160,6 @@ int hugetlb_reserve_pages(struct inode *inode, long from, long to)
void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed)
{
long chg = region_truncate(&inode->i_mapping->private_list, offset);
- hugetlb_acct_memory(freed - chg);
+ hugetlb_put_quota(inode->i_mapping, (chg - freed));
+ hugetlb_acct_memory(-(chg - freed));
}