hugetlb: debit quota in alloc_huge_page
Now that quota is credited by free_huge_page(), calls to hugetlb_get_quota()
seem out of place. The alloc/free API is unbalanced because we handle the
hugetlb_put_quota() but expect the caller to open-code hugetlb_get_quota().
Move the get inside alloc_huge_page to clean up this disparity.
This patch has been kept apart from the previous patch because of the somewhat
dodgy ERR_PTR() use herein. Moving the quota logic means that
alloc_huge_page() has two failure modes. Quota failure must result in a
SIGBUS while a standard allocation failure is OOM. Unfortunately, ERR_PTR()
doesn't like the small positive errnos we have in VM_FAULT_* so they must be
negated before they are used.
Does anyone take issue with the way I am using PTR_ERR. If so, what are your
thoughts on how to clean this up (without needing an if,else if,else block at
each alloc_huge_page() callsite)?
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>
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 3992bd5..bc12b0ad 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -388,6 +388,10 @@
unsigned long addr)
{
struct page *page;
+ struct address_space *mapping = vma->vm_file->f_mapping;
+
+ if (hugetlb_get_quota(mapping))
+ return ERR_PTR(-VM_FAULT_SIGBUS);
if (vma->vm_flags & VM_MAYSHARE)
page = alloc_huge_page_shared(vma, addr);
@@ -395,9 +399,10 @@
page = alloc_huge_page_private(vma, addr);
if (page) {
set_page_refcounted(page);
- set_page_private(page, (unsigned long) vma->vm_file->f_mapping);
- }
- return page;
+ set_page_private(page, (unsigned long) mapping);
+ return page;
+ } else
+ return ERR_PTR(-VM_FAULT_OOM);
}
static int __init hugetlb_init(void)
@@ -737,15 +742,13 @@
set_huge_ptep_writable(vma, address, ptep);
return 0;
}
- if (hugetlb_get_quota(vma->vm_file->f_mapping))
- return VM_FAULT_SIGBUS;
page_cache_get(old_page);
new_page = alloc_huge_page(vma, address);
- if (!new_page) {
+ if (IS_ERR(new_page)) {
page_cache_release(old_page);
- return VM_FAULT_OOM;
+ return -PTR_ERR(new_page);
}
spin_unlock(&mm->page_table_lock);
@@ -789,12 +792,9 @@
size = i_size_read(mapping->host) >> HPAGE_SHIFT;
if (idx >= size)
goto out;
- if (hugetlb_get_quota(mapping))
- goto out;
page = alloc_huge_page(vma, address);
- if (!page) {
- hugetlb_put_quota(mapping);
- ret = VM_FAULT_OOM;
+ if (IS_ERR(page)) {
+ ret = -PTR_ERR(page);
goto out;
}
clear_huge_page(page, address);
