hugetlb: debit quota in alloc_huge_page (2fc39cec) · Commits · 戴 / test

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>

mm/hugetlb.c

+12 −12

Original line number	Diff line number	Diff line
		@@ -388,6 +388,10 @@ static struct page alloc_huge_page(struct vm_area_struct vma,
		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 @@ static struct page alloc_huge_page(struct vm_area_struct vma,
		page = alloc_huge_page_private(vma, addr);
		if (page) {
		set_page_refcounted(page);
		set_page_private(page, (unsigned long) vma->vm_file->f_mapping);
		}
		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 @@ static int hugetlb_cow(struct mm_struct mm, struct vm_area_struct vma,
		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 @@ retry:
		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);

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