From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adam Litke Subject: [PATCH 2/5] hugetlb: Fix quota management for private mappings Date: Tue, 30 Oct 2007 13:46:15 -0700 Message-Id: <20071030204615.16585.60817.stgit@kernel> In-Reply-To: <20071030204554.16585.80588.stgit@kernel> References: <20071030204554.16585.80588.stgit@kernel> Content-Type: text/plain; charset=utf-8; format=fixed Content-Transfer-Encoding: 8bit Sender: owner-linux-mm@kvack.org Return-Path: To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@kvack.org, Ken Chen , Andy Whitcroft , Dave Hansen , Adam Litke List-ID: The hugetlbfs quota management system was never taught to handle MAP_PRIVATE mappings when that support was added. Currently, quota is debited at page instantiation and credited at file truncation. This approach works correctly for shared pages but is incomplete for private pages. In addition to hugetlb_no_page(), private pages can be instantiated by hugetlb_cow(); but this function does not respect quotas. Private huge pages are treated very much like normal, anonymous pages. They are not "backed" by the hugetlbfs file and are not stored in the mapping's radix tree. This means that private pages are invisible to truncate_hugepages() so that function will not credit the quota. This patch (based on a prototype provided by Ken Chen) moves quota crediting for all pages into free_huge_page(). page->private is used to store a pointer to the mapping to which this page belongs. This is used to credit quota on the appropriate hugetlbfs instance. Signed-off-by: Adam Litke CC: Ken Chen --- fs/hugetlbfs/inode.c | 1 - mm/hugetlb.c | 13 ++++++++++--- 2 files changed, 10 insertions(+), 4 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 04598e1..5f4e888 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -364,7 +364,6 @@ static void truncate_hugepages(struct inode *inode, loff_t lstart) ++next; truncate_huge_page(page); unlock_page(page); - hugetlb_put_quota(mapping); freed++; } huge_pagevec_release(&pvec); diff --git a/mm/hugetlb.c b/mm/hugetlb.c index d319e8e..0b09ef2 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -116,7 +116,9 @@ static void update_and_free_page(struct page *page) static void free_huge_page(struct page *page) { int nid = page_to_nid(page); + struct address_space *mapping; + mapping = (struct address_space *) page_private(page); BUG_ON(page_count(page)); INIT_LIST_HEAD(&page->lru); @@ -129,6 +131,9 @@ static void free_huge_page(struct page *page) enqueue_huge_page(page); } spin_unlock(&hugetlb_lock); + if (mapping) + hugetlb_put_quota(mapping); + set_page_private(page, 0); } /* @@ -388,8 +393,10 @@ static struct page *alloc_huge_page(struct vm_area_struct *vma, page = alloc_huge_page_shared(vma, addr); else page = alloc_huge_page_private(vma, addr); - if (page) + if (page) { set_page_refcounted(page); + set_page_private(page, (unsigned long) vma->vm_file->f_mapping); + } return page; } @@ -730,6 +737,8 @@ 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); @@ -796,7 +805,6 @@ retry: err = add_to_page_cache(page, mapping, idx, GFP_KERNEL); if (err) { put_page(page); - hugetlb_put_quota(mapping); if (err == -EEXIST) goto retry; goto out; @@ -830,7 +838,6 @@ out: backout: spin_unlock(&mm->page_table_lock); - hugetlb_put_quota(mapping); unlock_page(page); put_page(page); goto out; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org