From mboxrd@z Thu Jan 1 00:00:00 1970 From: Adam Litke Subject: [PATCH 5/5] hugetlb: Enforce quotas during reservation for shared mappings Date: Tue, 30 Oct 2007 13:46:50 -0700 Message-Id: <20071030204650.16585.6498.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: 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 --- mm/hugetlb.c | 23 +++++++++++++---------- 1 files changed, 13 insertions(+), 10 deletions(-) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index deba411..2fc3cd6 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) @@ -1147,6 +1147,8 @@ 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; @@ -1157,5 +1159,6 @@ 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)); } -- 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