From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx156.postini.com [74.125.245.156]) by kanga.kvack.org (Postfix) with SMTP id C83BD6B00E8 for ; Thu, 17 May 2012 20:55:04 -0400 (EDT) Received: by ggm4 with SMTP id 4so3521749ggm.14 for ; Thu, 17 May 2012 17:55:03 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: <4FB580A9.6020305@linux.vnet.ibm.com> References: <4FB580A9.6020305@linux.vnet.ibm.com> From: KOSAKI Motohiro Date: Thu, 17 May 2012 20:54:42 -0400 Message-ID: Subject: Re: Huge pages: Memory leak on mmap failure Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Sender: owner-linux-mm@kvack.org List-ID: To: Dave Hansen Cc: Christoph Lameter , Andrea Arcangeli , Hugh Dickins , David Rientjes , Alexey Dobriyan , linux-mm@kvack.org, Andrew Morton , Mel Gorman On Thu, May 17, 2012 at 6:50 PM, Dave Hansen wrot= e: > On 05/17/2012 02:07 PM, Christoph Lameter wrote: >> >> On 2.6.32 and 3.4-rc6 mmap failure of a huge page causes a memory >> leak. The 32 byte kmalloc cache grows by 10 mio entries if running >> the following code: > > When called for anonymous (non-shared) mappings, hugetlb_reserve_pages() > does a resv_map_alloc(). =A0It depends on code in hugetlbfs's > vm_ops->close() to release that allocation. > > However, in the mmap() failure path, we do a plain unmap_region() > without the remove_vma() which actually calls vm_ops->close(). > > As the code stands today, I think we can fix this by just making sure we > release the resv_map after hugetlb_acct_memory() fails. =A0But, this seem= s > like a bit of a superficial fix and if we end up with another path or > two that can return -ESOMETHING, this might get reintroduced. =A0The > assumption that vm_ops->close() will get called on all VMAs passed in to > hugetlbfs_file_mmap() seems like something that needs to get corrected. I agree. Now, resv_map_alloc() is called file open path and resv_map_free() is called vma close path. It seems asymmetry. It would be nice if resv_map_alloc can use vma->open ops. -- 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/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org