From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754559AbZA0WrT (ORCPT ); Tue, 27 Jan 2009 17:47:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752138AbZA0WrJ (ORCPT ); Tue, 27 Jan 2009 17:47:09 -0500 Received: from host64.cybernetics.com ([98.174.209.230]:3716 "EHLO mail.cybernetics.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751678AbZA0WrJ (ORCPT ); Tue, 27 Jan 2009 17:47:09 -0500 Message-ID: <497F8EE8.8070402@cybernetics.com> Date: Tue, 27 Jan 2009 17:47:04 -0500 From: Tony Battersby User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: linux-kernel@vger.kernel.org Cc: Jiri Olsa , Jiri Kosina , Andrew Morton Subject: [PATCH 1/2] fix shmctl(SHM_INFO) lockup with !CONFIG_SHMEM Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org shm_get_stat() assumes that the inode is a "struct shmem_inode_info", which is incorrect for !CONFIG_SHMEM (see fs/ramfs/inode.c::ramfs_get_inode() vs. mm/shmem.c::shmem_get_inode()). This bad assumption can cause shmctl(SHM_INFO) to lockup when shm_get_stat() tries to spin_lock(&info->lock). Users of !CONFIG_SHMEM may encounter this lockup simply by invoking the 'ipcs' command. Signed-off-by: Tony Battersby CC: --- This bug was reported by Jiri Olsa back in February 2008; CC'ing the people involved in the original discussion. http://lkml.org/lkml/2008/2/29/74 --- linux-2.6.29-rc2-git3/ipc/shm.c.orig 2009-01-27 16:23:10.000000000 -0500 +++ linux-2.6.29-rc2-git3/ipc/shm.c 2009-01-27 16:23:32.000000000 -0500 @@ -565,11 +565,15 @@ static void shm_get_stat(struct ipc_name struct hstate *h = hstate_file(shp->shm_file); *rss += pages_per_huge_page(h) * mapping->nrpages; } else { +#ifdef CONFIG_SHMEM struct shmem_inode_info *info = SHMEM_I(inode); spin_lock(&info->lock); *rss += inode->i_mapping->nrpages; *swp += info->swapped; spin_unlock(&info->lock); +#else + *rss += inode->i_mapping->nrpages; +#endif } total++;