Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758885AbYAVXOV (ORCPT ); Tue, 22 Jan 2008 18:14:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753558AbYAVXOG (ORCPT ); Tue, 22 Jan 2008 18:14:06 -0500 Received: from e4.ny.us.ibm.com ([32.97.182.144]:34458 "EHLO e4.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753437AbYAVXOE (ORCPT ); Tue, 22 Jan 2008 18:14:04 -0500 Subject: Re: 2.6.24-rc8-mm1: sparc64 warning at fs/file_table.c:49 __fput+0x1a8/0x1e0() From: Dave Hansen To: Andrew Morton Cc: Mariusz Kozlowski , linux-kernel@vger.kernel.org, davem@davemloft.net, sparclinux@vger.kernel.org, Christoph Hellwig In-Reply-To: <20080122130228.e7596163.akpm@linux-foundation.org> References: <20080117023514.9df393cf.akpm@linux-foundation.org> <200801222130.24136.m.kozlowski@tuxland.pl> <20080122130228.e7596163.akpm@linux-foundation.org> Content-Type: text/plain Date: Tue, 22 Jan 2008 15:13:58 -0800 Message-Id: <1201043638.7585.47.camel@nimitz.home.sr71.net> Mime-Version: 1.0 X-Mailer: Evolution 2.12.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2970 Lines: 97 On Tue, 2008-01-22 at 13:02 -0800, Andrew Morton wrote: > > On Tue, 22 Jan 2008 21:30:23 +0100 Mariusz Kozlowski wrote: > > Hello, > > > > Issuing "sysrq-s sysrq-u" sequence causes these warnings on sparc64: > > > > ------------[ cut here ]------------ > > WARNING: at fs/file_table.c:49 __fput+0x1a8/0x1e0() > > Modules linked in: sg sr_mod cdrom > > Call Trace: > > [00000000004c9ac8] __fput+0x1b0/0x1e0 > > [00000000004c6978] filp_close+0x60/0x80 > > [00000000004c6a18] sys_close+0x80/0xe0 > > [00000000004062d4] linux_sparc_syscall32+0x3c/0x40 > > [0000000000012f1c] 0x12f24 > > ---[ end trace 6dbe14ff8ec57744 ]--- > > ------------[ cut here ]------------ ... > That's > > WARN_ON(f->f_mnt_write_state == FILE_MNT_WRITE_TAKEN); The emergency remount code forcibly removes FMODE_WRITE from filps. The r/o bind mount code notices that this was done without a proper mnt_drop_write() and properly gives a warning. This patch does a mnt_drop_write() and also notes in the filp that this was done to suppress any warning that would have otherwise been triggered. I also wonder if inode->i_writecount is made inconsistent by the emergency remount code. I guess it is, but the damage is limited to a single inode instead of being visible more globally like the mnt write count. Probably not really worth fixing. BTW, this wasn't just a sparc thing. I triggered it in about 3 seconds on a plain old x86 machine. Signed-off-by: Dave Hansen --- linux-2.6.git-dave/fs/super.c | 21 +++++++++++++++++++-- 1 file changed, 19 insertions(+), 2 deletions(-) diff -puN fs/super.c~robind-sysrq-fix fs/super.c --- linux-2.6.git/fs/super.c~robind-sysrq-fix 2008-01-22 14:33:38.000000000 -0800 +++ linux-2.6.git-dave/fs/super.c 2008-01-22 14:51:13.000000000 -0800 @@ -37,6 +37,7 @@ #include #include #include +#include #include @@ -566,10 +567,26 @@ static void mark_files_ro(struct super_b { struct file *f; +retry: file_list_lock(); list_for_each_entry(f, &sb->s_files, f_u.fu_list) { - if (S_ISREG(f->f_path.dentry->d_inode->i_mode) && file_count(f)) - f->f_mode &= ~FMODE_WRITE; + struct vfsmount mnt; + if (!S_ISREG(f->f_path.dentry->d_inode->i_mode)) + continue; + if (!file_count(f)) + continue; + if (!(f->f_mode & FMODE_WRITE)) + continue; + f->f_mode &= ~FMODE_WRITE; + f->f_mnt_write_state |= FILE_MNT_WRITE_RELEASED; + mnt = f->f_path.mnt; + file_list_unlock(); + /* + * This can sleep, so we can't hold + * the file_list_lock() spinlock. + */ + mnt_drop_write(mnt); + goto retry; } file_list_unlock(); } _ -- Dave -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/