From 50338b889dc504c69e0cb316ac92d1b9e51f3c8a Mon Sep 17 00:00:00 2001 From: Török Edwin Date: Thu, 16 Jun 2011 00:06:14 +0300 Subject: fix wrong iput on d_inode introduced by e6bc45d65d MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Git bisection shows that commit e6bc45d65df8599fdbae73be9cec4ceed274db53 causes BUG_ONs under high I/O load: kernel BUG at fs/inode.c:1368! [ 2862.501007] Call Trace: [ 2862.501007] [] d_kill+0xf8/0x140 [ 2862.501007] [] dput+0xc9/0x190 [ 2862.501007] [] fput+0x15f/0x210 [ 2862.501007] [] filp_close+0x61/0x90 [ 2862.501007] [] sys_close+0xb1/0x110 [ 2862.501007] [] system_call_fastpath+0x16/0x1b A reliable way to reproduce this bug is: Login to KDE, run 'rsnapshot sync', and apt-get install openjdk-6-jdk, and apt-get remove openjdk-6-jdk. The buggy part of the patch is this: struct inode *inode = NULL; ..... - if (nd.last.name[nd.last.len]) - goto slashes; inode = dentry->d_inode; - if (inode) - ihold(inode); + if (nd.last.name[nd.last.len] || !inode) + goto slashes; + ihold(inode) ... if (inode) iput(inode); /* truncate the inode here */ If nd.last.name[nd.last.len] is nonzero (and thus goto slashes branch is taken), and dentry->d_inode is non-NULL, then this code now does an additional iput on the inode, which is wrong. Fix this by only setting the inode variable if nd.last.name[nd.last.len] is 0. Reference: https://lkml.org/lkml/2011/6/15/50 Reported-by: Norbert Preining Reported-by: Török Edwin Cc: "Theodore Ts'o" Cc: Al Viro Signed-off-by: Török Edwin Signed-off-by: Al Viro --- fs/namei.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'fs') diff --git a/fs/namei.c b/fs/namei.c index 9802345df5e7..6301963b161f 100644 --- a/fs/namei.c +++ b/fs/namei.c @@ -2713,8 +2713,10 @@ static long do_unlinkat(int dfd, const char __user *pathname) error = PTR_ERR(dentry); if (!IS_ERR(dentry)) { /* Why not before? Because we want correct error value */ + if (nd.last.name[nd.last.len]) + goto slashes; inode = dentry->d_inode; - if (nd.last.name[nd.last.len] || !inode) + if (!inode) goto slashes; ihold(inode); error = mnt_want_write(nd.path.mnt); -- cgit v1.2.3