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authorTörök Edwin <edwintorok@gmail.com>2011-06-16 00:06:14 +0300
committerAl Viro <viro@zeniv.linux.org.uk>2011-06-16 11:27:39 -0400
commit50338b889dc504c69e0cb316ac92d1b9e51f3c8a (patch)
tree8e353de07b21b350664eff5d69f3a67014d01bcd /fs
parenta685e08987d1edf1995b76511d4c98ea0e905377 (diff)
fix wrong iput on d_inode introduced by e6bc45d65d
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] [<ffffffff811691d8>] d_kill+0xf8/0x140 [ 2862.501007] [<ffffffff81169c19>] dput+0xc9/0x190 [ 2862.501007] [<ffffffff8115577f>] fput+0x15f/0x210 [ 2862.501007] [<ffffffff81152171>] filp_close+0x61/0x90 [ 2862.501007] [<ffffffff81152251>] sys_close+0xb1/0x110 [ 2862.501007] [<ffffffff814c14fb>] 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 <preining@logic.at> Reported-by: Török Edwin <edwintorok@gmail.com> Cc: "Theodore Ts'o" <tytso@mit.edu> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Török Edwin <edwintorok@gmail.com> Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Diffstat (limited to 'fs')
-rw-r--r--fs/namei.c4
1 files changed, 3 insertions, 1 deletions
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);