2.5.62 Oops during nfs mount

I get the following on 2.5.62 when I mount over NFS:

Feb 21 19:45:00 elm3b78 kernel: Oops: 0002
Feb 21 19:45:00 elm3b78 kernel: CPU:    6
Feb 21 19:45:00 elm3b78 kernel: EIP:    0060:[<c035c4c3>]    Not tainted
Feb 21 19:45:00 elm3b78 kernel: EFLAGS: 00010246
Feb 21 19:45:00 elm3b78 kernel: EIP is at rpc_depopulate+0x33/0x110
Feb 21 19:45:00 elm3b78 kernel: eax: 00000000   ebx: 0000006c   ecx: 0000006c   edx: f69f42c0
Feb 21 19:45:00 elm3b78 kernel: esi: f6bc9bf0   edi: f6bc9bf0   ebp: f6bc9c04   esp: f6bc9be0
Feb 21 19:45:00 elm3b78 kernel: ds: 007b   es: 007b   ss: 0068
Feb 21 19:45:00 elm3b78 kernel: Process mount (pid: 1193, threadinfo=f6bc8000 task=f668b920)
Feb 21 19:45:00 elm3b78 kernel: Stack: c036a428 00000077 c0157e30 00000000 f6bc9bf0 f6bc9bf0 f701ae60 f701ae60 
Feb 21 19:45:00 elm3b78 kernel:        f66c4dc0 f6bc9c3c c035ca15 f701ae60 f69f42c0 f7ff9b60 f6bc9ce8 00000000 
Feb 21 19:45:00 elm3b78 kernel:        f6bc9c30 00000010 00000001 00000000 f73dd540 f6bc9ce8 00000000 f6bc9c4c 
Feb 21 19:45:00 elm3b78 kernel: Call Trace:
Feb 21 19:45:01 elm3b78 kernel:  [<c0157e30>] lookup_hash+0x70/0xa0
Feb 21 19:45:01 elm3b78 kernel:  [<c035ca15>] rpc_rmdir+0x65/0xa0
Feb 21 19:45:01 elm3b78 kernel:  [<c034ddd6>] rpc_destroy_client+0x46/0x70
Feb 21 19:45:01 elm3b78 kernel:  [<c034de4b>] rpc_release_client+0x4b/0x60
Feb 21 19:45:01 elm3b78 kernel:  [<c0352957>] rpc_release_task+0x1a7/0x1d0
Feb 21 19:45:01 elm3b78 kernel:  [<c03522db>] __rpc_execute+0x35b/0x370
Feb 21 19:45:01 elm3b78 kernel:  [<c0119900>] default_wake_function+0x0/0x20
Feb 21 19:45:01 elm3b78 kernel:  [<c034dfe4>] rpc_call_sync+0x64/0xa0
Feb 21 19:45:01 elm3b78 kernel:  [<c034dff7>] rpc_call_sync+0x77/0xa0
Feb 21 19:45:01 elm3b78 kernel:  [<c0351440>] rpc_run_timer+0x0/0xa0
Feb 21 19:45:01 elm3b78 kernel:  [<c035941b>] rpc_register+0xcb/0x100
Feb 21 19:45:01 elm3b78 kernel:  [<c0354af4>] svc_register+0x94/0x100
Feb 21 19:45:01 elm3b78 kernel:  [<c0354714>] svc_create+0xd4/0xe0
Feb 21 19:45:01 elm3b78 kernel:  [<c01b5069>] lockd_up+0x69/0x130
Feb 21 19:45:01 elm3b78 kernel:  [<c01a28b4>] nfs_fill_super+0x364/0x390
Feb 21 19:45:01 elm3b78 kernel:  [<c01a434d>] nfs_get_sb+0x1ed/0x230
Feb 21 19:45:01 elm3b78 kernel:  [<c0151592>] do_kern_mount+0x42/0xa0
Feb 21 19:45:01 elm3b78 kernel:  [<c0164d23>] do_add_mount+0x73/0x170
Feb 21 19:45:01 elm3b78 kernel:  [<c01349b6>] __alloc_pages+0x96/0x2e0
Feb 21 19:45:01 elm3b78 kernel:  [<c0165037>] do_mount+0x147/0x160
Feb 21 19:45:01 elm3b78 kernel:  [<c01654b8>] sys_mount+0xa8/0x110
Feb 21 19:45:01 elm3b78 kernel:  [<c010909b>] syscall_call+0x7/0xb
Feb 21 19:45:01 elm3b78 kernel: 
Feb 21 19:45:01 elm3b78 kernel: Code: f0 ff 48 6c 0f 88 bf 09 00 00 59 5b f0 fe 0d 60 a6 47 c0 0f 

Hi Janet,

Following patch should fix this problem. I think Trond can say whether it is correct or not. In my opinion rpc_rmdir should test for negative dentry after lookup_hash() returns, like rpc_unlink() does.

Thanks
Maneesh

diff -urN linux-2.5.62-bk6/net/sunrpc/rpc_pipe.c linux-2.5.62-bk6-rpc_depopulate/net/sunrpc/rpc_pipe.c
@@ -665,8 +665,10 @@
 		error = PTR_ERR(dentry);
 		goto out_release;
 	}
-	rpc_depopulate(dentry);
-	error = __rpc_rmdir(dir, dentry);
+	if (dentry->d_inode) {
+		rpc_depopulate(dentry);
+		error = __rpc_rmdir(dir, dentry);
+	}
 	dput(dentry);
 out_release:
 	up(&dir->i_sem);

Maneesh Soni
IBM Linux Technology Center, 
IBM India Software Lab, Bangalore.
Phone: +91-80-5044999 email: [email protected]
http://lse.sourceforge.net/

> Hi Janet,

> Following patch should fix this problem. I think Trond can say > whether it is correct or not. In my opinion rpc_rmdir should > test for negative dentry after lookup_hash() returns, like > rpc_unlink() does.

No. You are 'fixing' a symptom of a more fundamental bug/misunderstanding: lookup_path("") returns no error, and is sometimes causing us to remove the top level directory. See the 2-line patch I posted yesterday. It should fix the Oops you are reporting.

Cheers,
Trond

Thanks Trond, your patch below indeed fixed the Oops I reported:

--- linux-2.5.61-up/net/sunrpc/clnt.c.orig 2003-02-15
21:05:02.000000000 +0100
+++ linux-2.5.61-up/net/sunrpc/clnt.c 2003-02-17 19:39:20.000000000
+0100
@@ -208,7 +208,8 @@

                rpcauth_destroy(clnt->cl_auth);
                clnt->cl_auth = NULL;
        }
-       rpc_rmdir(clnt->cl_pathname);
+       if (clnt->cl_pathname[0])
+               rpc_rmdir(clnt->cl_pathname);
        if (clnt->cl_xprt) {
                xprt_destroy(clnt->cl_xprt);
                clnt->cl_xprt = NULL;