On Mon, 2011-03-28 at 00:05 +0900, OGAWA Hirofumi wrote:
> Hi,
>
> BUG: atomic_dec_and_test(): -1: atomic counter underflow at:
> Pid: 2827, comm: mount.nfs Not tainted 2.6.38 #1
> Call Trace:
> [<ffffffffa02223a0>] ? put_rpccred+0x44/0x14e [sunrpc]
> [<ffffffffa021bbe9>] ? rpc_ping+0x4e/0x58 [sunrpc]
> [<ffffffffa021c4a5>] ? rpc_create+0x481/0x4fc [sunrpc]
> [<ffffffffa022298a>] ? rpcauth_lookup_credcache+0xab/0x22d [sunrpc]
> [<ffffffffa028be8c>] ? nfs_create_rpc_client+0xa6/0xeb [nfs]
> [<ffffffffa028c660>] ? nfs4_set_client+0xc2/0x1f9 [nfs]
> [<ffffffffa028cd3c>] ? nfs4_create_server+0xf2/0x2a6 [nfs]
> [<ffffffffa0295d07>] ? nfs4_remote_mount+0x4e/0x14a [nfs]
> [<ffffffff810dd570>] ? vfs_kern_mount+0x6e/0x133
> [<ffffffffa029605a>] ? nfs_do_root_mount+0x76/0x95 [nfs]
> [<ffffffffa029643d>] ? nfs4_try_mount+0x56/0xaf [nfs]
> [<ffffffffa0297434>] ? nfs_get_sb+0x435/0x73c [nfs]
> [<ffffffff810dd59b>] ? vfs_kern_mount+0x99/0x133
> [<ffffffff810dd693>] ? do_kern_mount+0x48/0xd8
> [<ffffffff810f5b75>] ? do_mount+0x6da/0x741
> [<ffffffff810f5c5f>] ? sys_mount+0x83/0xc0
> [<ffffffff8100293b>] ? system_call_fastpath+0x16/0x1b
>
> This is not oops, and debug code is not in vanilla. This debug code is
> simple - detects atomic_dec_and_test() underflow.
>
> Well, so, I think this is real bug of nfs codes somewhere. With some
> review, the code
>
> rpc_call_sync()
> rpc_run_task
> rpc_execute()
> __rpc_execute()
> rpc_release_task()
> rpc_release_resources_task()
> put_rpccred() <= release cred
> rpc_put_task
> rpc_do_put_task()
> rpc_release_resources_task()
> put_rpccred() <= release cred again
>
> seems to be release cred unintendedly.
>
> static void rpc_release_resources_task(struct rpc_task *task)
> {
> if (task->tk_rqstp)
> xprt_release(task);
> if (task->tk_msg.rpc_cred) {
> put_rpccred(task->tk_msg.rpc_cred);
> task->tk_msg.rpc_cred = NULL;
> }
> rpc_task_release_client(task);
> }
May I add a signed-off-by from you, and just push the above fix to
Linus?
Cheers
Trond
--
Trond Myklebust
Linux NFS client maintainer
NetApp
Trond.Myklebust@xxxxxxxxxx
www.netapp.com
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