From beb0f0a9fba1fa98b378329a9a5b0a73f25097ae Mon Sep 17 00:00:00 2001 From: Trond Myklebust Date: Mon, 20 Dec 2010 21:19:26 +0000 Subject: [PATCH] kernel panic when mount NFSv4 On Tue, 2010-12-14 at 16:58 +0800, Mi Jinlong wrote: > Hi, > > When testing NFSv4 at RHEL6 with kernel 2.6.32, I got a kernel panic > at NFS client's __rpc_create_common function. > > The panic place is: > rpc_mkpipe > __rpc_lookup_create() <=== find pipefile *idmap* > __rpc_mkpipe() <=== pipefile is *idmap* > __rpc_create_common() > ****** BUG_ON(!d_unhashed(dentry)); ****** *panic* > > It means that the dentry's d_flags have be set DCACHE_UNHASHED, > but it should not be set here. > > Is someone known this bug? or give me some idea? > > A reproduce program is append, but it can't reproduce the bug every time. > the export is: "/nfsroot *(rw,no_root_squash,fsid=0,insecure)" > > And the panic message is append. > > ============================================================================ > #!/bin/sh > > LOOPTOTAL=768 > LOOPCOUNT=0 > ret=0 > > while [ $LOOPCOUNT -ne $LOOPTOTAL ] > do > ((LOOPCOUNT += 1)) > service nfs restart > /usr/sbin/rpc.idmapd > mount -t nfs4 127.0.0.1:/ /mnt|| return 1; > ls -l /var/lib/nfs/rpc_pipefs/nfs/*/ > umount /mnt > echo $LOOPCOUNT > done > > =============================================================================== > Code: af 60 01 00 00 89 fa 89 f0 e8 64 cf 89 f0 e8 5c 7c 64 cf 31 c0 8b 5c 24 10 8b > 74 24 14 8b 7c 24 18 8b 6c 24 1c 83 c4 20 c3 <0f> 0b eb fc 8b 46 28 c7 44 24 08 20 > de ee f0 c7 44 24 04 56 ea > EIP:[] __rpc_create_common+0x8a/0xc0 [sunrpc] SS:ESP 0068:eccb5d28 > ---[ end trace 8f5606cd08928ed2]--- > Kernel panic - not syncing: Fatal exception > Pid:7131, comm: mount.nfs4 Tainted: G D -------------------2.6.32 #1 > Call Trace: > [] ? panic+0x42/0xed > [] ? oops_end+0xbc/0xd0 > [] ? do_invalid_op+0x0/0x90 > [] ? do_invalid_op+0x7f/0x90 > [] ? __rpc_create_common+0x8a/0xc0[sunrpc] > [] ? rpc_free_task+0x33/0x70[sunrpc] > [] ? prc_call_sync+0x48/0x60[sunrpc] > [] ? rpc_ping+0x4e/0x60[sunrpc] > [] ? rpc_create+0x38f/0x4f0[sunrpc] > [] ? error_code+0x73/0x78 > [] ? __rpc_create_common+0x8a/0xc0[sunrpc] > [] ? d_lookup+0x2a/0x40 > [] ? rpc_mkpipe+0x111/0x1b0[sunrpc] > [] ? nfs_create_rpc_client+0xb4/0xf0[nfs] > [] ? nfs_fscache_get_client_cookie+0x1d/0x50[nfs] > [] ? nfs_idmap_new+0x7b/0x140[nfs] > [] ? strlcpy+0x3a/0x60 > [] ? nfs4_set_client+0xea/0x2b0[nfs] > [] ? nfs4_create_server+0xac/0x1b0[nfs] > [] ? krealloc+0x40/0x50 > [] ? nfs4_remote_get_sb+0x6b/0x250[nfs] > [] ? kstrdup+0x3c/0x60 > [] ? vfs_kern_mount+0x69/0x170 > [] ? nfs_do_root_mount+0x6c/0xa0[nfs] > [] ? nfs4_try_mount+0x37/0xa0[nfs] > [] ? nfs4_validate_text_mount_data+-x7d/0xf0[nfs] > [] ? nfs4_get_sb+0x92/0x2f0 > [] ? vfs_kern_mount+0x69/0x170 > [] ? get_fs_type+0x32/0xb0 > [] ? do_kern_mount+0x3f/0xe0 > [] ? do_mount+0x2ef/0x740 > [] ? copy_mount_options+0xb0/0x120 > [] ? sys_mount+0x6e/0xa0 Hi, Does the following patch fix the problem? Cheers Trond -------------------------- SUNRPC: Fix a BUG in __rpc_create_common From: Trond Myklebust Mi Jinlong reports: When testing NFSv4 at RHEL6 with kernel 2.6.32, I got a kernel panic at NFS client's __rpc_create_common function. The panic place is: rpc_mkpipe __rpc_lookup_create() <=== find pipefile *idmap* __rpc_mkpipe() <=== pipefile is *idmap* __rpc_create_common() ****** BUG_ON(!d_unhashed(dentry)); ****** *panic* The test is wrong: we can find ourselves with a hashed negative dentry here if the idmapper tried to look up the file before we got round to creating it. Just replace the BUG_ON() with a d_drop(dentry). Reported-by: Mi Jinlong Signed-off-by: Trond Myklebust --- net/sunrpc/rpc_pipe.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/net/sunrpc/rpc_pipe.c b/net/sunrpc/rpc_pipe.c index 10a17a37ec4e..5356d95343f3 100644 --- a/net/sunrpc/rpc_pipe.c +++ b/net/sunrpc/rpc_pipe.c @@ -466,7 +466,7 @@ static int __rpc_create_common(struct inode *dir, struct dentry *dentry, { struct inode *inode; - BUG_ON(!d_unhashed(dentry)); + d_drop(dentry); inode = rpc_get_inode(dir->i_sb, mode); if (!inode) goto out_err; -- 2.30.2