linux-kernel - Re: nfs failure causes bad page state

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Message-Id: <1195860554.7671.38.camel@heimdal.trondhjem.org>
Date:	Fri, 23 Nov 2007 18:29:14 -0500
From:	Trond Myklebust <trond.myklebust@....uio.no>
To:	Russell King <rmk@....linux.org.uk>
Cc:	Linux Kernel List <linux-kernel@...r.kernel.org>
Subject: Re: nfs failure causes bad page state


On Fri, 2007-11-16 at 22:13 +0000, Russell King wrote:
> While testing a kernel based upon
> ecd744eec3aa8bbc949ec04ed3fbf7ecb2958a0e
> (with wrong boot arguments), I got the following bad page state entry
> while
> NFS was trying to mount it's rootfs:
> 
> IP-Config: Complete:
>       device=eth0, addr=192.168.1.101, mask=255.255.255.0,
> gw=255.255.255.255,
>      host=192.168.1.101, domain=, nis-domain=(none),
>      bootserver=192.168.1.100, rootserver=192.168.1.100, rootpath=
> Looking up port of RPC 100003/2 on 192.168.1.100
> rpcbind: server 192.168.1.100 not responding, timed out
> Root-NFS: Unable to get nfsd port number from server, using default
> Looking up port of RPC 100005/1 on 192.168.1.100
> rpcbind: server 192.168.1.100 not responding, timed out
> Root-NFS: Unable to get mountd port number from server, using default
> mount: server 192.168.1.100 not responding, timed out
> Root-NFS: Server returned error -5 while mounting /nfs/rootfs/
> VFS: Unable to mount root fs via NFS, trying floppy.
> Bad page state in process 'swapper'
> page:c02b1260 flags:0x00000400 mapping:00000000 mapcount:0 count:0
> Trying to fix it up, but a reboot is needed
> Backtrace:
> [<c0023e34>] (dump_stack+0x0/0x14) from [<c0062570>] (bad_page
> +0x70/0xac)
> [<c0062500>] (bad_page+0x0/0xac) from [<c0064914>] (free_hot_cold_page
> +0x80/0x178)
> [<c0064894>] (free_hot_cold_page+0x0/0x178) from [<c0064a74>]
> (free_hot_page+0x14/0x18)
> [<c0064a60>] (free_hot_page+0x0/0x18) from [<c0067078>] (put_page
> +0xf8/0x154)
> [<c0066f80>] (put_page+0x0/0x154) from [<c007dbc8>] (kfree+0xc8/0xd0)
> [<c007db00>] (kfree+0x0/0xd0) from [<c00cbb54>] (nfs_get_sb
> +0x230/0x710)
> [<c00cb924>] (nfs_get_sb+0x0/0x710) from [<c0084334>] (vfs_kern_mount
> +0x58/0xac)[<c00842dc>] (vfs_kern_mount+0x0/0xac) from [<c00843c0>]
> (do_kern_mount+0x38/0xf4)
> [<c0084388>] (do_kern_mount+0x0/0xf4) from [<c0099c7c>] (do_mount
> +0x1e8/0x614)
> ...
> 
> This seems to be caused by use of an uninitialised structure due to
> NULL
> options being passed to nfs_validate_mount_data().  Ensure that the
> parsed mount data is always initialised.
> 
> Signed-off-by: Russell King <rmk+kernel@....linux.org.uk>
> 
> diff --git a/fs/nfs/super.c b/fs/nfs/super.c
> index fa517ae..0b1080c 100644
> --- a/fs/nfs/super.c
> +++ b/fs/nfs/super.c
> @@ -1054,10 +1054,11 @@ static int nfs_validate_mount_data(void
> *options,
>  {
>  	struct nfs_mount_data *data = (struct nfs_mount_data *)options;
>  
> +	memset(args, 0, sizeof(*args));
> +
>  	if (data == NULL)
>  		goto out_no_data;
>  
> -	memset(args, 0, sizeof(*args));
>  	args->flags		= (NFS_MOUNT_VER3 | NFS_MOUNT_TCP);
>  	args->rsize		= NFS_MAX_FILE_IO_SIZE;
>  	args->wsize		= NFS_MAX_FILE_IO_SIZE;

Thanks Russell,

It looks as if the same bug exists in nfs4_validate_mount_data(), so I
added the same fix.

Cheers
  Trond


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