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Old 10-01-2012, 08:38 AM
Jonathan Nieder
 
Default Bug#689274: (almost 100% reproducible) kernel bug when trying to mount nfs filesystem

tags 689274 = upstream fixed-upstream
quit

Hi Rogério,

Rogério Brito wrote:

> I have been semi-consistently (the almost 100% reproducible) getting a
> kernel Oops whenever I try to mount a NFS filesystem from another computer
> (an ARM, 32-bit NAS, running pure Debian armel unstable) from my network.
>
> This has only happened with kernel 3.5, but not with previous kernels.
[...]
> [ 9608.475559] kernel BUG at /build/buildd-linux_3.5.2-1~experimental.1-amd64-bLqIZ_/linux-3.5.2/fs/nfs/idmap.c:684!

This is the "BUG_ON(idmap->idmap_key_cons != NULL);"
discussed at http://thread.gmane.org/gmane.linux.nfs/51316/focus=1365689
The assertion was introduced in v3.5.1~32, so wheezy is not affected.

Could you try the attached patch, for example using instructions
from [1]?

Thanks for a pleasant report,
Jonathan

[1] http://kernel-handbook.alioth.debian.org/ch-common-tasks.html#s4.2.2


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Old 10-01-2012, 08:47 AM
Jonathan Nieder
 
Default Bug#689274: (almost 100% reproducible) kernel bug when trying to mount nfs filesystem

Jonathan Nieder wrote:

> This is the "BUG_ON(idmap->idmap_key_cons != NULL);"
> discussed at http://thread.gmane.org/gmane.linux.nfs/51316/focus=1365689
> The assertion was introduced in v3.5.1~32, so wheezy is not affected.
>
> Could you try the attached patch, for example using instructions
> from [1]?

Attached.
From: Bryan Schumaker <bjschuma@netapp.com>
Date: Thu, 9 Aug 2012 14:05:49 -0400
Subject: NFS: Clear key construction data if the idmap upcall fails

commit c5066945b7ea346a11424dbeb7830b7d7d00c206 upstream.

idmap_pipe_downcall already clears this field if the upcall succeeds,
but if it fails (rpc.idmapd isn't running) the field will still be set
on the next call triggering a BUG_ON(). This patch tries to handle all
possible ways that the upcall could fail and clear the idmap key data
for each one.

Signed-off-by: Bryan Schumaker <bjschuma@netapp.com>
Tested-by: William Dauchy <wdauchy@gmail.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
fs/nfs/idmap.c | 56 ++++++++++++++++++++++++++++++++++++++++++--------------
1 file changed, 42 insertions(+), 14 deletions(-)

diff --git a/fs/nfs/idmap.c b/fs/nfs/idmap.c
index 1b5058b4043b..bf184841f595 100644
--- a/fs/nfs/idmap.c
+++ b/fs/nfs/idmap.c
@@ -63,6 +63,12 @@ struct idmap {
struct mutex idmap_mutex;
};

+struct idmap_legacy_upcalldata {
+ struct rpc_pipe_msg pipe_msg;
+ struct idmap_msg idmap_msg;
+ struct idmap *idmap;
+};
+
/**
* nfs_fattr_init_names - initialise the nfs_fattr owner_name/group_name fields
* @fattr: fully initialised struct nfs_fattr
@@ -326,6 +332,7 @@ static ssize_t nfs_idmap_get_key(const char *name, size_t namelen,
ret = nfs_idmap_request_key(&key_type_id_resolver_legacy ,
name, namelen, type, data,
data_size, idmap);
+ idmap->idmap_key_cons = NULL;
mutex_unlock(&idmap->idmap_mutex);
}
return ret;
@@ -383,11 +390,13 @@ static const match_table_t nfs_idmap_tokens = {
static int nfs_idmap_legacy_upcall(struct key_construction *, const char *, void *);
static ssize_t idmap_pipe_downcall(struct file *, const char __user *,
size_t);
+static void idmap_release_pipe(struct inode *);
static void idmap_pipe_destroy_msg(struct rpc_pipe_msg *);

static const struct rpc_pipe_ops idmap_upcall_ops = {
.upcall = rpc_pipe_generic_upcall,
.downcall = idmap_pipe_downcall,
+ .release_pipe = idmap_release_pipe,
.destroy_msg = idmap_pipe_destroy_msg,
};

@@ -619,7 +628,8 @@ void nfs_idmap_quit(void)
nfs_idmap_quit_keyring();
}

-static int nfs_idmap_prepare_message(char *desc, struct idmap_msg *im,
+static int nfs_idmap_prepare_message(char *desc, struct idmap *idmap,
+ struct idmap_msg *im,
struct rpc_pipe_msg *msg)
{
substring_t substr;
@@ -662,6 +672,7 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
const char *op,
void *aux)
{
+ struct idmap_legacy_upcalldata *data;
struct rpc_pipe_msg *msg;
struct idmap_msg *im;
struct idmap *idmap = (struct idmap *)aux;
@@ -669,15 +680,15 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,
int ret = -ENOMEM;

/* msg and im are freed in idmap_pipe_destroy_msg */
- msg = kmalloc(sizeof(*msg), GFP_KERNEL);
- if (!msg)
- goto out0;
-
- im = kmalloc(sizeof(*im), GFP_KERNEL);
- if (!im)
+ data = kmalloc(sizeof(*data), GFP_KERNEL);
+ if (!data)
goto out1;

- ret = nfs_idmap_prepare_message(key->description, im, msg);
+ msg = &data->pipe_msg;
+ im = &data->idmap_msg;
+ data->idmap = idmap;
+
+ ret = nfs_idmap_prepare_message(key->description, idmap, im, msg);
if (ret < 0)
goto out2;

@@ -686,15 +697,15 @@ static int nfs_idmap_legacy_upcall(struct key_construction *cons,

ret = rpc_queue_upcall(idmap->idmap_pipe, msg);
if (ret < 0)
- goto out2;
+ goto out3;

return ret;

+out3:
+ idmap->idmap_key_cons = NULL;
out2:
- kfree(im);
+ kfree(data);
out1:
- kfree(msg);
-out0:
complete_request_key(cons, ret);
return ret;
}
@@ -778,9 +789,26 @@ out_incomplete:
static void
idmap_pipe_destroy_msg(struct rpc_pipe_msg *msg)
{
+ struct idmap_legacy_upcalldata *data = container_of(msg,
+ struct idmap_legacy_upcalldata,
+ pipe_msg);
+ struct idmap *idmap = data->idmap;
+ struct key_construction *cons;
+ if (msg->errno) {
+ cons = ACCESS_ONCE(idmap->idmap_key_cons);
+ idmap->idmap_key_cons = NULL;
+ complete_request_key(cons, msg->errno);
+ }
/* Free memory allocated in nfs_idmap_legacy_upcall() */
- kfree(msg->data);
- kfree(msg);
+ kfree(data);
+}
+
+static void
+idmap_release_pipe(struct inode *inode)
+{
+ struct rpc_inode *rpci = RPC_I(inode);
+ struct idmap *idmap = (struct idmap *)rpci->private;
+ idmap->idmap_key_cons = NULL;
}

int nfs_map_name_to_uid(const struct nfs_server *server, const char *name, size_t namelen, __u32 *uid)
--
1.7.10.4
 

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