| Message ID | 20120813113731.9629.31906.stgit@localhost.localdomain (mailing list archive) |
|---|---|
| State | New, archived |
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On Mon, 13 Aug 2012 15:37:31 +0400 Stanislav Kinsbursky <skinsbursky@parallels.com> wrote: > v2: > 1) rpc_clnt_set_nodename() prototype updated. > 2) fixed errors in comment. > > When child reaper exits, it can destroy mount namespace it belongs to, and if > there are NFS mounts inside, then it will try to umount them. But in this > point current->nsproxy is set to NULL and all namespaces will be destroyed one > by one. I.e. we can't dereference current->nsproxy to obtain uts namespace. > > Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> > --- > net/sunrpc/clnt.c | 16 +++++++++++++--- > 1 files changed, 13 insertions(+), 3 deletions(-) > > diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c > index 9a9676e..8fbcbc8 100644 > --- a/net/sunrpc/clnt.c > +++ b/net/sunrpc/clnt.c > @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void) > return rpc_pipefs_notifier_unregister(&rpc_clients_block); > } > > -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename) > +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt) > { > + const char *nodename; > + > + /* > + * We have to protect against dying child reaper, which has released > + * its nsproxy already and is trying to destroy mount namespace. > + */ > + if (current->nsproxy == NULL) > + return; > + > + nodename = utsname()->nodename; > clnt->cl_nodelen = strlen(nodename); > if (clnt->cl_nodelen > UNX_MAXNODENAME) > clnt->cl_nodelen = UNX_MAXNODENAME; > @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru > } > > /* save the nodename */ > - rpc_clnt_set_nodename(clnt, utsname()->nodename); > + rpc_clnt_set_nodename(clnt); > rpc_register_client(clnt); > return clnt; > > @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt) > err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name); > if (err != 0) > goto out_no_path; > - rpc_clnt_set_nodename(new, utsname()->nodename); > + rpc_clnt_set_nodename(new); > if (new->cl_auth) > atomic_inc(&new->cl_auth->au_count); > atomic_inc(&clnt->cl_count); > > -- > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html Acked-by: Jeff Layton <jlayton@redhat.com> -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Mon, 2012-08-13 at 08:10 -0400, Jeff Layton wrote: > On Mon, 13 Aug 2012 15:37:31 +0400 > Stanislav Kinsbursky <skinsbursky@parallels.com> wrote: > > > v2: > > 1) rpc_clnt_set_nodename() prototype updated. > > 2) fixed errors in comment. > > > > When child reaper exits, it can destroy mount namespace it belongs to, and if > > there are NFS mounts inside, then it will try to umount them. But in this > > point current->nsproxy is set to NULL and all namespaces will be destroyed one > > by one. I.e. we can't dereference current->nsproxy to obtain uts namespace. > > > > Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> > > --- > > net/sunrpc/clnt.c | 16 +++++++++++++--- > > 1 files changed, 13 insertions(+), 3 deletions(-) > > > > diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c > > index 9a9676e..8fbcbc8 100644 > > --- a/net/sunrpc/clnt.c > > +++ b/net/sunrpc/clnt.c > > @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void) > > return rpc_pipefs_notifier_unregister(&rpc_clients_block); > > } > > > > -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename) > > +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt) > > { > > + const char *nodename; > > + > > + /* > > + * We have to protect against dying child reaper, which has released > > + * its nsproxy already and is trying to destroy mount namespace. > > + */ > > + if (current->nsproxy == NULL) > > + return; > > + > > + nodename = utsname()->nodename; > > clnt->cl_nodelen = strlen(nodename); > > if (clnt->cl_nodelen > UNX_MAXNODENAME) > > clnt->cl_nodelen = UNX_MAXNODENAME; > > @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru > > } > > > > /* save the nodename */ > > - rpc_clnt_set_nodename(clnt, utsname()->nodename); > > + rpc_clnt_set_nodename(clnt); > > rpc_register_client(clnt); > > return clnt; > > > > @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt) > > err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name); > > if (err != 0) > > goto out_no_path; > > - rpc_clnt_set_nodename(new, utsname()->nodename); > > + rpc_clnt_set_nodename(new); > > if (new->cl_auth) > > atomic_inc(&new->cl_auth->au_count); > > atomic_inc(&clnt->cl_count); > > > > -- > > To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > > the body of a message to majordomo@vger.kernel.org > > More majordomo info at http://vger.kernel.org/majordomo-info.html > > Acked-by: Jeff Layton <jlayton@redhat.com> OK, colour me confused (again). Why should a umount trigger an rpc_create() or rpc_clone_client()? -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com
08.09.2012 01:32, Myklebust, Trond ?????: > On Mon, 2012-08-13 at 08:10 -0400, Jeff Layton wrote: >> On Mon, 13 Aug 2012 15:37:31 +0400 >> Stanislav Kinsbursky <skinsbursky@parallels.com> wrote: >> >>> v2: >>> 1) rpc_clnt_set_nodename() prototype updated. >>> 2) fixed errors in comment. >>> >>> When child reaper exits, it can destroy mount namespace it belongs to, and if >>> there are NFS mounts inside, then it will try to umount them. But in this >>> point current->nsproxy is set to NULL and all namespaces will be destroyed one >>> by one. I.e. we can't dereference current->nsproxy to obtain uts namespace. >>> >>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> >>> --- >>> net/sunrpc/clnt.c | 16 +++++++++++++--- >>> 1 files changed, 13 insertions(+), 3 deletions(-) >>> >>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c >>> index 9a9676e..8fbcbc8 100644 >>> --- a/net/sunrpc/clnt.c >>> +++ b/net/sunrpc/clnt.c >>> @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void) >>> return rpc_pipefs_notifier_unregister(&rpc_clients_block); >>> } >>> >>> -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename) >>> +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt) >>> { >>> + const char *nodename; >>> + >>> + /* >>> + * We have to protect against dying child reaper, which has released >>> + * its nsproxy already and is trying to destroy mount namespace. >>> + */ >>> + if (current->nsproxy == NULL) >>> + return; >>> + >>> + nodename = utsname()->nodename; >>> clnt->cl_nodelen = strlen(nodename); >>> if (clnt->cl_nodelen > UNX_MAXNODENAME) >>> clnt->cl_nodelen = UNX_MAXNODENAME; >>> @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru >>> } >>> >>> /* save the nodename */ >>> - rpc_clnt_set_nodename(clnt, utsname()->nodename); >>> + rpc_clnt_set_nodename(clnt); >>> rpc_register_client(clnt); >>> return clnt; >>> >>> @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt) >>> err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name); >>> if (err != 0) >>> goto out_no_path; >>> - rpc_clnt_set_nodename(new, utsname()->nodename); >>> + rpc_clnt_set_nodename(new); >>> if (new->cl_auth) >>> atomic_inc(&new->cl_auth->au_count); >>> atomic_inc(&clnt->cl_count); >>> >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >> Acked-by: Jeff Layton <jlayton@redhat.com> > OK, colour me confused (again). What color? > Why should a umount trigger an > rpc_create() or rpc_clone_client()? It calls nsm_create(). Here is the trace (https://bugzilla.redhat.com/show_bug.cgi?id=830862, comment 68): CR2: 0000000000000008 Process mysqld Call Trace: ? __schedule+0x3c7 nsm_create+0x8b nsm_mon_unmon+0x64 nlm_destroy_host_locked+0x6b nlmclnt_release_host+0x88 nlmclnt_done+0x1a nfs_destroy_server+0x24 nfs_free_server+0xce nfs_kill_super+0x34 deactivate_locked_super+0x57 deactivate_super+0x4e mntput_no_expire+0xcc mntput+0x26 release_mounts+0x77 put_mnt_ns+0x78 free_nsproxy+0x1f switch_task_namespaces+0x50 exit_task_namespaces+0x10 do_exit+0x456 do_group_exit+0x3f sys_exit_group+0x17 system_call_fastpath+0x16 RIP rpc_create+0x401 [sunrpc] Kernel panic - not syncing > -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Sat, 2012-09-08 at 08:59 +0300, Stanislav Kinsbursky wrote: > 08.09.2012 01:32, Myklebust, Trond ?????: > > On Mon, 2012-08-13 at 08:10 -0400, Jeff Layton wrote: > >> On Mon, 13 Aug 2012 15:37:31 +0400 > >> Stanislav Kinsbursky <skinsbursky@parallels.com> wrote: > >> > >>> v2: > >>> 1) rpc_clnt_set_nodename() prototype updated. > >>> 2) fixed errors in comment. > >>> > >>> When child reaper exits, it can destroy mount namespace it belongs to, and if > >>> there are NFS mounts inside, then it will try to umount them. But in this > >>> point current->nsproxy is set to NULL and all namespaces will be destroyed one > >>> by one. I.e. we can't dereference current->nsproxy to obtain uts namespace. > >>> > >>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> > >>> --- > >>> net/sunrpc/clnt.c | 16 +++++++++++++--- > >>> 1 files changed, 13 insertions(+), 3 deletions(-) > >>> > >>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c > >>> index 9a9676e..8fbcbc8 100644 > >>> --- a/net/sunrpc/clnt.c > >>> +++ b/net/sunrpc/clnt.c > >>> @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void) > >>> return rpc_pipefs_notifier_unregister(&rpc_clients_block); > >>> } > >>> > >>> -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename) > >>> +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt) > >>> { > >>> + const char *nodename; > >>> + > >>> + /* > >>> + * We have to protect against dying child reaper, which has released > >>> + * its nsproxy already and is trying to destroy mount namespace. > >>> + */ > >>> + if (current->nsproxy == NULL) > >>> + return; > >>> + > >>> + nodename = utsname()->nodename; > >>> clnt->cl_nodelen = strlen(nodename); > >>> if (clnt->cl_nodelen > UNX_MAXNODENAME) > >>> clnt->cl_nodelen = UNX_MAXNODENAME; > >>> @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru > >>> } > >>> > >>> /* save the nodename */ > >>> - rpc_clnt_set_nodename(clnt, utsname()->nodename); > >>> + rpc_clnt_set_nodename(clnt); > >>> rpc_register_client(clnt); > >>> return clnt; > >>> > >>> @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt) > >>> err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name); > >>> if (err != 0) > >>> goto out_no_path; > >>> - rpc_clnt_set_nodename(new, utsname()->nodename); > >>> + rpc_clnt_set_nodename(new); > >>> if (new->cl_auth) > >>> atomic_inc(&new->cl_auth->au_count); > >>> atomic_inc(&clnt->cl_count); > >>> > >>> -- > >>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > >>> the body of a message to majordomo@vger.kernel.org > >>> More majordomo info at http://vger.kernel.org/majordomo-info.html > >> Acked-by: Jeff Layton <jlayton@redhat.com> > > OK, colour me confused (again). > > What color? > > > Why should a umount trigger an > > rpc_create() or rpc_clone_client()? > > It calls nsm_create(). > Here is the trace (https://bugzilla.redhat.com/show_bug.cgi?id=830862, > comment 68): Right, but if we're using NFSv3 lock monitoring, we know in advance that we're going to need an nsm call to localhost. Why can't we just cache the one that we used to start lock monitoring in the first place? -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com
08.09.2012 18:33, Myklebust, Trond ?????: > On Sat, 2012-09-08 at 08:59 +0300, Stanislav Kinsbursky wrote: >> 08.09.2012 01:32, Myklebust, Trond ?????: >>> On Mon, 2012-08-13 at 08:10 -0400, Jeff Layton wrote: >>>> On Mon, 13 Aug 2012 15:37:31 +0400 >>>> Stanislav Kinsbursky <skinsbursky@parallels.com> wrote: >>>> >>>>> v2: >>>>> 1) rpc_clnt_set_nodename() prototype updated. >>>>> 2) fixed errors in comment. >>>>> >>>>> When child reaper exits, it can destroy mount namespace it belongs to, and if >>>>> there are NFS mounts inside, then it will try to umount them. But in this >>>>> point current->nsproxy is set to NULL and all namespaces will be destroyed one >>>>> by one. I.e. we can't dereference current->nsproxy to obtain uts namespace. >>>>> >>>>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> >>>>> --- >>>>> net/sunrpc/clnt.c | 16 +++++++++++++--- >>>>> 1 files changed, 13 insertions(+), 3 deletions(-) >>>>> >>>>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c >>>>> index 9a9676e..8fbcbc8 100644 >>>>> --- a/net/sunrpc/clnt.c >>>>> +++ b/net/sunrpc/clnt.c >>>>> @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void) >>>>> return rpc_pipefs_notifier_unregister(&rpc_clients_block); >>>>> } >>>>> >>>>> -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename) >>>>> +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt) >>>>> { >>>>> + const char *nodename; >>>>> + >>>>> + /* >>>>> + * We have to protect against dying child reaper, which has released >>>>> + * its nsproxy already and is trying to destroy mount namespace. >>>>> + */ >>>>> + if (current->nsproxy == NULL) >>>>> + return; >>>>> + >>>>> + nodename = utsname()->nodename; >>>>> clnt->cl_nodelen = strlen(nodename); >>>>> if (clnt->cl_nodelen > UNX_MAXNODENAME) >>>>> clnt->cl_nodelen = UNX_MAXNODENAME; >>>>> @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru >>>>> } >>>>> >>>>> /* save the nodename */ >>>>> - rpc_clnt_set_nodename(clnt, utsname()->nodename); >>>>> + rpc_clnt_set_nodename(clnt); >>>>> rpc_register_client(clnt); >>>>> return clnt; >>>>> >>>>> @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt) >>>>> err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name); >>>>> if (err != 0) >>>>> goto out_no_path; >>>>> - rpc_clnt_set_nodename(new, utsname()->nodename); >>>>> + rpc_clnt_set_nodename(new); >>>>> if (new->cl_auth) >>>>> atomic_inc(&new->cl_auth->au_count); >>>>> atomic_inc(&clnt->cl_count); >>>>> >>>>> -- >>>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >>>>> the body of a message to majordomo@vger.kernel.org >>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>> Acked-by: Jeff Layton <jlayton@redhat.com> >>> OK, colour me confused (again). >> >> What color? >> >>> Why should a umount trigger an >>> rpc_create() or rpc_clone_client()? >> >> It calls nsm_create(). >> Here is the trace (https://bugzilla.redhat.com/show_bug.cgi?id=830862, >> comment 68): > > Right, but if we're using NFSv3 lock monitoring, we know in advance that > we're going to need an nsm call to localhost. Why can't we just cache > the one that we used to start lock monitoring in the first place? > Do you suggest to cache the call or the client for the call?
On Mon, 2012-09-10 at 12:43 +0400, Stanislav Kinsbursky wrote: > 08.09.2012 18:33, Myklebust, Trond ?????: > > On Sat, 2012-09-08 at 08:59 +0300, Stanislav Kinsbursky wrote: > >> 08.09.2012 01:32, Myklebust, Trond ?????: > >>> On Mon, 2012-08-13 at 08:10 -0400, Jeff Layton wrote: > >>>> On Mon, 13 Aug 2012 15:37:31 +0400 > >>>> Stanislav Kinsbursky <skinsbursky@parallels.com> wrote: > >>>> > >>>>> v2: > >>>>> 1) rpc_clnt_set_nodename() prototype updated. > >>>>> 2) fixed errors in comment. > >>>>> > >>>>> When child reaper exits, it can destroy mount namespace it belongs to, and if > >>>>> there are NFS mounts inside, then it will try to umount them. But in this > >>>>> point current->nsproxy is set to NULL and all namespaces will be destroyed one > >>>>> by one. I.e. we can't dereference current->nsproxy to obtain uts namespace. > >>>>> > >>>>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> > >>>>> --- > >>>>> net/sunrpc/clnt.c | 16 +++++++++++++--- > >>>>> 1 files changed, 13 insertions(+), 3 deletions(-) > >>>>> > >>>>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c > >>>>> index 9a9676e..8fbcbc8 100644 > >>>>> --- a/net/sunrpc/clnt.c > >>>>> +++ b/net/sunrpc/clnt.c > >>>>> @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void) > >>>>> return rpc_pipefs_notifier_unregister(&rpc_clients_block); > >>>>> } > >>>>> > >>>>> -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename) > >>>>> +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt) > >>>>> { > >>>>> + const char *nodename; > >>>>> + > >>>>> + /* > >>>>> + * We have to protect against dying child reaper, which has released > >>>>> + * its nsproxy already and is trying to destroy mount namespace. > >>>>> + */ > >>>>> + if (current->nsproxy == NULL) > >>>>> + return; > >>>>> + > >>>>> + nodename = utsname()->nodename; > >>>>> clnt->cl_nodelen = strlen(nodename); > >>>>> if (clnt->cl_nodelen > UNX_MAXNODENAME) > >>>>> clnt->cl_nodelen = UNX_MAXNODENAME; > >>>>> @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru > >>>>> } > >>>>> > >>>>> /* save the nodename */ > >>>>> - rpc_clnt_set_nodename(clnt, utsname()->nodename); > >>>>> + rpc_clnt_set_nodename(clnt); > >>>>> rpc_register_client(clnt); > >>>>> return clnt; > >>>>> > >>>>> @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt) > >>>>> err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name); > >>>>> if (err != 0) > >>>>> goto out_no_path; > >>>>> - rpc_clnt_set_nodename(new, utsname()->nodename); > >>>>> + rpc_clnt_set_nodename(new); > >>>>> if (new->cl_auth) > >>>>> atomic_inc(&new->cl_auth->au_count); > >>>>> atomic_inc(&clnt->cl_count); > >>>>> > >>>>> -- > >>>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in > >>>>> the body of a message to majordomo@vger.kernel.org > >>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html > >>>> Acked-by: Jeff Layton <jlayton@redhat.com> > >>> OK, colour me confused (again). > >> > >> What color? > >> > >>> Why should a umount trigger an > >>> rpc_create() or rpc_clone_client()? > >> > >> It calls nsm_create(). > >> Here is the trace (https://bugzilla.redhat.com/show_bug.cgi?id=830862, > >> comment 68): > > > > Right, but if we're using NFSv3 lock monitoring, we know in advance that > > we're going to need an nsm call to localhost. Why can't we just cache > > the one that we used to start lock monitoring in the first place? > > > > Do you suggest to cache the call or the client for the call? Hi Stanislav, Sorry, I agree that the above was unclear. My intention was to suggest that we should cache a reference to the rpc client that we used to connect to rpc.statd when initiating lock monitoring. Basically, I'm suggesting that we should do something similar to the rpcbind rpc_client caching scheme in net/sunrpc/rpcb_clnt.c. Cheers Trond -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com
10.09.2012 19:27, Myklebust, Trond ?????: > On Mon, 2012-09-10 at 12:43 +0400, Stanislav Kinsbursky wrote: >> 08.09.2012 18:33, Myklebust, Trond ?????: >>> On Sat, 2012-09-08 at 08:59 +0300, Stanislav Kinsbursky wrote: >>>> 08.09.2012 01:32, Myklebust, Trond ?????: >>>>> On Mon, 2012-08-13 at 08:10 -0400, Jeff Layton wrote: >>>>>> On Mon, 13 Aug 2012 15:37:31 +0400 >>>>>> Stanislav Kinsbursky <skinsbursky@parallels.com> wrote: >>>>>> >>>>>>> v2: >>>>>>> 1) rpc_clnt_set_nodename() prototype updated. >>>>>>> 2) fixed errors in comment. >>>>>>> >>>>>>> When child reaper exits, it can destroy mount namespace it belongs to, and if >>>>>>> there are NFS mounts inside, then it will try to umount them. But in this >>>>>>> point current->nsproxy is set to NULL and all namespaces will be destroyed one >>>>>>> by one. I.e. we can't dereference current->nsproxy to obtain uts namespace. >>>>>>> >>>>>>> Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> >>>>>>> --- >>>>>>> net/sunrpc/clnt.c | 16 +++++++++++++--- >>>>>>> 1 files changed, 13 insertions(+), 3 deletions(-) >>>>>>> >>>>>>> diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c >>>>>>> index 9a9676e..8fbcbc8 100644 >>>>>>> --- a/net/sunrpc/clnt.c >>>>>>> +++ b/net/sunrpc/clnt.c >>>>>>> @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void) >>>>>>> return rpc_pipefs_notifier_unregister(&rpc_clients_block); >>>>>>> } >>>>>>> >>>>>>> -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename) >>>>>>> +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt) >>>>>>> { >>>>>>> + const char *nodename; >>>>>>> + >>>>>>> + /* >>>>>>> + * We have to protect against dying child reaper, which has released >>>>>>> + * its nsproxy already and is trying to destroy mount namespace. >>>>>>> + */ >>>>>>> + if (current->nsproxy == NULL) >>>>>>> + return; >>>>>>> + >>>>>>> + nodename = utsname()->nodename; >>>>>>> clnt->cl_nodelen = strlen(nodename); >>>>>>> if (clnt->cl_nodelen > UNX_MAXNODENAME) >>>>>>> clnt->cl_nodelen = UNX_MAXNODENAME; >>>>>>> @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru >>>>>>> } >>>>>>> >>>>>>> /* save the nodename */ >>>>>>> - rpc_clnt_set_nodename(clnt, utsname()->nodename); >>>>>>> + rpc_clnt_set_nodename(clnt); >>>>>>> rpc_register_client(clnt); >>>>>>> return clnt; >>>>>>> >>>>>>> @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt) >>>>>>> err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name); >>>>>>> if (err != 0) >>>>>>> goto out_no_path; >>>>>>> - rpc_clnt_set_nodename(new, utsname()->nodename); >>>>>>> + rpc_clnt_set_nodename(new); >>>>>>> if (new->cl_auth) >>>>>>> atomic_inc(&new->cl_auth->au_count); >>>>>>> atomic_inc(&clnt->cl_count); >>>>>>> >>>>>>> -- >>>>>>> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >>>>>>> the body of a message to majordomo@vger.kernel.org >>>>>>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>>>>> Acked-by: Jeff Layton <jlayton@redhat.com> >>>>> OK, colour me confused (again). >>>> >>>> What color? >>>> >>>>> Why should a umount trigger an >>>>> rpc_create() or rpc_clone_client()? >>>> >>>> It calls nsm_create(). >>>> Here is the trace (https://bugzilla.redhat.com/show_bug.cgi?id=830862, >>>> comment 68): >>> >>> Right, but if we're using NFSv3 lock monitoring, we know in advance that >>> we're going to need an nsm call to localhost. Why can't we just cache >>> the one that we used to start lock monitoring in the first place? >>> >> >> Do you suggest to cache the call or the client for the call? > > Hi Stanislav, > > Sorry, I agree that the above was unclear. My intention was to suggest > that we should cache a reference to the rpc client that we used to > connect to rpc.statd when initiating lock monitoring. > > Basically, I'm suggesting that we should do something similar to the > rpcbind rpc_client caching scheme in net/sunrpc/rpcb_clnt.c. > Hi, Trond. So, if I understand you right, we can create rpc client (or increase usage counter) on NSMPROC_MON call and destroy (or decrease usage counter) on NSMPROC_UNMON call. Will this solution works? > Cheers > Trond >
On Mon, 2012-09-10 at 19:37 +0400, Stanislav Kinsbursky wrote: > Hi, Trond. > So, if I understand you right, we can create rpc client (or increase usage > counter) on NSMPROC_MON call and destroy (or decrease usage counter) on > NSMPROC_UNMON call. > Will this solution works? The rpc client(s) will need to be per-net-namespace, which complicates matters a little bit, but yes, creation at NSMPROC_MON, and destruction at NSMPROC_UNMON should work. -- Trond Myklebust Linux NFS client maintainer NetApp Trond.Myklebust@netapp.com www.netapp.com
10.09.2012 19:41, Myklebust, Trond ?????: > On Mon, 2012-09-10 at 19:37 +0400, Stanislav Kinsbursky wrote: >> Hi, Trond. >> So, if I understand you right, we can create rpc client (or increase usage >> counter) on NSMPROC_MON call and destroy (or decrease usage counter) on >> NSMPROC_UNMON call. >> Will this solution works? > > The rpc client(s) will need to be per-net-namespace, which complicates > matters a little bit, but yes, creation at NSMPROC_MON, and destruction > at NSMPROC_UNMON should work. > Not really. We already have per-net Lockd data. So, adding one more reference-counted rpc client doesn't look that complicated. Ok, thanks. I'll try to implement this.
10.09.2012 19:41, Myklebust, Trond ?????: > On Mon, 2012-09-10 at 19:37 +0400, Stanislav Kinsbursky wrote: >> Hi, Trond. >> So, if I understand you right, we can create rpc client (or increase usage >> counter) on NSMPROC_MON call and destroy (or decrease usage counter) on >> NSMPROC_UNMON call. >> Will this solution works? > > The rpc client(s) will need to be per-net-namespace, which complicates > matters a little bit, but yes, creation at NSMPROC_MON, and destruction > at NSMPROC_UNMON should work. > Hi, Trond. With reference-counted NSM client I got this: BUG: unable to handle kernel NULL pointer dereference at 0000000000000008 IP: [<ffffffffa00c0d7f>] encode_mon_id+0x2e/0x64 [lockd] PGD 0 Oops: 0000 [#1] SMP DEBUG_PAGEALLOC Modules linked in: nfsv3 nfs_acl nfs lockd veth sunrpc bridge stp llc i2c_piix4 i2c_core virtio_blk virtio_net floppy virtio_pci virtio_ring virtio CPU 1 Pid: 1174, comm: bash Not tainted 3.5.0-kitchensink+ #44 Bochs Bochs RIP: 0010:[<ffffffffa00c0d7f>] [<ffffffffa00c0d7f>] encode_mon_id+0x2e/0x64 [lockd] RSP: 0018:ffff88001d0f1a08 EFLAGS: 00010246 RAX: 0000000000000000 RBX: ffff88001d0f1c38 RCX: 0000000000000000 RDX: ffff88001c85803f RSI: ffff88001d23b204 RDI: ffff88001d0f1a48 RBP: ffff88001d0f1a18 R08: ffff88001c858040 R09: 0000000000000003 R10: ffff88001a5aba10 R11: ffff88001d0f1ac8 R12: ffff88001d0f1a48 R13: ffff88001a8a3138 R14: ffffffffa008d580 R15: ffffffffa00c0db5 FS: 00007f0d60eea700(0000) GS:ffff88001f700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 0000000000000008 CR3: 000000001db3d000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process bash (pid: 1174, threadinfo ffff88001d0f0000, task ffff88001d1f4160) Stack: ffff88001d0f1a48 ffff88001c858030 ffff88001d0f1a28 ffffffffa00c0dc9 ffff88001d0f1ab8 ffffffffa00731a0 ffff88001a5aba10 ffff88001d0f1c38 ffff88001c858040 ffff88001a8a3140 ffff88001c858854 ffff88001a8a3140 Call Trace: [<ffffffffa00c0dc9>] nsm_xdr_enc_unmon+0x14/0x16 [lockd] [<ffffffffa00731a0>] rpcauth_wrap_req+0xa1/0xb2 [sunrpc] [<ffffffffa006b83f>] ? xprt_prepare_transmit+0x83/0x93 [sunrpc] [<ffffffffa0068e54>] call_transmit+0x1e4/0x263 [sunrpc] [<ffffffffa00728e2>] __rpc_execute+0xe7/0x313 [sunrpc] [<ffffffffa0068c70>] ? call_transmit_status+0xb8/0xb8 [sunrpc] [<ffffffff81055ed9>] ? wake_up_bit+0x25/0x2a [<ffffffffa0072be0>] rpc_execute+0x9d/0xa5 [sunrpc] [<ffffffffa006a6ae>] rpc_run_task+0x7e/0x86 [sunrpc] [<ffffffffa006a7a3>] rpc_call_sync+0x44/0x65 [sunrpc] [<ffffffffa00c0883>] nsm_mon_unmon+0x81/0xad [lockd] [<ffffffffa00c0931>] nsm_unmonitor+0x82/0x13a [lockd] [<ffffffffa00bc251>] nlm_destroy_host_locked+0x93/0xc9 [lockd] [<ffffffffa00bc33a>] nlmclnt_release_host+0xb3/0xc3 [lockd] [<ffffffffa00ba09f>] nlmclnt_done+0x1a/0x26 [lockd] [<ffffffffa00d583e>] nfs_destroy_server+0x24/0x26 [nfs] [<ffffffffa00d5d85>] nfs_free_server+0xad/0x134 [nfs] [<ffffffffa00dd5ff>] nfs_kill_super+0x22/0x26 [nfs] [<ffffffff8112b278>] deactivate_locked_super+0x26/0x57 [<ffffffff8112bd89>] deactivate_super+0x45/0x4c [<ffffffff811423ec>] mntput_no_expire+0x110/0x119 [<ffffffff8114241f>] mntput+0x2a/0x2c [<ffffffff81142605>] release_mounts+0x72/0x84 [<ffffffff811427cf>] put_mnt_ns+0x6f/0x7e [<ffffffff8105a3db>] free_nsproxy+0x1f/0x87 [<ffffffff8105a49f>] switch_task_namespaces+0x5c/0x65 [<ffffffff8105a4b8>] exit_task_namespaces+0x10/0x12 [<ffffffff8103c232>] do_exit+0x69b/0x84f [<ffffffff8103c469>] do_group_exit+0x83/0xae [<ffffffff8103c4ab>] sys_exit_group+0x17/0x1b [<ffffffff814657e9>] system_call_fastpath+0x16/0x1b Code: e5 41 54 53 66 66 66 66 90 48 89 f3 49 89 fc 48 8b 76 18 e8 93 ff ff ff 4c 89 e7 65 48 8b 04 25 c0 b9 00 00 48 8b 80 00 05 00 00 <48> 8b 70 08 48 83 c6 45 e8 73 ff ff ff 4c 89 e7 be 0c 00 00 00 RIP [<ffffffffa00c0d7f>] encode_mon_id+0x2e/0x64 [lockd] There are more places, where NFS and Lockd code dereference utsname(). In XDR layer, for instance. So, probably, we have to tie NFS to utsns as well as to netns. Add one more ns to xprt? What do you think?
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diff --git a/net/sunrpc/clnt.c b/net/sunrpc/clnt.c index 9a9676e..8fbcbc8 100644 --- a/net/sunrpc/clnt.c +++ b/net/sunrpc/clnt.c @@ -277,8 +277,18 @@ void rpc_clients_notifier_unregister(void) return rpc_pipefs_notifier_unregister(&rpc_clients_block); } -static void rpc_clnt_set_nodename(struct rpc_clnt *clnt, const char *nodename) +static void rpc_clnt_set_nodename(struct rpc_clnt *clnt) { + const char *nodename; + + /* + * We have to protect against dying child reaper, which has released + * its nsproxy already and is trying to destroy mount namespace. + */ + if (current->nsproxy == NULL) + return; + + nodename = utsname()->nodename; clnt->cl_nodelen = strlen(nodename); if (clnt->cl_nodelen > UNX_MAXNODENAME) clnt->cl_nodelen = UNX_MAXNODENAME; @@ -365,7 +375,7 @@ static struct rpc_clnt * rpc_new_client(const struct rpc_create_args *args, stru } /* save the nodename */ - rpc_clnt_set_nodename(clnt, utsname()->nodename); + rpc_clnt_set_nodename(clnt); rpc_register_client(clnt); return clnt; @@ -524,7 +534,7 @@ rpc_clone_client(struct rpc_clnt *clnt) err = rpc_setup_pipedir(new, clnt->cl_program->pipe_dir_name); if (err != 0) goto out_no_path; - rpc_clnt_set_nodename(new, utsname()->nodename); + rpc_clnt_set_nodename(new); if (new->cl_auth) atomic_inc(&new->cl_auth->au_count); atomic_inc(&clnt->cl_count);
v2: 1) rpc_clnt_set_nodename() prototype updated. 2) fixed errors in comment. When child reaper exits, it can destroy mount namespace it belongs to, and if there are NFS mounts inside, then it will try to umount them. But in this point current->nsproxy is set to NULL and all namespaces will be destroyed one by one. I.e. we can't dereference current->nsproxy to obtain uts namespace. Signed-off-by: Stanislav Kinsbursky <skinsbursky@parallels.com> --- net/sunrpc/clnt.c | 16 +++++++++++++--- 1 files changed, 13 insertions(+), 3 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html