[PATCH 06/21] nfs client: exit_net cleanup check added

[PATCH 06/21] nfs client: exit_net cleanup check added

[Vasily Averin]

Be sure that nfs_client_list and nfs_volume_list lists initialized
in net_init hook were return to initial state in net_exit hook.

Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
---
 fs/nfs/client.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/fs/nfs/client.c b/fs/nfs/client.c
index 22880ef..7c0691c 100644
--- a/fs/nfs/client.c
+++ b/fs/nfs/client.c
@@ -204,6 +204,10 @@ void nfs_cleanup_cb_ident_idr(struct net *net)
 	struct nfs_net *nn = net_generic(net, nfs_net_id);
 
 	idr_destroy(&nn->cb_ident_idr);
+	WARN(!list_empty(&nn->nfs_client_list),
+	     "net %p exit: nfs_client_list is not empty\n", net);
+	WARN(!list_empty(&nn->nfs_volume_list),
+	     "net %p exit: nfs_volume_list is not empty\n", net);
 }
 
 /* nfs_client_lock held */
-- 
2.7.4

Re: [PATCH 06/21] nfs client: exit_net cleanup check added

[Trond Myklebust]
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Re: [PATCH 06/21] nfs client: exit_net cleanup check added

[Trond Myklebust]

On Sun, 2017-11-05 at 13:00 +0300, Vasily Averin wrote:
> Be sure that nfs_client_list and nfs_volume_list lists initialized
> in net_init hook were return to initial state in net_exit hook.
> 
> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
> ---
>  fs/nfs/client.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> index 22880ef..7c0691c 100644
> --- a/fs/nfs/client.c
> +++ b/fs/nfs/client.c
> @@ -204,6 +204,10 @@ void nfs_cleanup_cb_ident_idr(struct net *net)
>  	struct nfs_net *nn = net_generic(net, nfs_net_id);
>  
>  	idr_destroy(&nn->cb_ident_idr);
> +	WARN(!list_empty(&nn->nfs_client_list),
> +	     "net %p exit: nfs_client_list is not empty\n", net);
> +	WARN(!list_empty(&nn->nfs_volume_list),
> +	     "net %p exit: nfs_volume_list is not empty\n", net);
>  }
>  

Why do we need these? Is there a specific bug that you are trying to
track down?

-- 
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com

Re: [PATCH 06/21] nfs client: exit_net cleanup check added

[Vasily Averin]

On 2017-11-05 19:02, Trond Myklebust wrote:
> On Sun, 2017-11-05 at 13:00 +0300, Vasily Averin wrote:
>> Be sure that nfs_client_list and nfs_volume_list lists initialized
>> in net_init hook were return to initial state in net_exit hook.
>>
>> Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
>> ---
>>  fs/nfs/client.c | 4 ++++
>>  1 file changed, 4 insertions(+)
>>
>> diff --git a/fs/nfs/client.c b/fs/nfs/client.c
>> index 22880ef..7c0691c 100644
>> --- a/fs/nfs/client.c
>> +++ b/fs/nfs/client.c
>> @@ -204,6 +204,10 @@ void nfs_cleanup_cb_ident_idr(struct net *net)
>>  	struct nfs_net *nn = net_generic(net, nfs_net_id);
>>  
>>  	idr_destroy(&nn->cb_ident_idr);
>> +	WARN(!list_empty(&nn->nfs_client_list),
>> +	     "net %p exit: nfs_client_list is not empty\n", net);
>> +	WARN(!list_empty(&nn->nfs_volume_list),
>> +	     "net %p exit: nfs_volume_list is not empty\n", net);
>>  }
>>  
> 
> Why do we need these? Is there a specific bug that you are trying to
> track down?

I hope such checks allows to detect leaked per-netns objects.
Also I hope that all new pernet_operations will inherit such checks too.

I assume that elements added into per-net lists should not live longer than net namespace,
and should be deleted from the list. I think exit_net hook is good place for such check.

Recently I've found lost list_entry and enabled timer on stop of net namespace.
Then I've reviewed all existing pernet_operations and found that many drivers
have such checks already. So I decided to complete this task and add such checks
into all affected subsystems.

Re: [PATCH 06/21] nfs client: exit_net cleanup check added

[Trond Myklebust]

T24gU3VuLCAyMDE3LTExLTA1IGF0IDE5OjQ4ICswMzAwLCBWYXNpbHkgQXZlcmluIHdyb3RlOg0K
PiBPbiAyMDE3LTExLTA1IDE5OjAyLCBUcm9uZCBNeWtsZWJ1c3Qgd3JvdGU6DQo+ID4gT24gU3Vu
LCAyMDE3LTExLTA1IGF0IDEzOjAwICswMzAwLCBWYXNpbHkgQXZlcmluIHdyb3RlOg0KPiA+ID4g
QmUgc3VyZSB0aGF0IG5mc19jbGllbnRfbGlzdCBhbmQgbmZzX3ZvbHVtZV9saXN0IGxpc3RzDQo+
ID4gPiBpbml0aWFsaXplZA0KPiA+ID4gaW4gbmV0X2luaXQgaG9vayB3ZXJlIHJldHVybiB0byBp
bml0aWFsIHN0YXRlIGluIG5ldF9leGl0IGhvb2suDQo+ID4gPiANCj4gPiA+IFNpZ25lZC1vZmYt
Ynk6IFZhc2lseSBBdmVyaW4gPHZ2c0B2aXJ0dW96em8uY29tPg0KPiA+ID4gLS0tDQo+ID4gPiAg
ZnMvbmZzL2NsaWVudC5jIHwgNCArKysrDQo+ID4gPiAgMSBmaWxlIGNoYW5nZWQsIDQgaW5zZXJ0
aW9ucygrKQ0KPiA+ID4gDQo+ID4gPiBkaWZmIC0tZ2l0IGEvZnMvbmZzL2NsaWVudC5jIGIvZnMv
bmZzL2NsaWVudC5jDQo+ID4gPiBpbmRleCAyMjg4MGVmLi43YzA2OTFjIDEwMDY0NA0KPiA+ID4g
LS0tIGEvZnMvbmZzL2NsaWVudC5jDQo+ID4gPiArKysgYi9mcy9uZnMvY2xpZW50LmMNCj4gPiA+
IEBAIC0yMDQsNiArMjA0LDEwIEBAIHZvaWQgbmZzX2NsZWFudXBfY2JfaWRlbnRfaWRyKHN0cnVj
dCBuZXQNCj4gPiA+ICpuZXQpDQo+ID4gPiAgCXN0cnVjdCBuZnNfbmV0ICpubiA9IG5ldF9nZW5l
cmljKG5ldCwgbmZzX25ldF9pZCk7DQo+ID4gPiAgDQo+ID4gPiAgCWlkcl9kZXN0cm95KCZubi0+
Y2JfaWRlbnRfaWRyKTsNCj4gPiA+ICsJV0FSTighbGlzdF9lbXB0eSgmbm4tPm5mc19jbGllbnRf
bGlzdCksDQo+ID4gPiArCSAgICAgIm5ldCAlcCBleGl0OiBuZnNfY2xpZW50X2xpc3QgaXMgbm90
IGVtcHR5XG4iLA0KPiA+ID4gbmV0KTsNCj4gPiA+ICsJV0FSTighbGlzdF9lbXB0eSgmbm4tPm5m
c192b2x1bWVfbGlzdCksDQo+ID4gPiArCSAgICAgIm5ldCAlcCBleGl0OiBuZnNfdm9sdW1lX2xp
c3QgaXMgbm90IGVtcHR5XG4iLA0KPiA+ID4gbmV0KTsNCj4gPiA+ICB9DQo+ID4gPiAgDQo+ID4g
DQo+ID4gV2h5IGRvIHdlIG5lZWQgdGhlc2U/IElzIHRoZXJlIGEgc3BlY2lmaWMgYnVnIHRoYXQg
eW91IGFyZSB0cnlpbmcNCj4gPiB0bw0KPiA+IHRyYWNrIGRvd24/DQo+IA0KPiBJIGhvcGUgc3Vj
aCBjaGVja3MgYWxsb3dzIHRvIGRldGVjdCBsZWFrZWQgcGVyLW5ldG5zIG9iamVjdHMuDQo+IEFs
c28gSSBob3BlIHRoYXQgYWxsIG5ldyBwZXJuZXRfb3BlcmF0aW9ucyB3aWxsIGluaGVyaXQgc3Vj
aCBjaGVja3MNCj4gdG9vLg0KPiANCj4gSSBhc3N1bWUgdGhhdCBlbGVtZW50cyBhZGRlZCBpbnRv
IHBlci1uZXQgbGlzdHMgc2hvdWxkIG5vdCBsaXZlDQo+IGxvbmdlciB0aGFuIG5ldCBuYW1lc3Bh
Y2UsDQo+IGFuZCBzaG91bGQgYmUgZGVsZXRlZCBmcm9tIHRoZSBsaXN0LiBJIHRoaW5rIGV4aXRf
bmV0IGhvb2sgaXMgZ29vZA0KPiBwbGFjZSBmb3Igc3VjaCBjaGVjay4NCj4gDQo+IFJlY2VudGx5
IEkndmUgZm91bmQgbG9zdCBsaXN0X2VudHJ5IGFuZCBlbmFibGVkIHRpbWVyIG9uIHN0b3Agb2Yg
bmV0DQo+IG5hbWVzcGFjZS4NCj4gVGhlbiBJJ3ZlIHJldmlld2VkIGFsbCBleGlzdGluZyBwZXJu
ZXRfb3BlcmF0aW9ucyBhbmQgZm91bmQgdGhhdCBtYW55DQo+IGRyaXZlcnMNCj4gaGF2ZSBzdWNo
IGNoZWNrcyBhbHJlYWR5LiBTbyBJIGRlY2lkZWQgdG8gY29tcGxldGUgdGhpcyB0YXNrIGFuZCBh
ZGQNCj4gc3VjaCBjaGVja3MNCj4gaW50byBhbGwgYWZmZWN0ZWQgc3Vic3lzdGVtcy4NCj4gDQoN
ClVubGVzcyB0aGVyZSBpcyBhIGtub3duIHByb2JsZW0gdGhhdCBoYXMgc3BlY2lmaWMgZGVidWdn
aW5nIG5lZWRzLCB0aGlzDQpraW5kIG9mIGFzc2VydCBzaG91bGQgdGFrZSB0aGUgZm9ybSBvZiBh
IFdBUk5fT05DRSgpIHNvIHRoYXQgaXQgZG9lc24ndA0KZmlsbCB1c2VyIHN5c2xvZ3Mgd2l0aCBy
ZWR1bmRhbnQgd2FybmluZ3MgaWYgdHJpZ2dlcmVkLg0KDQotLSANClRyb25kIE15a2xlYnVzdA0K
TGludXggTkZTIGNsaWVudCBtYWludGFpbmVyLCBQcmltYXJ5RGF0YQ0KdHJvbmQubXlrbGVidXN0
QHByaW1hcnlkYXRhLmNvbQ0K

Re: [PATCH 06/21] nfs client: exit_net cleanup check added

[Trond Myklebust]

[-- Warning: decoded text below may be mangled, UTF-8 assumed --]
[-- Attachment #1: Type: text/plain; charset=UTF-8, Size: 2259 bytes --]

On Sun, 2017-11-05 at 19:48 +0300, Vasily Averin wrote:
> On 2017-11-05 19:02, Trond Myklebust wrote:
> > On Sun, 2017-11-05 at 13:00 +0300, Vasily Averin wrote:
> > > Be sure that nfs_client_list and nfs_volume_list lists
> > > initialized
> > > in net_init hook were return to initial state in net_exit hook.
> > > 
> > > Signed-off-by: Vasily Averin <vvs@virtuozzo.com>
> > > ---
> > >  fs/nfs/client.c | 4 ++++
> > >  1 file changed, 4 insertions(+)
> > > 
> > > diff --git a/fs/nfs/client.c b/fs/nfs/client.c
> > > index 22880ef..7c0691c 100644
> > > --- a/fs/nfs/client.c
> > > +++ b/fs/nfs/client.c
> > > @@ -204,6 +204,10 @@ void nfs_cleanup_cb_ident_idr(struct net
> > > *net)
> > >  	struct nfs_net *nn = net_generic(net, nfs_net_id);
> > >  
> > >  	idr_destroy(&nn->cb_ident_idr);
> > > +	WARN(!list_empty(&nn->nfs_client_list),
> > > +	     "net %p exit: nfs_client_list is not empty\n",
> > > net);
> > > +	WARN(!list_empty(&nn->nfs_volume_list),
> > > +	     "net %p exit: nfs_volume_list is not empty\n",
> > > net);
> > >  }
> > >  
> > 
> > Why do we need these? Is there a specific bug that you are trying
> > to
> > track down?
> 
> I hope such checks allows to detect leaked per-netns objects.
> Also I hope that all new pernet_operations will inherit such checks
> too.
> 
> I assume that elements added into per-net lists should not live
> longer than net namespace,
> and should be deleted from the list. I think exit_net hook is good
> place for such check.
> 
> Recently I've found lost list_entry and enabled timer on stop of net
> namespace.
> Then I've reviewed all existing pernet_operations and found that many
> drivers
> have such checks already. So I decided to complete this task and add
> such checks
> into all affected subsystems.
> 

Unless there is a known problem that has specific debugging needs, this
kind of assert should take the form of a WARN_ONCE() so that it doesn't
fill user syslogs with redundant warnings if triggered.

-- 
Trond Myklebust
Linux NFS client maintainer, PrimaryData
trond.myklebust@primarydata.com
N‹§²æìr¸›yúèšØb²X¬¶Ç§vØ^–)Þº{.nÇ+‰·¥Š{±û"žØ^n‡r¡ö¦zË\x1aëh™¨è­Ú&¢îý»\x05ËÛÔØï¦v¬Îf\x1dp)¹¹br	šê+€Ê+zf£¢·hšˆ§~†­†Ûiÿûàz¹\x1e®w¥¢¸?™¨è­Ú&¢)ߢ^[f