* net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
@ 2016-11-08 5:42 Ross Zwisler
2016-11-08 11:53 ` Jeff Layton
0 siblings, 1 reply; 6+ messages in thread
From: Ross Zwisler @ 2016-11-08 5:42 UTC (permalink / raw)
To: Trond Myklebust, Anna Schumaker, J. Bruce Fields, Jeff Layton,
David S. Miller, linux-nfs, netdev, linux-kernel, Andy Adamson
I've got a virtual machine that has some NFS mounts, and with a newly compiled
kernel based on v4.9-rc3 I see the following warning/info message:
[ 42.750181] ===============================
[ 42.750192] [ INFO: suspicious RCU usage. ]
[ 42.750203] 4.9.0-rc3-00002-g7b6e7de #3 Not tainted
[ 42.750213] -------------------------------
[ 42.750225] net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
[ 42.750235]
[ 42.750235] other info that might help us debug this:
[ 42.750235]
[ 42.750246]
[ 42.750246] rcu_scheduler_active = 1, debug_locks = 0
[ 42.750257] 1 lock held by mount.nfs4/6440:
[ 42.750278] #0:
[ 42.750299] (
[ 42.750319] &(&nn->nfs_client_lock)->rlock
[ 42.750340] ){+.+...}
[ 42.750362] , at:
[ 42.750372] [<ffffffff813012b5>] nfs_get_client+0x105/0x5e0
[ 42.750383]
[ 42.750383] stack backtrace:
[ 42.750394] CPU: 0 PID: 6440 Comm: mount.nfs4 Not tainted 4.9.0-rc3-00002-g7b6e7de #3
[ 42.750406] Hardware name: Intel Corporation PURLEY/PURLEY, BIOS PLYDCRB1.MBH.0096.D23.1608240105 08/24/2016
[ 42.750429] ffffc9000092fa68 ffffffff8150730f ffff88014ec8da40 0000000000000001
[ 42.750452] ffffc9000092fa98 ffffffff810bc3f7 ffff880150b0b228 ffff88015068dbb0
[ 42.750475] ffffc9000092fb38 ffff88014fc99180 ffffc9000092fac0 ffffffff81b243e5
[ 42.750486] Call Trace:
[ 42.750498] [<ffffffff8150730f>] dump_stack+0x67/0x98
[ 42.750511] [<ffffffff810bc3f7>] lockdep_rcu_suspicious+0xe7/0x120
[ 42.750524] [<ffffffff81b243e5>] rpc_clnt_xprt_switch_has_addr+0x115/0x150
[ 42.750536] [<ffffffff813013f4>] nfs_get_client+0x244/0x5e0
[ 42.750549] [<ffffffff813012ac>] ? nfs_get_client+0xfc/0x5e0
[ 42.750561] [<ffffffff813568f8>] nfs4_set_client+0x98/0x130
[ 42.750574] [<ffffffff8135872e>] nfs4_create_server+0x13e/0x390
[ 42.750588] [<ffffffff8134cd0e>] nfs4_remote_mount+0x2e/0x60
[ 42.750600] [<ffffffff811f3a29>] mount_fs+0x39/0x170
[ 42.750614] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
[ 42.750626] [<ffffffff8134cbec>] ? nfs_do_root_mount+0x3c/0xc0
[ 42.750639] [<ffffffff8134cc36>] nfs_do_root_mount+0x86/0xc0
[ 42.750652] [<ffffffff8134d014>] nfs4_try_mount+0x44/0xc0
[ 42.750664] [<ffffffff81302097>] ? get_nfs_version+0x27/0x90
[ 42.750677] [<ffffffff81310f8c>] nfs_fs_mount+0x4ac/0xd80
[ 42.750689] [<ffffffff810bb938>] ? lockdep_init_map+0x88/0x1f0
[ 42.750701] [<ffffffff81311ac0>] ? nfs_clone_super+0x130/0x130
[ 42.750713] [<ffffffff8130f300>] ? param_set_portnr+0x70/0x70
[ 42.750726] [<ffffffff811f3a29>] mount_fs+0x39/0x170
[ 42.750740] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
[ 42.750752] [<ffffffff812176f1>] do_mount+0x1f1/0xd10
[ 42.750765] [<ffffffff81217441>] ? copy_mount_options+0xa1/0x140
[ 42.750777] [<ffffffff81218543>] SyS_mount+0x83/0xd0
[ 42.750790] [<ffffffff81002abc>] do_syscall_64+0x5c/0x130
[ 42.750802] [<ffffffff81c479a4>] entry_SYSCALL64_slow_path+0x25/0x25
This rcu_dereference_check() was introduced by the following commit:
commit 39e5d2df959dd4aea81fa33d765d2a5cc67a0512
Author: Andy Adamson <andros@netapp.com>
Date: Fri Sep 9 09:22:25 2016 -0400
SUNRPC search xprt switch for sockaddr
Signed-off-by: Andy Adamson <andros@netapp.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Thanks,
- Ross
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
2016-11-08 5:42 net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage! Ross Zwisler
@ 2016-11-08 11:53 ` Jeff Layton
2016-11-08 12:09 ` Jeff Layton
0 siblings, 1 reply; 6+ messages in thread
From: Jeff Layton @ 2016-11-08 11:53 UTC (permalink / raw)
To: Ross Zwisler, Trond Myklebust, Anna Schumaker, J. Bruce Fields,
David S. Miller, linux-nfs, netdev, linux-kernel, Andy Adamson
On Mon, 2016-11-07 at 22:42 -0700, Ross Zwisler wrote:
> I've got a virtual machine that has some NFS mounts, and with a newly compiled
> kernel based on v4.9-rc3 I see the following warning/info message:
>
> [ 42.750181] ===============================
> [ 42.750192] [ INFO: suspicious RCU usage. ]
> [ 42.750203] 4.9.0-rc3-00002-g7b6e7de #3 Not tainted
> [ 42.750213] -------------------------------
> [ 42.750225] net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
> [ 42.750235]
> [ 42.750235] other info that might help us debug this:
> [ 42.750235]
> [ 42.750246]
> [ 42.750246] rcu_scheduler_active = 1, debug_locks = 0
> [ 42.750257] 1 lock held by mount.nfs4/6440:
> [ 42.750278] #0:
> [ 42.750299] (
> [ 42.750319] &(&nn->nfs_client_lock)->rlock
> [ 42.750340] ){+.+...}
> [ 42.750362] , at:
> [ 42.750372] [<ffffffff813012b5>] nfs_get_client+0x105/0x5e0
> [ 42.750383]
> [ 42.750383] stack backtrace:
> [ 42.750394] CPU: 0 PID: 6440 Comm: mount.nfs4 Not tainted 4.9.0-rc3-00002-g7b6e7de #3
> [ 42.750406] Hardware name: Intel Corporation PURLEY/PURLEY, BIOS PLYDCRB1.MBH.0096.D23.1608240105 08/24/2016
> [ 42.750429] ffffc9000092fa68 ffffffff8150730f ffff88014ec8da40 0000000000000001
> [ 42.750452] ffffc9000092fa98 ffffffff810bc3f7 ffff880150b0b228 ffff88015068dbb0
> [ 42.750475] ffffc9000092fb38 ffff88014fc99180 ffffc9000092fac0 ffffffff81b243e5
> [ 42.750486] Call Trace:
> [ 42.750498] [<ffffffff8150730f>] dump_stack+0x67/0x98
> [ 42.750511] [<ffffffff810bc3f7>] lockdep_rcu_suspicious+0xe7/0x120
> [ 42.750524] [<ffffffff81b243e5>] rpc_clnt_xprt_switch_has_addr+0x115/0x150
> [ 42.750536] [<ffffffff813013f4>] nfs_get_client+0x244/0x5e0
> [ 42.750549] [<ffffffff813012ac>] ? nfs_get_client+0xfc/0x5e0
> [ 42.750561] [<ffffffff813568f8>] nfs4_set_client+0x98/0x130
> [ 42.750574] [<ffffffff8135872e>] nfs4_create_server+0x13e/0x390
> [ 42.750588] [<ffffffff8134cd0e>] nfs4_remote_mount+0x2e/0x60
> [ 42.750600] [<ffffffff811f3a29>] mount_fs+0x39/0x170
> [ 42.750614] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
> [ 42.750626] [<ffffffff8134cbec>] ? nfs_do_root_mount+0x3c/0xc0
> [ 42.750639] [<ffffffff8134cc36>] nfs_do_root_mount+0x86/0xc0
> [ 42.750652] [<ffffffff8134d014>] nfs4_try_mount+0x44/0xc0
> [ 42.750664] [<ffffffff81302097>] ? get_nfs_version+0x27/0x90
> [ 42.750677] [<ffffffff81310f8c>] nfs_fs_mount+0x4ac/0xd80
> [ 42.750689] [<ffffffff810bb938>] ? lockdep_init_map+0x88/0x1f0
> [ 42.750701] [<ffffffff81311ac0>] ? nfs_clone_super+0x130/0x130
> [ 42.750713] [<ffffffff8130f300>] ? param_set_portnr+0x70/0x70
> [ 42.750726] [<ffffffff811f3a29>] mount_fs+0x39/0x170
> [ 42.750740] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
> [ 42.750752] [<ffffffff812176f1>] do_mount+0x1f1/0xd10
> [ 42.750765] [<ffffffff81217441>] ? copy_mount_options+0xa1/0x140
> [ 42.750777] [<ffffffff81218543>] SyS_mount+0x83/0xd0
> [ 42.750790] [<ffffffff81002abc>] do_syscall_64+0x5c/0x130
> [ 42.750802] [<ffffffff81c479a4>] entry_SYSCALL64_slow_path+0x25/0x25
>
> This rcu_dereference_check() was introduced by the following commit:
>
> commit 39e5d2df959dd4aea81fa33d765d2a5cc67a0512
> Author: Andy Adamson <andros@netapp.com>
> Date: Fri Sep 9 09:22:25 2016 -0400
>
> SUNRPC search xprt switch for sockaddr
>
> Signed-off-by: Andy Adamson <andros@netapp.com>
> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
>
> Thanks,
> - Ross
Thanks Ross,
----------------------8<----------------------
bool rpc_clnt_xprt_switch_has_addr(struct rpc_clnt *clnt,
const struct sockaddr *sap)
{
struct rpc_xprt_switch *xps;
bool ret;
xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);
rcu_read_lock();
ret = rpc_xprt_switch_has_addr(xps, sap);
rcu_read_unlock();
return ret;
}
----------------------8<----------------------
Looks like the simple fix is to just move that rcu_dereference call
inside the rcu_read_lock there.
Cheers,
--
Jeff Layton <jlayton@redhat.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
2016-11-08 11:53 ` Jeff Layton
@ 2016-11-08 12:09 ` Jeff Layton
2016-11-08 12:42 ` Anna Schumaker
0 siblings, 1 reply; 6+ messages in thread
From: Jeff Layton @ 2016-11-08 12:09 UTC (permalink / raw)
To: Ross Zwisler, Trond Myklebust, Anna Schumaker, J. Bruce Fields,
David S. Miller, linux-nfs, netdev, linux-kernel, Andy Adamson
On Tue, 2016-11-08 at 06:53 -0500, Jeff Layton wrote:
> On Mon, 2016-11-07 at 22:42 -0700, Ross Zwisler wrote:
> >
> > I've got a virtual machine that has some NFS mounts, and with a newly compiled
> > kernel based on v4.9-rc3 I see the following warning/info message:
> >
> > [ 42.750181] ===============================
> > [ 42.750192] [ INFO: suspicious RCU usage. ]
> > [ 42.750203] 4.9.0-rc3-00002-g7b6e7de #3 Not tainted
> > [ 42.750213] -------------------------------
> > [ 42.750225] net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
> > [ 42.750235]
> > [ 42.750235] other info that might help us debug this:
> > [ 42.750235]
> > [ 42.750246]
> > [ 42.750246] rcu_scheduler_active = 1, debug_locks = 0
> > [ 42.750257] 1 lock held by mount.nfs4/6440:
> > [ 42.750278] #0:
> > [ 42.750299] (
> > [ 42.750319] &(&nn->nfs_client_lock)->rlock
> > [ 42.750340] ){+.+...}
> > [ 42.750362] , at:
> > [ 42.750372] [<ffffffff813012b5>] nfs_get_client+0x105/0x5e0
> > [ 42.750383]
> > [ 42.750383] stack backtrace:
> > [ 42.750394] CPU: 0 PID: 6440 Comm: mount.nfs4 Not tainted 4.9.0-rc3-00002-g7b6e7de #3
> > [ 42.750406] Hardware name: Intel Corporation PURLEY/PURLEY, BIOS PLYDCRB1.MBH.0096.D23.1608240105 08/24/2016
> > [ 42.750429] ffffc9000092fa68 ffffffff8150730f ffff88014ec8da40 0000000000000001
> > [ 42.750452] ffffc9000092fa98 ffffffff810bc3f7 ffff880150b0b228 ffff88015068dbb0
> > [ 42.750475] ffffc9000092fb38 ffff88014fc99180 ffffc9000092fac0 ffffffff81b243e5
> > [ 42.750486] Call Trace:
> > [ 42.750498] [<ffffffff8150730f>] dump_stack+0x67/0x98
> > [ 42.750511] [<ffffffff810bc3f7>] lockdep_rcu_suspicious+0xe7/0x120
> > [ 42.750524] [<ffffffff81b243e5>] rpc_clnt_xprt_switch_has_addr+0x115/0x150
> > [ 42.750536] [<ffffffff813013f4>] nfs_get_client+0x244/0x5e0
> > [ 42.750549] [<ffffffff813012ac>] ? nfs_get_client+0xfc/0x5e0
> > [ 42.750561] [<ffffffff813568f8>] nfs4_set_client+0x98/0x130
> > [ 42.750574] [<ffffffff8135872e>] nfs4_create_server+0x13e/0x390
> > [ 42.750588] [<ffffffff8134cd0e>] nfs4_remote_mount+0x2e/0x60
> > [ 42.750600] [<ffffffff811f3a29>] mount_fs+0x39/0x170
> > [ 42.750614] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
> > [ 42.750626] [<ffffffff8134cbec>] ? nfs_do_root_mount+0x3c/0xc0
> > [ 42.750639] [<ffffffff8134cc36>] nfs_do_root_mount+0x86/0xc0
> > [ 42.750652] [<ffffffff8134d014>] nfs4_try_mount+0x44/0xc0
> > [ 42.750664] [<ffffffff81302097>] ? get_nfs_version+0x27/0x90
> > [ 42.750677] [<ffffffff81310f8c>] nfs_fs_mount+0x4ac/0xd80
> > [ 42.750689] [<ffffffff810bb938>] ? lockdep_init_map+0x88/0x1f0
> > [ 42.750701] [<ffffffff81311ac0>] ? nfs_clone_super+0x130/0x130
> > [ 42.750713] [<ffffffff8130f300>] ? param_set_portnr+0x70/0x70
> > [ 42.750726] [<ffffffff811f3a29>] mount_fs+0x39/0x170
> > [ 42.750740] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
> > [ 42.750752] [<ffffffff812176f1>] do_mount+0x1f1/0xd10
> > [ 42.750765] [<ffffffff81217441>] ? copy_mount_options+0xa1/0x140
> > [ 42.750777] [<ffffffff81218543>] SyS_mount+0x83/0xd0
> > [ 42.750790] [<ffffffff81002abc>] do_syscall_64+0x5c/0x130
> > [ 42.750802] [<ffffffff81c479a4>] entry_SYSCALL64_slow_path+0x25/0x25
> >
> > This rcu_dereference_check() was introduced by the following commit:
> >
> > commit 39e5d2df959dd4aea81fa33d765d2a5cc67a0512
> > Author: Andy Adamson <andros@netapp.com>
> > Date: Fri Sep 9 09:22:25 2016 -0400
> >
> > SUNRPC search xprt switch for sockaddr
> >
> > Signed-off-by: Andy Adamson <andros@netapp.com>
> > Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> >
> > Thanks,
> > - Ross
>
> Thanks Ross,
>
> ----------------------8<----------------------
> bool rpc_clnt_xprt_switch_has_addr(struct rpc_clnt *clnt,
> const struct sockaddr *sap)
> {
> struct rpc_xprt_switch *xps;
> bool ret;
>
> xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);
>
> rcu_read_lock();
> ret = rpc_xprt_switch_has_addr(xps, sap);
> rcu_read_unlock();
> return ret;
> }
> ----------------------8<----------------------
>
> Looks like the simple fix is to just move that rcu_dereference call
> inside the rcu_read_lock there.
>
Hmm...that said though, there are some other suspicious accesses
of xpi_xpswitch. Looks like these are called without the rcu_read_lock
clearly being held:
rpc_clnt_xprt_switch_add_xprt
rpc_clnt_xprt_switch_put
...though it's possible I missed something there.
--
Jeff Layton <jlayton@redhat.com>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
2016-11-08 12:09 ` Jeff Layton
@ 2016-11-08 12:42 ` Anna Schumaker
2016-11-08 17:43 ` Ross Zwisler
0 siblings, 1 reply; 6+ messages in thread
From: Anna Schumaker @ 2016-11-08 12:42 UTC (permalink / raw)
To: Jeff Layton, Ross Zwisler, Trond Myklebust, J. Bruce Fields,
David S. Miller, linux-nfs, netdev, linux-kernel, Andy Adamson
On 11/08/2016 07:09 AM, Jeff Layton wrote:
> On Tue, 2016-11-08 at 06:53 -0500, Jeff Layton wrote:
>> On Mon, 2016-11-07 at 22:42 -0700, Ross Zwisler wrote:
>>>
>>> I've got a virtual machine that has some NFS mounts, and with a newly compiled
>>> kernel based on v4.9-rc3 I see the following warning/info message:
>>>
>>> [ 42.750181] ===============================
>>> [ 42.750192] [ INFO: suspicious RCU usage. ]
>>> [ 42.750203] 4.9.0-rc3-00002-g7b6e7de #3 Not tainted
>>> [ 42.750213] -------------------------------
>>> [ 42.750225] net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
>>> [ 42.750235]
>>> [ 42.750235] other info that might help us debug this:
>>> [ 42.750235]
>>> [ 42.750246]
>>> [ 42.750246] rcu_scheduler_active = 1, debug_locks = 0
>>> [ 42.750257] 1 lock held by mount.nfs4/6440:
>>> [ 42.750278] #0:
>>> [ 42.750299] (
>>> [ 42.750319] &(&nn->nfs_client_lock)->rlock
>>> [ 42.750340] ){+.+...}
>>> [ 42.750362] , at:
>>> [ 42.750372] [<ffffffff813012b5>] nfs_get_client+0x105/0x5e0
>>> [ 42.750383]
>>> [ 42.750383] stack backtrace:
>>> [ 42.750394] CPU: 0 PID: 6440 Comm: mount.nfs4 Not tainted 4.9.0-rc3-00002-g7b6e7de #3
>>> [ 42.750406] Hardware name: Intel Corporation PURLEY/PURLEY, BIOS PLYDCRB1.MBH.0096.D23.1608240105 08/24/2016
>>> [ 42.750429] ffffc9000092fa68 ffffffff8150730f ffff88014ec8da40 0000000000000001
>>> [ 42.750452] ffffc9000092fa98 ffffffff810bc3f7 ffff880150b0b228 ffff88015068dbb0
>>> [ 42.750475] ffffc9000092fb38 ffff88014fc99180 ffffc9000092fac0 ffffffff81b243e5
>>> [ 42.750486] Call Trace:
>>> [ 42.750498] [<ffffffff8150730f>] dump_stack+0x67/0x98
>>> [ 42.750511] [<ffffffff810bc3f7>] lockdep_rcu_suspicious+0xe7/0x120
>>> [ 42.750524] [<ffffffff81b243e5>] rpc_clnt_xprt_switch_has_addr+0x115/0x150
>>> [ 42.750536] [<ffffffff813013f4>] nfs_get_client+0x244/0x5e0
>>> [ 42.750549] [<ffffffff813012ac>] ? nfs_get_client+0xfc/0x5e0
>>> [ 42.750561] [<ffffffff813568f8>] nfs4_set_client+0x98/0x130
>>> [ 42.750574] [<ffffffff8135872e>] nfs4_create_server+0x13e/0x390
>>> [ 42.750588] [<ffffffff8134cd0e>] nfs4_remote_mount+0x2e/0x60
>>> [ 42.750600] [<ffffffff811f3a29>] mount_fs+0x39/0x170
>>> [ 42.750614] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
>>> [ 42.750626] [<ffffffff8134cbec>] ? nfs_do_root_mount+0x3c/0xc0
>>> [ 42.750639] [<ffffffff8134cc36>] nfs_do_root_mount+0x86/0xc0
>>> [ 42.750652] [<ffffffff8134d014>] nfs4_try_mount+0x44/0xc0
>>> [ 42.750664] [<ffffffff81302097>] ? get_nfs_version+0x27/0x90
>>> [ 42.750677] [<ffffffff81310f8c>] nfs_fs_mount+0x4ac/0xd80
>>> [ 42.750689] [<ffffffff810bb938>] ? lockdep_init_map+0x88/0x1f0
>>> [ 42.750701] [<ffffffff81311ac0>] ? nfs_clone_super+0x130/0x130
>>> [ 42.750713] [<ffffffff8130f300>] ? param_set_portnr+0x70/0x70
>>> [ 42.750726] [<ffffffff811f3a29>] mount_fs+0x39/0x170
>>> [ 42.750740] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
>>> [ 42.750752] [<ffffffff812176f1>] do_mount+0x1f1/0xd10
>>> [ 42.750765] [<ffffffff81217441>] ? copy_mount_options+0xa1/0x140
>>> [ 42.750777] [<ffffffff81218543>] SyS_mount+0x83/0xd0
>>> [ 42.750790] [<ffffffff81002abc>] do_syscall_64+0x5c/0x130
>>> [ 42.750802] [<ffffffff81c479a4>] entry_SYSCALL64_slow_path+0x25/0x25
>>>
>>> This rcu_dereference_check() was introduced by the following commit:
>>>
>>> commit 39e5d2df959dd4aea81fa33d765d2a5cc67a0512
>>> Author: Andy Adamson <andros@netapp.com>
>>> Date: Fri Sep 9 09:22:25 2016 -0400
>>>
>>> SUNRPC search xprt switch for sockaddr
>>>
>>> Signed-off-by: Andy Adamson <andros@netapp.com>
>>> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
>>>
>>> Thanks,
>>> - Ross
>>
>> Thanks Ross,
Hi Ross,
Can you try this patch and let me know if it helps:
http://git.linux-nfs.org/?p=anna/linux-nfs.git;a=commitdiff;h=bb29dd84333a96f309c6d0f88b285b5b78927058
I'm planning on sending it to Linus soon, so it should be in rc5.
Anna
>>
>> ----------------------8<----------------------
>> bool rpc_clnt_xprt_switch_has_addr(struct rpc_clnt *clnt,
>> const struct sockaddr *sap)
>> {
>> struct rpc_xprt_switch *xps;
>> bool ret;
>>
>> xps = rcu_dereference(clnt->cl_xpi.xpi_xpswitch);
>>
>> rcu_read_lock();
>> ret = rpc_xprt_switch_has_addr(xps, sap);
>> rcu_read_unlock();
>> return ret;
>> }
>> ----------------------8<----------------------
>>
>> Looks like the simple fix is to just move that rcu_dereference call
>> inside the rcu_read_lock there.
>>
>
> Hmm...that said though, there are some other suspicious accesses
> of xpi_xpswitch. Looks like these are called without the rcu_read_lock
> clearly being held:
>
> rpc_clnt_xprt_switch_add_xprt
> rpc_clnt_xprt_switch_put
>
> ...though it's possible I missed something there.
>
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
2016-11-08 12:42 ` Anna Schumaker
@ 2016-11-08 17:43 ` Ross Zwisler
2016-11-08 17:56 ` Anna Schumaker
0 siblings, 1 reply; 6+ messages in thread
From: Ross Zwisler @ 2016-11-08 17:43 UTC (permalink / raw)
To: Anna Schumaker
Cc: Jeff Layton, Ross Zwisler, Trond Myklebust, J. Bruce Fields,
David S. Miller, linux-nfs, netdev, linux-kernel, Andy Adamson
On Tue, Nov 08, 2016 at 07:42:59AM -0500, Anna Schumaker wrote:
> On 11/08/2016 07:09 AM, Jeff Layton wrote:
> > On Tue, 2016-11-08 at 06:53 -0500, Jeff Layton wrote:
> >> On Mon, 2016-11-07 at 22:42 -0700, Ross Zwisler wrote:
> >>>
> >>> I've got a virtual machine that has some NFS mounts, and with a newly compiled
> >>> kernel based on v4.9-rc3 I see the following warning/info message:
> >>>
> >>> [ 42.750181] ===============================
> >>> [ 42.750192] [ INFO: suspicious RCU usage. ]
> >>> [ 42.750203] 4.9.0-rc3-00002-g7b6e7de #3 Not tainted
> >>> [ 42.750213] -------------------------------
> >>> [ 42.750225] net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
> >>> [ 42.750235]
> >>> [ 42.750235] other info that might help us debug this:
> >>> [ 42.750235]
> >>> [ 42.750246]
> >>> [ 42.750246] rcu_scheduler_active = 1, debug_locks = 0
> >>> [ 42.750257] 1 lock held by mount.nfs4/6440:
> >>> [ 42.750278] #0:
> >>> [ 42.750299] (
> >>> [ 42.750319] &(&nn->nfs_client_lock)->rlock
> >>> [ 42.750340] ){+.+...}
> >>> [ 42.750362] , at:
> >>> [ 42.750372] [<ffffffff813012b5>] nfs_get_client+0x105/0x5e0
> >>> [ 42.750383]
> >>> [ 42.750383] stack backtrace:
> >>> [ 42.750394] CPU: 0 PID: 6440 Comm: mount.nfs4 Not tainted 4.9.0-rc3-00002-g7b6e7de #3
> >>> [ 42.750406] Hardware name: Intel Corporation PURLEY/PURLEY, BIOS PLYDCRB1.MBH.0096.D23.1608240105 08/24/2016
> >>> [ 42.750429] ffffc9000092fa68 ffffffff8150730f ffff88014ec8da40 0000000000000001
> >>> [ 42.750452] ffffc9000092fa98 ffffffff810bc3f7 ffff880150b0b228 ffff88015068dbb0
> >>> [ 42.750475] ffffc9000092fb38 ffff88014fc99180 ffffc9000092fac0 ffffffff81b243e5
> >>> [ 42.750486] Call Trace:
> >>> [ 42.750498] [<ffffffff8150730f>] dump_stack+0x67/0x98
> >>> [ 42.750511] [<ffffffff810bc3f7>] lockdep_rcu_suspicious+0xe7/0x120
> >>> [ 42.750524] [<ffffffff81b243e5>] rpc_clnt_xprt_switch_has_addr+0x115/0x150
> >>> [ 42.750536] [<ffffffff813013f4>] nfs_get_client+0x244/0x5e0
> >>> [ 42.750549] [<ffffffff813012ac>] ? nfs_get_client+0xfc/0x5e0
> >>> [ 42.750561] [<ffffffff813568f8>] nfs4_set_client+0x98/0x130
> >>> [ 42.750574] [<ffffffff8135872e>] nfs4_create_server+0x13e/0x390
> >>> [ 42.750588] [<ffffffff8134cd0e>] nfs4_remote_mount+0x2e/0x60
> >>> [ 42.750600] [<ffffffff811f3a29>] mount_fs+0x39/0x170
> >>> [ 42.750614] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
> >>> [ 42.750626] [<ffffffff8134cbec>] ? nfs_do_root_mount+0x3c/0xc0
> >>> [ 42.750639] [<ffffffff8134cc36>] nfs_do_root_mount+0x86/0xc0
> >>> [ 42.750652] [<ffffffff8134d014>] nfs4_try_mount+0x44/0xc0
> >>> [ 42.750664] [<ffffffff81302097>] ? get_nfs_version+0x27/0x90
> >>> [ 42.750677] [<ffffffff81310f8c>] nfs_fs_mount+0x4ac/0xd80
> >>> [ 42.750689] [<ffffffff810bb938>] ? lockdep_init_map+0x88/0x1f0
> >>> [ 42.750701] [<ffffffff81311ac0>] ? nfs_clone_super+0x130/0x130
> >>> [ 42.750713] [<ffffffff8130f300>] ? param_set_portnr+0x70/0x70
> >>> [ 42.750726] [<ffffffff811f3a29>] mount_fs+0x39/0x170
> >>> [ 42.750740] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
> >>> [ 42.750752] [<ffffffff812176f1>] do_mount+0x1f1/0xd10
> >>> [ 42.750765] [<ffffffff81217441>] ? copy_mount_options+0xa1/0x140
> >>> [ 42.750777] [<ffffffff81218543>] SyS_mount+0x83/0xd0
> >>> [ 42.750790] [<ffffffff81002abc>] do_syscall_64+0x5c/0x130
> >>> [ 42.750802] [<ffffffff81c479a4>] entry_SYSCALL64_slow_path+0x25/0x25
> >>>
> >>> This rcu_dereference_check() was introduced by the following commit:
> >>>
> >>> commit 39e5d2df959dd4aea81fa33d765d2a5cc67a0512
> >>> Author: Andy Adamson <andros@netapp.com>
> >>> Date: Fri Sep 9 09:22:25 2016 -0400
> >>>
> >>> SUNRPC search xprt switch for sockaddr
> >>>
> >>> Signed-off-by: Andy Adamson <andros@netapp.com>
> >>> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
> >>>
> >>> Thanks,
> >>> - Ross
> >>
> >> Thanks Ross,
>
> Hi Ross,
>
> Can you try this patch and let me know if it helps:
>
> http://git.linux-nfs.org/?p=anna/linux-nfs.git;a=commitdiff;h=bb29dd84333a96f309c6d0f88b285b5b78927058
>
> I'm planning on sending it to Linus soon, so it should be in rc5.
Hi Anna,
Yep, this patch makes the warning go away in my setup.
Thanks,
- Ross
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
2016-11-08 17:43 ` Ross Zwisler
@ 2016-11-08 17:56 ` Anna Schumaker
0 siblings, 0 replies; 6+ messages in thread
From: Anna Schumaker @ 2016-11-08 17:56 UTC (permalink / raw)
To: Ross Zwisler
Cc: Jeff Layton, Trond Myklebust, J. Bruce Fields, David S. Miller,
linux-nfs, netdev, linux-kernel, Andy Adamson
On 11/08/2016 12:43 PM, Ross Zwisler wrote:
> On Tue, Nov 08, 2016 at 07:42:59AM -0500, Anna Schumaker wrote:
>> On 11/08/2016 07:09 AM, Jeff Layton wrote:
>>> On Tue, 2016-11-08 at 06:53 -0500, Jeff Layton wrote:
>>>> On Mon, 2016-11-07 at 22:42 -0700, Ross Zwisler wrote:
>>>>>
>>>>> I've got a virtual machine that has some NFS mounts, and with a newly compiled
>>>>> kernel based on v4.9-rc3 I see the following warning/info message:
>>>>>
>>>>> [ 42.750181] ===============================
>>>>> [ 42.750192] [ INFO: suspicious RCU usage. ]
>>>>> [ 42.750203] 4.9.0-rc3-00002-g7b6e7de #3 Not tainted
>>>>> [ 42.750213] -------------------------------
>>>>> [ 42.750225] net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage!
>>>>> [ 42.750235]
>>>>> [ 42.750235] other info that might help us debug this:
>>>>> [ 42.750235]
>>>>> [ 42.750246]
>>>>> [ 42.750246] rcu_scheduler_active = 1, debug_locks = 0
>>>>> [ 42.750257] 1 lock held by mount.nfs4/6440:
>>>>> [ 42.750278] #0:
>>>>> [ 42.750299] (
>>>>> [ 42.750319] &(&nn->nfs_client_lock)->rlock
>>>>> [ 42.750340] ){+.+...}
>>>>> [ 42.750362] , at:
>>>>> [ 42.750372] [<ffffffff813012b5>] nfs_get_client+0x105/0x5e0
>>>>> [ 42.750383]
>>>>> [ 42.750383] stack backtrace:
>>>>> [ 42.750394] CPU: 0 PID: 6440 Comm: mount.nfs4 Not tainted 4.9.0-rc3-00002-g7b6e7de #3
>>>>> [ 42.750406] Hardware name: Intel Corporation PURLEY/PURLEY, BIOS PLYDCRB1.MBH.0096.D23.1608240105 08/24/2016
>>>>> [ 42.750429] ffffc9000092fa68 ffffffff8150730f ffff88014ec8da40 0000000000000001
>>>>> [ 42.750452] ffffc9000092fa98 ffffffff810bc3f7 ffff880150b0b228 ffff88015068dbb0
>>>>> [ 42.750475] ffffc9000092fb38 ffff88014fc99180 ffffc9000092fac0 ffffffff81b243e5
>>>>> [ 42.750486] Call Trace:
>>>>> [ 42.750498] [<ffffffff8150730f>] dump_stack+0x67/0x98
>>>>> [ 42.750511] [<ffffffff810bc3f7>] lockdep_rcu_suspicious+0xe7/0x120
>>>>> [ 42.750524] [<ffffffff81b243e5>] rpc_clnt_xprt_switch_has_addr+0x115/0x150
>>>>> [ 42.750536] [<ffffffff813013f4>] nfs_get_client+0x244/0x5e0
>>>>> [ 42.750549] [<ffffffff813012ac>] ? nfs_get_client+0xfc/0x5e0
>>>>> [ 42.750561] [<ffffffff813568f8>] nfs4_set_client+0x98/0x130
>>>>> [ 42.750574] [<ffffffff8135872e>] nfs4_create_server+0x13e/0x390
>>>>> [ 42.750588] [<ffffffff8134cd0e>] nfs4_remote_mount+0x2e/0x60
>>>>> [ 42.750600] [<ffffffff811f3a29>] mount_fs+0x39/0x170
>>>>> [ 42.750614] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
>>>>> [ 42.750626] [<ffffffff8134cbec>] ? nfs_do_root_mount+0x3c/0xc0
>>>>> [ 42.750639] [<ffffffff8134cc36>] nfs_do_root_mount+0x86/0xc0
>>>>> [ 42.750652] [<ffffffff8134d014>] nfs4_try_mount+0x44/0xc0
>>>>> [ 42.750664] [<ffffffff81302097>] ? get_nfs_version+0x27/0x90
>>>>> [ 42.750677] [<ffffffff81310f8c>] nfs_fs_mount+0x4ac/0xd80
>>>>> [ 42.750689] [<ffffffff810bb938>] ? lockdep_init_map+0x88/0x1f0
>>>>> [ 42.750701] [<ffffffff81311ac0>] ? nfs_clone_super+0x130/0x130
>>>>> [ 42.750713] [<ffffffff8130f300>] ? param_set_portnr+0x70/0x70
>>>>> [ 42.750726] [<ffffffff811f3a29>] mount_fs+0x39/0x170
>>>>> [ 42.750740] [<ffffffff81214a0b>] vfs_kern_mount+0x6b/0x150
>>>>> [ 42.750752] [<ffffffff812176f1>] do_mount+0x1f1/0xd10
>>>>> [ 42.750765] [<ffffffff81217441>] ? copy_mount_options+0xa1/0x140
>>>>> [ 42.750777] [<ffffffff81218543>] SyS_mount+0x83/0xd0
>>>>> [ 42.750790] [<ffffffff81002abc>] do_syscall_64+0x5c/0x130
>>>>> [ 42.750802] [<ffffffff81c479a4>] entry_SYSCALL64_slow_path+0x25/0x25
>>>>>
>>>>> This rcu_dereference_check() was introduced by the following commit:
>>>>>
>>>>> commit 39e5d2df959dd4aea81fa33d765d2a5cc67a0512
>>>>> Author: Andy Adamson <andros@netapp.com>
>>>>> Date: Fri Sep 9 09:22:25 2016 -0400
>>>>>
>>>>> SUNRPC search xprt switch for sockaddr
>>>>>
>>>>> Signed-off-by: Andy Adamson <andros@netapp.com>
>>>>> Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
>>>>>
>>>>> Thanks,
>>>>> - Ross
>>>>
>>>> Thanks Ross,
>>
>> Hi Ross,
>>
>> Can you try this patch and let me know if it helps:
>>
>> http://git.linux-nfs.org/?p=anna/linux-nfs.git;a=commitdiff;h=bb29dd84333a96f309c6d0f88b285b5b78927058
>>
>> I'm planning on sending it to Linus soon, so it should be in rc5.
>
> Hi Anna,
>
> Yep, this patch makes the warning go away in my setup.
Great! Thanks for testing!
Anna
>
> Thanks,
> - Ross
>
^ permalink raw reply [flat|nested] 6+ messages in thread
end of thread, other threads:[~2016-11-08 17:56 UTC | newest]
Thread overview: 6+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-11-08 5:42 net/sunrpc/clnt.c:2773 suspicious rcu_dereference_check() usage! Ross Zwisler
2016-11-08 11:53 ` Jeff Layton
2016-11-08 12:09 ` Jeff Layton
2016-11-08 12:42 ` Anna Schumaker
2016-11-08 17:43 ` Ross Zwisler
2016-11-08 17:56 ` Anna Schumaker
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