On 3.19-rc2 I'm getting:
[ 426.715480] WARNING: CPU: 2 PID: 7920 at kernel/sched/core.c:7303 __might_sleep+0x92/0xa0()
[ 426.715485] do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff810ad99f>] prepare_to_wait+0x2f/0x90
...
[ 426.715613] [<ffffffff81094eb4>] groups_alloc+0x34/0x110
[ 426.715638] [<ffffffffa00181da>] svcauth_unix_accept+0x14a/0x280 [sunrpc]
[ 426.715659] [<ffffffffa00170a8>] svc_authenticate+0xc8/0xe0 [sunrpc]
[ 426.715683] [<ffffffffa0012cf2>] svc_process_common+0x202/0x6d0 [sunrpc]
[ 426.715703] [<ffffffffa00135d8>] bc_svc_process+0x1c8/0x260 [sunrpc]
[ 426.715725] [<ffffffffa01da8e0>] nfs41_callback_svc+0x100/0x1b0 [nfsv4]
...
Looks like this is a new check added by 8eb23b9f35aa "sched: Debug
nested sleeps". I don't *think* it's catching a real problem here, but
maybe I'm missing some subtlety. I suppose nfs41_callback_svc() could
move the finish_wait() so it's done before the bc_svc_process()?
--b.
On Mon, 5 Jan 2015 15:20:26 -0500
"J. Bruce Fields" <[email protected]> wrote:
> On 3.19-rc2 I'm getting:
>
> [ 426.715480] WARNING: CPU: 2 PID: 7920 at kernel/sched/core.c:7303 __might_sleep+0x92/0xa0()
> [ 426.715485] do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff810ad99f>] prepare_to_wait+0x2f/0x90
> ...
> [ 426.715613] [<ffffffff81094eb4>] groups_alloc+0x34/0x110
> [ 426.715638] [<ffffffffa00181da>] svcauth_unix_accept+0x14a/0x280 [sunrpc]
> [ 426.715659] [<ffffffffa00170a8>] svc_authenticate+0xc8/0xe0 [sunrpc]
> [ 426.715683] [<ffffffffa0012cf2>] svc_process_common+0x202/0x6d0 [sunrpc]
> [ 426.715703] [<ffffffffa00135d8>] bc_svc_process+0x1c8/0x260 [sunrpc]
> [ 426.715725] [<ffffffffa01da8e0>] nfs41_callback_svc+0x100/0x1b0 [nfsv4]
> ...
>
> Looks like this is a new check added by 8eb23b9f35aa "sched: Debug
> nested sleeps". I don't *think* it's catching a real problem here, but
> maybe I'm missing some subtlety. I suppose nfs41_callback_svc() could
> move the finish_wait() so it's done before the bc_svc_process()?
>
Yeah, the current code looks quite goofy. We really shouldn't be doing
all of the bc_svc_process stuff while in TASK_INTERRUPTIBLE. Doing what
you suggest looks like the right fix to me.
--
Jeff Layton <[email protected]>
On Mon, 5 Jan 2015 14:00:03 -0800
Jeff Layton <[email protected]> wrote:
> On Mon, 5 Jan 2015 15:20:26 -0500
> "J. Bruce Fields" <[email protected]> wrote:
>
> > On 3.19-rc2 I'm getting:
> >
> > [ 426.715480] WARNING: CPU: 2 PID: 7920 at kernel/sched/core.c:7303 __might_sleep+0x92/0xa0()
> > [ 426.715485] do not call blocking ops when !TASK_RUNNING; state=1 set at [<ffffffff810ad99f>] prepare_to_wait+0x2f/0x90
> > ...
> > [ 426.715613] [<ffffffff81094eb4>] groups_alloc+0x34/0x110
> > [ 426.715638] [<ffffffffa00181da>] svcauth_unix_accept+0x14a/0x280 [sunrpc]
> > [ 426.715659] [<ffffffffa00170a8>] svc_authenticate+0xc8/0xe0 [sunrpc]
> > [ 426.715683] [<ffffffffa0012cf2>] svc_process_common+0x202/0x6d0 [sunrpc]
> > [ 426.715703] [<ffffffffa00135d8>] bc_svc_process+0x1c8/0x260 [sunrpc]
> > [ 426.715725] [<ffffffffa01da8e0>] nfs41_callback_svc+0x100/0x1b0 [nfsv4]
> > ...
> >
> > Looks like this is a new check added by 8eb23b9f35aa "sched: Debug
> > nested sleeps". I don't *think* it's catching a real problem here, but
> > maybe I'm missing some subtlety. I suppose nfs41_callback_svc() could
> > move the finish_wait() so it's done before the bc_svc_process()?
> >
>
> Yeah, the current code looks quite goofy. We really shouldn't be doing
> all of the bc_svc_process stuff while in TASK_INTERRUPTIBLE. Doing what
> you suggest looks like the right fix to me.
>
...and while we're on the subject...
Why is nfs41_callback_svc sleeping in TASK_INTERRUPTIBLE anyway? Do we
expect that kthread to receive signals? If not, perhaps we should go
ahead and switch that over to TASK_UNINTERRUPTIBLE instead?
--
Jeff Layton <[email protected]>