From: Jason Gunthorpe <jgg@ziepe.ca>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Leonid Ravich <leonid.ravich@toganetworks.com>,
"linux-trace-kernel@vger.kernel.org"
<IMCEAMAILTO-linux-trace-kernel+40vger+2Ekernel+2Eorg@eurprd02.prod.outlook.com>,
"mingo@redhat.com" <mingo@redhat.com>,
"linux-rdma@vger.kernel.org" <linux-rdma@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Yigal Korman <yigal.korman@toganetworks.com>
Subject: Re: BUG: ib_mad ftrace event unsupported migration
Date: Wed, 2 Nov 2022 10:02:23 -0300 [thread overview]
Message-ID: <Y2JqX3vC1mG/JDex@ziepe.ca> (raw)
In-Reply-To: <20221102074457.08f538a8@rorschach.local.home>
On Wed, Nov 02, 2022 at 07:44:57AM -0400, Steven Rostedt wrote:
> > before starting throwing some patch into the the air I would like to align with you the approach we should take here.
> >
> > my suggestion here :
> > - ftrace infra should verify no migration happen (end and start happens on same CPU) in case not we will throw warning for the issue .
>
> The scheduler should have. On entering the ring buffer code
> ring_buffer_lock_reserver() it disables preemption and does not
> re-enable it until ring_buffer_unlock_commit().
>
> The only way to migrate is if you re-enable preemption. WHICH IS A
> BUG!
So what on earth did that?
I'm guessing some driver's query_pkey op, but AFAIK we don't have any
explicit pre-emption reenablements in the code - unless it is sneaky..
Leonid what driver are you testing?
Jason
next prev parent reply other threads:[~2022-11-02 13:02 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-11-02 10:49 BUG: ib_mad ftrace event unsupported migration Leonid Ravich
2022-11-02 11:44 ` Steven Rostedt
2022-11-02 13:02 ` Jason Gunthorpe [this message]
2022-11-02 14:02 ` Leonid Ravich
2022-11-02 14:04 ` Jason Gunthorpe
2022-11-02 14:17 ` Steven Rostedt
2022-11-02 14:24 ` Jason Gunthorpe
2022-11-02 15:59 ` Steven Rostedt
2022-11-02 16:01 ` Jason Gunthorpe
2022-11-02 20:01 ` Leonid Ravich
2022-11-02 22:19 ` Steven Rostedt
2022-11-03 12:22 ` Leonid Ravich
2022-11-03 16:32 ` Steven Rostedt
2022-11-02 14:20 ` Steven Rostedt
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