From: Leonid Ravich <lravich@gmail.com>
To: Steven Rostedt <rostedt@goodmis.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>,
Leonid Ravich <leonid.ravich@toganetworks.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>,
"linux-trace-kernel@vger.kernel.org"
<linux-trace-kernel@vger.kernel.org>
Subject: Re: BUG: ib_mad ftrace event unsupported migration
Date: Wed, 2 Nov 2022 22:01:17 +0200 [thread overview]
Message-ID: <Y2LMjYNAE5LwtcOp@leonid-Inspiron-3421> (raw)
In-Reply-To: <20221102115947.000897fa@rorschach.local.home>
> On Wed, 2 Nov 2022 11:24:20 -0300
> Jason Gunthorpe <jgg@ziepe.ca> wrote:
>
> > No, it doesn't muck with preemption, it will have some sleeping lock,
> > eg mlx5_ib_query_pkey() does a memory allocation as the first thing
> >
> > It seems like a bug that calling kmalloc(GFP_KERNEL)/might_sleep()
> > from within a tracepoint doesn't trigger a warning?
>
> Has nothing to do with tracepoints. You could call it a bug that it
> doesn't trigger a warning when preemption is disabled. But then again,
> it would if you enabled DEBUG_PREEMPT and possibly LOCKDEP too. So, I chalk
> this up to a lack of proper testing.
>
disagree, without CONFIG_PREEMPTION (which is the default case in some
destros) we will not get any warning, because there will not be
preamption disable.
second issue I see and maybe it is only me, is that the assuption of
atomicity in trace is not a common knowledge for trace users.
next prev parent reply other threads:[~2022-11-02 20:01 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
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 [this message]
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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