From: Steven Rostedt <rostedt@goodmis.org>
To: Leonid Ravich <lravich@gmail.com>
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 18:19:00 -0400 [thread overview]
Message-ID: <20221102181900.5bc9812f@rorschach.local.home> (raw)
In-Reply-To: <Y2LMjYNAE5LwtcOp@leonid-Inspiron-3421>
On Wed, 2 Nov 2022 22:01:17 +0200
Leonid Ravich <lravich@gmail.com> wrote:
> 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.
I test all for my code (NON_PREEMPT, VOLUNTEER_PREEMPT, PREEMPT) and
with and without lockdep enabled.
This would be a bug if you called kmalloc(X, GFP_KERNEL) in *any* non
preempt section.
>
> 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.
Well, I suppose we could add more documentation. Would that help? Where
would you see it? In the sample code?
I advise not even grabbing locks in trace events, because in most cases
lockdep will not catch any issues with them (it will be hidden unless
the trace event is enabled).
-- Steve
next prev parent reply other threads:[~2022-11-02 22:19 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
2022-11-02 22:19 ` Steven Rostedt [this message]
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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