linux-kernel - Re: [syzbot] possible deadlock in vm_mmap

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Message-ID: <YJAc5EnwL59DNojt@hirez.programming.kicks-ass.net>
Date:   Mon, 3 May 2021 17:55:16 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Steven Rostedt <rostedt@...dmis.org>
Cc:     Hillf Danton <hdanton@...a.com>,
        syzbot <syzbot+f619f7c0a2a5f87694e6@...kaller.appspotmail.com>,
        linux-kernel@...r.kernel.org, Oleg Nesterov <oleg@...hat.com>,
        syzkaller-bugs@...glegroups.com, Jiri Olsa <jolsa@...hat.com>
Subject: Re: [syzbot] possible deadlock in vm_mmap_pgoff

On Wed, Apr 28, 2021 at 09:30:18AM -0400, Steven Rostedt wrote:

> > Break the lock chain by asking kworker to destroy perf event.
> > Thoughts other than workqueue are appreciated.
> 
> I think this could cause a problem with the delay.
> 
> This is called from event->destroy()
> 
> 
> 	if (event->destroy)
> 		event->destroy(event);
> 	module_put(pmu->module);

The uprobe and tracepoint pmus will never be a module.