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Date:   Mon, 16 Sep 2019 10:42:39 -0400
From:   Steven Rostedt <rostedt@goodmis.org>
To:     Qian Cai <cai@lca.pw>
Cc:     Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
        Petr Mladek <pmladek@suse.com>,
        Catalin Marinas <catalin.marinas@arm.com>,
        Will Deacon <will@kernel.org>,
        Dan Williams <dan.j.williams@intel.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org,
        Peter Zijlstra <peterz@infradead.org>,
        Waiman Long <longman@redhat.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        Theodore Ts'o <tytso@mit.edu>, Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Subject: Re: page_alloc.shuffle=1 + CONFIG_PROVE_LOCKING=y = arm64 hang
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On Thu, 12 Sep 2019 08:05:41 -0400
Qian Cai <cai@lca.pw> wrote:

> >  drivers/char/random.c | 7 ++++---
> >  1 file changed, 4 insertions(+), 3 deletions(-)
> > 
> > diff --git a/drivers/char/random.c b/drivers/char/random.c
> > index 9b54cdb301d3..975015857200 100644
> > --- a/drivers/char/random.c
> > +++ b/drivers/char/random.c
> > @@ -1687,8 +1687,9 @@ static void _warn_unseeded_randomness(const char *func_name, void *caller,
> >  	print_once = true;
> >  #endif
> >  	if (__ratelimit(&unseeded_warning))
> > -		pr_notice("random: %s called from %pS with crng_init=%d\n",
> > -			  func_name, caller, crng_init);
> > +		printk_deferred(KERN_NOTICE "random: %s called from %pS "
> > +				"with crng_init=%d\n", func_name, caller,
> > +				crng_init);
> >  }
> >  
> >  /*
> > @@ -2462,4 +2463,4 @@ void add_bootloader_randomness(const void *buf, unsigned int size)
> >  	else
> >  		add_device_randomness(buf, size);
> >  }
> > -EXPORT_SYMBOL_GPL(add_bootloader_randomness);
> > \ No newline at end of file
> > +EXPORT_SYMBOL_GPL(add_bootloader_randomness);  
> 
> This will also fix the hang.
> 
> Sergey, do you plan to submit this Ted?

Perhaps for a quick fix (and a comment that says this needs to be fixed
properly). I think the changes to printk() that was discussed at
Plumbers may also solve this properly.

-- Steve