linux-kernel - Re: eb9d1bf079 [ 88.881528] EIP: _random

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Message-ID: <5408d2e0-53ec-55ee-3ad5-b6c797a9cf5a@intel.com>
Date:   Tue, 28 May 2019 08:19:04 +0800
From:   Rong Chen <rong.a.chen@...el.com>
To:     Theodore Ts'o <tytso@....edu>, linux-kernel@...r.kernel.org,
        LKP <lkp@...org>
Subject: Re: eb9d1bf079 [ 88.881528] EIP: _random_read


On 5/23/19 12:24 AM, Theodore Ts'o wrote:
> Can you check and see if this addresses the issue?  I'm not able to
> easily repro the softlockup.

Hi,

The patch could fix the issue in our testing environment.

Best Regards,
Rong Chen


>
> Thanks!
>
> 						- Ted
>
> commit f93d3e94983bf8b4697ceb121c79afd941862860
> Author: Theodore Ts'o <tytso@....edu>
> Date:   Wed May 22 12:02:16 2019 -0400
>
>      random: fix soft lockup when trying to read from an uninitialized blocking pool
>      
>      Fixes: eb9d1bf079bb: "random: only read from /dev/random after its pool has received 128 bits"
>      Reported-by: kernel test robot <lkp@...el.com>
>      Signed-off-by: Theodore Ts'o <tytso@....edu>
>
> diff --git a/drivers/char/random.c b/drivers/char/random.c
> index a42b3d764da8..9cea93d0bfb3 100644
> --- a/drivers/char/random.c
> +++ b/drivers/char/random.c
> @@ -1936,8 +1936,8 @@ _random_read(int nonblock, char __user *buf, size_t nbytes)
>   			return -EAGAIN;
>   
>   		wait_event_interruptible(random_read_wait,
> -			ENTROPY_BITS(&input_pool) >=
> -			random_read_wakeup_bits);
> +		    blocking_pool.initialized &&
> +		    (ENTROPY_BITS(&input_pool) >= random_read_wakeup_bits));
>   		if (signal_pending(current))
>   			return -ERESTARTSYS;
>   	}