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

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Date:   Wed, 22 May 2019 12:24:44 -0400
From:   "Theodore Ts'o" <tytso@....edu>
To:     kernel test robot <rong.a.chen@...el.com>
Cc:     linux-kernel@...r.kernel.org, LKP <lkp@...org>
Subject: Re: eb9d1bf079 [   88.881528] EIP: _random_read

Can you check and see if this addresses the issue?  I'm not able to
easily repro the softlockup.

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;
 	}