linux-kernel - Re: [PATCH] random: Support freezable kthreads in add_hwgenerator

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Date:   Wed, 4 Sep 2019 13:00:38 +0200
From:   Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To:     Herbert Xu <herbert@...dor.apana.org.au>,
        Stephen Boyd <swboyd@...omium.org>
Cc:     linux-kernel@...r.kernel.org, Theodore Ts'o <tytso@....edu>,
        linux-crypto@...r.kernel.org, Matt Mackall <mpm@...enic.com>,
        Keerthy <j-keerthy@...com>, Thomas Gleixner <tglx@...utronix.de>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH] random: Support freezable kthreads in
 add_hwgenerator_randomness()

On 2019-08-22 15:55:19 [+1000], Herbert Xu wrote:
> Patch applied.  Thanks.
[ ff296293b3538 ("random: Support freezable kthreads in add_hwgenerator_randomness()") ]

and since kthread_freezable_should_stop() has might_sleep() in it, I get
this:

|: do not call blocking ops when !TASK_RUNNING; state=1 set at [<00000000349d1489>] prepare_to_wait_event+0x5a/0x180
|: WARNING: CPU: 0 PID: 828 at kernel/sched/core.c:6741 __might_sleep+0x6f/0x80
|: Modules linked in:
|:
|: CPU: 0 PID: 828 Comm: hwrng Not tainted 5.3.0-rc7-next-20190903+ #46
|: RIP: 0010:__might_sleep+0x6f/0x80
…
|: Call Trace:
|:  kthread_freezable_should_stop+0x1b/0x60
|:  add_hwgenerator_randomness+0xdd/0x130
|:  hwrng_fillfn+0xbf/0x120
|:  kthread+0x10c/0x140
|:  ret_from_fork+0x27/0x50

Sebastian