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From: Herbert Xu <herbert@gondor.apana.org.au>
To: Edward Adam Davis <eadavis@qq.com>
Cc: davem@davemloft.net, linux-crypto@vger.kernel.org,
	linux-kernel@vger.kernel.org, olivia@selenic.com,
	syzbot+c52ab18308964d248092@syzkaller.appspotmail.com,
	syzkaller-bugs@googlegroups.com
Subject: Re: [PATCH] hwrng: core - fix task hung in hwrng_fillfn
Date: Sat, 2 Dec 2023 07:38:58 +0800	[thread overview]
Message-ID: <ZWpukgSDlA6UFR6e@gondor.apana.org.au> (raw)
In-Reply-To: <tencent_B2D2C5864C49BDAEE0AEC1CC9627E3C6CF06@qq.com>

On Fri, Dec 01, 2023 at 08:34:12PM +0800, Edward Adam Davis wrote:
>
> According to splat, after a page fault occurred, the attempt to retrieve 
> rcu_read_lock() failed, resulting in a timeout of 143s. This is my speculation.

Oh I see what's going on.  The reproducer is mapping /dev/hwrng, so
the write to user-space is then triggering another read which then
dead-locks.

Let me think about this.

Thanks,
-- 
Email: Herbert Xu <herbert@gondor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt

  reply	other threads:[~2023-12-01 23:39 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-25 13:21 [syzbot] [crypto?] INFO: task hung in hwrng_fillfn syzbot
2023-11-26  3:52 ` syzbot
2023-11-26  4:05 ` syzbot
2023-11-26  4:06 ` syzbot
2023-11-26  5:35 ` syzbot
2023-11-26  7:07 ` [PATCH] hwrng: core - fix " Edward Adam Davis
2023-12-01  9:56   ` Herbert Xu
2023-12-01 11:37     ` Edward Adam Davis
2023-12-01 11:41       ` Herbert Xu
2023-12-01 12:34         ` Edward Adam Davis
2023-12-01 23:38           ` Herbert Xu [this message]
2023-12-02  1:01             ` [PATCH] hwrng: core - Fix page fault dead lock on mmap-ed hwrng Herbert Xu
2023-12-12 14:03               ` PrasannaKumar Muralidharan
2023-11-29  2:59 ` [syzbot] [wireless?] WARNING in rate_control_rate_init syzbot

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