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From: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
To: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
	Petr Mladek <pmladek@suse.com>,
	LKML <linux-kernel@vger.kernel.org>,
	syzkaller <syzkaller@googlegroups.com>
Subject: Re: [syzbot? printk?] no WARN_ON() messages printed before "Kernel panic - not syncing: panic_on_warn set ..."
Date: Thu, 9 May 2019 19:40:28 +0900	[thread overview]
Message-ID: <1f0f2e88-a6ed-4bb8-4e91-869708c8dc58@i-love.sakura.ne.jp> (raw)
In-Reply-To: <20190509101830.GB23572@jagdpanzerIV>

On 2019/05/09 19:18, Sergey Senozhatsky wrote:
> What are these lines right before the kernel panic output?
> TTY writes (user space logging)?

I guess that the user space is calling printf() on stdout
which will be readable as console output.

> 
> 
> 03:54:05 executing program 5:
> syz_mount_image$xfs(&(0x7f0000000000)='xfs\x00', &(0x7f0000000040)='./file0\x00', 0x0, 0x0, 0x0, 0xe003, &(0x7f00000005c0)={[{@nolargeio='nolargeio'}]})
> 
> 03:54:06 executing program 2:
> syz_emit_ethernet(0x66, &(0x7f0000000080)={@local, @random="029cce98941b", [], {@ipv6={0x86dd, {0x0, 0x6, 'v`Q', 0x30, 0x3a, 0xffffffffffffffff, @remote={0xfe, 0x80, [0x29c, 0x0, 0x700, 0x5], 0xffffffffffffffff}, @mcast2={0xff, 0x2, [0x0, 0xfffffffffffff000]}, {[], @icmpv6=@dest_unreach={0xffffff86, 0x0, 0x0, 0x0, [0x7], {0x0, 0x6, "c5961e", 0x0, 0x0, 0x0, @mcast1={0xff, 0x1, [0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x3, 0x3, 0x0, 0x0, 0x8906], 0x8200}, @mcast2}}}}}}}, 0x0)
> 
> [ 2396.035331][T10223] Kernel panic - not syncing: panic_on_warn set ...
> [ 2396.042217][T10223] CPU: 0 PID: 10223 Comm: syz-executor.1 Not tainted 5.1.0-next-20190507 #2
> 
> 
> Hmm... Dunno... Don't really have any explanations yet...
> 
> Can you add
> 
> 	if (oops_in_progress)
> 		return IRQ_HANDLED;
> 
> to you console driver's IRQ handler (xmit TX/RX path)? Just to
> check if this will change anything...

The first userspace timestamp available is

  03:51:19 executing program 2:
  syz_emit_ethernet(0x66, &(0x7f0000000080)={@local, @random="029cce98941b", [], {@ipv6={0x86dd, {0x0, 0x6, 'v`Q', 0x30, 0x3a, 0xffffffffffffffff, @remote={0xfe, 0x80, [0x29c, 0x0, 0x700, 0x5], 0xffffffffffffffff}, @mcast2={0xff, 0x2, [0x0, 0xfffffffffffff000]}, {[], @icmpv6=@dest_unreach={0xffffff86, 0x0, 0x0, 0x0, [0x7], {0x0, 0x6, "c5961e", 0x0, 0x0, 0xf5ffffff00000000, @mcast1={0xff, 0x1, [0x0, 0x0, 0x0, 0x0, 0x0, 0x0, 0x3, 0x3], 0x8200}, @mcast2}}}}}}}, 0x0)

which means that there was no printk() message for nearly 3 minutes.
Can't be oops_in_progress for such long period.

Since printk() timestamp says that the uptime is nearly 40 minutes, I think
that something changed console loglevel (in a way console_verbose() from
panic() can restore) many minutes ago from the crash...


  reply	other threads:[~2019-05-09 10:40 UTC|newest]

Thread overview: 29+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-03-16  2:09 [syzbot? printk?] no WARN_ON() messages printed before "Kernel panic - not syncing: panic_on_warn set ..." Tetsuo Handa
2019-03-16  9:11 ` Dmitry Vyukov
2019-03-16 10:18   ` Tetsuo Handa
2019-03-16 14:14     ` Sergey Senozhatsky
2019-03-16 14:16       ` Dmitry Vyukov
2019-03-16 14:40         ` Sergey Senozhatsky
2019-03-16 14:53         ` Tetsuo Handa
2019-03-16 14:57           ` Dmitry Vyukov
2019-03-16 15:02             ` Tetsuo Handa
2019-03-16 15:10               ` Dmitry Vyukov
2019-03-18  5:27                 ` Tetsuo Handa
2019-03-18 12:07                   ` Dmitry Vyukov
2019-03-18 12:32                     ` Dmitry Vyukov
2019-03-18 12:39                       ` Dmitry Vyukov
2019-03-19  0:41                         ` Tetsuo Handa
2019-03-18 12:50                       ` Sergey Senozhatsky
2019-03-18 13:42                         ` Dmitry Vyukov
2019-03-18 14:09                           ` Sergey Senozhatsky
2019-03-19  8:10                             ` Dmitry Vyukov
2019-03-19 12:35                               ` Sergey Senozhatsky
2019-03-19 13:35                                 ` Dmitry Vyukov
2019-05-08 10:31                                   ` Tetsuo Handa
2019-05-09  9:58                                     ` Sergey Senozhatsky
2019-05-09 10:18                                       ` Sergey Senozhatsky
2019-05-09 10:40                                         ` Tetsuo Handa [this message]
2019-05-09 10:26                                       ` Tetsuo Handa
2019-05-09 10:36                                         ` Sergey Senozhatsky
2019-05-10 14:12                                     ` Petr Mladek
2019-05-10 14:53                                       ` Tetsuo Handa

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