Messages in this thread | | | Subject | Re: [syzbot? printk?] no WARN_ON() messages printed before "Kernel panic - not syncing: panic_on_warn set ..." | From | Tetsuo Handa <> | Date | Thu, 9 May 2019 19:40:28 +0900 |
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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...
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