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	Tue, 17 Nov 2015 09:44:07 -0500
From: Stefan Priebe - Profihost AG <s.priebe@profihost.ag>
To: linux-netdev@vger.kernel.org
Subject: Asterisk deadlocks since Kernel 4.1
Cc: linux-fsdevel@vger.kernel.org, tglx@linutronix.de,
	linux-kernel@vger.kernel.org
Message-ID: <564B3D35.50004@profihost.ag>
Date: Tue, 17 Nov 2015 15:44:05 +0100
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Sender: linux-fsdevel-owner@vger.kernel.org
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Hello,

since Upgrading our Asterisk System from Kernel 3.18.17 to 4.1.13 it
deadlocks every few hours (kill -9 is the only thing working). Booting
with 3.18 again let it run smooth again.

An strace shows asterisk is looping like this:

[pid  6068] timerfd_gettime(8, , {it_interval={0, 20000000},
it_value={0, 140592906050976}}) = 0
[pid  6068] read(8, "\1\0\0\0\0\0\0\0", 8) = 8
[pid  6068] poll([{fd=9, events=POLLIN}, {fd=8, events=POLLIN|POLLPRI}],
2, 1000) = 1 ([{fd=8, revents=POLLIN}])
[pid  6068] timerfd_gettime(8, , {it_interval={0, 20000000},
it_value={0, 140592906050976}}) = 0
[pid  6068] read(8, "\1\0\0\0\0\0\0\0", 8) = 8
[pid  6068] poll([{fd=9, events=POLLIN}, {fd=8, events=POLLIN|POLLPRI}],
2, 1000) = 1 ([{fd=8, revents=POLLIN}])
[pid  6068] timerfd_gettime(8, , {it_interval={0, 20000000},
it_value={0, 140592906050976}}) = 0
[pid  6068] read(8, "\1\0\0\0\0\0\0\0", 8) = 8
[pid  6068] poll([{fd=9, events=POLLIN}, {fd=8, events=POLLIN|POLLPRI}],
2, 1000) = 1 ([{fd=8, revents=POLLIN}])
[pid  6068] timerfd_gettime(8, , {it_interval={0, 20000000},
it_value={0, 140592906050976}}) = 0
[pid  6068] read(8, "\1\0\0\0\0\0\0\0", 8) = 8
[pid  6068] poll([{fd=9, events=POLLIN}, {fd=8, events=POLLIN|POLLPRI}],
2, 1000) = 1 ([{fd=8, revents=POLLIN}])
[pid  6068] timerfd_gettime(8, , {it_interval={0, 20000000},
it_value={0, 140592906050976}}) = 0
[pid  6068] read(8, "\1\0\0\0\0\0\0\0", 8) = 8
[pid  6068] poll([{fd=9, events=POLLIN}, {fd=8, events=POLLIN|POLLPRI}],
2, 1000) = 1 ([{fd=8, revents=POLLIN}])
[pid  6068] timerfd_gettime(8, , {it_interval={0, 20000000},
it_value={0, 140592906050976}}) = 0
[pid  6068] read(8, "\1\0\0\0\0\0\0\0", 8) = 8
[pid  6068] poll([{fd=9, events=POLLIN}, {fd=8, events=POLLIN|POLLPRI}],
2, 1000) = 1 ([{fd=8, revents=POLLIN}])
[pid  6068] timerfd_gettime(8, , {it_interval={0, 20000000},
it_value={0, 140592906050976}}) = 0
[pid  6068] read(8, "\1\0\0\0\0\0\0\0", 8) = 8
[pid  6068] poll([{fd=9, events=POLLIN}, {fd=8, events=POLLIN|POLLPRI}],
2, 1000) = 1 ([{fd=8, revents=POLLIN}])
[pid  6068] timerfd_gettime(8, , {it_interval={0, 20000000},
it_value={0, 140592906050976}}) = 0
[pid  6068] read(8, "\1\0\0\0\0\0\0\0", 8) = 8
[pid  6068] poll([{fd=9, events=POLLIN}, {fd=8, events=POLLIN|POLLPRI}],
2, 1000) = 1 ([{fd=8, revents=POLLIN}])
[pid  6068] timerfd_gettime(8, , {it_interval={0, 20000000},
it_value={0, 140592906050976}}) = 0
[pid  6068] read(8, "\1\0\0\0\0\0\0\0", 8) = 8
[pid  6068] poll([{fd=9, events=POLLIN}, {fd=8, events=POLLIN|POLLPRI}],
2, 1000) = 1 ([{fd=8, revents=POLLIN}])
[pid  6068] timerfd_gettime(8, , {it_interval={0, 20000000},
it_value={0, 140592906050976}}) = 0

fd 8 is:

lrwx------ 1 root root 64 Nov 17 15:27 /proc/6025/fd/8 ->
anon_inode:[timerfd]


# cat /proc/6025/stack
[<ffffffff941d60e9>] poll_schedule_timeout+0x49/0x70
[<ffffffff941d76c7>] do_sys_poll+0x3d7/0x590
[<ffffffff941d78bc>] do_restart_poll+0x3c/0x70
[<ffffffff9408e7ff>] sys_restart_syscall+0x1f/0x30
[<ffffffff9463f1ee>] system_call_fastpath+0x12/0x71
[<ffffffffffffffff>] 0xffffffffffffffff

Any ideas how to debug this?

Greets,
Stefan