On 28 Apr 2014, Hannes Frederic Sowa uttered the following: > On Mon, Apr 28, 2014 at 04:35:38PM +0100, Nix wrote: >> /proc/$pid/stack of the two communicating ssh daemons was instructive: >> >> [<ffffffff814e3512>] unix_wait_for_peer+0x9f/0xbc >> [<ffffffff814e5d48>] unix_dgram_sendmsg+0x41b/0x534 > > This one is a dgram socket... > >> [<ffffffff8146618f>] sock_sendmsg+0x84/0x9e >> [<ffffffff81467f3d>] SyS_sendto+0x10e/0x13f >> [<ffffffff815770e2>] system_call_fastpath+0x16/0x1b >> [<ffffffffffffffff>] 0xffffffffffffffff >> spindle:/var/log.real/by-facility# cat /proc/5941/stack >> [<ffffffff814e493a>] unix_stream_recvmsg+0x289/0x6d5 > > ...and that's a stream receiver. > >> [<ffffffff814673e0>] sock_aio_read.part.12+0xf0/0xff >> [<ffffffff8146740b>] sock_aio_read+0x1c/0x28 >> [<ffffffff811388fd>] do_sync_read+0x59/0x78 >> [<ffffffff81138d8b>] vfs_read+0xa2/0x13f >> [<ffffffff81139699>] SyS_read+0x47/0x8b >> [<ffffffff81577259>] tracesys+0xd0/0xd5 >> [<ffffffffffffffff>] 0xffffffffffffffff > > Are you sure those are the communicating tasks? Normally I'd say yes. This time I'd say probably not. I am very much not at my best right now. I'll wait for it to implode and try the same thing again. On past form I won't have to wait very many days... (this time, there was a six-hour interval between boot and misbehaviour. Whatever the misbehaviour *is*.) One more instance I didn't share because I only have one end of it: starting up ISC dhcpd 4.2.4 also hung unexpectedly (which it did not after rebooting): [<ffffffff814e3512>] unix_wait_for_peer+0x9f/0xbc [<ffffffff814e5d48>] unix_dgram_sendmsg+0x41b/0x534 [<ffffffff8146618f>] sock_sendmsg+0x84/0x9e [<ffffffff81467f3d>] SyS_sendto+0x10e/0x13f [<ffffffff815770e2>] system_call_fastpath+0x16/0x1b [<ffffffffffffffff>] 0xffffffffffffffff The common factor in these hangs is definitely unix_wait_for_peer. The question is, what are they talking to? (In theory this could be a userspace bug... but what common userspace factor is there between the NFS server, OpenSSH, and ISC dhcpd? If it helps, named pipes may well be suffering from the same malaise: /sbin/shutdown from sysvinit also hangs and I have to /sbin/reboot -f instead. I'll check next time it hits, but I'll bet it's trying to talk over /dev/initctl and getting nowhere.) -- To unsubscribe from this list: send the line "unsubscribe linux-nfs" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
