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Date: Mon, 27 Feb 2017 11:28:51 +0000 From: bugzilla-dae...@bugzilla.kernel.org To: step...@networkplumber.org Subject: [Bug 194723] New: connect() to localhost stalls after 4.9 -> 4.10 upgrade https://bugzilla.kernel.org/show_bug.cgi?id=194723 Bug ID: 194723 Summary: connect() to localhost stalls after 4.9 -> 4.10 upgrade Product: Networking Version: 2.5 Kernel Version: 4.10 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: high Priority: P1 Component: IPV4 Assignee: step...@networkplumber.org Reporter: l...@5t9.de Regression: No After upgrading a machine running the latest CentOS from using mainline kernel linux-4.9 to linux-4.10, attempts to connect() via IPv4 to localhost fail in about half of the cases, leaving the process trying to connect() stalled. Reproduction: > ncat -k -l 19999 & > C=1 ; while true ; do echo -n "$C " ; echo ping | ncat localhost 19999 ; > C=`expr $C + 1` ; sleep 1 ; done Using linux-4.10, the output looks like this: > 1 ping > 2 Ncat: Connection timed out. > 3 ping > 4 Ncat: Connection timed out. > 5 ping > 6 ping > 7 ping > 8 Ncat: Connection timed out. > 9 ping > 10 ping > 11 Ncat: Connection timed out. > 12 ping > 13 Ncat: Connection timed out. > 14 ping > 15 Ncat: Connection timed out. > 16 ping > 17 Ncat: Connection timed out. > 18 ping > 19 ping > 20 Ncat: Connection timed out. > 21 ping > 22 ping > 23 Ncat: Connection timed out. > 24 ping > 25 Ncat: Connection timed out. > 26 Ncat: Connection timed out. > 27 ping > 28 Ncat: Connection timed out. > 29 ping Using linux-4.9, the output looks like this: > 1 ping > 2 ping > 3 ping > 4 ping > 5 ping > 6 ping > 7 ping > 8 ping > 9 ping > 10 ping > 11 ping > 12 ping > 13 ping > 14 ping > 15 ping > 16 ping > 17 ping > 18 ping > 19 ping (The same behaviour was later also confirmed by a colleague on an Ubuntu running machine after upgrading to Ubuntu's 4.10 kernel.) -- You are receiving this mail because: You are the assignee for the bug.