Comment 27 for bug 1887661

I can confirm the issue is now fixed on the 5.4 kernels.

Results with bionic/linux-oracle-5.4 5.4.0-1053.57~18.04.1:

# selftests: net: pmtu.sh
# TEST: ipv4: PMTU exceptions [ OK ]
# TEST: ipv6: PMTU exceptions [ OK ]
# vxlan4 not supported
# TEST: IPv4 over vxlan4: PMTU exceptions [SKIP]
# vxlan4 not supported
# TEST: IPv6 over vxlan4: PMTU exceptions [SKIP]
# TEST: IPv4 over vxlan6: PMTU exceptions [ OK ]
# TEST: IPv6 over vxlan6: PMTU exceptions [ OK ]
# geneve4 not supported
# TEST: IPv4 over geneve4: PMTU exceptions [SKIP]
# geneve4 not supported
# TEST: IPv6 over geneve4: PMTU exceptions [SKIP]
# TEST: IPv4 over geneve6: PMTU exceptions [ OK ]
# TEST: IPv6 over geneve6: PMTU exceptions [ OK ]
# TEST: IPv4 over fou4: PMTU exceptions [ OK ]
# TEST: IPv6 over fou4: PMTU exceptions [ OK ]
# TEST: IPv4 over fou6: PMTU exceptions [ OK ]
# TEST: IPv6 over fou6: PMTU exceptions [ OK ]
# TEST: IPv4 over gue4: PMTU exceptions [ OK ]
# TEST: IPv6 over gue4: PMTU exceptions [ OK ]
# TEST: IPv4 over gue6: PMTU exceptions [ OK ]
# TEST: IPv6 over gue6: PMTU exceptions [ OK ]
# TEST: vti6: PMTU exceptions [ OK ]
# TEST: vti4: PMTU exceptions [ OK ]
# TEST: vti4: default MTU assignment [ OK ]
# TEST: vti6: default MTU assignment [ OK ]
# TEST: vti4: MTU setting on link creation [ OK ]
# TEST: vti6: MTU setting on link creation [ OK ]
# TEST: vti6: MTU changes on link changes [ OK ]
# vxlan4 not supported
# TEST: ipv4: cleanup of cached exceptions [SKIP]
# TEST: ipv6: cleanup of cached exceptions [ OK ]
# TEST: ipv4: list and flush cached exceptions [ OK ]
# TEST: ipv6: list and flush cached exceptions [ OK ]
# TEST: ipv4: PMTU exception w/route replace [ OK ]
# TEST: ipv6: PMTU exception w/route replace [ OK ]
ok 16 selftests: net: pmtu.sh