The adaptive-rx and adaptive-tx checks use 'ethtool -c | grep -q' under 'set -o pipefail'. grep -q exits as soon as it finds a match, which can happen before ethtool finishes writing its output. When that occurs, ethtool receives SIGPIPE causing (uninformative): # selftests: drivers/net/netdevsim: ethtool-coalesce.sh # FAILED 1/22 checks not ok 1 selftests: drivers/net/netdevsim: ethtool-coalesce.sh # exit=1 This happens on debug kernels in NIPA, ~4% of the time. Link: https://patch.msgid.link/20260808163416.2456810-1-kuba@kernel.org Signed-off-by: Jakub Kicinski <kuba@kernel.org>