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Naresh reported that selftests: pidfd: pidfd_wait hangs on linux next kernel on
x86_64, i386 and arm64 Juno-r2
These devices are using NFS mounted rootfs.
I have tested pidfd testcases independently and all test PASS.
The Hang or exit from test run noticed when run by run_kselftest.sh
pidfd_wait.c:208:wait_nonblock:Expected sys_waitid(P_PIDFD, pidfd,
&info, WSTOPPED, NULL) (-1) == 0 (0)
wait_nonblock: Test terminated by assertion
metadata:
git branch: master
git repo: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
git commit: e64997027d5f171148687e58b78c8b3c869a6158
git describe: next-20200922
make_kernelversion: 5.9.0-rc6
kernel-config:
http://snapshots.linaro.org/openembedded/lkft/lkft/sumo/intel-core2-32/lkft/linux-next/865/config
The reason for this is a simple race in the selftests, that I overlooked and
which is more likely to hit when there's a lot of processes running on the
system. Basically the child process hasn't SIGSTOPed itself yet but the parent
is already calling waitid() on a O_NONBLOCK pidfd. Since it doesn't find a
WSTOPPED process it returns -EAGAIN correctly.
The fix for this is to move the line where we're removing the O_NONBLOCK
property from the fd before the waitid() WSTOPPED call so we hang until the
child becomes stopped.
Fixes:
|
||
|---|---|---|
| .. | ||
| .gitignore | ||
| config | ||
| Makefile | ||
| pidfd_fdinfo_test.c | ||
| pidfd_getfd_test.c | ||
| pidfd_open_test.c | ||
| pidfd_poll_test.c | ||
| pidfd_setns_test.c | ||
| pidfd_test.c | ||
| pidfd_wait.c | ||
| pidfd.h | ||