netdev - VRF and/or cgroups problem on Fedora-30, 5.2.21+ kernel

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Date:   Fri, 22 Nov 2019 16:03:37 -0800
From:   Ben Greear <greearb@...delatech.com>
To:     netdev <netdev@...r.kernel.org>
Cc:     David Ahern <dsahern@...il.com>
Subject: VRF and/or cgroups problem on Fedora-30, 5.2.21+ kernel

Hello,

We see a problem on a particular system when trying to run 'ip vrf exec _vrf1 ping 1.1.1.1'.
This system reproduces the problem all the time, but other systems with exact same (as far as
we can tell) software may fail occasionally, but then it will work again.

Here is an strace output.  I changed to the "/sys/fs/cgroup/unified/user.slice/user-1000.slice/session-2.scope/vrf/_vrf1"
directory as root user, and could view the files in that directory, so I'm not sure why the strace shows error 5.

Any idea what could be the problem and/or how to fix it or debug further?


This command was run as root user.

....

openat(AT_FDCWD, "/proc/15650/cgroup", O_RDONLY) = 5
fstat(5, {st_mode=S_IFREG|0444, st_size=0, ...}) = 0
read(5, "10:pids:/user.slice/user-1000.sl"..., 1024) = 274
close(5)                               = 0
mkdir("/sys", 0755)                     = -1 EEXIST (File exists)
mkdir("/sys", 0755)                     = -1 EEXIST (File exists)
mkdir("/sys/fs", 0755)                  = -1 EEXIST (File exists)
mkdir("/sys/fs", 0755)                  = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup", 0755)           = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup", 0755)           = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified", 0755)   = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified", 0755)   = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified/user.slice", 0755) = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified/user.slice", 0755) = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified/user.slice/user-1000.slice", 0755) = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified/user.slice/user-1000.slice", 0755) = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified/user.slice/user-1000.slice/session-2.scope", 0755) = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified/user.slice/user-1000.slice/session-2.scope", 0755) = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified/user.slice/user-1000.slice/session-2.scope/vrf", 0755) = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified/user.slice/user-1000.slice/session-2.scope/vrf", 0755) = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified/user.slice/user-1000.slice/session-2.scope/vrf/_vrf1", 0755) = -1 EEXIST (File exists)
mkdir("/sys/fs/cgroup/unified/user.slice/user-1000.slice/session-2.scope/vrf/_vrf1", 0755) = -1 EEXIST (File exists)
openat(AT_FDCWD, "/sys/fs/cgroup/unified/user.slice/user-1000.slice/session-2.scope/vrf/_vrf1", O_RDONLY|O_DIRECTORY) = 5
bpf(BPF_PROG_LOAD, {prog_type=BPF_PROG_TYPE_CGROUP_SOCK, insn_cnt=6, insns=0x7ffc8e5d1e00, license="GPL", log_level=1, log_size=262144, log_buf="", 
kern_version=KERNEL_VERSION(0, 0, 0), prog_flags=0, prog_name="", prog_ifindex=0, expected_attach_type=BPF_CGROUP_INET_INGRESS, prog_btf_fd=0, 
func_info_rec_size=0, func_info=NULL, func_info_cnt=0, line_info_rec_size=0, line_info=NULL, line_info_cnt=0}, 112) = -1 EPERM (Operation not permitted)
write(2, "Failed to load BPF prog: 'Operat"..., 51Failed to load BPF prog: 'Operation not permitted'


Thanks,
Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com