Li Zefan wrote: >>>>> How cute... Same mountpoint in both, so these mount(2) will sometimes >>>>> fail (cgroup picks the same sb on the same options, AFAICS) and fail >>>>> silently due to these redirects... >>>>> >>>>> That's a lovely way to stress-test a large part of ro-bind stuff *and* >>>>> umount()-related code. Could you do C equivalent of the above (just >>>>> the same syscalls in loop, nothing fancier) and do time-stamped strace? >>>>> >>>> Sure, I'll write a C version and try to reproduce the warning. >>>> >>> Unfortunately, the C equivalent can't reproduce the warning, I've run the >>> test for the whole night. :( While using the script, often I can trigger >>> the warning in several mins. >> Ho-hum... I wonder if we are hitting cgroup_clone() in all that fun... > > I don't think so, I think cgroup_clone() will be called only if namespace is > used, like clone(CLONE_NEWNS). Even if cgroup_clone() gets called, it will > return before doing any vfs work unless the ns_cgroup subsystem is mounted. > But the following testcase can also trigger the warning: thread 1: for ((; ;)) { mount -t cgroup -o ns xxx cgroup/ > /dev/null 2>&1 # remove the dirs generated by cgroup_clone() rmdir cgroup/[1-9]* > /dev/null 2>&1 umount cgroup/ > /dev/null 2>&1 } thread 2: int foo(void *arg) { return 0; } char *stack[4096]; int main(int argc, char **argv) { int usec = DEFAULT_USEC; while (1) { usleep(usec); # cgroup_clone() will be called clone(foo, stack+4096, CLONE_NEWNS, NULL); } return 0; } _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/containers