Re: [Crash-utility] [PATCHv2] Add the proccgroup extension

> And lastly, I only have one 3.14-based kernel, which shows this: > > crash> sys | grep RELEASE > RELEASE: 3.14.0-rc1+ > crash> showcg > showcg: zero-size memory allocation! (called from 7f3280273719) > crash> > > which would come a cgroup_subsys_arr value of 0 from here > > en_subsys_cnt = MEMBER_SIZE("css_set", "subsys") / sizeof(void *); > cgroup_subsys_arr = (ulong *)GETBUF(en_subsys_cnt * sizeof(ulong)); > > which depends upon CGROUP_SUBSYS_COUNT being something non-zero: > /* > * Set of subsystem states, one for each subsystem. This array is > * immutable after creation apart from the init_css_set during > * subsystem registration (at boot time). > */ > struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT]; > > And in that kernel apparently CONFIG_GROUPS was not configured and > therefore CGROUP_SUBSYS_COUNT is 0: But there is already logic in the initialization routine which should handle cases where CONFIG_CGROUP is not selected, simply by checking whether the "cgroups" member in task_struct exists. I checked on LXR and this member has always been protected by #ifdef CONFIG_CGROUPS. Maybe this is fedora kernel specific? Can you please take a look in the definition of task_struct whether the 'cgroups' member is protected by an ifdef guard? I can easily augment the check to consider the size of subsys array. I tested the code on 3.12 and on !CONFIG_CGROUPS the extension correctly bails out.