Messages in this thread Patch in this message | | | From | Ming Liu <> | Subject | [PATCH V1] oom: avoid selecting threads sharing mm with init | Date | Thu, 26 Sep 2013 16:09:17 +0800 |
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It won't help free memory for killing tasks sharing mm with init, we should skip them in oom_unkillable_task(), or we may risk init process getting killed because after selecting a task to kill, the oom killer iterates all processes and kills all other user threads that share the same mm_struct in different thread groups.
In some extreme cases, the selected task happens to be a vfork child of init process sharing the same mm_struct with it, which causes kernel panic on init getting killed. This panic is observed in a busybox shell that busybox itself is init, with a kthread keeps consuming memories.
Signed-off-by: Ming Liu <ming.liu@windriver.com> --- mm/oom_kill.c | 11 +++++++++++ 1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/mm/oom_kill.c b/mm/oom_kill.c index 314e9d2..7e50a95 100644 --- a/mm/oom_kill.c +++ b/mm/oom_kill.c @@ -113,11 +113,22 @@ struct task_struct *find_lock_task_mm(struct task_struct *p) static bool oom_unkillable_task(struct task_struct *p, const struct mem_cgroup *memcg, const nodemask_t *nodemask) { + struct task_struct *init_tsk; + if (is_global_init(p)) return true; if (p->flags & PF_KTHREAD) return true; + /* It won't help free memory if p is sharing mm with init */ + rcu_read_lock(); + init_tsk = find_task_by_pid_ns(1, &init_pid_ns); + if(p->mm == init_tsk->mm) { + rcu_read_unlock(); + return true; + } + rcu_read_unlock(); + /* When mem_cgroup_out_of_memory() and p is not member of the group */ if (memcg && !task_in_mem_cgroup(p, memcg)) return true; -- 1.7.0.4
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