oom_kill_task() kills the whole thread group, but only one task gets
TIF_MEMDIE. This can't be right, every test_thread_flag(TIF_MEMDIE)
check is per-thread.
I think it should be replaced by MMF_, but as a first step let's change
oom_kill_task() to mark every sub-thread as TIF_MEMDIE. And change the
"Kill all processes sharing p->mm" code the same way.
This also fixes another problem. sysctl_oom_kill_allocating_task case
does oom_kill_process(current). If current is not the main thread, then
select_bad_process() won't see the TIF_MEMDIE task.
Note:
- oom_kill_task()->for_each_process() is wrong. It can't detect
all processes sharing p->mm. The fix is simple
- This patch doesn't change other callers of set_*(TIF_MEMDIE).
This needs a separate discussion, but oom_kill_process() is
simply wrong.
Signed-off-by: Oleg Nesterov <oleg@xxxxxxxxxx>
---
mm/oom_kill.c | 18 ++++++++++++++----
1 file changed, 14 insertions(+), 4 deletions(-)
--- 38/mm/oom_kill.c~oom_kill_spread_memdie 2011-03-12 14:19:36.000000000 +0100
+++ 38/mm/oom_kill.c 2011-03-12 14:20:42.000000000 +0100
@@ -401,6 +401,18 @@ static void dump_header(struct task_stru
dump_tasks(mem, nodemask);
}
+static void do_oom_kill(struct task_struct *p)
+{
+ struct task_struct *t;
+
+ t = p;
+ do {
+ set_tsk_thread_flag(t, TIF_MEMDIE);
+ } while_each_thread(p, t);
+
+ force_sig(SIGKILL, p);
+}
+
#define K(x) ((x) << (PAGE_SHIFT-10))
static int oom_kill_task(struct task_struct *p, struct mem_cgroup *mem)
{
@@ -436,12 +448,10 @@ static int oom_kill_task(struct task_str
pr_err("Kill process %d (%s) sharing same memory\n",
task_pid_nr(q), q->comm);
task_unlock(q);
- force_sig(SIGKILL, q);
+ do_oom_kill(q);
}
- set_tsk_thread_flag(p, TIF_MEMDIE);
- force_sig(SIGKILL, p);
-
+ do_oom_kill(p);
/*
* We give our sacrificial lamb high priority and access to
* all the memory it needs. That way it should be able to
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