Re: [PATCH] bugfix oom kill init lead panic

[Chenjie (K)]

My kernel version is 3.10 ,but the 4.3 is the same
and the newest code is

	for_each_process(p) {
		if (!process_shares_mm(p, mm))
			continue;
		if (same_thread_group(p, victim))
			continue;
		if (unlikely(p->flags & PF_KTHREAD))
			continue;
		if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
			continue;

so this not add the ïis_global_init also.

when we vfork (CLONE_VM) a process,the copy_mm
	if (clone_flags & CLONE_VM) {
		atomic_inc(&oldmm->mm_users);
		mm = oldmm;
		goto good_mm;
	}
use the parent mm.




On 2015/11/30 11:08, Andrew Morton wrote:
> On Mon, 30 Nov 2015 18:54:29 +0800 <chenjie6@xxxxxxxxxx> wrote:
>
> > From: chenjie <chenjie6@xxxxxxxxxx>
> >
> > when oom happened we can see:
> > Out of memory: Kill process 9134 (init) score 3 or sacrifice child
> > Killed process 9134 (init) total-vm:1868kB, anon-rss:84kB, file-rss:572kB
> > Kill process 1 (init) sharing same memory
> > ...
> > Kernel panic - not syncing: Attempted to kill init! exitcode=0x00000009
> >
> > That's because:
> > 	the busybox init will vfork a process,oom_kill_process found
> > the init not the children,their mm is the same when vfork.
> >
> > ...
> >
> > --- a/mm/oom_kill.c
> > +++ b/mm/oom_kill.c
> > @@ -513,7 +513,7 @@ void oom_kill_process(struct task_struct *p, gfp_t gfp_mask, int order,
> >   	rcu_read_lock();
> >   	for_each_process(p)
> >   		if (p->mm == mm && !same_thread_group(p, victim) &&
> > -		    !(p->flags & PF_KTHREAD)) {
> > +		    !(p->flags & PF_KTHREAD) && !is_global_init(p)) {
> >   			if (p->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
> >   				continue;
>
> What kernel version are you using?
>
> I don't think this can happen in current code...
>
> .

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