Re: [Patch 6/6] per task delay accounting taskstats interface: fix clone skbs for each listener

[Herbert Xu]

Andrew Morton <akpm@xxxxxxxx> wrote:
> On Tue, 11 Jul 2006 00:36:39 -0400
> Shailabh Nagar <nagar@xxxxxxxxxxxxxx> wrote:
> 
>>       down_write(&listeners->sem);
>>       list_for_each_entry_safe(s, tmp, &listeners->list, list) {
>> -             ret = genlmsg_unicast(skb, s->pid);
>> +             skb_next = NULL;
>> +             if (!list_islast(&s->list, &listeners->list)) {
>> +                     skb_next = skb_clone(skb_cur, GFP_KERNEL);
> 
> If we do a GFP_KERNEL allocation with this semaphore held, and the
> oom-killer tries to kill something to satisfy the allocation, and the
> killed task gets stuck on that semaphore, I wonder of the box locks up.

We do GFP_KERNEL inside semaphores/mutexes in lots of places.  So if this
can deadlock with the oom-killer we probably should fix that, preferably
by having GFP_KERNEL fail in that case.

Cheers,
-- 
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Email: Herbert Xu ~{PmV>HI~} <herbert@xxxxxxxxxxxxxxxxxxx>
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