oom: select_bad_process: check PF_KTHREAD instead of !mm to skip kthreads
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From: Oleg Nesterov on 1 Jun 2010 17:30 On 06/01, David Rientjes wrote: > > On Mon, 31 May 2010, KOSAKI Motohiro wrote: > > > select_bad_process() thinks a kernel thread can't have ->mm != NULL, this > > is not true due to use_mm(). > > > > Change the code to check PF_KTHREAD. > > This is already pushed in my oom killer rewrite as patch 14/18 "check > PF_KTHREAD instead of !mm to skip kthreads". > > This does not need to be merged immediately since it's not vital: use_mm() > is only temporary state and these kthreads will once again be excluded > when they call unuse_mm(). The worst case scenario here is that the oom > killer will erroneously select one of these kthreads which cannot die It can't die but force_sig() does bad things which shouldn't be done with workqueue thread. Note that it removes SIG_IGN, sets SIGNAL_GROUP_EXIT, makes signal_pending/fatal_signal_pedning true, etc. But yes, I agree, the problem is minor. But nevertheless it is bug, the longstanding bug with the simple fix. Why should we "hide" this fix inside the long series of non-trivial patches which rewrite oom-killer? And it is completely orthogonal to other changes. Oleg. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |