On Tue, Jul 19, 2016 at 07:52:28PM +0900, Tetsuo Handa wrote: > On 2016/07/19 8:18, Dave Jones wrote: > > Whoa. Why did it pick systemd-journal ? > > I guess that it is because all trinity processes' mm already had MMF_OOM_REAPED set. > > The OOM reaper sets MMF_OOM_REAPED when OOM reap operation succeeded. But > "[ pid ] uid tgid total_vm rss nr_ptes nr_pmds swapents oom_score_adj name" listing > includes processes whose mm already has MMF_OOM_REAPED set. As a result, trinity-c15 and > trinity-c4 are shown again in the listing. While I can't confirm that trinity-c10, trinity-c2, > trinity-c0 and trinity-c11 are already OOM killed, I guess they are already OOM killed and > their mm already had MMF_OOM_REAPED set. That still doesn't explain why it picked the journal process, instead of waiting until the previous reaping operation had actually killed those Trinity tasks. > > My 'skip over !trinity processes' code kicks in, and it then kills the right processes, and the box lives on, > > but if I hadn't have had that diff, the wrong process would have been killed. > > As of Linux 4.7, processes whose mm already has MMF_OOM_REAPED can be selected for many > times due to not checking MMF_OOM_REAPED when using task_will_free_mem() shortcut in > out_of_memory(). (It will be fixed in Linux 4.8.) That is, I guess that your system had > already hit > > panic("Out of memory and no killable processes...\n") > > if trinity processes with MMF_OOM_REAPED mm were not selected again and again. That panic was not hit. The machine continued running after killing the right tasks. Dave -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx"> email@xxxxxxxxx </a>