Messages in this thread | | | From | Zhaoyang Huang <> | Date | Tue, 10 Apr 2018 14:39:35 +0800 | Subject | Re: [PATCH v1] ringbuffer: Don't choose the process with adj equal OOM_SCORE_ADJ_MIN |
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On Tue, Apr 10, 2018 at 2:14 PM, Michal Hocko <mhocko@kernel.org> wrote: > On Tue 10-04-18 11:41:44, Zhaoyang Huang wrote: >> On Tue, Apr 10, 2018 at 11:12 AM, Steven Rostedt <rostedt@goodmis.org> wrote: >> > On Tue, 10 Apr 2018 10:32:36 +0800 >> > Zhaoyang Huang <huangzhaoyang@gmail.com> wrote: >> > >> >> For bellowing scenario, process A have no intension to exhaust the >> >> memory, but will be likely to be selected by OOM for we set >> >> OOM_CORE_ADJ_MIN for it. >> >> process A(-1000) process B >> >> >> >> i = si_mem_available(); >> >> if (i < nr_pages) >> >> return -ENOMEM; >> >> schedule >> >> ---------------> >> >> allocate huge memory >> >> <------------- >> >> if (user_thread) >> >> set_current_oom_origin(); >> >> >> >> for (i = 0; i < nr_pages; i++) { >> >> bpage = kzalloc_node >> > >> > Is this really an issue though? >> > >> > Seriously, do you think you will ever hit this? >> > >> > How often do you increase the size of the ftrace ring buffer? For this >> > to be an issue, the system has to trigger an OOM at the exact moment >> > you decide to increase the size of the ring buffer. That would be an >> > impressive attack, with little to gain. >> > >> > Ask the memory management people. If they think this could be a >> > problem, then I'll be happy to take your patch. >> > >> > -- Steve >> add Michael for review. >> Hi Michael, >> I would like suggest Steve NOT to set OOM_CORE_ADJ_MIN for the process >> with adj = -1000 when setting the user space process as potential >> victim of OOM. > > OOM_SCORE_ADJ_MIN means "hide the process from the OOM killer completely". > So what exactly do you want to achieve here? Because from the above it > sounds like opposite things. /me confused... > > -- > Michal Hocko > SUSE Labs Steve's patch intend to have the process be OOM's victim when it over-allocating pages for ring buffer. I amend a patch over to protect process with OOM_SCORE_ADJ_MIN from doing so. Because it will make such process to be selected by current OOM's way of selecting.(consider OOM_FLAG_ORIGIN first before the adj)
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