Messages in this thread | | | Date | Mon, 14 Apr 2008 16:06:40 +0800 | From | Li Zefan <> | Subject | Re: kernel warning: tried to kill an mm-less task! |
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Balbir Singh wrote: > Li Zefan wrote: >> When I ran the same test program I described in a previous patch, >> I got the following warning: >> >> WARNING: at mm/oom_kill.c:320 __oom_kill_task+0x6d/0x101() >> Modules linked in: >> >> Pid: 3856, comm: a.out Not tainted 2.6.25-rc8-mm2 #37 >> [<ffffffff80243941>] warn_on_slowpath+0x64/0xa2 >> [<ffffffff80244e16>] printk+0x5e/0x7b >> [<ffffffff8022b096>] page_count+0x25/0x49 >> [<ffffffff8022b2cd>] show_mem+0x125/0x15a >> [<ffffffff8028f00f>] __oom_kill_task+0x6d/0x101 >> [<ffffffff8028f319>] oom_kill_process+0x16c/0x22e >> [<ffffffff8028f72c>] select_bad_process+0xb0/0x122 >> [<ffffffff8028f8d3>] mem_cgroup_out_of_memory+0x65/0x8a >> [<ffffffff802bee84>] mem_cgroup_charge_common+0xf8/0x215 >> [<ffffffff802a14ac>] handle_mm_fault+0x216/0x6c8 >> [<ffffffff8029ebca>] follow_page+0x191/0x27d >> [<ffffffff80234155>] need_resched+0x31/0x4f >> [<ffffffff802a1c53>] get_user_pages+0x2f5/0x3eb >> [<ffffffff802a1f64>] make_pages_present+0x9e/0xca >> [<ffffffff802a51fc>] mmap_region+0x38c/0x452 >> [<ffffffff802119c4>] arch_get_unmapped_area_topdown+0x1bf/0x2a7 >> [<ffffffff802a5971>] do_mmap_pgoff+0x321/0x39b >> [<ffffffff805037ee>] _cond_resched+0x1c/0x5f >> [<ffffffff80211715>] sys_mmap+0xf5/0x138 >> [<ffffffff8020c6d2>] tracesys+0xd5/0xda >> ---[ end trace fe959fb2f0473e7c ]--- >> tried to kill an mm-less task! >> >> This showed up several times in some seconds, but then didn't appear >> any more. And it's reproducable in a x86_64 box, but doesn't happen >> in a x86_32 one. >> >> And this happens both with and without the oops fixing. >> > > Could we get some more details on which task was chosen to be killed? It will be > nice to see the task flags as well to see if PF_EXITING is set. > > oom_kill_task() has a big WARNING in the comment > > /* WARNING: mm may not be dereferenced since we did not obtain its > * value from get_task_mm(p). This is OK since all we need to do is > * compare mm to q->mm below. > > > I want to see the flags to see if > > PF_BORROWED_MM or PF_EXIT* is set. > >
OK, I'll try.
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