Messages in this thread | | | Date | Mon, 14 Apr 2008 13:31:45 +0530 | From | Balbir Singh <> | Subject | Re: kernel warning: tried to kill an mm-less task! |
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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.
-- Warm Regards, Balbir Singh Linux Technology Center IBM, ISTL
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