From mboxrd@z Thu Jan 1 00:00:00 1970 Message-ID: <48031090.5050002@cn.fujitsu.com> Date: Mon, 14 Apr 2008 16:06:40 +0800 From: Li Zefan MIME-Version: 1.0 Subject: Re: kernel warning: tried to kill an mm-less task! References: <4803030D.3070906@cn.fujitsu.com> <48030F69.7040801@linux.vnet.ibm.com> In-Reply-To: <48030F69.7040801@linux.vnet.ibm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: balbir@linux.vnet.ibm.com Cc: "linux-mm@kvack.org" , LKML , Andrew Morton , KAMEZAWA Hiroyuki , Pavel Emelianov List-ID: 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 >> [] warn_on_slowpath+0x64/0xa2 >> [] printk+0x5e/0x7b >> [] page_count+0x25/0x49 >> [] show_mem+0x125/0x15a >> [] __oom_kill_task+0x6d/0x101 >> [] oom_kill_process+0x16c/0x22e >> [] select_bad_process+0xb0/0x122 >> [] mem_cgroup_out_of_memory+0x65/0x8a >> [] mem_cgroup_charge_common+0xf8/0x215 >> [] handle_mm_fault+0x216/0x6c8 >> [] follow_page+0x191/0x27d >> [] need_resched+0x31/0x4f >> [] get_user_pages+0x2f5/0x3eb >> [] make_pages_present+0x9e/0xca >> [] mmap_region+0x38c/0x452 >> [] arch_get_unmapped_area_topdown+0x1bf/0x2a7 >> [] do_mmap_pgoff+0x321/0x39b >> [] _cond_resched+0x1c/0x5f >> [] sys_mmap+0xf5/0x138 >> [] 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. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org