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Date: Wed, 22 Dec 2010 17:41:51 +0100
From: Johannes Weiner <hannes@cmpxchg.org>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: Thomas Meyer <thomas@m3y3r.de>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Balbir Singh <balbir@linux.vnet.ibm.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        Hugh Dickins <hughd@google.com>
Subject: Re: 2.6.37-rc7: NULL pointer dereference
Message-ID: <20101222164151.GA2048@cmpxchg.org>
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On Thu, Dec 23, 2010 at 12:37:11AM +0900, Minchan Kim wrote:
> Cced linux-mm and maintainers of memcg.
> 
> On Wed, Dec 22, 2010 at 9:25 PM, Thomas Meyer <thomas@m3y3r.de> wrote:
> > BUG: unable to handle kernel NULL pointer dereference at 00000008
> > IP: [<c04eae14>] __mem_cgroup_try_charge+0x234/0x430
> > *pde = 00000000
> > Oops: 0000 [#1]
> > last sysfs file: /sys/devices/platform/regulatory.0/uevent
> > Modules linked in: vfat fat usb_storage fuse sco bnep l2cap bluetooth cpufreq_ondemand acpi_cpufreq mperf ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 ip6table_filter ip6_tables kvm_intel kvm uinput arc4 ecb snd_hda_codec_hdmi snd_hda_codec_realtek iwlagn snd_hda_intel snd_hda_codec iwlcore uvcvideo snd_hwdep mac80211 snd_seq videodev snd_seq_device snd_pcm cfg80211 snd_timer rfkill v4l1_compat wmi snd pcspkr soundcore joydev serio_raw snd_page_alloc ipv6 sha256_generic aes_i586 aes_generic cbc dm_crypt [last unloaded: scsi_wait_scan]
> > Pid: 8058, comm: swapoff Tainted: G ? ? ? ? ?I 2.6.37-rc7 #221 JM11-MS/Aspire 1810T
> > EIP: 0060:[<c04eae14>] EFLAGS: 00010246 CPU: 0
> > EIP is at __mem_cgroup_try_charge+0x234/0x430
> > EAX: 00000008 EBX: 00000000 ECX: f2e71f10 EDX: f2f96380
> > ESI: f3e55860 EDI: 00020000 EBP: f2e71eb4 ESP: f2e71e54
> > ?DS: 007b ES: 007b FS: 0000 GS: 00e0 SS: 0068
> > Process swapoff (pid: 8058, ti=f2e70000 task=f3e55860 task.ti=f2e70000)
> > Stack:
> > ?f2e71e88 c0456607 26ba7c1c f3e55860 00000010 f3e55860 069d208a b2ee651d
> > ?00000008 000000d0 f2f96380 00000005 01ffffff f2e71f10 00000246 ec1a64ae
> > ?ffffffff 00000000 27b52eae f044dc84 00000000 f2f96380 00000000 000000d0
> > Call Trace:
> > ?[<c0456607>] ? ktime_get_ts+0x107/0x140
> > ?[<c04ebb89>] ? mem_cgroup_try_charge_swapin+0x49/0xb0
> > ?[<c04d9b4b>] ? unuse_mm+0x1db/0x300
> > ?[<c04dad9a>] ? sys_swapoff+0x2aa/0x890
> > ?[<c047cd58>] ? audit_syscall_entry+0x218/0x240
> > ?[<c047d043>] ? audit_syscall_exit+0x1f3/0x220
> > ?[<c0403013>] ? sysenter_do_call+0x12/0x22
> > Code: 55 c8 8b 82 90 01 00 00 85 c0 74 09 8b 80 7c 03 00 00 8b 58 2c 3b 1d 54 20 a9 c0 74 61 3b 1d 4c ca a4 c0 74 6a 8d 43 08 89 45 c0 <8b> 43 08 a8 01 0f 85 73 fe ff ff 8d 4b 04 89 5d bc 8d 76 00 8b
> > EIP: [<c04eae14>] __mem_cgroup_try_charge+0x234/0x430 SS:ESP 0068:f2e71e54
> > CR2: 0000000000000008

This could be explained by a kernel without VM_BUG_ON(), where
!mm->owner goes uncaught until css_tryget() reads mem.css.flags (eight
bytes member offset on 32-bit).

Does
	http://marc.info/?l=linux-mm&m=128889198016021&w=2
help?
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