From mboxrd@z Thu Jan 1 00:00:00 1970 Received: by gv-out-0910.google.com with SMTP id l14so1348277gvf.19 for ; Mon, 18 Aug 2008 14:22:58 -0700 (PDT) Message-ID: <48A9E82E.3060009@gmail.com> Date: Mon, 18 Aug 2008 23:22:54 +0200 From: Jiri Slaby MIME-Version: 1.0 Subject: Re: [PATCH 1/1] mm_owner: fix cgroup null dereference References: <1218745013-9537-1-git-send-email-jirislaby@gmail.com> <48A49C78.7070100@linux.vnet.ibm.com> In-Reply-To: <48A49C78.7070100@linux.vnet.ibm.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org Return-Path: To: balbir@linux.vnet.ibm.com Cc: Andrew Morton , containers@lists.linux-foundation.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org List-ID: On 08/14/2008 10:58 PM, Balbir Singh wrote: > Jiri Slaby wrote: >> Hi, >> >> found this in mmotm, a fix for >> mm-owner-fix-race-between-swap-and-exit.patch >> > > Thanks for catching this Hmm, unfortunately there is one more issue with this patch. memrlimit_cgroup_subsys doesn't expect NULL new cgroup and NULL task. memrlimit_cgroup_mm_owner_changed blows up (called from cgroup_mm_owner_callbacks as ss->mm_owner_changed). I'm out for few days, please solve it somehow. Full oops message follows. BUG: unable to handle kernel NULL pointer dereference at 00000000000004ac IP: [] _spin_lock+0x9/0x20 PGD 3ef84067 PUD 0 Oops: 0002 [2] SMP last sysfs file: /sys/devices/platform/coretemp.1/temp1_input CPU 0 Modules linked in: usblp ath5k mac80211 cfg80211 arc4 ecb cryptomgr aead crypto_blkcipher crypto_algapi usbhid ohci1394 hid led_class ieee1394 evdev rtc_cmos floppy ff_memless [last unloaded: cfg80211] Pid: 27360, comm: automount Tainted: G D W 2.6.27-rc3-mm1_64 #441 RIP: 0010:[] [] _spin_lock+0x9/0x20 RSP: 0018:ffff88007839fd98 EFLAGS: 00010282 RAX: 0000000000000100 RBX: 0000000000000000 RCX: 0000000000000000 RDX: 0000000000000000 RSI: ffffffff807d5f28 RDI: 00000000000004ac RBP: ffff88007839fd98 R08: 00000000cc62b515 R09: 00000000f8f36e74 R10: 0000000000000001 R11: 0000000000000000 R12: 00000000000004ac R13: ffffffff807d5f28 R14: ffff880047e2e500 R15: ffff880047e2e680 FS: 00007fca50fa66f0(0000) GS:ffffffff8070a480(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005003b CR2: 00000000000004ac CR3: 000000004510f000 CR4: 00000000000006e0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 Process automount (pid: 27360, threadinfo ffff88007839e000, task ffff880047e2e500) Stack: ffff88007839fdb8 ffffffff80238ab3 ffffffff80589750 0000000000000000 ffff88007839fde8 ffffffff802b3f4b ffff8800010205b0 ffffffff80589750 0000000000000000 0000000000000000 ffff88007839fe18 ffffffff80270446 Call Trace: [] get_task_mm+0x23/0x60 [] memrlimit_cgroup_mm_owner_changed+0x1b/0x80 [] cgroup_mm_owner_callbacks+0x76/0x90 [] mm_update_next_owner+0x1c4/0x240 [] exit_mm+0x10a/0x150 [] do_exit+0x1dc/0x940 [] ? wake_up_state+0xb/0x10 [] ? signal_wake_up+0x38/0x40 [] do_group_exit+0x40/0xb0 [] sys_exit_group+0x12/0x20 [] system_call_fastpath+0x16/0x1b Code: 00 00 55 48 89 e5 fa f0 81 2f 00 00 00 01 74 05 e8 dd 17 de ff c9 c3 66 66 2e 0f 1f 84 00 00 00 00 00 55 b8 00 01 00 00 48 89 e5 66 0f c1 07 38 e0 74 06 f3 90 8a 07 eb f6 c9 c3 66 0f 1f 44 RIP [] _spin_lock+0x9/0x20 RSP CR2: 00000000000004ac ---[ end trace 4eaa2a86a8e2da22 ]--- -- 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