From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with SMTP id E84B26B01E3 for ; Fri, 23 Apr 2010 00:00:34 -0400 (EDT) Message-ID: <4BD11BCD.4070409@cn.fujitsu.com> Date: Fri, 23 Apr 2010 12:02:21 +0800 From: Li Zefan MIME-Version: 1.0 Subject: Re: [BUGFIX][PATCH] memcg rcu lock fix in swap code (Was Re: [BUG] an RCU warning in memcg References: <4BD10D59.9090504@cn.fujitsu.com> <20100423121424.ae47efcb.kamezawa.hiroyu@jp.fujitsu.com> <4BD118E2.7080307@cn.fujitsu.com> <4BD11A24.2070500@cn.fujitsu.com> <20100423125043.b3b964cd.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20100423125043.b3b964cd.kamezawa.hiroyu@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org To: KAMEZAWA Hiroyuki Cc: Balbir Singh , Daisuke Nishimura , "Paul E. McKenney" , "linux-mm@kvack.org" , LKML , "akpm@linux-foundation.org" List-ID: KAMEZAWA Hiroyuki wrote: > On Fri, 23 Apr 2010 11:55:16 +0800 > Li Zefan wrote: > >> Li Zefan wrote: >>> KAMEZAWA Hiroyuki wrote: >>>> On Fri, 23 Apr 2010 11:00:41 +0800 >>>> Li Zefan wrote: >>>> >>>>> with CONFIG_PROVE_RCU=y, I saw this warning, it's because >>>>> css_id() is not under rcu_read_lock(). >>>>> >>>> Ok. Thank you for reporting. >>>> This is ok ? >>> Yes, and I did some more simple tests on memcg, no more warning >>> showed up. >>> >> oops, after trigging oom, I saw 2 more warnings: >> > > ok, I will update. thank you. > one more: =================================================== [ INFO: suspicious rcu_dereference_check() usage. ] --------------------------------------------------- kernel/cgroup.c:4438 invoked rcu_dereference_check() without protection! other info that might help us debug this: rcu_scheduler_active = 1, debug_locks = 1 3 locks held by bash/2270: #0: (cgroup_mutex){+.+.+.}, at: [] cgroup_lock_live_group+0x17/0x30 #1: (&mm->mmap_sem){++++++}, at: [] mem_cgroup_can_attach+0xb2/0x130 #2: (&(&mm->page_table_lock)->rlock){+.+.-.}, at: [] mem_cgroup_count_precharge_pte_range+0x93/0x130 stack backtrace: Pid: 2270, comm: bash Not tainted 2.6.34-rc5-tip+ #14 Call Trace: [] ? printk+0x1d/0x1f [] lockdep_rcu_dereference+0x94/0xb0 [] css_id+0x5d/0x60 [] is_target_pte_for_mc+0x16f/0x1c0 [] ? _raw_spin_lock+0x6b/0x80 [] mem_cgroup_count_precharge_pte_range+0xbd/0x130 [] ? mem_cgroup_count_precharge_pte_range+0x0/0x130 [] walk_page_range+0x25d/0x3f0 [] mem_cgroup_can_attach+0xf4/0x130 [] ? mem_cgroup_count_precharge_pte_range+0x0/0x130 [] ? mem_cgroup_can_attach+0x0/0x130 [] cgroup_attach_task+0x70/0x280 [] cgroup_tasks_write+0x63/0x1c0 [] ? cgroup_tasks_write+0x90/0x1c0 [] cgroup_file_write+0x1f5/0x230 [] ? do_page_fault+0x0/0x500 [] ? up_read+0x1b/0x30 [] ? do_page_fault+0x205/0x500 [] vfs_write+0xa4/0x1a0 [] ? cgroup_file_write+0x0/0x230 [] sys_write+0x46/0x70 [] sysenter_do_call+0x12/0x36 -- 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