Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751473AbaLZRkA (ORCPT ); Fri, 26 Dec 2014 12:40:00 -0500 Received: from mx1.redhat.com ([209.132.183.28]:60878 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751285AbaLZRj7 (ORCPT ); Fri, 26 Dec 2014 12:39:59 -0500 Date: Fri, 26 Dec 2014 18:38:49 +0100 From: Oleg Nesterov To: Leon Ma , Al Viro Cc: akpm@linux-foundation.org, mhocko@suse.cz, mingo@kernel.org, peterz@infradead.org, riel@redhat.com, ionut.m.alexa@gmail.com, peter@hurleysoftware.com, linux-kernel@vger.kernel.org, di.zhang@intel.com, zhonghua.sun@intel.com Subject: Re: [PATCH] move exit_task_work() before exit_fs(). Message-ID: <20141226173849.GA9460@redhat.com> References: <1419579926-28512-1-git-send-email-xindong.ma@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1419579926-28512-1-git-send-email-xindong.ma@intel.com> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/26, Leon Ma wrote: > > We encountered following panic. The scenario is the process is exiting and executing its > task work. When closing dev node, the driver triggers a firmware reload according to device > status. Because task->fs is set to NULL in exit_fs(), panic happens. I think this should be fixed somewhere else... > Task work is a common interface, we should not limite the resource the user will utilize. Exactly. And note that with this patch exit_mm()..disassociate_ctty() paths can't use task works. Not to mention that this patch moves exit_files() up, even before exit_mm(), without any explanation. Add Al. May be we can move exit_fs() down after exit_task_work(), I dunno, but to me it would be better to change the driver. > [ 118.521972] task: ffff880038de5cd0 ti: ffff880038e86000 task.ti: ffff880038e86000 > [ 118.521977] RIP: 0010:[] [] path_init+0x336/0x440 > [ 118.521986] RSP: 0000:ffff880038e876a0 EFLAGS: 00010246 > [ 118.521991] RAX: 0000000000000000 RBX: ffff880038e87790 RCX: 0000000000000071 > [ 118.521996] RDX: ffff88003f30f5d4 RSI: ffffffff82179f75 RDI: ffffffff8209b167 > [ 118.522000] RBP: ffff880038e876e0 R08: ffff880038e87730 R09: ffff8800218b44c0 > [ 118.522005] R10: 0000000000000000 R11: 000000000000000f R12: ffff880038ebf000 > [ 118.522010] R13: ffff880038e87870 R14: ffff880038e87850 R15: 00000000ffffff9c > [ 118.522015] FS: 0000000000000000(0000) GS:ffff88003f300000(0000) knlGS:0000000000000000 > [ 118.522020] CS: 0010 DS: 002b ES: 002b CR0: 0000000080050033 > [ 118.522025] CR2: 0000000000000020 CR3: 0000000039d4f000 CR4: 00000000001007e0 > [ 118.522030] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 118.522035] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > [ 118.522039] Stack: > [ 118.522043] ffff880038dbc300 ffff880038e876b8 ffffffff822cf046 ffff88002e434f00 > [ 118.522056] ffff880038e87790 ffff880038e87870 ffff880038e87850 00000000ffffff9c > [ 118.522069] ffff880038e87780 ffffffff8217d419 ffff88003b1de480 ffff88003bbf7700 > [ 118.522082] Call Trace: > [ 118.522092] [] ? security_file_alloc+0x16/0x20 > [ 118.522100] [] path_openat+0x69/0x4b0 > [ 118.522109] [] ? is_connected_output_ep+0x15f/0x260 > [ 118.522117] [] do_filp_open+0x39/0x90 > [ 118.522125] [] ? string.isra.3+0x3a/0xe0 > [ 118.522133] [] ? vsnprintf+0x209/0x620 > [ 118.522141] [] file_open_name+0xb2/0xf0 > [ 118.522148] [] filp_open+0x36/0x40 > [ 118.522157] [] _request_firmware+0x351/0x9c0 > [ 118.522164] [] request_firmware+0x16/0x20 > [ 118.522172] [] sst_request_fw+0x63/0x510 > [ 118.522180] [] ? __mutex_lock_slowpath+0x280/0x3b0 > [ 118.522188] [] sst_load_fw+0x1f7/0x4a0 > [ 118.522195] [] sst_download_fw+0xf/0x60 > [ 118.522202] [] intel_sst_check_device+0x92/0x1f0 > [ 118.522209] [] sst_set_generic_params+0x18d/0x500 > [ 118.522218] [] sst_fill_and_send_cmd.constprop.7+0x95/0x130 > [ 118.522226] [] sst_send_gain_cmd+0x9d/0xe0 > [ 118.522233] [] sst_set_pipe_gain+0x63/0xa0 > [ 118.522241] [] sst_send_pipe_gains+0xd5/0x2b0 > [ 118.522248] [] sst_media_digital_mute+0x46/0x80 > [ 118.522257] [] snd_soc_dai_digital_mute+0x21/0x60 > [ 118.522265] [] soc_pcm_close+0xbd/0x250 > [ 118.522272] [] dpcm_fe_dai_close+0x7a/0x150 > [ 118.522281] [] snd_pcm_release_substream+0x58/0xb0 > [ 118.522289] [] snd_pcm_release+0x3f/0xa0////////// > [ 118.522296] [] __fput+0xf0/0x240 > [ 118.522304] [] ____fput+0xe/0x10 > [ 118.522312] [] task_work_run+0xa5/0xd0 > [ 118.522320] [] do_exit+0x2b8/0xad0 > [ 118.522327] [] ? __schedule+0x3df/0x820 > [ 118.522335] [] do_group_exit+0x3f/0xa0 > [ 118.522343] [] get_signal_to_deliver+0x24e/0x650 > [ 118.522352] [] do_signal+0x4d/0x960 > [ 118.522360] [] ? hrtimer_start_range_ns+0x14/0x20 > [ 118.522368] [] ? binder_ioctl+0x15d/0x990 > [ 118.522377] [] do_notify_resume+0x65/0x80 > [ 118.522384] [] int_signal+0x12/0x17 > > Signed-off-by: Leon Ma > Signed-off-by: Zhang Di > Signed-off-by: Sun Zhonghua > --- > kernel/exit.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/kernel/exit.c b/kernel/exit.c > index 1ea4369..64ba13b 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -729,6 +729,8 @@ void do_exit(long code) > tsk->exit_code = code; > taskstats_exit(tsk, group_dead); > > + exit_files(tsk); > + exit_task_work(tsk); > exit_mm(tsk); > > if (group_dead) > @@ -737,12 +739,10 @@ void do_exit(long code) > > exit_sem(tsk); > exit_shm(tsk); > - exit_files(tsk); > exit_fs(tsk); > if (group_dead) > disassociate_ctty(1); > exit_task_namespaces(tsk); > - exit_task_work(tsk); > exit_thread(); > > /* > -- > 1.7.9.5 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/