From mboxrd@z Thu Jan 1 00:00:00 1970 From: ebiederm-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org (Eric W. Biederman) Subject: Re: [PATCH] namespace:unmount pid_namespace's proc_mnt when copy_net_ns failed Date: Fri, 02 Nov 2012 02:10:34 -0700 Message-ID: <87mwz0fjzp.fsf@xmission.com> References: <1351816703-8805-1-git-send-email-gaofeng@cn.fujitsu.com> <87ehkcij1a.fsf@xmission.com> <5093773B.5010706@cn.fujitsu.com> <87wqy4fkqx.fsf@xmission.com> <50938C2D.90908@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <50938C2D.90908-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org> (Gao feng's message of "Fri, 02 Nov 2012 17:02:37 +0800") List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: Gao feng Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: containers.vger.kernel.org R2FvIGZlbmcgPGdhb2ZlbmdAY24uZnVqaXRzdS5jb20+IHdyaXRlczoKCj4g5LqOIDIwMTLlubQx MeaciDAy5pelIDE2OjU0LCBFcmljIFcuIEJpZWRlcm1hbiDlhpnpgZM6Cj4+IEdhbyBmZW5nIDxn YW9mZW5nQGNuLmZ1aml0c3UuY29tPiB3cml0ZXM6Cj4+IAo+Pj4g5LqOIDIwMTLlubQxMeaciDAy 5pelIDE1OjAyLCBFcmljIFcuIEJpZWRlcm1hbiDlhpnpgZM6Cj4+Pj4gR2FvIGZlbmcgPGdhb2Zl bmdAY24uZnVqaXRzdS5jb20+IHdyaXRlczoKPj4+Pgo+Pj4+PiB3ZSBzaG91bGQgY2FsbCBwaWRf bnNfcmVsZWFzZV9wcm9jIHRvIHVubW91bnQgcGlkX25hbWVzcGFjZSdzCj4+Pj4+IHByb2NfbW50 IHdoZW4gY29weV9uZXRfbnMgZmFpbGVkIGluIGZ1bmN0aW9uIGNyZWF0ZV9uZXdfbmFtZXNwYWNl cy4KPj4+Pj4KPj4+Pj4gb3RoZXJ3aXNlLHRoZSBwcm9jX21udCB3aWxsIG5vdCBiZSBmcmVlZCBh bmQgYmVjYXVzZSB0aGUgc3VwZXJfYmxvY2sKPj4+Pj4gb2YgcHJvY19tbnQgYWxzbyBhZGQgdGhl IHJlZmVyZW5jZSBvZiB0aGUgcGlkX25hbWVzcGFjZSxzbyB0aGlzCj4+Pj4+IHBpZF9uYW1lc3Bh Y2Ugd2lsbCBuZXZlciBiZSByZWxlYXNlZCB0b28uCj4+Pj4KPj4+PiBPdWNoIQo+Pj4+Cj4+Pj4g SGF2ZSB5b3UgZW5jb3VudGVyZWQgdGhpcyBmYWlsdXJlIGluIHByYWN0aWNlIG9yIGlzIHRoaXMg anVzdCBmcm9tCj4+Pj4gcmV2aWV3Pwo+Pj4KPj4+IEkgYWRkIHNvbWUgcHJpbnRrIGluIHBpZF9u c19yZWxlYXNlX3Byb2MsaXQncyBub3QgY2FsbGVkIGluIGFib3ZlIGNhc2UuCj4+PiB3aGVuIGNv cHlfbmV0X25zIGZhaWxlZCx0aGlzIHBpZF9uYW1lc3BhY2UgaXMgbm90IHVzZWQgYnkgYW55IHRh c2ssCj4+PiBzbyBwcm9jX2ZsdXNoX3Rhc2sgY2FuJ3QgY2FsbCBwaWRfbnNfcmVsZWFzZV9wcm9j IHRvIHVtb3VudCB0aGlzIHBpZG5zLT5wcm9jX21udC4KPj4+IGl0J3MgdGhlIG9ubHkgY2hhbmNl IHdlIGNhbiB1bm1vdW50IHRoaXMgcGluZG5zLT5wcm9jX21udC4KPj4+Cj4+PiBXaXRoIHRoaXMg cGF0Y2gsZXZlcnl0aGluZyBydW5zIHdlbGwuCj4+IAo+PiBJIGhhdmUgcmV2aWV3ZWQgdGhlIGNv ZGUgYW5kIEkgZG9uJ3QgZG91YnQgdGhhdCB0aGlzIGlzIG5lY2Vzc2FyeS4KPj4gCj4+IFdoYXQg Y2F1c2VkIHlvdSB0byBsb29rIGludG8gdGhpcyBmYWlsdXJlPyAgSXMgdGhlcmUgc29tZSBzZW1p LXByYWN0aWNhbAo+PiByZWFsIHdvcmxkIGNhc2UgdGhhdCBzb21lb25lIGlzIGhpdHRpbmc/Cj4+ IAo+Cj4gU28gZmFyLHRoZXJlIGlzIG5vIGNhc2UgaGl0dGluZyB0aGlzIHByb2JsZW0uCgpJIHRo aW5rIHdoYXQgSSB3YW50IHRvIGRvIGlzIHRvIHB1c2ggdGhlIGNoYW5nZXMgaW4gbXkgdXNlcm5z CmRldmVsb3BtZW50IHRyZWUgaW5zdGVhZCBvZiBzb2x2aW5nIGl0IHRoZSB3YXkgeW91IGhhdmUg c29sdmVkIGl0LgoKVGhlIHdheSB0aGluZ3MgYXJlIGN1cnJlbnRseSBzdHJ1Y3R1cmVkIEkgZG9u J3QgdGhpbmsgd2UgY2FuIGJlIGNlcnRhaW4Kb2YgZmluZGluZyBhbGwgb2YgdGhlIGNvcm5lciBj YXNlcy4KCldvdWxkIHlvdSBiZSBpbnRlcmVzdGluZyBpbiBjb25maXJtaW5nIHRoYXQgcHJvYmxl bSBkb2VzIG5vdCBleGlzdCBpbiBteQp1c2VybnMgZGV2ZWxvcG1lbnQgYnJhbmNoPwoKRXJpYwpf X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fXwpDb250YWluZXJz IG1haWxpbmcgbGlzdApDb250YWluZXJzQGxpc3RzLmxpbnV4LWZvdW5kYXRpb24ub3JnCmh0dHBz Oi8vbGlzdHMubGludXhmb3VuZGF0aW9uLm9yZy9tYWlsbWFuL2xpc3RpbmZvL2NvbnRhaW5lcnM= From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755710Ab2KBJKl (ORCPT ); Fri, 2 Nov 2012 05:10:41 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:57243 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752205Ab2KBJKj convert rfc822-to-8bit (ORCPT ); Fri, 2 Nov 2012 05:10:39 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Gao feng Cc: linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org References: <1351816703-8805-1-git-send-email-gaofeng@cn.fujitsu.com> <87ehkcij1a.fsf@xmission.com> <5093773B.5010706@cn.fujitsu.com> <87wqy4fkqx.fsf@xmission.com> <50938C2D.90908@cn.fujitsu.com> Date: Fri, 02 Nov 2012 02:10:34 -0700 In-Reply-To: <50938C2D.90908@cn.fujitsu.com> (Gao feng's message of "Fri, 02 Nov 2012 17:02:37 +0800") Message-ID: <87mwz0fjzp.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT X-XM-AID: U2FsdGVkX1/jel5dKUd3W6aCfmw0udMjrRyM6mgCb1A= X-SA-Exim-Connect-IP: 98.207.153.68 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 1.5 TR_Symld_Words too many words that have symbols inside * 0.1 XMSubLong Long Subject * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -3.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% * [score: 0.0065] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa06 1397; Body=1 Fuz1=1 Fuz2=1] * 0.0 T_TooManySym_01 4+ unique symbols in subject X-Spam-DCC: XMission; sa06 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Gao feng X-Spam-Relay-Country: Subject: Re: [PATCH] namespace:unmount pid_namespace's proc_mnt when copy_net_ns failed X-SA-Exim-Version: 4.2.1 (built Sun, 08 Jan 2012 03:05:19 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Gao feng writes: > 于 2012年11月02日 16:54, Eric W. Biederman 写道: >> Gao feng writes: >> >>> 于 2012年11月02日 15:02, Eric W. Biederman 写道: >>>> Gao feng writes: >>>> >>>>> we should call pid_ns_release_proc to unmount pid_namespace's >>>>> proc_mnt when copy_net_ns failed in function create_new_namespaces. >>>>> >>>>> otherwise,the proc_mnt will not be freed and because the super_block >>>>> of proc_mnt also add the reference of the pid_namespace,so this >>>>> pid_namespace will never be released too. >>>> >>>> Ouch! >>>> >>>> Have you encountered this failure in practice or is this just from >>>> review? >>> >>> I add some printk in pid_ns_release_proc,it's not called in above case. >>> when copy_net_ns failed,this pid_namespace is not used by any task, >>> so proc_flush_task can't call pid_ns_release_proc to umount this pidns->proc_mnt. >>> it's the only chance we can unmount this pindns->proc_mnt. >>> >>> With this patch,everything runs well. >> >> I have reviewed the code and I don't doubt that this is necessary. >> >> What caused you to look into this failure? Is there some semi-practical >> real world case that someone is hitting? >> > > So far,there is no case hitting this problem. I think what I want to do is to push the changes in my userns development tree instead of solving it the way you have solved it. The way things are currently structured I don't think we can be certain of finding all of the corner cases. Would you be interesting in confirming that problem does not exist in my userns development branch? Eric