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 01:54:14 -0700 Message-ID: <87wqy4fkqx.fsf@xmission.com> References: <1351816703-8805-1-git-send-email-gaofeng@cn.fujitsu.com> <87ehkcij1a.fsf@xmission.com> <5093773B.5010706@cn.fujitsu.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <5093773B.5010706-BthXqXjhjHXQFUHtdCDX3A@public.gmane.org> (Gao feng's message of "Fri, 02 Nov 2012 15:33:15 +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 MeaciDAy5pelIDE1OjAyLCBFcmljIFcuIEJpZWRlcm1hbiDlhpnpgZM6Cj4+IEdhbyBmZW5nIDxn YW9mZW5nQGNuLmZ1aml0c3UuY29tPiB3cml0ZXM6Cj4+IAo+Pj4gd2Ugc2hvdWxkIGNhbGwgcGlk X25zX3JlbGVhc2VfcHJvYyB0byB1bm1vdW50IHBpZF9uYW1lc3BhY2Uncwo+Pj4gcHJvY19tbnQg d2hlbiBjb3B5X25ldF9ucyBmYWlsZWQgaW4gZnVuY3Rpb24gY3JlYXRlX25ld19uYW1lc3BhY2Vz Lgo+Pj4KPj4+IG90aGVyd2lzZSx0aGUgcHJvY19tbnQgd2lsbCBub3QgYmUgZnJlZWQgYW5kIGJl Y2F1c2UgdGhlIHN1cGVyX2Jsb2NrCj4+PiBvZiBwcm9jX21udCBhbHNvIGFkZCB0aGUgcmVmZXJl bmNlIG9mIHRoZSBwaWRfbmFtZXNwYWNlLHNvIHRoaXMKPj4+IHBpZF9uYW1lc3BhY2Ugd2lsbCBu ZXZlciBiZSByZWxlYXNlZCB0b28uCj4+IAo+PiBPdWNoIQo+PiAKPj4gSGF2ZSB5b3UgZW5jb3Vu dGVyZWQgdGhpcyBmYWlsdXJlIGluIHByYWN0aWNlIG9yIGlzIHRoaXMganVzdCBmcm9tCj4+IHJl dmlldz8KPgo+IEkgYWRkIHNvbWUgcHJpbnRrIGluIHBpZF9uc19yZWxlYXNlX3Byb2MsaXQncyBu b3QgY2FsbGVkIGluIGFib3ZlIGNhc2UuCj4gd2hlbiBjb3B5X25ldF9ucyBmYWlsZWQsdGhpcyBw aWRfbmFtZXNwYWNlIGlzIG5vdCB1c2VkIGJ5IGFueSB0YXNrLAo+IHNvIHByb2NfZmx1c2hfdGFz ayBjYW4ndCBjYWxsIHBpZF9uc19yZWxlYXNlX3Byb2MgdG8gdW1vdW50IHRoaXMgcGlkbnMtPnBy b2NfbW50Lgo+IGl0J3MgdGhlIG9ubHkgY2hhbmNlIHdlIGNhbiB1bm1vdW50IHRoaXMgcGluZG5z LT5wcm9jX21udC4KPgo+IFdpdGggdGhpcyBwYXRjaCxldmVyeXRoaW5nIHJ1bnMgd2VsbC4KCkkg aGF2ZSByZXZpZXdlZCB0aGUgY29kZSBhbmQgSSBkb24ndCBkb3VidCB0aGF0IHRoaXMgaXMgbmVj ZXNzYXJ5LgoKV2hhdCBjYXVzZWQgeW91IHRvIGxvb2sgaW50byB0aGlzIGZhaWx1cmU/ICBJcyB0 aGVyZSBzb21lIHNlbWktcHJhY3RpY2FsCnJlYWwgd29ybGQgY2FzZSB0aGF0IHNvbWVvbmUgaXMg aGl0dGluZz8KCkVyaWMKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X19fX18KQ29udGFpbmVycyBtYWlsaW5nIGxpc3QKQ29udGFpbmVyc0BsaXN0cy5saW51eC1mb3Vu ZGF0aW9uLm9yZwpodHRwczovL2xpc3RzLmxpbnV4Zm91bmRhdGlvbi5vcmcvbWFpbG1hbi9saXN0 aW5mby9jb250YWluZXJz From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759247Ab2KBIy0 (ORCPT ); Fri, 2 Nov 2012 04:54:26 -0400 Received: from out03.mta.xmission.com ([166.70.13.233]:51169 "EHLO out03.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758644Ab2KBIyV convert rfc822-to-8bit (ORCPT ); Fri, 2 Nov 2012 04:54:21 -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> Date: Fri, 02 Nov 2012 01:54:14 -0700 In-Reply-To: <5093773B.5010706@cn.fujitsu.com> (Gao feng's message of "Fri, 02 Nov 2012 15:33:15 +0800") Message-ID: <87wqy4fkqx.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+UAX7MWmKysIlr/9WDGDa6OHuypRredDU= 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: 0.0039] * -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 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? Eric