From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gao feng Subject: Re: [PATCH] namespace:unmount pid_namespace's proc_mnt when copy_net_ns failed Date: Fri, 02 Nov 2012 17:02:37 +0800 Message-ID: <50938C2D.90908@cn.fujitsu.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> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Return-path: In-Reply-To: <87wqy4fkqx.fsf-aS9lmoZGLiVWk0Htik3J/w@public.gmane.org> 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: "Eric W. Biederman" Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: containers.vger.kernel.org 5LqOIDIwMTLlubQxMeaciDAy5pelIDE2OjU0LCBFcmljIFcuIEJpZWRlcm1hbiDlhpnpgZM6Cj4g R2FvIGZlbmcgPGdhb2ZlbmdAY24uZnVqaXRzdS5jb20+IHdyaXRlczoKPiAKPj4g5LqOIDIwMTLl ubQxMeaciDAy5pelIDE1OjAyLCBFcmljIFcuIEJpZWRlcm1hbiDlhpnpgZM6Cj4+PiBHYW8gZmVu ZyA8Z2FvZmVuZ0Bjbi5mdWppdHN1LmNvbT4gd3JpdGVzOgo+Pj4KPj4+PiB3ZSBzaG91bGQgY2Fs bCBwaWRfbnNfcmVsZWFzZV9wcm9jIHRvIHVubW91bnQgcGlkX25hbWVzcGFjZSdzCj4+Pj4gcHJv Y19tbnQgd2hlbiBjb3B5X25ldF9ucyBmYWlsZWQgaW4gZnVuY3Rpb24gY3JlYXRlX25ld19uYW1l c3BhY2VzLgo+Pj4+Cj4+Pj4gb3RoZXJ3aXNlLHRoZSBwcm9jX21udCB3aWxsIG5vdCBiZSBmcmVl ZCBhbmQgYmVjYXVzZSB0aGUgc3VwZXJfYmxvY2sKPj4+PiBvZiBwcm9jX21udCBhbHNvIGFkZCB0 aGUgcmVmZXJlbmNlIG9mIHRoZSBwaWRfbmFtZXNwYWNlLHNvIHRoaXMKPj4+PiBwaWRfbmFtZXNw YWNlIHdpbGwgbmV2ZXIgYmUgcmVsZWFzZWQgdG9vLgo+Pj4KPj4+IE91Y2ghCj4+Pgo+Pj4gSGF2 ZSB5b3UgZW5jb3VudGVyZWQgdGhpcyBmYWlsdXJlIGluIHByYWN0aWNlIG9yIGlzIHRoaXMganVz dCBmcm9tCj4+PiByZXZpZXc/Cj4+Cj4+IEkgYWRkIHNvbWUgcHJpbnRrIGluIHBpZF9uc19yZWxl YXNlX3Byb2MsaXQncyBub3QgY2FsbGVkIGluIGFib3ZlIGNhc2UuCj4+IHdoZW4gY29weV9uZXRf bnMgZmFpbGVkLHRoaXMgcGlkX25hbWVzcGFjZSBpcyBub3QgdXNlZCBieSBhbnkgdGFzaywKPj4g c28gcHJvY19mbHVzaF90YXNrIGNhbid0IGNhbGwgcGlkX25zX3JlbGVhc2VfcHJvYyB0byB1bW91 bnQgdGhpcyBwaWRucy0+cHJvY19tbnQuCj4+IGl0J3MgdGhlIG9ubHkgY2hhbmNlIHdlIGNhbiB1 bm1vdW50IHRoaXMgcGluZG5zLT5wcm9jX21udC4KPj4KPj4gV2l0aCB0aGlzIHBhdGNoLGV2ZXJ5 dGhpbmcgcnVucyB3ZWxsLgo+IAo+IEkgaGF2ZSByZXZpZXdlZCB0aGUgY29kZSBhbmQgSSBkb24n dCBkb3VidCB0aGF0IHRoaXMgaXMgbmVjZXNzYXJ5Lgo+IAo+IFdoYXQgY2F1c2VkIHlvdSB0byBs b29rIGludG8gdGhpcyBmYWlsdXJlPyAgSXMgdGhlcmUgc29tZSBzZW1pLXByYWN0aWNhbAo+IHJl YWwgd29ybGQgY2FzZSB0aGF0IHNvbWVvbmUgaXMgaGl0dGluZz8KPiAKClNvIGZhcix0aGVyZSBp cyBubyBjYXNlIGhpdHRpbmcgdGhpcyBwcm9ibGVtLgpUaGFua3MKCl9fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX19fCkNvbnRhaW5lcnMgbWFpbGluZyBsaXN0CkNv bnRhaW5lcnNAbGlzdHMubGludXgtZm91bmRhdGlvbi5vcmcKaHR0cHM6Ly9saXN0cy5saW51eGZv dW5kYXRpb24ub3JnL21haWxtYW4vbGlzdGluZm8vY29udGFpbmVycw== From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932570Ab2KBJCx (ORCPT ); Fri, 2 Nov 2012 05:02:53 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:50520 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1753802Ab2KBJCu convert rfc822-to-8bit (ORCPT ); Fri, 2 Nov 2012 05:02:50 -0400 X-IronPort-AV: E=Sophos;i="4.80,698,1344182400"; d="scan'208";a="6124533" Message-ID: <50938C2D.90908@cn.fujitsu.com> Date: Fri, 02 Nov 2012 17:02:37 +0800 From: Gao feng User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 MIME-Version: 1.0 To: "Eric W. Biederman" CC: linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org Subject: Re: [PATCH] namespace:unmount pid_namespace's proc_mnt when copy_net_ns failed References: <1351816703-8805-1-git-send-email-gaofeng@cn.fujitsu.com> <87ehkcij1a.fsf@xmission.com> <5093773B.5010706@cn.fujitsu.com> <87wqy4fkqx.fsf@xmission.com> In-Reply-To: <87wqy4fkqx.fsf@xmission.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/02 17:02:01, Serialize by Router on mailserver/fnst(Release 8.5.3|September 15, 2011) at 2012/11/02 17:02:01 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Thanks