linux-kernel - Re: 3.7.10+: BUG Dentry still in use [unmount of cifs cifs]

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <51391225.1020403@candelatech.com>
Date:	Thu, 07 Mar 2013 14:18:13 -0800
From:	Ben Greear <greearb@...delatech.com>
To:	Mateusz Guzik <mguzik@...hat.com>
CC:	linux-cifs@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Jeff Layton <jlayton@...hat.com>
Subject: Re: 3.7.10+:  BUG Dentry still in use [unmount of cifs cifs]

On 03/07/2013 11:19 AM, Mateusz Guzik wrote:
> On Tue, Mar 05, 2013 at 10:54:56AM -0800, Ben Greear wrote:
>> In doing some CIFS testing (utilizing it's feature to bind to local
>> address..but not sure that matters), we saw this error when trying
>> to un-mount.
>>
>> Our kernel is patched (nfs, some networking related patches), but there
>> are no out-of-kernel patches to CIFS, so I don't *think* this is anything
>> we could have caused.
>>
>> This problem appears to be easily reproducible, so we will be happy
>> to test patches if anyone has any suggestions.
>>
>> BUG: Dentry ffff8800c07e43c0{i=45762,n=cifs2-01.7.lf-data} still in use (1) [unmount of cifs cifs]
>
> We encountered similar panic, but it was related to writes. In our case
> the problem was that some cifsInodeInfo holding dentry references were
> still around (in slow-work queue) during superblock destruction in unmount.
>
> I reproduced the problem on 3.8 kernel (sorry, no 3.7 handy) with reads
> as well, which should match your scenario.
>
> I attached a patch that deals with this problem by grabbing refcounts to
> cifs superblock on cifsInodeInfo creation. This delays sb destruction
> until all cifsInodeInfos are gone. I didn't test it on 3.7.10 kernel but
> it should work fine.

The 3.7.10 patch applied cleanly and appears to fix our problem.

Thanks so much for the patch!

Ben

-- 
Ben Greear <greearb@...delatech.com>
Candela Technologies Inc  http://www.candelatech.com

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/