linux-kernel - Re: 2.6.24-rc2 XFS nfsd hang

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: <20071114152952.GA4210@infradead.org>
Date:	Wed, 14 Nov 2007 15:29:52 +0000
From:	Christoph Hellwig <hch@...radead.org>
To:	Chris Wedgwood <cw@...f.org>
Cc:	linux-xfs@....sgi.com, LKML <linux-kernel@...r.kernel.org>
Subject: Re: 2.6.24-rc2 XFS nfsd hang

On Tue, Nov 13, 2007 at 11:04:00PM -0800, Chris Wedgwood wrote:
> With 2.6.24-rc2 (amd64) I sometimes (usually but perhaps not always)
> see a hang when accessing some NFS exported XFS filesystems.  Local
> access to these filesystems ahead of time works without problems.
> 
> This does not occur with 2.6.23.1.  The filesystem does not appear to
> be corrupt.
> 

>     [ 1462.911360]  ffffffff80744020 ffffffff80746dc0 ffff81010129c140 ffff8101000ad100
>     [ 1462.911391] Call Trace:
>     [ 1462.911417]  [<ffffffff8052e638>] __down+0xe9/0x101
>     [ 1462.911437]  [<ffffffff8022cc80>] default_wake_function+0x0/0xe
>     [ 1462.911458]  [<ffffffff8052e275>] __down_failed+0x35/0x3a
>     [ 1462.911480]  [<ffffffff8035ac25>] _xfs_buf_find+0x84/0x24d
>     [ 1462.911501]  [<ffffffff8035ad34>] _xfs_buf_find+0x193/0x24d
>     [ 1462.911522]  [<ffffffff803599b1>] xfs_buf_lock+0x43/0x45

this is bp->b_sema which lookup wants.

>     [ 1462.915534]  [<ffffffff8032b6da>] xfs_readdir+0x91/0xb6
>     [ 1462.915557]  [<ffffffff8030415b>] nfs3svc_encode_entry_plus+0x0/0x13
>     [ 1462.915579]  [<ffffffff8035be9d>] xfs_file_readdir+0x31/0x40
>     [ 1462.915599]  [<ffffffff8028c9f8>] vfs_readdir+0x61/0x93
>     [ 1462.915619]  [<ffffffff8030415b>] nfs3svc_encode_entry_plus+0x0/0x13
>     [ 1462.915642]  [<ffffffff802fc78e>] nfsd_readdir+0x6d/0xc5

and this is the nasty nfsd case where a filldir callback calls back
into lookup.  I suspect we're somehow holding b_sema already.  Previously
this was okay because we weren't inside the actualy readdir code when
calling filldir but operate on a copy of the data.

This gem has bitten other filesystem before, I'll see if I can find a
way around it.

-
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/