From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Morton <akpm@linux-foundation.org>
Date: Wed, 1 Oct 2014 15:55:49 -0700
Subject: [Ocfs2-devel] [PATCH] ocfs2/dlm: call dlm_lockres_put without
 resource spinlock
In-Reply-To: <542526C3.2090302@huawei.com>
References: <542526C3.2090302@huawei.com>
Message-ID: <20141001155549.e64a41bbf797482eb388f65b@linux-foundation.org>
List-Id: <ocfs2-devel.oss.oracle.com>
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To: ocfs2-devel@oss.oracle.com

On Fri, 26 Sep 2014 16:41:39 +0800 alex chen <alex.chen@huawei.com> wrote:

> dlm_lockres_put should be called without &res->spinlock, otherwise a
> deadlock case may happen.
> 
> spin_lock(&res->spinlock)
> ...
> dlm_lockres_put
>   ->dlm_lockres_release
>     ->dlm_print_one_lock_resource
>       ->spin_lock(&res->spinlock)
> 
> Signed-off-by: Alex Chen <alex.chen@huawei.com>
> Reviewed-by: Joseph Qi <joseph.qi@huawei.com>
> ---
>  fs/ocfs2/dlm/dlmrecovery.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/fs/ocfs2/dlm/dlmrecovery.c b/fs/ocfs2/dlm/dlmrecovery.c
> index 45067fa..3365839 100644
> --- a/fs/ocfs2/dlm/dlmrecovery.c
> +++ b/fs/ocfs2/dlm/dlmrecovery.c
> @@ -1710,9 +1710,12 @@ int dlm_master_requery_handler(struct o2net_msg *msg, u32 len, void *data,
>  				BUG();

This code does a GFP_ATOMIC allocation attempt and if that fails, it
goes BUG().

Guys, GFP_ATOMIC is unreliable.  This isn't production quality code :(