From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <stable-owner@vger.kernel.org>
Received: from zeniv.linux.org.uk ([195.92.253.2]:52546 "EHLO
        ZenIV.linux.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
        with ESMTP id S1757003AbcIPMKf (ORCPT
        <rfc822;stable@vger.kernel.org>); Fri, 16 Sep 2016 08:10:35 -0400
Date: Fri, 16 Sep 2016 13:10:23 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Vaishali Thakkar <vaishali.thakkar@oracle.com>
Cc: Wei Fang <fangwei1@huawei.com>, linux-fsdevel@vger.kernel.org,
        akpm@linux-foundation.org, jack@suse.com, axboe@kernel.dk,
        tj@kernel.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v2] fs/dcache.c: avoid soft-lockup in dput()
Message-ID: <20160916121023.GX2356@ZenIV.linux.org.uk>
References: <1466564475-30417-1-git-send-email-fangwei1@huawei.com>
 <57DBA3FF.4080201@oracle.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <57DBA3FF.4080201@oracle.com>
Sender: stable-owner@vger.kernel.org
List-ID: <stable.vger.kernel.org>

On Fri, Sep 16, 2016 at 01:19:19PM +0530, Vaishali Thakkar wrote:

> Hi,
> 
> Just a question regarding this change. As after this change
> dput() is sleepable, is it still safe to use if under the
> spinlock in the function d_prune_aliases?

It has always been sleepable and it wouldn't have been safe to use
under spinlocks.  Which d_prune_aliases() does not do - __dentry_kill()
is called with dentry, its parent and its inode (if present) all locked and
it drops all those locks before returning.