From: Linus Torvalds Subject: Re: [RFC, PATCH] fs: push rcu_barrier() from deactivate_locked_super() to filesystems Date: Fri, 8 Jun 2012 15:06:20 -0700 Message-ID: References: <1339191663-17693-1-git-send-email-kirill.shutemov@linux.intel.com> <20120608220049.GA18024@otc-wbsnb-06> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Cc: Boaz Harrosh , Tao Ma , Andrew Morton , Nick Piggin , "Dmitry V. Levin" , v9fs-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-afs@lists.infradead.org, linux-btrfs@vger.kernel.org, ceph-devel@vger.kernel.org, linux-cifs@vger.kernel.org, samba-technical@lists.samba.org, codalist@coda.cs.cmu.edu, ecryptfs@vger.kernel.org, osd-dev@open-osd.org, linux-ext4@vger.kernel.org, fuse-devel@lists.sourceforge.net, linux-mtd@lists.infradead.org, jfs-discussion@lists.sourceforge.net, logfs@logfs.org, linux-nfs@vger.kernel.org, linux-nilfs@vger.kernel.org, linux-ntfs-dev@lists.sourceforge.net, ocfs2-devel@oss.oracle.com, reiserfs-devel@vger.kernel.org To: "Kirill A. Shutemov" Return-path: In-Reply-To: <20120608220049.GA18024@otc-wbsnb-06> Sender: linux-btrfs-owner@vger.kernel.org List-Id: linux-ext4.vger.kernel.org On Fri, Jun 8, 2012 at 3:00 PM, Kirill A. Shutemov wrote: > > IIUC, moving rcu_barrier() up should help, but I can't say that I fully > understand SLAB_DESTROY_BY_RCU semantics. .. hmm. I think you may be right. Even if we do move it up, we probably shouldn't use it. We don't even want SLAB_DESTROY_BY_RCU, since we do the delayed RCU free for other reasons anyway, so it would duplicate the RCU delaying and cause problems. I forgot about that little complication. We could have a separate "RCU_BARRIER_ON_DESTROY" thing, but that's just silly too. Maybe your patch is the right thing. Linus