From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from bombadil.infradead.org ([198.137.202.133]:58088 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726513AbfGWRIo (ORCPT ); Tue, 23 Jul 2019 13:08:44 -0400 Date: Tue, 23 Jul 2019 10:08:43 -0700 From: Christoph Hellwig Subject: Re: [PATCH] xfs: Do not free xfs_extent_busy from inside a spinlock Message-ID: <20190723170843.GA1952@infradead.org> References: <20190723150017.31891-1-cmaiolino@redhat.com> <20190723151102.GA1561054@magnolia> <20190723153133.wqt3p3dqaghxbkpr@orion.maiolino.org> <20190723155135.GA16481@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-xfs-owner@vger.kernel.org List-ID: List-Id: xfs To: Jeff Layton Cc: Christoph Hellwig , "Darrick J. Wong" , linux-xfs@vger.kernel.org, Al Viro On Tue, Jul 23, 2019 at 01:07:00PM -0400, Jeff Layton wrote: > Note that those places are already broken. AIUI, the basic issue is that > vmalloc/vfree have to fix up page tables and that requires being able to > sleep. This patch just makes this situation more evident. If that patch > gets merged, I imagine we'll have a lot of places to clean up (not just > in xfs). > > Anyway, in the case of being in an interrupt, we currently queue the > freeing to a workqueue. Al mentioned that we could create a new > kvfree_atomic that we could use from atomic contexts like this. That may > be another option (though Carlos' patch looked reasonable to me and > would probably be more efficient). The point is for XFS we generally only use kmem_free for pure kmalloc allocations under spinlocks. But yes, the interfac is a little suboptimal and a kmem_free_large would be nicer and then warnings like this that might be pretty useful could be added.