From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752972AbaE0WkL (ORCPT ); Tue, 27 May 2014 18:40:11 -0400 Received: from mail-ob0-f170.google.com ([209.85.214.170]:39609 "EHLO mail-ob0-f170.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751413AbaE0WkG (ORCPT ); Tue, 27 May 2014 18:40:06 -0400 Date: Tue, 27 May 2014 17:40:02 -0500 From: Seth Jennings To: Dan Streetman Cc: Minchan Kim , Weijie Yang , Nitin Gupta , Andrew Morton , Bob Liu , Hugh Dickins , Mel Gorman , Rik van Riel , Johannes Weiner , Sergey Senozhatsky , Linux-MM , linux-kernel Subject: Re: [PATCH 6/6] mm/zpool: prevent zbud/zsmalloc from unloading when used Message-ID: <20140527224002.GB25781@cerebellum.variantweb.net> References: <1399499496-3216-1-git-send-email-ddstreet@ieee.org> <1400958369-3588-1-git-send-email-ddstreet@ieee.org> <1400958369-3588-7-git-send-email-ddstreet@ieee.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1400958369-3588-7-git-send-email-ddstreet@ieee.org> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 24, 2014 at 03:06:09PM -0400, Dan Streetman wrote: > Add try_module_get() to pool creation functions for zbud and zsmalloc, > and module_put() to pool destruction functions, since they now can be > modules used via zpool. Without usage counting, they could be unloaded > while pool(s) were active, resulting in an oops. I like the idea here, but what about doing this in the zpool layer? For me, it is kinda weird for a module to be taking a ref on itself. Maybe this is excepted practice. Is there precedent for this? What about having the zbud/zsmalloc drivers pass their module pointers to zpool_register_driver() as an additional field in struct zpool_driver and have zpool take the reference? Since zpool is the one in trouble if the driver is unloaded. Seth > > Signed-off-by: Dan Streetman > Cc: Seth Jennings > Cc: Minchan Kim > Cc: Nitin Gupta > Cc: Weijie Yang > --- > > New for this patch set. > > mm/zbud.c | 5 +++++ > mm/zsmalloc.c | 5 +++++ > 2 files changed, 10 insertions(+) > > diff --git a/mm/zbud.c b/mm/zbud.c > index 8a72cb1..2b3689c 100644 > --- a/mm/zbud.c > +++ b/mm/zbud.c > @@ -282,6 +282,10 @@ struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops) > pool = kmalloc(sizeof(struct zbud_pool), GFP_KERNEL); > if (!pool) > return NULL; > + if (!try_module_get(THIS_MODULE)) { > + kfree(pool); > + return NULL; > + } > spin_lock_init(&pool->lock); > for_each_unbuddied_list(i, 0) > INIT_LIST_HEAD(&pool->unbuddied[i]); > @@ -302,6 +306,7 @@ struct zbud_pool *zbud_create_pool(gfp_t gfp, struct zbud_ops *ops) > void zbud_destroy_pool(struct zbud_pool *pool) > { > kfree(pool); > + module_put(THIS_MODULE); > } > > /** > diff --git a/mm/zsmalloc.c b/mm/zsmalloc.c > index 07c3130..2cc2647 100644 > --- a/mm/zsmalloc.c > +++ b/mm/zsmalloc.c > @@ -946,6 +946,10 @@ struct zs_pool *zs_create_pool(gfp_t flags) > pool = kzalloc(ovhd_size, GFP_KERNEL); > if (!pool) > return NULL; > + if (!try_module_get(THIS_MODULE)) { > + kfree(pool); > + return NULL; > + } > > for (i = 0; i < ZS_SIZE_CLASSES; i++) { > int size; > @@ -985,6 +989,7 @@ void zs_destroy_pool(struct zs_pool *pool) > } > } > kfree(pool); > + module_put(THIS_MODULE); > } > EXPORT_SYMBOL_GPL(zs_destroy_pool); > > -- > 1.8.3.1 >