From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759209AbcCDJG7 (ORCPT ); Fri, 4 Mar 2016 04:06:59 -0500 Received: from mx2.suse.de ([195.135.220.15]:60596 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756532AbcCDJGv (ORCPT ); Fri, 4 Mar 2016 04:06:51 -0500 Subject: Re: [PATCH] crypto/async_pq: use __free_page() instead of put_page() To: Arnd Bergmann , Joonsoo Kim , linux-mm@kvack.org, Herbert Xu References: <1456738445-876239-1-git-send-email-arnd@arndb.de> Cc: linux-arm-kernel@lists.infradead.org, Michal Nazarewicz , Steven Rostedt , Andrew Morton , Dan Williams , "David S. Miller" , NeilBrown , Markus Stockhausen , Vinod Koul , linux-crypto@vger.kernel.org, linux-kernel@vger.kernel.org From: Vlastimil Babka Message-ID: <56D95025.1060500@suse.cz> Date: Fri, 4 Mar 2016 10:06:45 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.6.0 MIME-Version: 1.0 In-Reply-To: <1456738445-876239-1-git-send-email-arnd@arndb.de> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 02/29/2016 10:33 AM, Arnd Bergmann wrote: > The addition of tracepoints to the page reference tracking had an > unfortunate side-effect in at least one driver that calls put_page > from its exit function, resulting in a link error: > > `.exit.text' referenced in section `__jump_table' of crypto/built-in.o: defined in discarded section `.exit.text' of crypto/built-in.o > > From a cursory look at that this driver, it seems that it may be > doing the wrong thing here anyway, as the page gets allocated > using 'alloc_page()', and should be freed using '__free_page()' > rather than 'put_page()'. > > With this patch, I no longer get any other build errors from the > page_ref patch, so hopefully we can assume that it's always wrong > to call any of those functions from __exit code, and that no other > driver does it. Hopefully that's true. If any such driver was leaking references to those pages, so the put_page() didn't actually result in freeing, the explicit __free_page should catch this via built-in checks. > Fixes: 0f80830dd044 ("mm/page_ref: add tracepoint to track down page reference manipulation") Since it's in mmotm which is quilt-based, the commit hash from -next is not stable. > Signed-off-by: Arnd Bergmann Acked-by: Vlastimil Babka > --- > crypto/async_tx/async_pq.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/crypto/async_tx/async_pq.c b/crypto/async_tx/async_pq.c > index c0748bbd4c08..08b3ac68952b 100644 > --- a/crypto/async_tx/async_pq.c > +++ b/crypto/async_tx/async_pq.c > @@ -444,7 +444,7 @@ static int __init async_pq_init(void) > > static void __exit async_pq_exit(void) > { > - put_page(pq_scribble_page); > + __free_page(pq_scribble_page); > } > > module_init(async_pq_init); >