Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755739Ab3JHUI4 (ORCPT ); Tue, 8 Oct 2013 16:08:56 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:44070 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751751Ab3JHUIz (ORCPT ); Tue, 8 Oct 2013 16:08:55 -0400 Date: Tue, 8 Oct 2013 13:08:53 -0700 From: Andrew Morton To: Krzysztof Kozlowski Cc: linux-mm@kvack.org, Konrad Rzeszutek Wilk , linux-kernel@vger.kernel.org, Shaohua Li , Minchan Kim Subject: Re: [PATCH] frontswap: enable call to invalidate area on swapoff Message-Id: <20131008130853.96139b79a0a4d3aaacc79ed2@linux-foundation.org> In-Reply-To: <1381220000.16135.10.camel@AMDC1943> References: <1381159541-13981-1-git-send-email-k.kozlowski@samsung.com> <20131007150338.1fdee18b536bb1d9fe41a07b@linux-foundation.org> <1381220000.16135.10.camel@AMDC1943> X-Mailer: Sylpheed 3.2.0beta5 (GTK+ 2.24.10; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1757 Lines: 39 On Tue, 08 Oct 2013 10:13:20 +0200 Krzysztof Kozlowski wrote: > On pon, 2013-10-07 at 15:03 -0700, Andrew Morton wrote: > > On Mon, 07 Oct 2013 17:25:41 +0200 Krzysztof Kozlowski wrote: > > > > > During swapoff the frontswap_map was NULL-ified before calling > > > frontswap_invalidate_area(). However the frontswap_invalidate_area() > > > exits early if frontswap_map is NULL. Invalidate was never called during > > > swapoff. > > > > > > This patch moves frontswap_map_set() in swapoff just after calling > > > frontswap_invalidate_area() so outside of locks > > > (swap_lock and swap_info_struct->lock). This shouldn't be a problem as > > > during swapon the frontswap_map_set() is called also outside of any > > > locks. > > > > > > > Ahem. So there's a bunch of code in __frontswap_invalidate_area() > > which hasn't ever been executed and nobody noticed it. So perhaps that > > code isn't actually needed? > > > > More seriously, this patch looks like it enables code which hasn't been > > used or tested before. How well tested was this? > > > > Are there any runtime-visible effects from this change? > > I tested zswap on x86 and x86-64 and there was no difference. This is > good as there shouldn't be visible anything because swapoff is unusing > all pages anyway: > try_to_unuse(type, false, 0); /* force all pages to be unused */ > > I haven't tested other frontswap users. So is that code in __frontswap_invalidate_area() unneeded? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/