From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751032AbeBQA2L (ORCPT ); Fri, 16 Feb 2018 19:28:11 -0500 Received: from mail.linuxfoundation.org ([140.211.169.12]:46798 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750933AbeBQA2K (ORCPT ); Fri, 16 Feb 2018 19:28:10 -0500 Date: Fri, 16 Feb 2018 16:28:09 -0800 From: Andrew Morton To: Vitaly Wool Cc: Linux-MM , linux-kernel@vger.kernel.org, Oleksiy.Avramchenko@sony.com Subject: Re: [PATCH] z3fold: limit use of stale list for allocation Message-Id: <20180216162809.30b2278f0cacefa66c95c1aa@linux-foundation.org> In-Reply-To: <47ab51e7-e9c1-d30e-ab17-f734dbc3abce@gmail.com> References: <47ab51e7-e9c1-d30e-ab17-f734dbc3abce@gmail.com> X-Mailer: Sylpheed 3.4.1 (GTK+ 2.24.23; 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 On Sat, 10 Feb 2018 12:02:52 +0100 Vitaly Wool wrote: > Currently if z3fold couldn't find an unbuddied page it would first > try to pull a page off the stale list. The problem with this > approach is that we can't 100% guarantee that the page is not > processed by the workqueue thread at the same time unless we run > cancel_work_sync() on it, which we can't do if we're in an atomic > context. So let's just limit stale list usage to non-atomic > contexts only. This smells like a bugfix. What are the end-user visible effects of the bug?