From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f72.google.com (mail-pl0-f72.google.com [209.85.160.72]) by kanga.kvack.org (Postfix) with ESMTP id F1F3C6B0003 for ; Wed, 14 Feb 2018 09:02:00 -0500 (EST) Received: by mail-pl0-f72.google.com with SMTP id d21so10976199pll.12 for ; Wed, 14 Feb 2018 06:02:00 -0800 (PST) Received: from mail-sor-f65.google.com (mail-sor-f65.google.com. [209.85.220.65]) by mx.google.com with SMTPS id n189sor299068pfn.108.2018.02.14.06.01.59 for (Google Transport Security); Wed, 14 Feb 2018 06:01:59 -0800 (PST) MIME-Version: 1.0 In-Reply-To: <20171101235456.GA3928@X58A-UD3R> References: <20171030100921.GA18085@X58A-UD3R> <20171030151009.ip4k7nwan7muouca@hirez.programming.kicks-ass.net> <20171031131333.pr2ophwd2bsvxc3l@dhcp22.suse.cz> <20171031135104.rnlytzawi2xzuih3@hirez.programming.kicks-ass.net> <20171031145247.5kjbanjqged34lbp@hirez.programming.kicks-ass.net> <20171031145804.ulrpk245ih6t7q7h@dhcp22.suse.cz> <20171031151024.uhbaynabzq6k7fbc@hirez.programming.kicks-ass.net> <20171101085927.GB3172@X58A-UD3R> <20171101120101.d6jlzwjks2j3az2v@hirez.programming.kicks-ass.net> <20171101235456.GA3928@X58A-UD3R> From: Dmitry Vyukov Date: Wed, 14 Feb 2018 15:01:38 +0100 Message-ID: Subject: Re: possible deadlock in lru_add_drain_all Content-Type: text/plain; charset="UTF-8" Sender: owner-linux-mm@kvack.org List-ID: To: Byungchul Park Cc: Peter Zijlstra , Michal Hocko , syzbot , Andrew Morton , Dan Williams , Johannes Weiner , Jan Kara , Jerome Glisse , LKML , Linux-MM , shli@fb.com, syzkaller-bugs@googlegroups.com, Thomas Gleixner , Vlastimil Babka , ying.huang@intel.com, kernel-team@lge.com On Thu, Nov 2, 2017 at 12:54 AM, Byungchul Park wrote: > On Wed, Nov 01, 2017 at 01:01:01PM +0100, Peter Zijlstra wrote: >> On Wed, Nov 01, 2017 at 05:59:27PM +0900, Byungchul Park wrote: >> > On Tue, Oct 31, 2017 at 04:10:24PM +0100, Peter Zijlstra wrote: >> > > On Tue, Oct 31, 2017 at 03:58:04PM +0100, Michal Hocko wrote: >> > > > On Tue 31-10-17 15:52:47, Peter Zijlstra wrote: >> > > > [...] >> > > > > If we want to save those stacks; we have to save a stacktrace on _every_ >> > > > > lock acquire, simply because we never know ahead of time if there will >> > > > > be a new link. Doing this is _expensive_. >> > > > > >> > > > > Furthermore, the space into which we store stacktraces is limited; >> > > > > since memory allocators use locks we can't very well use dynamic memory >> > > > > for lockdep -- that would give recursive and robustness issues. >> > >> > I agree with all you said. >> > >> > But, I have a better idea, that is, to save only the caller's ip of each >> > acquisition as an additional information? Of course, it's not enough in >> > some cases, but it's cheep and better than doing nothing. >> > >> > For example, when building A->B, let's save not only full stack of B, >> > but also caller's ip of A together, then use them on warning like: >> >> Like said; I've never really had trouble finding where we take A. And > > Me, either, since I know the way. But I've seen many guys who got > confused with it, which is why I suggested it. > > But, leave it if you don't think so. > >> for the most difficult cases, just the IP isn't too useful either. >> >> So that would solve a non problem while leaving the real problem. Hi, What's the status of this? Was any patch submitted for this? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org