linux-kernel - Re: [mm] 4e2c82a409: ltp.overcommit

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Message-Id: <FAAE2B23-2565-4F36-B278-018A5AD219EE@lca.pw>
Date:   Sun, 5 Jul 2020 08:15:03 -0400
From:   Qian Cai <cai@....pw>
To:     Feng Tang <feng.tang@...el.com>
Cc:     kernel test robot <rong.a.chen@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Michal Hocko <mhocko@...e.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Matthew Wilcox <willy@...radead.org>,
        Mel Gorman <mgorman@...e.de>,
        Kees Cook <keescook@...omium.org>,
        Luis Chamberlain <mcgrof@...nel.org>,
        Iurii Zaikin <yzaikin@...gle.com>, andi.kleen@...el.com,
        tim.c.chen@...el.com, dave.hansen@...el.com, ying.huang@...el.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org, lkp@...ts.01.org
Subject: Re: [mm] 4e2c82a409: ltp.overcommit_memory01.fail



> On Jul 5, 2020, at 12:45 AM, Feng Tang <feng.tang@...el.com> wrote:
> 
> I did reproduce the problem, and from the debugging, this should
> be the same root cause as lore.kernel.org/lkml/20200526181459.GD991@....pw/
> that loosing the batch cause some accuracy problem, and the solution of
> adding some sync is still needed, which is dicussed in

Well, before taking any of those patches now to fix the regression, we will need some performance data first. If it turned out the original performance gain is no longer relevant anymore due to this regression fix on top, it is best to drop this patchset and restore that VM_WARN_ONCE, so you can retry later once you found a better way to optimize.