Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: quoted-printable
From:   Qian Cai <cai@lca.pw>
Mime-Version: 1.0 (1.0)
Subject: Re: [PATCH] mm/page_owner: print largest memory consumer when OOM panic occurs
Date:   Fri, 27 Dec 2019 08:46:03 -0500
Message-Id: <2EA70B54-A7E1-4C5A-A447-844A3FEA7E93@lca.pw>
References: <1577432670.4248.3.camel@mtkswgap22>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Michal Hocko <mhocko@suse.com>, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, linux-mediatek@lists.infradead.org,
        wsd_upstream@mediatek.com
In-Reply-To: <1577432670.4248.3.camel@mtkswgap22>
To:     Miles Chen <miles.chen@mediatek.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk


> On Dec 27, 2019, at 2:44 AM, Miles Chen <miles.chen@mediatek.com> wrote:
>=20
> It's not complete situation.
>=20
> I've listed different OOM panic situations in previous email [1]
> and what we can do about them with current information.
>=20
> There are some cases which cannot be covered by current information
> easily.
> For example: a memory leakage caused by alloc_pages() or vmalloc() with
> a large size.
> I keep seeing these issues for years and that's why I built this patch.=20=

> It's like a missing piece of the puzzle.
>=20
> To prove that the approach is practical and useful, I have collected
> real test cases
> under real devices and posted the test result in the commit message.
> These are real cases, not my imagination.

Of course this may help debug *your* problems in the past, but if that is th=
e only requirement to merge the debugging patch like this, we would end up w=
ith endless of those. If your goal is to stop developers from reproducing is=
sues unnecessarily again using page_owner to debug, then your patch does not=
 help much for the majority of other developers=E2=80=99 issues.

The page_owner is designed to give information about the top candidates that=
 might cause issues, so it make somewhat sense if it dumps the top 10 greate=
st memory consumer for example, but that also clutter the OOM report so much=
, so it is no-go.=