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From:   Qian Cai <cai@lca.pw>
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Subject: Re: [PATCH] mm/page_owner: print largest memory consumer when OOM panic occurs
Date:   Tue, 24 Dec 2019 08:47:15 -0500
Message-Id: <5E08DE19-5B71-4245-8908-548BB4FA861F@lca.pw>
References: <1577169946.4959.4.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: <1577169946.4959.4.camel@mtkswgap22>
To:     Miles Chen <miles.chen@mediatek.com>
Sender: linux-kernel-owner@vger.kernel.org
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> On Dec 24, 2019, at 1:45 AM, Miles Chen <miles.chen@mediatek.com> wrote:
>=20
> We use kmemleak too, but a memory leakage which is caused by
> alloc_pages() in a kernel device driver cannot be caught by kmemleak.
> We have fought against this kind of real problems for a few years and=20
> find a way to make the debugging easier.
>=20
> We currently have information during OOM: process Node, zone, swap,=20
> process (pid, rss, name), slab usage, and the backtrace, order, and
> gfp flags of the OOM backtrace.=20
> We can tell many different types of OOM problems by the information
> above except the alloc_pages() leakage.
>=20
> The patch does work and save a lot of debugging time.
> Could we consider the "greatest memory consumer" as another useful=20
> OOM information?

This is rather situational considering there are memory leaks here and there=
 but it is not necessary that straightforward as a single place of greatest c=
onsumer.

The other question is why the offensive drivers that use alloc_pages() repea=
tedly without using any object allocator? Do you have examples of this in dr=
ivers that could happen?=