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Subject: Re: [mm? 4.15-rc7] Random oopses under memory pressure.
From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
References: <20180110124519.GU1732@dhcp22.suse.cz>
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Message-Id: <201801120559.FIE00099.MHJFVQSOFFOtLO@I-love.SAKURA.ne.jp>
Date: Fri, 12 Jan 2018 05:59:04 +0900
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To: torvalds@linux-foundation.org
Cc: mhocko@suse.com, linux-mm@kvack.org, x86@kernel.org, linux-fsdevel@vger.kernel.org

Linus Torvalds wrote:
> On Thu, Jan 11, 2018 at 6:11 AM, Tetsuo Handa
> <penguin-kernel@i-love.sakura.ne.jp> wrote:
> >
> > I retested with some debug printk() patch.
> 
> Could you perhaps enable KASAN too?

Unfortunately, KASAN is not available for x86_32 kernels. Thus, I'm stuck.

> So presumably "page->mem_cgroup" was just a random pointer. Which
> probably means that "page" itself is not actually a page pointer, sinc
> e I assume there was no memory hotplug going on here?

Nothing special. No memory hotplug etc.

> Most (all?) of your other oopses seem to have somewhat similar
> patterns: shrink_inactive_list() -> rmap_walk_file() -> oops due to
> garbage.

Yes. In most cases, problems are detected by that sequence.

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