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From: Linus Torvalds <torvalds@linux-foundation.org>
Date: Tue, 16 Jan 2018 11:34:46 -0800
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Subject: Re: [mm 4.15-rc8] Random oopses under memory pressure.
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
        Ingo Molnar <mingo@kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        linux-mm <linux-mm@kvack.org>,
        "the arch/x86 maintainers" <x86@kernel.org>,
        linux-fsdevel <linux-fsdevel@vger.kernel.org>,
        Michal Hocko <mhocko@kernel.org>
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On Tue, Jan 16, 2018 at 9:33 AM, Tetsuo Handa
<penguin-kernel@i-love.sakura.ne.jp> wrote:
>
> Since I got a faster reproducer, I tried full bisection between 4.11 and 4.12-rc1.
> But I have no idea why bisection arrives at c0332694903a37cf.

I don't think your reproducer is 100% reliable.

And bisection is great because it's very aggressive and optimal when
it comes to testing. But that also implies that if *any* of the
good/bad choices were incorrect, then the end result is pure garbage
and isn't even *close* to the right commit.

> It turned out that CONFIG_FLATMEM was irrelevant. I just did not hit it.

So have you actually been able to see the problem with FLATMEM, or is
this based on the bisect? Because I really think the bisect is pretty
much guaranteed to be wrong.

               Linus