linux-kernel - Re: [x86/mm] e2a7dcce31: kernel_BUG_at

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Message-ID: <CALCETrXr-+AUXe8nkK0QDiFhBB_=JLpykXbCdnbi+UR=iMM72g@mail.gmail.com>
Date:   Sun, 28 May 2017 08:57:15 -0700
From:   Andy Lutomirski <luto@...nel.org>
To:     Rik van Riel <riel@...hat.com>
Cc:     Andy Lutomirski <luto@...nel.org>,
        kernel test robot <xiaolong.ye@...el.com>,
        X86 ML <x86@...nel.org>, Dave Hansen <dave.hansen@...el.com>,
        Nadav Amit <namit@...are.com>, Michal Hocko <mhocko@...e.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        LKML <linux-kernel@...r.kernel.org>, LKP <lkp@...org>
Subject: Re: [x86/mm] e2a7dcce31: kernel_BUG_at_arch/x86/mm/tlb.c

On Sun, May 28, 2017 at 7:11 AM, Rik van Riel <riel@...hat.com> wrote:
> On Sat, 2017-05-27 at 09:00 -0700, Andy Lutomirski wrote:
>> On Sat, May 27, 2017 at 6:31 AM, kernel test robot
>> <xiaolong.ye@...el.com> wrote:
>> >
>> > FYI, we noticed the following commit:
>> >
>> > commit: e2a7dcce31f10bd7471b4245a6d1f2de344e7adf ("x86/mm: Rework
>> > lazy TLB to track the actual loaded mm")
>> > https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git
>> > x86/tlbflush_cleanup
>>
>> Ugh, there's an unpleasant interaction between this patch and
>> intel_idle.  I suspect that the intel_idle code in question is either
>> wrong or pointless,
>
> It would be pointless if my "make lazy TLB mode even lazier"
> patch from last year had been applied.
>
> https://patchwork.kernel.org/patch/9307541/
>
> I guess I'll go re-send that and investigate the intel_idle
> code in addition to that.

You might want to wait a bit until I'm done churning the code.  I
suspect that increased TLB laziness will look a bit different on top.