linux-kernel - Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request at 0000a7cf

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Message-ID: <CA+55aFy5vi3af5VBuG6ZOdTeKNxqGSq64J-EkrjaRhGVKXPy0A@mail.gmail.com>
Date:   Thu, 9 Mar 2017 15:26:02 -0800
From:   Linus Torvalds <torvalds@...ux-foundation.org>
To:     Borislav Petkov <bp@...e.de>
Cc:     Daniel Borkmann <daniel@...earbox.net>,
        Thomas Gleixner <tglx@...utronix.de>,
        Kees Cook <keescook@...omium.org>,
        Laura Abbott <labbott@...hat.com>,
        Ingo Molnar <mingo@...nel.org>, Peter Anvin <hpa@...or.com>,
        Fengguang Wu <fengguang.wu@...el.com>,
        Network Development <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>, LKP <lkp@...org>,
        ast@...com, "the arch/x86 maintainers" <x86@...nel.org>,
        "David S. Miller" <davem@...emloft.net>
Subject: Re: [net/bpf] 3051bf36c2 BUG: unable to handle kernel paging request
 at 0000a7cf

On Thu, Mar 9, 2017 at 2:48 PM, Borislav Petkov <bp@...e.de> wrote:
>
> I guess we could return to doing boot_cpu_has() in __flush_tlb_all()
> then. I mean, the timing-sensitivity argument is meh - killing global
> TLB entries a bit faster doesn't bring me a whole lot when I have to go
> and walk pagetable and reestablish them, which is the real price to pay
> anyway.

So should all of commit ("c109bf95992b x86/cpufeature: Remove
cpu_has_pge") just be reverted (and then marked for stable)?

Or do we have some alternate plan?

This has apparently been going on for a long while (it got merged into
4.7), but presumably it only actually _matters_ if lguest is enabled
and used and we've triggered that lguest_arch_host_init() code.

Maybe it's the lguest games with PGE that need to be removed?

                Linus