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Subject: Re: TLB flushes on fixmap changes
From: Nadav Amit <nadav.amit@gmail.com>
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Date: Mon, 27 Aug 2018 12:10:34 -0700
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Sender: owner-linux-mm@kvack.org
List-ID: <linux-mm.kvack.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>, Peter Zijlstra <peterz@infradead.org>, Kees Cook <keescook@chromium.org>, Linus Torvalds <torvalds@linux-foundation.org>, Paolo Bonzini <pbonzini@redhat.com>, Jiri Kosina <jkosina@suse.cz>, Will Deacon <will.deacon@arm.com>, Benjamin Herrenschmidt <benh@au1.ibm.com>, Nick Piggin <npiggin@gmail.com>, the arch/x86 maintainers <x86@kernel.org>, Borislav Petkov <bp@alien8.de>, Rik van Riel <riel@surriel.com>, Jann Horn <jannh@google.com>, Adin Scannell <ascannell@google.com>, Dave Hansen <dave.hansen@intel.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>, David Miller <davem@davemloft.net>, Martin Schwidefsky <schwidefsky@de.ibm.com>, Michael Ellerman <mpe@ellerman.id.au>

at 11:58 AM, Andy Lutomirski <luto@kernel.org> wrote:

> On Mon, Aug 27, 2018 at 11:54 AM, Nadav Amit <nadav.amit@gmail.com> =
wrote:
>>> On Mon, Aug 27, 2018 at 10:34 AM, Nadav Amit <nadav.amit@gmail.com> =
wrote:
>>> What do you all think?
>>=20
>> I agree in general. But I think that current->mm would need to be =
loaded, as
>> otherwise I am afraid it would break switch_mm_irqs_off().
>=20
> What breaks?

Actually nothing. I just saw the IBPB stuff regarding tsk, but it should =
not
matter.