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Date: Mon, 27 Aug 2018 10:20:45 +0200
From: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 3/4] mm/tlb, x86/mm: Support invalidating TLB caches for
 RCU_TABLE_FREE
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To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Nicholas Piggin <npiggin@gmail.com>, Will Deacon <will.deacon@arm.com>, Linus Torvalds <torvalds@linux-foundation.org>, Andrew Lutomirski <luto@kernel.org>, 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>

On Mon, Aug 27, 2018 at 06:09:50PM +1000, Benjamin Herrenschmidt wrote:

> Sadly our architecture requires a precise match between the page size
> specified in the tlbie instruction and the entry in the TLB or it won't
> be flushed.

Argh.. OK I see. That is rather unfortunate and does seem to require
something along the lines of tlb_remove_check_page_size_change().