linux-kernel - Re: [PATCH v3 04/11] x86/mm: Give each mm TLB flush generation a unique ID

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Message-ID: <alpine.DEB.2.20.1706211005270.2328@nanos>
Date:   Wed, 21 Jun 2017 10:05:55 +0200 (CEST)
From:   Thomas Gleixner <tglx@...utronix.de>
To:     Andy Lutomirski <luto@...nel.org>
cc:     x86@...nel.org, linux-kernel@...r.kernel.org,
        Borislav Petkov <bp@...en8.de>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Mel Gorman <mgorman@...e.de>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        Nadav Amit <nadav.amit@...il.com>,
        Rik van Riel <riel@...hat.com>,
        Dave Hansen <dave.hansen@...el.com>,
        Arjan van de Ven <arjan@...ux.intel.com>,
        Peter Zijlstra <peterz@...radead.org>
Subject: Re: [PATCH v3 04/11] x86/mm: Give each mm TLB flush generation a
 unique ID

On Tue, 20 Jun 2017, Andy Lutomirski wrote:

> This adds two new variables to mmu_context_t: ctx_id and tlb_gen.
> ctx_id uniquely identifies the mm_struct and will never be reused.
> For a given mm_struct (and hence ctx_id), tlb_gen is a monotonic
> count of the number of times that a TLB flush has been requested.
> The pair (ctx_id, tlb_gen) can be used as an identifier for TLB
> flush actions and will be used in subsequent patches to reliably
> determine whether all needed TLB flushes have occurred on a given
> CPU.
> 
> This patch is split out for ease of review.  By itself, it has no
> real effect other than creating and updating the new variables.

Thanks for splitting this apart!

> 
> Signed-off-by: Andy Lutomirski <luto@...nel.org>

Reviewed-by: Thomas Gleixner <tglx@...utronix.de>