linux-kernel - Re: [RFC][PATCH 01/11] asm-generic/tlb: Provide a comment

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Message-ID: <20180919131254.GI24124@hirez.programming.kicks-ass.net>
Date:   Wed, 19 Sep 2018 15:12:54 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Will Deacon <will.deacon@....com>
Cc:     aneesh.kumar@...ux.vnet.ibm.com, akpm@...ux-foundation.org,
        npiggin@...il.com, linux-arch@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org, linux@...linux.org.uk,
        heiko.carstens@...ibm.com
Subject: Re: [RFC][PATCH 01/11] asm-generic/tlb: Provide a comment

On Wed, Sep 19, 2018 at 01:23:29PM +0100, Will Deacon wrote:

> > > > + *    which (when !need_flush_all; fullmm will have start = end = ~0UL) provides
> > > > + *    the range that needs to be flushed to cover the pages to be freed.
> > > 
> > > I don't understand the mention of need_flush_all here -- I didn't think it
> > > was used by the core code at all.
> > 
> > The core does indeed not use that flag; but if the architecture set
> > that, the range is still ignored.
> > 
> > Can you suggest clearer wording?
> 
> The range is only ignored if the default tlb_flush() implementation is used
> though, right? Since this text is about the fields that tlb_flush() can use,
> I think we can just delete the part in brackets.

Well, any architecture that actually uses need_flush_all will obviously
require a tlb_flush implementation that looks at it.

But OK, I'll remove the note.