linux-kernel - Re: [PATCH v5 3/4] x86/vmemmap: Handle unpopulated sub-pmd ranges

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Message-ID: <20210310174953.GA16289@linux>
Date:   Wed, 10 Mar 2021 18:49:57 +0100
From:   Oscar Salvador <osalvador@...e.de>
To:     David Hildenbrand <david@...hat.com>
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H . Peter Anvin" <hpa@...or.com>,
        Michal Hocko <mhocko@...nel.org>, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 3/4] x86/vmemmap: Handle unpopulated sub-pmd ranges

On Tue, Mar 09, 2021 at 06:52:38PM +0100, David Hildenbrand wrote:
> > -#define PAGE_INUSE 0xFD
> > +#ifdef CONFIG_SPARSEMEM_VMEMMAP
> > +#define PAGE_UNUSED 0xFD
> > +
> > +/* Returns true if the PMD is completely unused and thus it can be freed */
> > +static bool __meminit vmemmap_pmd_is_unused(unsigned long addr, unsigned long end)
> > +{
> 
> I don't think the new name is any better. It implies that all it does is a
> check - yet it actually clears the given range. (I prefer the old name, but
> well, I came up with that, so what do I know :D )

Sorry, I did not mean to offend here.

Something like: vmemmap_is_pmd_unused_after_clearing_it would be a bit better
I guess.
Tbh, both this and previous one looked fine to me, but I understand where Dave
confusion was coming from, that is why I decided to rename it.

Maybe a middle-ground would have been to expand the comment above.

-- 
Oscar Salvador
SUSE L3