linux-kernel - Re: [PATCH] x86/mm: vmemmap and vmalloc base addressess are usngined longs

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Message-ID: <nycvar.YFH.7.76.1804181143500.28129@cbobk.fhfr.pm>
Date:   Thu, 19 Apr 2018 08:35:37 +0200 (CEST)
From:   Jiri Kosina <jikos@...nel.org>
To:     "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
cc:     "Kirill A. Shutemov" <kirill@...temov.name>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, linux-kernel@...r.kernel.org,
        x86@...nel.org
Subject: Re: [PATCH] x86/mm: vmemmap and vmalloc base addressess are usngined
 longs

On Mon, 16 Apr 2018, Kirill A. Shutemov wrote:

> > > > Commits 9b46a051e4 ("x86/mm: Initialize vmemmap_base at boot-time") and 
> > > > a7412546d8 ("x86/mm: Adjust vmalloc base and size at boot-time") lost the 
> > > > type information for __VMALLOC_BASE_L4, __VMALLOC_BASE_L5, 
> > > > __VMEMMAP_BASE_L4 and __VMEMMAP_BASE_L5 constants.
> > > > 
> > > > Let's declare them explicitly unsigned long again.
> > > 
> > > It is just cosmetics, right? I mean these literals are 'unsigned long'
> > > anyway.
> > 
> > Yeah, I can't imagine this particular case leading to any overflow 
> > scenario, as the literal is big enough to be automatically treated as 
> > unsigned long by the compiler, but it shuts up sparse which treats this as 
> > a generic case (where the missing UL might be a problem), and totally 
> > pollutes the build output.
> > 
> > Either we put the 'UL' there, or teach sparse about figuring out the 
> > 'closer bigger fitting type' for hexadecimal literals, which might be more 
> > tricky.
> 
> I don't have a problem with the patch:
> 
> Acked-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>

x86 folks, any objections to merging this? Without it, the sparse build is 
currently totally unreadable mess.

Thanks,

-- 
Jiri Kosina
SUSE Labs