linux-kernel - Re: [RFC 1/2] lib/vsprintf: Add support for pte

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Message-ID: <20250624102346.4e175914@batman.local.home>
Date: Tue, 24 Jun 2025 10:23:46 -0400
From: Steven Rostedt <rostedt@...dmis.org>
To: Matthew Wilcox <willy@...radead.org>
Cc: Anshuman Khandual <anshuman.khandual@....com>, linux-mm@...ck.org, Andy
 Shevchenko <andriy.shevchenko@...ux.intel.com>, Rasmus Villemoes
 <linux@...musvillemoes.dk>, Sergey Senozhatsky <senozhatsky@...omium.org>,
 Petr Mladek <pmladek@...e.com>, Jonathan Corbet <corbet@....net>, Andrew
 Morton <akpm@...ux-foundation.org>, David Hildenbrand <david@...hat.com>,
 linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [RFC 1/2] lib/vsprintf: Add support for pte_t

On Tue, 24 Jun 2025 14:11:08 +0100
Matthew Wilcox <willy@...radead.org> wrote:

> On Fri, Jun 20, 2025 at 01:42:53PM +0530, Anshuman Khandual wrote:
> > On 19/06/25 6:56 PM, Matthew Wilcox wrote:  
> > > Unfortunately, the one example you've converted shows why this is a bad
> > > idea.  You're passing a pmd_t pointer to a function which is assuming a
> > > pte_t pointer.  And a pmd_t and a pte_t are sometimes different sizes!
> > > (eg sometimes one is 64 bit and the other 32 bit).  
> > 
> > As discussed on a separate thread, this might be addressed via separate
> > printf formats for each page table level e.g %ppte, %ppmd, and %ppud etc.   
> 
> There's still no typechecking!

There's lots of %pX formats that have no type checking. I think this is
an issue. Could we have one of the static checkers test these? Smatch,
sparse, whatever? Or maybe they do and I'm unaware of it?

-- Steve