linux-kernel - Re: [PATCH v2] x86/mm/pat: (un)track_pfn

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Message-ID: <acc128b8-2c29-44e3-ae83-da753e147060@redhat.com>
Date: Wed, 9 Apr 2025 12:34:47 +0200
From: David Hildenbrand <david@...hat.com>
To: Ingo Molnar <mingo@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
 kernel test robot <lkp@...el.com>, Dan Carpenter <error27@...il.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 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>, Rik van Riel <riel@...riel.com>,
 "H. Peter Anvin" <hpa@...or.com>,
 Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH v2] x86/mm/pat: (un)track_pfn_copy() fix + doc
 improvements

On 09.04.25 12:32, Ingo Molnar wrote:
> 
> * David Hildenbrand <david@...hat.com> wrote:
> 
>> We got a late smatch warning and some additional review feedback.
>>
>> 	smatch warnings:
>> 	mm/memory.c:1428 copy_page_range() error: uninitialized symbol 'pfn'.
>>
>> We actually use the pfn only when it is properly initialized; however,
>> we may pass an uninitialized value to a function -- although it will not
>> use it that likely still is UB in C.
>>
>> So let's just fix it by always initializing pfn in the caller of
>> track_pfn_copy(), and improving the documentation of track_pfn_copy().
>>
>> While at it, clarify the doc of untrack_pfn_copy(), that internal checks
>> make sure if we actually have to untrack anything.
> 
> Note that the title isn't accurate anymore, it's not an 'x86/mm/pat'
> patch, but an 'mm' patch.

Agreed. Who will take this patch? If it's Andrew, can you fixup the 
subject please?

-- 
Cheers,

David / dhildenb