linux-kernel - Re: [tip: x86/mm] x86/mm/pat: Fix VM_PAT handling when fork() fails in copy_page

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Message-ID: <d767a3d4-b54a-4bdd-91d3-dc1de00637ec@redhat.com>
Date: Wed, 19 Mar 2025 12:44:38 +0100
From: David Hildenbrand <david@...hat.com>
To: Ingo Molnar <mingo@...nel.org>
Cc: linux-kernel@...r.kernel.org, linux-tip-commits@...r.kernel.org,
 xingwei lee <xrivendell7@...il.com>, yuxin wang <wang1315768607@....com>,
 Marius Fleischer <fleischermarius@...il.com>,
 Andrew Morton <akpm@...ux-foundation.org>,
 Linus Torvalds <torvalds@...ux-foundation.org>,
 Dave Hansen <dave.hansen@...ux.intel.com>, Andy Lutomirski
 <luto@...nel.org>, Peter Zijlstra <peterz@...radead.org>,
 Rik van Riel <riel@...riel.com>, "H. Peter Anvin" <hpa@...or.com>,
 Peter Xu <peterx@...hat.com>, x86@...nel.org,
 Dan Carpenter <dan.carpenter@...aro.org>, Borislav Petkov <bp@...en8.de>
Subject: Re: [tip: x86/mm] x86/mm/pat: Fix VM_PAT handling when fork() fails
 in copy_page_range()

On 19.03.25 12:01, Ingo Molnar wrote:
> 
> * David Hildenbrand <david@...hat.com> wrote:
> 
>>> +void untrack_pfn_copy(struct vm_area_struct *dst_vma,
>>> +		struct vm_area_struct *src_vma)
>>> +{
>>> +	resource_size_t paddr;
>>> +	unsigned long size;
>>> +
>>> +	if (!(dst_vma->vm_flags & VM_PAT))
>>> +		return;
>>> +
>>> +	/*
>>> +	 * As the page tables might not have been copied yet, the PAT
>>> +	 * information is obtained from the src VMA, just like during
>>> +	 * track_pfn_copy().
>>> +	 */
>>> +	if (get_pat_info(src_vma, &paddr, NULL)) {
>>> +		size = src_vma->vm_end - src_vma->vm_start;
>>> +		free_pfn_range(paddr, size);
>>>    	}
>>
>> @Ingo, can you drop this patch for now?
> 
> Done.

I can resend the whole thing, or just the fixup suggested by Boris, just 
let me know.

-- 
Cheers,

David / dhildenb