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: <Z9tASMtphcvCvqsi@gmail.com>
Date: Wed, 19 Mar 2025 23:08:08 +0100
From: Ingo Molnar <mingo@...nel.org>
To: David Hildenbrand <david@...hat.com>
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()


* David Hildenbrand <david@...hat.com> wrote:

> 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.

Please do, thanks!

Thanks,

	Ingo